.forgejo/workflows/build-website.yaml

@@ -0,0 +1,26 @@
+on:
+  push:
+    branches:
+      - trunk
+jobs:
+  test:
+    runs-on: host
+    steps:
+      - run: git clone --depth=1 https://$FORGEJO_TOKEN@forge.cbaines.net/cbaines/guile-knots.git knots-trunk
+      - run: git clone --depth=1 https://$FORGEJO_TOKEN@forge.cbaines.net/cbaines/guile-knots.git --branch=pages knots-pages
+      - run: |
+          cd knots-trunk
+          guix shell -D -f guix-dev.scm -- documenta api "knots.scm knots/"
+          guix shell texinfo -- makeinfo --css-ref=https://luis-felipe.gitlab.io/texinfo-css/static/css/texinfo-7.css --no-split --html -c SHOW_TITLE=true -o ../knots-pages/index.html doc/index.texi
+
+      - run: |
+          cd knots-pages
+          git add .
+          if [[ -z "$(git status -s)" ]]; then
+            echo "Nothing to push"
+          else
+            git config user.email ""
+            git config user.name "Automatic website updater"
+            git commit -m "Automatic website update"
+            git push
+          fi

.gitignore

@@ -0,0 +1,20 @@
+*.go
+Makefile.in
+Makefile
+aclocal.m4
+autom4te.cache
+config.log
+config.status
+configure
+
+build-aux/install-sh
+build-aux/missing
+
+*.log
+tests/*.log
+tests/*.trs
+
+pre-inst-env
+test-env
+
+.local.envrc

COPYING

@@ -0,0 +1,674 @@
+                    GNU GENERAL PUBLIC LICENSE
+                       Version 3, 29 June 2007
+
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+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+  Each version is given a distinguishing version number.  If the
+Program specifies that a certain numbered version of the GNU General
+Public License "or any later version" applies to it, you have the
+option of following the terms and conditions either of that numbered
+version or of any later version published by the Free Software
+Foundation.  If the Program does not specify a version number of the
+GNU General Public License, you may choose any version ever published
+by the Free Software Foundation.
+
+  If the Program specifies that a proxy can decide which future
+versions of the GNU General Public License can be used, that proxy's
+public statement of acceptance of a version permanently authorizes you
+to choose that version for the Program.
+
+  Later license versions may give you additional or different
+permissions.  However, no additional obligations are imposed on any
+author or copyright holder as a result of your choosing to follow a
+later version.
+
+  15. Disclaimer of Warranty.
+
+  THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY
+APPLICABLE LAW.  EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT
+HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY
+OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO,
+THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE.  THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM
+IS WITH YOU.  SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF
+ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
+
+  16. Limitation of Liability.
+
+  IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MODIFIES AND/OR CONVEYS
+THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY
+GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE
+USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF
+DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD
+PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS),
+EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF
+SUCH DAMAGES.
+
+  17. Interpretation of Sections 15 and 16.
+
+  If the disclaimer of warranty and limitation of liability provided
+above cannot be given local legal effect according to their terms,
+reviewing courts shall apply local law that most closely approximates
+an absolute waiver of all civil liability in connection with the
+Program, unless a warranty or assumption of liability accompanies a
+copy of the Program in return for a fee.
+
+                     END OF TERMS AND CONDITIONS
+
+            How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+state the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) <year>  <name of author>
+
+    This program is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+Also add information on how to contact you by electronic and paper mail.
+
+  If the program does terminal interaction, make it output a short
+notice like this when it starts in an interactive mode:
+
+    <program>  Copyright (C) <year>  <name of author>
+    This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, your program's commands
+might be different; for a GUI interface, you would use an "about box".
+
+  You should also get your employer (if you work as a programmer) or school,
+if any, to sign a "copyright disclaimer" for the program, if necessary.
+For more information on this, and how to apply and follow the GNU GPL, see
+<http://www.gnu.org/licenses/>.
+
+  The GNU General Public License does not permit incorporating your program
+into proprietary programs.  If your program is a subroutine library, you
+may consider it more useful to permit linking proprietary applications with
+the library.  If this is what you want to do, use the GNU Lesser General
+Public License instead of this License.  But first, please read
+<http://www.gnu.org/philosophy/why-not-lgpl.html>.

Makefile.am

@@ -0,0 +1,33 @@
+include guile.am
+
+SOURCES =			\
+  knots.scm			\
+  knots/non-blocking.scm	\
+  knots/parallelism.scm	\
+  knots/promise.scm		\
+  knots/queue.scm		\
+  knots/resource-pool.scm	\
+  knots/timeout.scm		\
+  knots/web-server.scm		\
+  knots/thread-pool.scm
+
+SCM_TESTS =			\
+  tests/non-blocking.scm	\
+  tests/promise.scm		\
+  tests/timeout.scm		\
+  tests/non-blocking.scm	\
+  tests/queue.scm		\
+  tests/web-server.scm		\
+  tests/parallelism.scm	\
+  tests/resource-pool.scm	\
+  tests/thread-pool.scm
+
+TESTS_GOBJECTS = $(SCM_TESTS:%.scm=%.go)
+
+EXTRA_DIST =		\
+  README		\
+  bootstrap		\
+  pre-inst-env.in
+
+check: $(GOBJECTS) $(TESTS_GOBJECTS)
+	find tests -name "*.scm" | xargs -t -L1 ./test-env guile

README

@@ -0,0 +1,4 @@
+-*- mode: org -*-
+
+This Guile library provides useful patterns and functionality to use
+Guile Fibers.

bootstrap

@@ -0,0 +1,3 @@
+#! /bin/sh
+
+autoreconf --verbose --install --force

configure.ac

@@ -0,0 +1,20 @@
+AC_INIT([guile-knots], [0.1])
+AC_CONFIG_AUX_DIR([build-aux])
+AM_INIT_AUTOMAKE([-Wall -Werror foreign])
+
+GUILE_PKG([3.0])
+GUILE_PROGS
+if test "x$GUILD" = "x"; then
+   AC_MSG_ERROR(['guild' binary not found; please check your guile 3 installation.])
+fi
+
+if test "$cross_compiling" != no; then
+   GUILE_TARGET="--target=$host_alias"
+   AC_SUBST([GUILE_TARGET])
+fi
+
+AC_CONFIG_FILES([Makefile])
+AC_CONFIG_FILES([pre-inst-env], [chmod +x pre-inst-env])
+AC_CONFIG_FILES([test-env], [chmod +x test-env])
+
+AC_OUTPUT

doc/index.texi

@@ -0,0 +1,96 @@
+\input texinfo
+@setfilename guile-knots
+
+
+@c HEADER
+@settitle Guile Knots
+@documentlanguage en
+@documentencoding UTF-8
+@afourpaper
+@c END HEADER
+
+
+
+@c MASTER MENU
+@node Top
+@top Overview
+
+Guile Knots is a library providing tools and patterns for programming
+with @url{https://github.com/wingo/fibers, Guile Fibers}.  Guile Knots
+provides higher level building blocks for writing programs using Guile
+Fibers, including managing code that can't run in a thread used by
+fibers.  Also included is a web server implementation using Fibers,
+which while being similar to the web server provided by Fibers, can
+provide some benefits in specific circumstances.
+
+@c END MASTER MENU
+
+
+@c TABLE OF CONTENTS
+@contents
+@c END TABLE OF CONTENTS
+
+
+@c CHAPTER: API
+@include api/index.texi
+@c END CHAPTER: API
+
+
+
+@c APPENDICES
+@node Version History
+@appendix Version History
+
+@table @dfn
+
+@item Version 0.Y.0, Month DD, 20YY
+@itemize
+@item
+No initial release has yet been made.
+@end itemize
+
+@end table
+
+
+
+@node Copying Information
+@appendix Copying Information
+
+Copyright © 2024, 2025 Christopher Baines <mail@@cbaines.net>
+
+This library is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation; either version 3 of the
+License, or (at your option) any later version.
+
+@c END APPENDICES
+
+
+
+@c INDICES
+@node Concept Index
+@unnumbered Concept Index
+
+@printindex cp
+
+
+@node Data Type Index
+@unnumbered Data Type Index
+
+@printindex tp
+
+
+@node Procedure Index
+@unnumbered Procedure Index
+
+@printindex fn
+
+
+@node Variable Index
+@unnumbered Variable Index
+
+@printindex vr
+@c END INDICES
+
+
+@bye

guile.am

@@ -0,0 +1,21 @@
+moddir=$(datadir)/guile/site/$(GUILE_EFFECTIVE_VERSION)
+godir=$(libdir)/guile/$(GUILE_EFFECTIVE_VERSION)/site-ccache
+
+GOBJECTS = $(SOURCES:%.scm=%.go)
+
+nobase_dist_mod_DATA = $(SOURCES) $(NOCOMP_SOURCES)
+nobase_go_DATA = $(GOBJECTS)
+
+# Make sure source files are installed first, so that the mtime of
+# installed compiled files is greater than that of installed source
+# files.  See
+# <http://lists.gnu.org/archive/html/guile-devel/2010-07/msg00125.html>
+# for details.
+guile_install_go_files = install-nobase_goDATA
+$(guile_install_go_files): install-nobase_dist_modDATA
+
+CLEANFILES = $(GOBJECTS)
+GUILE_WARNINGS = -Wunbound-variable -Warity-mismatch -Wformat
+SUFFIXES = .scm .go
+.scm.go:
+	$(AM_V_GEN)$(top_builddir)/pre-inst-env $(GUILD) compile $(GUILE_TARGET) $(GUILE_WARNINGS) -o "$@" "$<"

guix-dev.scm

@@ -0,0 +1,53 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+;;; Run the following command to enter a development environment for
+;;; Guile Knots:
+;;;
+;;;  $ guix environment -l guix-dev.scm
+
+(use-modules ((guix licenses) #:prefix license:)
+             (guix packages)
+             (guix build-system gnu)
+             (gnu packages)
+             (gnu packages autotools)
+             (gnu packages guile)
+             (gnu packages guile-xyz)
+             (gnu packages pkg-config)
+             (gnu packages texinfo)
+             (srfi srfi-1))
+
+(package
+  (name "guile-knots")
+  (version "0.0.0")
+  (source #f)
+  (build-system gnu-build-system)
+  (inputs
+   (list guile-next
+         guile-fibers-next))
+  (native-inputs
+   (list autoconf
+         automake
+         pkg-config
+         guile-documenta
+         texinfo))
+  (synopsis "TODO")
+  (description "TODO")
+  (home-page "TODO")
+  (license license:gpl3+))

knots.scm

@@ -0,0 +1,130 @@
+(define-module (knots)
+  #:use-module (srfi srfi-1)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 suspendable-ports)
+  #:use-module (fibers conditions)
+  #:use-module (system repl debug)
+  #:export (call-with-default-io-waiters
+
+            wait-when-system-clock-behind
+
+            call-with-sigint
+
+            &knots-exception
+            make-knots-exception
+            knots-exception?
+            knots-exception-stack
+
+            print-backtrace-and-exception/knots))
+
+(define (call-with-default-io-waiters thunk)
+  (parameterize
+      ((current-read-waiter (@@ (ice-9 suspendable-ports)
+                                default-read-waiter))
+       (current-write-waiter (@@ (ice-9 suspendable-ports)
+                                 default-write-waiter)))
+    (thunk)))
+
+(define (wait-when-system-clock-behind)
+  (let ((start-of-the-year-2000 946684800))
+    (while (< (current-time)
+              start-of-the-year-2000)
+      (simple-format (current-error-port)
+                     "warning: system clock potentially behind, waiting\n")
+      (sleep 20))))
+
+;; Copied from (fibers web server)
+(define (call-with-sigint thunk cvar)
+  (let ((handler #f))
+    (dynamic-wind
+      (lambda ()
+        (set! handler
+          (sigaction SIGINT (lambda (sig) (signal-condition! cvar)))))
+      thunk
+      (lambda ()
+        (if handler
+            ;; restore Scheme handler, SIG_IGN or SIG_DFL.
+            (sigaction SIGINT (car handler) (cdr handler))
+            ;; restore original C handler.
+            (sigaction SIGINT #f))))))
+
+(define &knots-exception
+  (make-exception-type '&knots-exception
+                       &exception
+                       '(stack)))
+
+(define make-knots-exception
+  (record-constructor &knots-exception))
+
+(define knots-exception?
+  (exception-predicate &knots-exception))
+
+(define knots-exception-stack
+  (exception-accessor
+   &knots-exception
+   (record-accessor &knots-exception 'stack)))
+
+(define* (print-backtrace-and-exception/knots
+          exn
+          #:key (port (current-error-port)))
+  (let* ((stack
+          (match (fluid-ref %stacks)
+            ((stack-tag . prompt-tag)
+             (make-stack #t
+                         0 prompt-tag
+                         0 (and prompt-tag 1)))
+            (_
+             (make-stack #t))))
+         (stack-len
+          (stack-length stack))
+         (error-string
+          (call-with-output-string
+            (lambda (port)
+              (let ((knots-stacks
+                     (map knots-exception-stack
+                          (filter knots-exception?
+                                  (simple-exceptions exn)))))
+
+                (let* ((stack-vec
+                        (stack->vector stack))
+                       (stack-vec-length
+                        (vector-length stack-vec)))
+                  (print-frames (list->vector
+                                 (drop
+                                  (vector->list stack-vec)
+                                  (if (< stack-vec-length 5)
+                                      0
+                                      4)))
+                                port
+                                #:count (stack-length stack)))
+                (for-each
+                 (lambda (stack)
+                   (let* ((stack-vec
+                           (stack->vector stack))
+                          (stack-vec-length
+                           (vector-length stack-vec)))
+                     (print-frames (list->vector
+                                    (drop
+                                     (vector->list stack-vec)
+                                     (if (< stack-vec-length 4)
+                                         0
+                                         3)))
+                                   port
+                                   #:count (stack-length stack))))
+                 knots-stacks)
+                (print-exception
+                 port
+                 (if (null? knots-stacks)
+                     (stack-ref stack
+                                (if (< stack-len 4)
+                                    stack-len
+                                    4))
+                     (let* ((stack (last knots-stacks))
+                            (stack-len (stack-length stack)))
+                       (stack-ref stack
+                                  (if (< stack-len 3)
+                                      stack-len
+                                      3))))
+                 '%exception
+                 (list exn)))))))
+    (display error-string port)))

knots/non-blocking.scm

@@ -0,0 +1,62 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (knots non-blocking)
+  #:use-module (web uri)
+  #:use-module (web client)
+  #:export (non-blocking-port
+            non-blocking-open-socket-for-uri))
+
+(define (non-blocking-port port)
+  "Make PORT non-blocking and return it."
+  (let ((flags (fcntl port F_GETFL)))
+    (when (zero? (logand O_NONBLOCK flags))
+      (fcntl port F_SETFL (logior O_NONBLOCK flags)))
+    port))
+
+(define* (non-blocking-open-socket-for-uri uri
+                                           #:key (verify-certificate? #t))
+  (define tls-wrap
+    (@@ (web client) tls-wrap))
+
+  (define https?
+    (eq? 'https (uri-scheme uri)))
+
+  (define plain-uri
+    (if https?
+        (build-uri
+         'http
+         #:userinfo (uri-userinfo uri)
+         #:host (uri-host uri)
+         #:port (or (uri-port uri) 443)
+         #:path (uri-path uri)
+         #:query (uri-query uri)
+         #:fragment (uri-fragment uri))
+        uri))
+
+  (let ((s (open-socket-for-uri plain-uri)))
+    (if https?
+        (let ((port
+               (tls-wrap s (uri-host uri)
+                         #:verify-certificate? verify-certificate?)))
+          ;; Guile/guile-gnutls don't handle the handshake happening on a non
+          ;; blocking socket, so change the behavior here.
+          (non-blocking-port s)
+          port)
+        (non-blocking-port s))))

knots/parallelism.scm

@@ -0,0 +1,340 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (knots parallelism)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-71)
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-9 gnu)
+  #:use-module (srfi srfi-43)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 control)
+  #:use-module (ice-9 exceptions)
+  #:use-module (fibers)
+  #:use-module (fibers channels)
+  #:use-module (fibers operations)
+  #:use-module (knots)
+  #:use-module (knots resource-pool)
+  #:export (fibers-batch-map
+            fibers-map
+
+            fibers-map-with-progress
+
+            fibers-batch-for-each
+            fibers-for-each
+
+            fibers-parallel
+            fibers-let
+
+            fiberize
+
+            make-parallelism-limiter
+            parallelism-limiter?
+            destroy-parallelism-limiter
+            call-with-parallelism-limiter
+            with-parallelism-limiter))
+
+(define (defer-to-parallel-fiber thunk)
+  (let ((reply (make-channel)))
+    (spawn-fiber
+     (lambda ()
+       (with-exception-handler
+           (lambda (exn)
+             (put-message
+              reply
+              (cons 'exception exn)))
+         (lambda ()
+           (with-exception-handler
+               (lambda (exn)
+                 (let ((stack
+                        (match (fluid-ref %stacks)
+                          ((stack-tag . prompt-tag)
+                           (make-stack #t
+                                       0 prompt-tag
+                                       0 (and prompt-tag 1)))
+                          (_
+                           (make-stack #t)))))
+                   (raise-exception
+                    (make-exception
+                     exn
+                     (make-knots-exception stack)))))
+             (lambda ()
+               (call-with-values
+                   (lambda ()
+                     (start-stack #t (thunk)))
+                 (lambda vals
+                   (put-message reply (cons 'result vals)))))))
+         #:unwind? #t))
+     #:parallel? #t)
+    reply))
+
+(define (fetch-result-of-defered-thunks . reply-channels)
+  (let ((responses (map get-message
+                        reply-channels)))
+    (map
+     (match-lambda
+       (('exception . exn)
+        (raise-exception exn))
+       (('result . vals)
+        (apply values vals)))
+     responses)))
+
+(define (fibers-batch-map proc parallelism-limit . lists)
+  "Map PROC over LISTS in parallel, with a PARALLELISM-LIMIT.  If any of
+the invocations of PROC raise an exception, this will be raised once
+all of the calls to PROC have finished."
+  (define vecs (map (lambda (list-or-vec)
+                      (if (vector? list-or-vec)
+                          list-or-vec
+                          (list->vector list-or-vec)))
+                    lists))
+
+  (define vecs-length
+    (vector-length (first vecs)))
+
+  (define result-vec
+    (make-vector vecs-length))
+
+  (let loop ((next-to-process-index
+              (if (= 0 vecs-length)
+                  #f
+                  0))
+             (channel-indexes '()))
+    (if (and (eq? #f next-to-process-index)
+             (null? channel-indexes))
+        (let ((processed-result-vec
+               (vector-map
+                (lambda (_ result-or-exn)
+                  (match result-or-exn
+                    (('exception . exn)
+                     (raise-exception exn))
+                    (('result . vals)
+                     (car vals))))
+                result-vec)))
+          (if (vector? (first lists))
+              processed-result-vec
+              (vector->list processed-result-vec)))
+
+        (if (or (= (length channel-indexes)
+                   (min parallelism-limit vecs-length))
+                (eq? #f next-to-process-index))
+            (let ((new-index
+                   new-channel-indexes
+                   (perform-operation
+                    (apply
+                     choice-operation
+                     (map
+                      (lambda (index)
+                        (wrap-operation
+                         (get-operation
+                          (vector-ref result-vec index))
+                         (lambda (result)
+                           (vector-set! result-vec
+                                        index
+                                        result)
+                           (values next-to-process-index
+                                   (lset-difference =
+                                                    channel-indexes
+                                                    (list index))))))
+                      channel-indexes)))))
+              (loop new-index
+                    new-channel-indexes))
+
+            (loop (if (= (+ 1 next-to-process-index)
+                         vecs-length)
+                      #f
+                      (+ 1 next-to-process-index))
+                  (begin
+                    (vector-set!
+                     result-vec
+                     next-to-process-index
+                     (defer-to-parallel-fiber
+                       (lambda ()
+                         (apply proc
+                                (map (lambda (vec)
+                                       (vector-ref vec next-to-process-index))
+                                     vecs)))))
+                    (cons next-to-process-index
+                          channel-indexes)))))))
+
+(define (fibers-map proc . lists)
+  "Map PROC over LISTS in parallel, running up to 20 fibers in
+ PARALLEL.  If any of the invocations of PROC raise an exception, this
+will be raised once all of the calls to PROC have finished."
+  (apply fibers-batch-map proc 20 lists))
+
+(define (fibers-batch-for-each proc parallelism-limit . lists)
+  "Call PROC on LISTS, running up to PARALLELISM-LIMIT fibers in
+parallel."
+  (apply fibers-batch-map
+         (lambda args
+           (apply proc args)
+           *unspecified*)
+         parallelism-limit
+         lists)
+
+  *unspecified*)
+
+(define (fibers-for-each proc . lists)
+  "Call PROC on LISTS, running up to 20 fibers in parallel."
+  (apply fibers-batch-for-each proc 20 lists))
+
+(define-syntax fibers-parallel
+  (lambda (x)
+    "Run each expression in parallel.  If any expression raises an
+ exception, this will be raised after all exceptions have finished."
+    (syntax-case x ()
+      ((_ e0 ...)
+       (with-syntax (((tmp0 ...) (generate-temporaries (syntax (e0 ...)))))
+         #'(let ((tmp0 (defer-to-parallel-fiber
+                         (lambda ()
+                           e0)))
+                 ...)
+             (apply values (fetch-result-of-defered-thunks tmp0 ...))))))))
+
+(define-syntax-rule (fibers-let ((v e) ...) b0 b1 ...)
+  "Let, but run each binding in a fiber in parallel."
+  (call-with-values
+      (lambda () (fibers-parallel e ...))
+    (lambda (v ...)
+      b0 b1 ...)))
+
+(define* (fibers-map-with-progress proc lists #:key report)
+  "Map PROC over LISTS, calling #:REPORT if specified after each
+invocation of PROC finishes.  REPORT is passed the results for each
+ element of LISTS, or #f if no result has been received yet."
+  (let loop ((channels-to-results
+              (apply map
+                     (lambda args
+                       (cons (defer-to-parallel-fiber
+                               (lambda ()
+                                 (apply proc args)))
+                             #f))
+                     lists)))
+    (let ((active-channels
+           (filter-map car channels-to-results)))
+      (when report
+        (report (apply map
+                       list
+                       (map cdr channels-to-results)
+                       lists)))
+      (if (null? active-channels)
+          (map
+           (match-lambda
+             ((#f . ('exception . exn))
+              (raise-exception exn))
+             ((#f . ('result . vals))
+              (car vals)))
+           channels-to-results)
+          (loop
+           (perform-operation
+            (apply
+             choice-operation
+             (filter-map
+              (lambda (p)
+                (match p
+                  ((channel . _)
+                   (if channel
+                       (wrap-operation
+                        (get-operation channel)
+                        (lambda (result)
+                          (map (match-lambda
+                                 ((c . r)
+                                  (if (eq? channel c)
+                                      (cons #f result)
+                                      (cons c r))))
+                               channels-to-results)))
+                       #f))))
+              channels-to-results))))))))
+
+(define* (fiberize proc
+                   #:key (parallelism 1)
+                   (input-channel (make-channel))
+                   (process-channel input-channel))
+  (for-each
+   (lambda _
+     (spawn-fiber
+      (lambda ()
+        (while #t
+          (let ((reply-channel args (car+cdr
+                                     (get-message process-channel))))
+            (put-message
+             reply-channel
+             (with-exception-handler
+                 (lambda (exn)
+                   (cons 'exception exn))
+               (lambda ()
+                 (with-exception-handler
+                     (lambda (exn)
+                       (let ((stack
+                              (match (fluid-ref %stacks)
+                                ((stack-tag . prompt-tag)
+                                 (make-stack #t
+                                             0 prompt-tag
+                                             0 (and prompt-tag 1)))
+                                (_
+                                 (make-stack #t)))))
+                         (raise-exception
+                          (make-exception
+                           exn
+                           (make-knots-exception stack)))))
+                   (lambda ()
+                     (call-with-values
+                         (lambda ()
+                           (start-stack #t (apply proc args)))
+                       (lambda vals
+                         (cons 'result vals))))))
+               #:unwind? #t)))))
+      #:parallel? #t))
+   (iota parallelism))
+
+  (lambda args
+    (let ((reply-channel (make-channel)))
+      (put-message input-channel (cons reply-channel args))
+      (match (get-message reply-channel)
+        (('result . vals) (apply values vals))
+        (('exception . exn)
+         (raise-exception exn))))))
+
+(define-record-type <parallelism-limiter>
+  (make-parallelism-limiter-record resource-pool)
+  parallelism-limiter?
+  (resource-pool     parallelism-limiter-resource-pool))
+
+(define* (make-parallelism-limiter limit #:key (name "unnamed"))
+  (make-parallelism-limiter-record
+   (make-fixed-size-resource-pool
+    (iota limit)
+    #:name name)))
+
+(define (destroy-parallelism-limiter parallelism-limiter)
+  (destroy-resource-pool
+   (parallelism-limiter-resource-pool
+    parallelism-limiter)))
+
+(define* (call-with-parallelism-limiter parallelism-limiter thunk)
+  (call-with-resource-from-pool
+      (parallelism-limiter-resource-pool parallelism-limiter)
+    (lambda _
+      (thunk))))
+
+(define-syntax-rule (with-parallelism-limiter parallelism-limiter exp ...)
+  (call-with-parallelism-limiter
+      parallelism-limiter
+    (lambda () exp ...)))

knots/promise.scm

@@ -0,0 +1,112 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (knots promise)
+  #:use-module (srfi srfi-9)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 atomic)
+  #:use-module (ice-9 exceptions)
+  #:use-module (fibers)
+  #:use-module (fibers conditions)
+  #:use-module (knots)
+  #:export (fibers-promise?
+
+            fibers-delay
+            fibers-force
+            fibers-promise-reset
+            fibers-promise-result-available?))
+
+(define-record-type <fibers-promise>
+  (make-fibers-promise thunk values-box evaluated-condition)
+  fibers-promise?
+  (thunk                fibers-promise-thunk)
+  (values-box           fibers-promise-values-box)
+  (evaluated-condition  fibers-promise-evaluated-condition))
+
+(define (fibers-delay thunk)
+  (make-fibers-promise
+   thunk
+   (make-atomic-box #f)
+   (make-condition)))
+
+(define (fibers-force fp)
+  (unless (fibers-promise? fp)
+    (raise-exception
+     (make-exception
+      (make-exception-with-message "fibers-force: not a fibers promise")
+      (make-exception-with-irritants fp))))
+
+  (let ((res (atomic-box-compare-and-swap!
+              (fibers-promise-values-box fp)
+              #f
+              'started)))
+    (cond
+     ((eq? #f res)
+      (call-with-values
+          (lambda ()
+            (with-exception-handler
+                (lambda (exn)
+                  (atomic-box-set! (fibers-promise-values-box fp)
+                                   exn)
+                  (signal-condition!
+                   (fibers-promise-evaluated-condition fp))
+                  (raise-exception exn))
+              (lambda ()
+                (with-exception-handler
+                    (lambda (exn)
+                      (let ((stack
+                             (match (fluid-ref %stacks)
+                               ((stack-tag . prompt-tag)
+                                (make-stack #t
+                                            0 prompt-tag
+                                            0 (and prompt-tag 1)))
+                               (_
+                                (make-stack #t)))))
+                        (raise-exception
+                         (make-exception
+                          exn
+                          (make-knots-exception stack)))))
+                  (fibers-promise-thunk fp)))
+              #:unwind? #t))
+        (lambda vals
+          (atomic-box-set! (fibers-promise-values-box fp)
+                           vals)
+          (signal-condition!
+           (fibers-promise-evaluated-condition fp))
+          (apply values vals))))
+      ((eq? res 'started)
+       (begin
+         (wait (fibers-promise-evaluated-condition fp))
+         (let ((result (atomic-box-ref (fibers-promise-values-box fp))))
+           (if (exception? result)
+               (raise-exception result)
+               (apply values result)))))
+      (else
+       (if (exception? res)
+           (raise-exception res)
+           (apply values res))))))
+
+(define (fibers-promise-reset fp)
+  (atomic-box-set! (fibers-promise-values-box fp)
+                   #f))
+
+(define (fibers-promise-result-available? fp)
+  (let ((val (atomic-box-ref (fibers-promise-values-box fp))))
+    (not (or (eq? val #f)
+             (eq? val 'started)))))

knots/queue.scm

@@ -0,0 +1,47 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (knots queue)
+  #:use-module (ice-9 q)
+  #:use-module (fibers)
+  #:use-module (fibers channels)
+  #:use-module (fibers operations)
+  #:export (spawn-queueing-fiber))
+
+(define (spawn-queueing-fiber dest-channel)
+  (define queue (make-q))
+
+  (let ((queue-channel (make-channel)))
+    (spawn-fiber
+     (lambda ()
+       (while #t
+         (if (q-empty? queue)
+             (enq! queue
+                   (perform-operation
+                    (get-operation queue-channel)))
+             (let ((front (q-front queue)))
+               (perform-operation
+                (choice-operation
+                 (wrap-operation (get-operation queue-channel)
+                                 (lambda (val)
+                                   (enq! queue val)))
+                 (wrap-operation (put-operation dest-channel front)
+                                 (lambda _
+                                   (q-pop! queue))))))))))
+    queue-channel))

knots/thread-pool.scm

@@ -0,0 +1,524 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (knots thread-pool)
+  #:use-module (srfi srfi-1)
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-19)
+  #:use-module (srfi srfi-71)
+  #:use-module (system foreign)
+  #:use-module (system base target)
+  #:use-module (rnrs bytevectors)
+  #:use-module (ice-9 q)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 atomic)
+  #:use-module (ice-9 threads)
+  #:use-module (fibers)
+  #:use-module (fibers timers)
+  #:use-module (fibers channels)
+  #:use-module (fibers operations)
+  #:use-module (knots)
+  #:use-module (knots resource-pool)
+  #:export (set-thread-name
+            thread-name
+
+            &thread-pool-timeout-error
+            thread-pool-timeout-error-pool
+            thread-pool-timeout-error?
+
+            make-thread-pool
+            thread-pool?
+            thread-pool-resource-pool
+
+            make-fixed-size-thread-pool
+            fixed-size-thread-pool?
+            fixed-size-thread-pool-channel
+            fixed-size-thread-pool-current-procedures
+
+            ;; These procedures work for thread pools and fixed size
+            ;; thread pools
+            thread-pool-arguments-parameter
+            thread-pool-default-checkout-timeout
+
+            destroy-thread-pool
+
+            call-with-thread))
+
+(define* (syscall->procedure return-type name argument-types
+                             #:key library)
+  "Return a procedure that wraps the C function NAME using the dynamic FFI,
+and that returns two values: NAME's return value, and errno.  When LIBRARY is
+specified, look up NAME in that library rather than in the global symbol name
+space.
+
+If an error occurs while creating the binding, defer the error report until
+the returned procedure is called."
+  (catch #t
+    (lambda ()
+      ;; Note: When #:library is set, try it first and fall back to libc
+      ;; proper.  This is because libraries like libutil.so have been subsumed
+      ;; by libc.so with glibc >= 2.34.
+      (let ((ptr (dynamic-func name
+                               (if library
+                                   (or (false-if-exception
+                                        (dynamic-link library))
+                                       (dynamic-link))
+                                   (dynamic-link)))))
+        ;; The #:return-errno? facility was introduced in Guile 2.0.12.
+        (pointer->procedure return-type ptr argument-types
+                            #:return-errno? #t)))
+    (lambda args
+      (lambda _
+        (throw 'system-error name  "~A" (list (strerror ENOSYS))
+               (list ENOSYS))))))
+
+(define %prctl
+  ;; Should it win the API contest against 'ioctl'?  You tell us!
+  (syscall->procedure int "prctl"
+                      (list int unsigned-long unsigned-long
+                            unsigned-long unsigned-long)))
+
+(define PR_SET_NAME 15)                           ;<linux/prctl.h>
+(define PR_GET_NAME 16)
+(define PR_SET_CHILD_SUBREAPER 36)
+
+(define (set-child-subreaper!)
+  "Set the CHILD_SUBREAPER capability for the current process."
+  (%prctl PR_SET_CHILD_SUBREAPER 1 0 0 0))
+
+(define %max-thread-name-length
+  ;; Maximum length in bytes of the process name, including the terminating
+  ;; zero.
+  16)
+
+(define (set-thread-name!/linux name)
+  "Set the name of the calling thread to NAME.  NAME is truncated to 15
+bytes."
+  (let ((ptr (string->pointer name)))
+    (let ((ret
+           err
+           (%prctl PR_SET_NAME
+                   (pointer-address ptr) 0 0 0)))
+      (unless (zero? ret)
+        (throw 'set-process-name "set-process-name"
+               "set-process-name: ~A"
+               (list (strerror err))
+               (list err))))))
+
+(define (bytes->string bytes)
+  "Read BYTES, a list of bytes, and return the null-terminated string decoded
+from there, or #f if that would be an empty string."
+  (match (take-while (negate zero?) bytes)
+    (()
+     #f)
+    (non-zero
+     (list->string (map integer->char non-zero)))))
+
+(define (thread-name/linux)
+  "Return the name of the calling thread as a string."
+  (let ((buf (make-bytevector %max-thread-name-length)))
+    (let ((ret
+           err
+           (%prctl PR_GET_NAME
+                   (pointer-address (bytevector->pointer buf))
+                   0 0 0)))
+      (if (zero? ret)
+          (bytes->string (bytevector->u8-list buf))
+          (throw 'process-name "process-name"
+                 "process-name: ~A"
+                 (list (strerror err))
+                 (list err))))))
+
+(define set-thread-name
+  (if (string-contains %host-type "linux")
+      set-thread-name!/linux
+      (const #f)))
+
+(define thread-name
+  (if (string-contains %host-type "linux")
+      thread-name/linux
+      (const "")))
+
+(define-record-type <thread-pool>
+  (thread-pool resource-pool arguments-parameter)
+  thread-pool?
+  (resource-pool       thread-pool-resource-pool)
+  (arguments-parameter thread-pool-arguments-parameter-accessor))
+
+(define-record-type <fixed-size-thread-pool>
+  (fixed-size-thread-pool channel arguments-parameter current-procedures
+                          default-checkout-timeout)
+  fixed-size-thread-pool?
+  (channel             fixed-size-thread-pool-channel)
+  (arguments-parameter fixed-size-thread-pool-arguments-parameter)
+  (current-procedures  fixed-size-thread-pool-current-procedures)
+  (default-checkout-timeout fixed-size-thread-pool-default-checkout-timeout))
+
+;; Since both thread pool records have this field, use a procedure
+;; than handles the appropriate accessor
+(define (thread-pool-arguments-parameter pool)
+  (if (fixed-size-thread-pool? pool)
+      (fixed-size-thread-pool-arguments-parameter pool)
+      (thread-pool-arguments-parameter-accessor pool)))
+
+(define (thread-pool-default-checkout-timeout pool)
+  (if (fixed-size-thread-pool? pool)
+      (fixed-size-thread-pool-default-checkout-timeout pool)
+      (assq-ref (resource-pool-configuration
+                 (thread-pool-resource-pool pool))
+                'default-checkout-timeout)))
+
+(define &thread-pool-timeout-error
+  (make-exception-type '&thread-pool-timeout-error
+                       &error
+                       '(pool)))
+
+(define make-thread-pool-timeout-error
+  (record-constructor &thread-pool-timeout-error))
+
+(define thread-pool-timeout-error-pool
+  (exception-accessor
+   &thread-pool-timeout-error
+   (record-accessor &thread-pool-timeout-error 'pool)))
+
+(define thread-pool-timeout-error?
+  (exception-predicate &thread-pool-timeout-error))
+
+(define* (make-fixed-size-thread-pool size
+                                      #:key
+                                      thread-initializer
+                                      thread-destructor
+                                      delay-logger
+                                      duration-logger
+                                      thread-lifetime
+                                      (expire-on-exception? #f)
+                                      (name "unnamed")
+                                      (use-default-io-waiters? #t)
+                                      default-checkout-timeout)
+  (define channel
+    (make-channel))
+
+  (define param
+    (make-parameter #f))
+
+  (define thread-proc-vector
+    (make-vector size #f))
+
+  (define (initializer/safe)
+    (let ((args
+           (with-exception-handler
+               (lambda _ #f)
+             (lambda ()
+               (with-exception-handler
+                   (lambda (exn)
+                     (simple-format
+                      (current-error-port)
+                      "exception running initializer in thread pool (~A): ~A\n"
+                      name
+                      thread-initializer)
+                     (print-backtrace-and-exception/knots exn)
+                     (raise-exception exn))
+                 thread-initializer))
+             #:unwind? #t)))
+
+      (if args
+          args
+          ;; never give up, just keep retrying
+          (begin
+            (sleep 1)
+            (initializer/safe)))))
+
+  (define (destructor/safe args)
+    (let ((success?
+           (with-exception-handler
+               (lambda _ #f)
+             (lambda ()
+               (with-exception-handler
+                   (lambda (exn)
+                     (simple-format
+                      (current-error-port)
+                      "exception running destructor in thread pool (~A): ~A\n"
+                      name
+                      thread-destructor)
+                     (print-backtrace-and-exception/knots exn)
+                     (raise-exception exn))
+                 (lambda ()
+                   (apply thread-destructor args)
+                   #t)))
+             #:unwind? #t)))
+
+      (or success?
+          #t
+          (begin
+            (sleep 1)
+            (destructor/safe args)))))
+
+  (define (process channel args)
+    (let loop ()
+      (match (get-message channel)
+        ('destroy #f)
+        ((reply sent-time proc)
+         (when delay-logger
+           (let ((time-delay
+                  (- (get-internal-real-time)
+                     sent-time)))
+             (delay-logger (/ time-delay
+                              internal-time-units-per-second)
+                           proc)))
+
+         (let* ((start-time (get-internal-real-time))
+                (response
+                 (with-exception-handler
+                     (lambda (exn)
+                       (list 'thread-pool-error
+                             (/ (- (get-internal-real-time)
+                                   start-time)
+                                internal-time-units-per-second)
+                             exn))
+                   (lambda ()
+                     (with-exception-handler
+                         (lambda (exn)
+                           (let ((stack
+                                  (match (fluid-ref %stacks)
+                                    ((stack-tag . prompt-tag)
+                                     (make-stack #t
+                                                 0 prompt-tag
+                                                 0 (and prompt-tag 1)))
+                                    (_
+                                     (make-stack #t)))))
+                             (raise-exception
+                              (make-exception
+                               exn
+                               (make-knots-exception stack)))))
+                       (lambda ()
+                         (call-with-values
+                             (lambda ()
+                               (start-stack
+                                #t
+                                (apply proc args)))
+                           (lambda vals
+                             (cons (/ (- (get-internal-real-time)
+                                         start-time)
+                                      internal-time-units-per-second)
+                                   vals))))))
+                   #:unwind? #t)))
+
+           (put-message reply
+                        response)
+
+           (let ((exception?
+                  (match response
+                    (('thread-pool-error duration _)
+                     (when duration-logger
+                       (duration-logger duration proc))
+                     #t)
+                    ((duration . _)
+                     (when duration-logger
+                       (duration-logger duration proc))
+                     #f))))
+             (if (and exception?
+                      expire-on-exception?)
+                 #t
+                 (loop))))))))
+
+  (define (start-thread index channel)
+    (call-with-new-thread
+     (lambda ()
+       (catch 'system-error
+         (lambda ()
+           (set-thread-name
+            (string-append
+             name " w t " (number->string index))))
+         (const #t))
+
+       (let init ((args (if thread-initializer
+                            (initializer/safe)
+                            '())))
+         (let ((continue?
+                (with-exception-handler
+                    (lambda (exn)
+                      (simple-format
+                       (current-error-port)
+                       "knots: thread-pool: internal exception: ~A\n" exn))
+                  (lambda ()
+                    (parameterize ((param args))
+                      (process channel args)))
+                  #:unwind? #t)))
+
+           (when thread-destructor
+             (destructor/safe args))
+
+           (when continue?
+             (init (if thread-initializer
+                       (initializer/safe)
+                       '()))))))))
+
+  (for-each
+   (lambda (i)
+     (if use-default-io-waiters?
+         (call-with-default-io-waiters
+          (lambda ()
+            (start-thread i channel)))
+         (start-thread i channel)))
+   (iota size))
+
+  (fixed-size-thread-pool channel
+                          param
+                          thread-proc-vector
+                          default-checkout-timeout))
+
+(define* (make-thread-pool max-size
+                           #:key
+                           (min-size max-size)
+                           scheduler
+                           thread-initializer
+                           thread-destructor
+                           (delay-logger (lambda _ #f))
+                           (duration-logger (const #f))
+                           thread-lifetime
+                           (expire-on-exception? #f)
+                           (name "unnamed")
+                           (use-default-io-waiters? #t)
+                           default-checkout-timeout)
+  "Return a channel used to offload work to a dedicated thread.  ARGS are the
+arguments of the thread pool procedure."
+  (define param
+    (make-parameter #f))
+
+  (let ((resource-pool
+         (make-resource-pool
+          (lambda ()
+            (make-fixed-size-thread-pool
+             1
+             #:thread-initializer thread-initializer
+             #:thread-destructor thread-destructor
+             #:thread-lifetime thread-lifetime
+             #:expire-on-exception? expire-on-exception?
+             #:name name
+             #:use-default-io-waiters? use-default-io-waiters?))
+          max-size
+          #:destructor destroy-thread-pool
+          #:min-size min-size
+          #:delay-logger delay-logger
+          #:scheduler scheduler
+          #:duration-logger duration-logger
+          #:default-checkout-timeout default-checkout-timeout)))
+
+    (thread-pool resource-pool
+                 param)))
+
+(define* (call-with-thread thread-pool
+                           proc
+                           #:key
+                           duration-logger
+                           checkout-timeout
+                           channel
+                           destroy-thread-on-exception?
+                           (max-waiters 'default))
+  "Send PROC to the thread pool through CHANNEL.  Return the result of PROC.
+If already in the thread pool, call PROC immediately."
+  (define (handle-proc fixed-size-thread-pool
+                       reply-channel
+                       start-time
+                       timeout)
+    (let* ((request-channel
+            (or channel
+                (fixed-size-thread-pool-channel
+                 fixed-size-thread-pool)))
+           (operation-success?
+            (perform-operation
+             (let ((put
+                    (wrap-operation
+                     (put-operation request-channel
+                                    (list reply-channel
+                                          start-time
+                                          proc))
+                     (const #t))))
+
+               (if timeout
+                   (choice-operation
+                    put
+                    (wrap-operation (sleep-operation timeout)
+                                    (const #f)))
+                   put)))))
+
+    (unless operation-success?
+      (raise-exception
+       (make-thread-pool-timeout-error)))
+
+    (let ((reply (get-message reply-channel)))
+      (match reply
+        (('thread-pool-error duration exn)
+         (when duration-logger
+           (duration-logger duration))
+         (raise-exception exn))
+        ((duration . result)
+         (when duration-logger
+           (duration-logger duration))
+         (apply values result))))))
+
+  (let ((args ((thread-pool-arguments-parameter thread-pool))))
+    (if args
+        (apply proc args)
+        (let ((start-time (get-internal-real-time))
+              (reply-channel (make-channel)))
+          (if (fixed-size-thread-pool? thread-pool)
+              (handle-proc thread-pool
+                           reply-channel
+                           start-time
+                           checkout-timeout)
+              (with-exception-handler
+                  (lambda (exn)
+                    (if (and (resource-pool-timeout-error? exn)
+                             (eq? (resource-pool-timeout-error-pool exn)
+                                  (thread-pool-resource-pool thread-pool)))
+                        (raise-exception
+                         (make-thread-pool-timeout-error thread-pool))
+                        (raise-exception exn)))
+                (lambda ()
+                  (call-with-resource-from-pool (thread-pool-resource-pool
+                                                 thread-pool)
+                    (lambda (fixed-size-thread-pool)
+                      (if checkout-timeout
+                          (let ((remaining-time
+                                 (/ (- (get-internal-real-time) start-time)
+                                    internal-time-units-per-second)))
+                            (if (< remaining-time checkout-timeout)
+                                (handle-proc fixed-size-thread-pool
+                                             reply-channel
+                                             start-time
+                                             remaining-time)
+                                (raise-exception
+                                 (make-thread-pool-timeout-error thread-pool))))
+                          (handle-proc fixed-size-thread-pool
+                                       reply-channel
+                                       start-time
+                                       #f)))
+                    #:max-waiters max-waiters
+                    #:timeout checkout-timeout
+                    #:destroy-resource-on-exception?
+                    destroy-thread-on-exception?))))))))
+
+(define (destroy-thread-pool pool)
+  (if (fixed-size-thread-pool? pool)
+      (put-message
+       (fixed-size-thread-pool-channel pool)
+       'destroy)
+      (destroy-resource-pool
+       (thread-pool-resource-pool pool))))

knots/timeout.scm

@@ -0,0 +1,203 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;;
+;;; This file is part of Guile Knots.
+;;;
+;;; The Guile Knots is free software; you can redistribute it and/or
+;;; modify it under the terms of the GNU General Public License as
+;;; published by the Free Software Foundation; either version 3 of the
+;;; License, or (at your option) any later version.
+;;;
+;;; The Guile Knots is distributed in the hope that it will be useful,
+;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;;; General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with the guix-data-service.  If not, see
+;;; <http://www.gnu.org/licenses/>.
+
+(define-module (knots timeout)
+  #:use-module (srfi srfi-71)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 atomic)
+  #:use-module (ice-9 exceptions)
+  #:use-module (ice-9 ports internal)
+  #:use-module (ice-9 suspendable-ports)
+  #:use-module (fibers)
+  #:use-module (fibers timers)
+  #:use-module (fibers channels)
+  #:use-module (fibers scheduler)
+  #:use-module (fibers operations)
+  #:export (with-fibers-timeout
+
+            wait-until-port-readable-operation
+            wait-until-port-writable-operation
+
+            &port-timeout-error
+            port-timeout-error?
+
+            &port-read-timeout-error
+            port-read-timeout-error?
+
+            &port-write-timeout-error
+            port-write-timeout-error?
+
+            with-port-timeouts))
+
+(define* (with-fibers-timeout thunk #:key timeout on-timeout)
+  (let ((channel (make-channel)))
+    (spawn-fiber
+     (lambda ()
+       (with-exception-handler
+           (lambda (exn)
+             (perform-operation
+              (choice-operation
+               (put-operation channel (cons 'exception exn))
+               (sleep-operation timeout))))
+         (lambda ()
+           (call-with-values thunk
+             (lambda vals
+               (perform-operation
+                (choice-operation
+                 (put-operation channel vals)
+                 (sleep-operation timeout))))))
+         #:unwind? #t)))
+
+    (match (perform-operation
+            (choice-operation
+             (get-operation channel)
+             (wrap-operation (sleep-operation timeout)
+                             (const 'timeout))))
+      ('timeout
+       (on-timeout))
+      (('exception . exn)
+       (raise-exception exn))
+      (vals
+       (apply values vals)))))
+
+(define &port-timeout-error
+  (make-exception-type '&port-timeout-error
+                       &external-error
+                       '(thunk port)))
+
+(define make-port-timeout-error
+  (record-constructor &port-timeout-error))
+
+(define port-timeout-error?
+  (exception-predicate &port-timeout-error))
+
+(define &port-read-timeout-error
+  (make-exception-type '&port-read-timeout-error
+                       &port-timeout-error
+                       '()))
+
+(define make-port-read-timeout-error
+  (record-constructor &port-read-timeout-error))
+
+(define port-read-timeout-error?
+  (exception-predicate &port-read-timeout-error))
+
+(define &port-write-timeout-error
+  (make-exception-type '&port-write-timeout-error
+                       &port-timeout-error
+                       '()))
+
+(define make-port-write-timeout-error
+  (record-constructor &port-write-timeout-error))
+
+(define port-write-timeout-error?
+  (exception-predicate &port-write-timeout-error))
+
+(define (readable? port)
+  "Test if PORT is writable."
+  (= 1 (port-poll port "r" 0)))
+
+(define (writable? port)
+  "Test if PORT is writable."
+  (= 1 (port-poll port "w" 0)))
+
+(define (make-wait-operation ready? schedule-when-ready port
+                             port-ready-fd this-procedure)
+  (make-base-operation #f
+                       (lambda _
+                         (and (ready? port) values))
+                       (lambda (flag sched resume)
+                         (define (commit)
+                           (match (atomic-box-compare-and-swap! flag 'W 'S)
+                             ('W (resume values))
+                             ('C (commit))
+                             ('S #f)))
+                         (schedule-when-ready
+                          sched (port-ready-fd port) commit))))
+
+(define (wait-until-port-readable-operation port)
+  "Make an operation that will succeed when PORT is readable."
+  (unless (input-port? port)
+    (error "refusing to wait forever for input on non-input port"))
+  (make-wait-operation readable? schedule-task-when-fd-readable port
+                       port-read-wait-fd
+                       wait-until-port-readable-operation))
+
+(define (wait-until-port-writable-operation port)
+  "Make an operation that will succeed when PORT is writable."
+  (unless (output-port? port)
+    (error "refusing to wait forever for output on non-output port"))
+  (make-wait-operation writable? schedule-task-when-fd-writable port
+                       port-write-wait-fd
+                       wait-until-port-writable-operation))
+
+(define* (with-port-timeouts thunk
+                             #:key timeout
+                             (read-timeout timeout)
+                             (write-timeout timeout))
+  (define (no-fibers-wait thunk port mode timeout)
+    (define poll-timeout-ms 200)
+
+    ;; When the GC runs, it restarts the poll syscall, but the timeout
+    ;; remains unchanged! When the timeout is longer than the time
+    ;; between the syscall restarting, I think this renders the
+    ;; timeout useless. Therefore, this code uses a short timeout, and
+    ;; repeatedly calls poll while watching the clock to see if it has
+    ;; timed out overall.
+    (let ((timeout-internal
+           (+ (get-internal-real-time)
+              (* internal-time-units-per-second timeout))))
+      (let loop ((poll-value
+                  (port-poll port mode poll-timeout-ms)))
+        (if (= poll-value 0)
+            (if (> (get-internal-real-time)
+                   timeout-internal)
+                (raise-exception
+                 (if (string=? mode "r")
+                     (make-port-read-timeout-error thunk port)
+                     (make-port-write-timeout-error thunk port)))
+                (loop (port-poll port mode poll-timeout-ms)))
+            poll-value))))
+
+  (parameterize
+      ((current-read-waiter
+        (lambda (port)
+          (if (current-scheduler)
+              (perform-operation
+               (choice-operation
+                (wait-until-port-readable-operation port)
+                (wrap-operation
+                 (sleep-operation read-timeout)
+                 (lambda ()
+                   (raise-exception
+                    (make-port-read-timeout-error thunk port))))))
+              (no-fibers-wait thunk port "r" read-timeout))))
+       (current-write-waiter
+        (lambda (port)
+          (if (current-scheduler)
+              (perform-operation
+               (choice-operation
+                (wait-until-port-writable-operation port)
+                (wrap-operation
+                 (sleep-operation write-timeout)
+                 (lambda ()
+                   (raise-exception
+                    (make-port-write-timeout-error thunk port))))))
+              (no-fibers-wait thunk port "w" write-timeout)))))
+    (thunk)))

knots/web-server.scm

@@ -0,0 +1,588 @@
+;;; Guile Knots
+;;; Copyright © 2020 Christopher Baines <mail@cbaines.net>
+;;; Copyright (C)  2010-2013,2015,2017 Free Software Foundation, Inc.
+
+;; This library is free software; you can redistribute it and/or
+;; modify it under the terms of the GNU Lesser General Public
+;; License as published by the Free Software Foundation; either
+;; version 3 of the License, or (at your option) any later version.
+;;
+;; This library is distributed in the hope that it will be useful,
+;; but WITHOUT ANY WARRANTY; without even the implied warranty of
+;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;; Lesser General Public License for more details.
+;;
+;; You should have received a copy of the GNU Lesser General Public License
+;; along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (knots web-server)
+  #:use-module (srfi srfi-9)
+  #:use-module (srfi srfi-71)
+  #:use-module (ice-9 control)
+  #:use-module (fibers)
+  #:use-module (fibers timers)
+  #:use-module (fibers operations)
+  #:use-module (fibers conditions)
+  #:use-module (rnrs bytevectors)
+  #:use-module (ice-9 binary-ports)
+  #:use-module (ice-9 textual-ports)
+  #:use-module (ice-9 iconv)
+  #:use-module (ice-9 match)
+  #:use-module (ice-9 exceptions)
+  #:use-module ((srfi srfi-9 gnu) #:select (set-field))
+  #:use-module (system repl error-handling)
+  #:use-module (web uri)
+  #:use-module (web http)
+  #:use-module (web request)
+  #:use-module (web response)
+  #:use-module (knots)
+  #:use-module (knots timeout)
+  #:use-module (knots non-blocking)
+  #:export (run-knots-web-server
+
+            make-chunked-output-port/knots
+
+            &request-body-ended-prematurely
+            request-body-ended-prematurely-error?
+
+            sanitize-response
+
+            request-body-port/knots
+            read-request-body/knots
+
+            default-write-response-exception-handler
+
+            web-server?
+            web-server-socket
+            web-server-port))
+
+(define (make-default-socket family addr port)
+  (let ((sock (socket PF_INET SOCK_STREAM 0)))
+    (setsockopt sock SOL_SOCKET SO_REUSEADDR 1)
+    (fcntl sock F_SETFD FD_CLOEXEC)
+    (bind sock family addr port)
+    sock))
+
+(define crlf-bv
+  (string->utf8 "\r\n"))
+
+(define (chunked-output-port-overhead-bytes write-size)
+  (+ (string-length (number->string write-size 16))
+     (bytevector-length crlf-bv)
+     (bytevector-length crlf-bv)))
+
+(define* (make-chunked-output-port/knots port #:key (keep-alive? #f)
+                                         (buffering 1200))
+  "Returns a new port which translates non-encoded data into a HTTP
+chunked transfer encoded data and writes this to PORT. Data written to
+this port is buffered until the port is flushed, at which point it is
+all sent as one chunk.  The port will otherwise be flushed every
+BUFFERING bytes, which defaults to 1200.  Take care to close the port
+when done, as it will output the remaining data, and encode the final
+zero chunk. When the port is closed it will also close PORT, unless
+KEEP-ALIVE? is true."
+  (define (write! bv start count)
+    (let ((len-string
+           (number->string count 16)))
+      (put-string port len-string))
+    (put-bytevector port crlf-bv 0 2)
+    (put-bytevector port bv start count)
+    (put-bytevector port crlf-bv 0 2)
+    (force-output port)
+    count)
+
+  (define (close)
+    (put-string port "0\r\n\r\n")
+    (force-output port)
+    (unless keep-alive?
+      (close-port port)))
+
+  (define ret
+    (make-custom-binary-output-port "chunked http" write! #f #f close))
+  (setvbuf ret 'block buffering)
+  ret)
+
+(define* (make-delimited-input-port port len fail
+                                    #:key (keep-alive? #t))
+  "Return an input port that reads from PORT, and makes sure that
+exactly LEN bytes are available from PORT.  Closing the returned port
+closes PORT, unless KEEP-ALIVE? is true."
+  (define bytes-read 0)
+
+  (define (read! bv start count)
+    (let ((count (min count (- len bytes-read))))
+      (let loop ((ret (get-bytevector-n! port bv start count)))
+        (cond ((eof-object? ret)
+               (if (= bytes-read len)
+                   0                              ; EOF
+                   (fail bytes-read)))
+              ((and (zero? ret) (> count 0))
+               ;; Do not return zero since zero means EOF, so try again.
+               (loop (get-bytevector-n! port bv start count)))
+              (else
+               (set! bytes-read (+ bytes-read ret))
+               ret)))))
+
+  (define close
+    (and (not keep-alive?)
+         (lambda ()
+           (close-port port))))
+
+  (make-custom-binary-input-port "delimited input port" read! #f #f close))
+
+;; Chunked Responses
+(define &request-body-ended-prematurely
+  (make-exception-type '&request-body-ended-prematurely
+                       &external-error
+                       '(bytes-read)))
+
+(define make-request-body-ended-prematurely-error
+  (record-constructor &request-body-ended-prematurely))
+
+(define request-body-ended-prematurely-error?
+  (exception-predicate &request-body-ended-prematurely))
+
+(define (request-body-port/knots r)
+  (cond
+   ((member '(chunked) (request-transfer-encoding r))
+    (make-chunked-input-port (request-port r)
+                             #:keep-alive? #t))
+   (else
+    (let ((content-length
+           (request-content-length r)))
+      (make-delimited-input-port
+       (request-port r)
+       content-length
+       (lambda (bytes-read)
+         (raise-exception
+          (make-request-body-ended-prematurely-error bytes-read))))))))
+
+(define (read-request-body/knots r)
+  (cond
+   ((member '(chunked) (request-transfer-encoding r))
+    (get-bytevector-all
+     (request-body-port/knots r)))
+   (else
+    (let ((content-length
+           (request-content-length r)))
+      (if content-length
+          (get-bytevector-n
+           (request-body-port/knots r)
+           content-length)
+          #f)))))
+
+(define (extend-response r k v . additional)
+  (define (extend-alist alist k v)
+    (let ((pair (assq k alist)))
+      (acons k v (if pair (delq pair alist) alist))))
+  (let ((r (set-field r (response-headers)
+                      (extend-alist (response-headers r) k v))))
+    (if (null? additional)
+        r
+        (apply extend-response r additional))))
+
+(define (response-maybe-add-connection-header-value request response)
+  (if (memq 'close (response-connection response))
+      ;; Nothing to do
+      response
+      (let* ((v (request-version request))
+             (add-close-header?
+              (case (car v)
+                ((1)
+                 (case (cdr v)
+                   ((1) (memq 'close (request-connection request)))
+                   ((0) (not (memq 'keep-alive (request-connection request))))))
+                (else #t))))
+        (if add-close-header?
+            (extend-response response 'connection '(close))
+            (if (and (= 1 (car v))
+                     (= 0 (cdr v)))
+                (extend-response response 'connection '(keep-alive))
+                response)))))
+
+;; -> response body
+(define (sanitize-response request response body)
+  "\"Sanitize\" the given response and body, making them appropriate for
+the given request.
+
+As a convenience to web handler authors, RESPONSE may be given as
+an alist of headers, in which case it is used to construct a default
+response.  Ensures that the response version corresponds to the request
+version.  If BODY is a string, encodes the string to a bytevector,
+in an encoding appropriate for RESPONSE.  Adds a
+‘content-length’ and ‘content-type’ header, as necessary.
+
+If BODY is a procedure, it is called with a port as an argument,
+and the output collected as a bytevector.  In the future we might try to
+instead use a compressing, chunk-encoded port, and call this procedure
+later, in the write-client procedure.  Authors are advised not to rely
+on the procedure being called at any particular time."
+  (cond
+   ((list? response)
+    (sanitize-response request
+                       (build-response #:version (request-version request)
+                                       #:headers response)
+                       body))
+   ((not (equal? (request-version request) (response-version response)))
+    (sanitize-response request
+                       (adapt-response-version response
+                                               (request-version request))
+                       body))
+   ((not body)
+    (values response #vu8()))
+   ((string? body)
+    (let* ((type (response-content-type response
+                                        '(text/plain)))
+           (declared-charset (assq-ref (cdr type) 'charset))
+           (charset (or declared-charset "utf-8")))
+      (sanitize-response
+       request
+       (if declared-charset
+           response
+           (extend-response response 'content-type
+                            `(,@type (charset . ,charset))))
+       (string->bytevector body charset))))
+   ((not (or (bytevector? body)
+             (procedure? body)))
+    (raise-exception
+     (make-exception-with-irritants
+      (list (make-exception-with-message
+             "unexpected body type")
+            body))))
+   ((and (response-must-not-include-body? response)
+         body
+         ;; FIXME make this stricter: even an empty body should be prohibited.
+         (not (zero? (bytevector-length body))))
+    (raise-exception
+     (make-exception-with-irritants
+      (list (make-exception-with-message
+             "response with this status code must not include body")
+            response))))
+   (else
+    ;; check length; assert type; add other required fields?
+    (values (response-maybe-add-connection-header-value
+             request
+             (if (procedure? body)
+                 (if (response-content-length response)
+                     response
+                     (extend-response response
+                                      'transfer-encoding
+                                      '((chunked))))
+                 (let ((rlen (response-content-length response))
+                       (blen (bytevector-length body)))
+                   (cond
+                    (rlen (if (= rlen blen)
+                              response
+                              (error "bad content-length" rlen blen)))
+                    (else (extend-response response 'content-length blen))))))
+            (if (eq? (request-method request) 'HEAD)
+                (raise-exception
+                 (make-exception-with-irritants
+                  (list (make-exception-with-message
+                         "unexpected body type")
+                        body)))
+                body)))))
+
+(define (with-stack-and-prompt thunk)
+  (call-with-prompt (default-prompt-tag)
+                    (lambda () (start-stack #t (thunk)))
+                    (lambda (k proc)
+                      (with-stack-and-prompt (lambda () (proc k))))))
+
+(define (keep-alive? response)
+  (not (memq 'close (response-connection response))))
+
+(define (default-read-request-exception-handler exn)
+  (display "While reading request:\n" (current-error-port))
+  (print-exception
+   (current-error-port)
+   #f
+   '%exception
+   (list exn))
+
+  #f)
+
+(define (default-write-response-exception-handler exn request)
+  (if (and (exception-with-origin? exn)
+           (string=? (exception-origin exn)
+                     "fport_write"))
+      (simple-format
+       (current-error-port)
+       "~A ~A: error replying to client\n"
+       (request-method request)
+       (uri-path (request-uri request)))
+      (simple-format
+       (current-error-port)
+       "knots web server: ~A ~A: exception replying to client: ~A\n"
+       (request-method request)
+       (uri-path (request-uri request))
+       exn))
+
+  ;; Close the client port
+  #f)
+
+(define (exception-handler exn request)
+  (let* ((error-string
+          (call-with-output-string
+            (lambda (port)
+              (simple-format
+               port
+               "exception when processing: ~A ~A\n"
+               (request-method request)
+               (uri-path (request-uri request)))
+              (print-backtrace-and-exception/knots
+               exn
+               #:port port)))))
+    (display error-string
+             (current-error-port)))
+
+  (values (build-response #:code 500)
+          ;; TODO Make this configurable
+          (string->utf8
+           "internal server error")))
+
+(define* (handle-request handler client
+                         read-request-exception-handler
+                         write-response-exception-handler
+                         buffer-size
+                         #:key post-request-hook)
+  (let ((request
+         (with-exception-handler
+             read-request-exception-handler
+           (lambda ()
+             (read-request client))
+           #:unwind? #t))
+        (read-request-time
+         (get-internal-real-time)))
+    (let ((response
+           body
+           (cond
+            ((not request)
+             ;; Bad request.
+             (values (build-response
+                      #:version '(1 . 0)
+                      #:code 400
+                      #:headers '((content-length . 0)
+                                  (connection . (close))))
+                     #vu8()))
+            (else
+             (call-with-escape-continuation
+              (lambda (return)
+                (with-exception-handler
+                    (lambda (exn)
+                      (call-with-values
+                          (lambda ()
+                            (exception-handler exn request))
+                        (lambda (response body)
+                          (call-with-values
+                              (lambda ()
+                                (sanitize-response request response body))
+                            return))))
+                  (lambda ()
+                    (start-stack
+                     #t
+                     (call-with-values
+                         (lambda ()
+                           (handler request))
+                       (match-lambda*
+                         ((response body)
+                          (sanitize-response request response body))
+                         (other
+                          (raise-exception
+                           (make-exception-with-irritants
+                            (list (make-exception-with-message
+                                   (simple-format
+                                    #f
+                                    "wrong number of values returned from handler, expecting 2, got ~A"
+                                    (length other)))
+                                  handler)))))))))))))))
+      (with-exception-handler
+          (lambda (exn)
+            (write-response-exception-handler exn request))
+        (lambda ()
+          (write-response response client)
+
+          (let ((response-start-time
+                 (get-internal-real-time))
+                (body-written?
+                 (if (procedure? body)
+                     (let* ((type (response-content-type response
+                                                         '(text/plain)))
+                            (declared-charset (assq-ref (cdr type) 'charset))
+                            (charset (or declared-charset "ISO-8859-1"))
+                            (body-port
+                             (if (response-content-length response)
+                                 client
+                                 (make-chunked-output-port/knots
+                                  client
+                                  #:keep-alive? #t
+                                  #:buffering
+                                  (- buffer-size
+                                     (chunked-output-port-overhead-bytes
+                                      buffer-size))))))
+                       (set-port-encoding! body-port charset)
+                       (let ((body-written?
+                              (with-exception-handler
+                                  (lambda (exn)
+                                    #f)
+                                (lambda ()
+                                  (with-exception-handler
+                                      (lambda (exn)
+                                        (print-backtrace-and-exception/knots exn)
+                                        (raise-exception exn))
+                                    (lambda ()
+                                      (body body-port)))
+                                  #t)
+                                #:unwind? #t)))
+                         (unless (response-content-length response)
+                           (close-port body-port))
+                         body-written?))
+                     (begin
+                       (put-bytevector client body)
+                       #t))))
+            (if body-written?
+                (begin
+                  (force-output client)
+                  (when post-request-hook
+                    (post-request-hook request
+                                       #:read-request-time read-request-time
+                                       #:response-start-time response-start-time
+                                       #:response-end-time (get-internal-real-time)))
+                  (when (and (procedure? body)
+                             (response-content-length response))
+                    (set-port-encoding! client "ISO-8859-1"))
+                  (keep-alive? response))
+                #f)))
+        #:unwind? #t))))
+
+(define* (client-loop client handler
+                      read-request-exception-handler
+                      write-response-exception-handler
+                      connection-idle-timeout
+                      buffer-size
+                      post-request-hook)
+  ;; Always disable Nagle's algorithm, as we handle buffering
+  ;; ourselves; when we force-output, we really want the data to go
+  ;; out.
+  (setvbuf client 'block buffer-size)
+  (setsockopt client IPPROTO_TCP TCP_NODELAY 1)
+  (let loop ()
+    (cond
+     ((with-exception-handler
+          (lambda (exn)
+            (unless (and (exception-with-origin? exn)
+                         (string=? (exception-origin exn)
+                                   "fport_read"))
+              (display "knots web-server, exception in client loop:\n"
+                       (current-error-port))
+              (print-exception
+               (current-error-port)
+               #f
+               '%exception
+               (list exn)))
+            #t)
+        (lambda ()
+          (or
+           (if (eq? #f connection-idle-timeout)
+               #f
+               (perform-operation
+                (choice-operation (wrap-operation
+                                   (wait-until-port-readable-operation client)
+                                   (const #f))
+                                  (wrap-operation
+                                   (sleep-operation connection-idle-timeout)
+                                   (const #t)))))
+           (eof-object? (lookahead-u8 client))))
+        #:unwind? #t)
+      (close-port client))
+     (else
+      (let ((keep-alive? (handle-request handler client
+                                         read-request-exception-handler
+                                         write-response-exception-handler
+                                         buffer-size
+                                         #:post-request-hook
+                                         post-request-hook)))
+        (if keep-alive?
+            (loop)
+            (close-port client)))))))
+
+(define (post-request-hook/safe post-request-hook)
+  (if post-request-hook
+      (lambda args
+        (with-exception-handler
+            (lambda (exn) #f)
+          (lambda ()
+            (with-exception-handler
+                (lambda (exn)
+                  (print-backtrace-and-exception/knots exn)
+                  (raise-exception exn))
+              (lambda ()
+                (apply post-request-hook args))))
+          #:unwind? #t))
+      #f))
+
+(define-record-type <web-server>
+  (make-web-server socket port)
+  web-server?
+  (socket    web-server-socket)
+  (port      web-server-port))
+
+(define* (run-knots-web-server handler #:key
+                               (host #f)
+                               (family AF_INET)
+                               (addr (if host
+                                         (inet-pton family host)
+                                         INADDR_LOOPBACK))
+                               (port 8080)
+                               (socket (make-default-socket family addr port))
+                               (read-request-exception-handler
+                                default-read-request-exception-handler)
+                               (write-response-exception-handler
+                                default-write-response-exception-handler)
+                               (connection-idle-timeout #f)
+                               (connection-buffer-size 1024)
+                               post-request-hook)
+  "Run the knots web server.
+
+HANDLER should be a procedure that takes one argument, the HTTP
+request and returns two values, the response and response body.
+
+For example, here is a simple \"Hello, World!\" server:
+
+@example
+ (define (handler request)
+   (let ((body (read-request-body request)))
+     (values '((content-type . (text/plain)))
+             \"Hello, World!\")))
+ (run-knots-web-server handler)
+@end example
+
+The response and body will be run through ‘sanitize-response’
+before sending back to the client."
+  (non-blocking-port socket)
+  ;; We use a large backlog by default.  If the server is suddenly hit
+  ;; with a number of connections on a small backlog, clients won't
+  ;; receive confirmation for their SYN, leading them to retry --
+  ;; probably successfully, but with a large latency.
+  (listen socket 1024)
+  (sigaction SIGPIPE SIG_IGN)
+
+  (spawn-fiber
+   (lambda ()
+     (let loop ()
+       (match (accept socket (logior SOCK_NONBLOCK SOCK_CLOEXEC))
+         ((client . sockaddr)
+          (spawn-fiber (lambda ()
+                         (client-loop client handler
+                                      read-request-exception-handler
+                                      write-response-exception-handler
+                                      connection-idle-timeout
+                                      connection-buffer-size
+                                      (post-request-hook/safe
+                                       post-request-hook)))
+                       #:parallel? #t)
+          (loop))))))
+
+  (make-web-server socket
+                   (vector-ref (getsockname socket)
+                               2)))  ; Not sure what this structure is

pre-inst-env.in

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+abs_top_srcdir="`cd "@abs_top_srcdir@" > /dev/null; pwd`"
+abs_top_builddir="`cd "@abs_top_builddir@" > /dev/null; pwd`"
+
+GUILE_LOAD_COMPILED_PATH="$abs_top_builddir${GUILE_LOAD_COMPILED_PATH:+:}$GUILE_LOAD_COMPILED_PATH"
+GUILE_LOAD_PATH="$abs_top_builddir:$abs_top_srcdir${GUILE_LOAD_PATH:+:}:$GUILE_LOAD_PATH"
+export GUILE_LOAD_COMPILED_PATH GUILE_LOAD_PATH
+
+PATH="$abs_top_builddir:$PATH"
+export PATH
+
+exec "$@"

test-env.in

@@ -0,0 +1,13 @@
+#!/bin/sh
+
+abs_top_srcdir="`cd "@abs_top_srcdir@" > /dev/null; pwd`"
+abs_top_builddir="`cd "@abs_top_builddir@" > /dev/null; pwd`"
+
+GUILE_LOAD_COMPILED_PATH="${abs_top_builddir}/tests${GUILE_LOAD_COMPILED_PATH:+:}$abs_top_builddir${GUILE_LOAD_COMPILED_PATH:+:}$GUILE_LOAD_COMPILED_PATH"
+GUILE_LOAD_PATH="$abs_top_builddir/tests:$abs_top_srcdir${GUILE_LOAD_PATH:+:}$abs_top_builddir:$abs_top_srcdir${GUILE_LOAD_PATH:+:}:$GUILE_LOAD_PATH"
+export GUILE_LOAD_COMPILED_PATH GUILE_LOAD_PATH
+
+PATH="$abs_top_builddir:$PATH"
+export PATH
+
+exec "$@"

tests.scm

@@ -0,0 +1,33 @@
+(define-module (tests)
+  #:use-module (ice-9 exceptions)
+  #:use-module (fibers)
+  #:use-module (knots)
+  #:export (run-fibers-for-tests
+            assert-no-heap-growth))
+
+(define* (run-fibers-for-tests thunk #:key (drain? #t))
+  (let ((result
+         (run-fibers
+          (lambda ()
+            (with-exception-handler
+                (lambda (exn)
+                  exn)
+              (lambda ()
+                (simple-format #t "running ~A\n" thunk)
+                (with-exception-handler
+                    (lambda (exn)
+                      (print-backtrace-and-exception/knots exn)
+                      (raise-exception exn))
+                  (lambda ()
+                    (start-stack #t (thunk))))
+                #t)
+              #:unwind? #t))
+          #:hz 0
+          #:parallelism 1
+          #:drain? drain?)))
+    (if (exception? result)
+        (raise-exception result)
+        result)))
+
+(define (assert-no-heap-growth thunk)
+  (thunk))

tests/non-blocking.scm

@@ -0,0 +1,31 @@
+(use-modules (tests)
+             (fibers)
+             (unit-test)
+             (web uri)
+             (web client)
+             (web response)
+             (knots web-server)
+             (knots non-blocking))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              (values '((content-type . (text/plain)))
+                      "Hello, World!"))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+
+     (assert-equal
+      200
+      (response-code
+       (http-get
+        uri
+        #:port (non-blocking-open-socket-for-uri uri)))))))
+
+(display "non-blocking test finished successfully\n")

tests/parallelism.scm

@@ -0,0 +1,144 @@
+(use-modules (tests)
+             (fibers)
+             (unit-test)
+             (ice-9 exceptions)
+             (knots parallelism))
+
+;; Test fibers-map
+(run-fibers-for-tests
+ (lambda ()
+   (assert-equal
+    1122
+    (apply + (fibers-map
+              (lambda (i)
+                (* 2 i))
+              (iota 34))))))
+
+;; Test fibers-batch-map with a large batch size
+(run-fibers-for-tests
+ (lambda ()
+   (assert-equal
+    1122
+    (apply + (fibers-batch-map
+              (lambda (i)
+                (* 2 i))
+              100
+              (iota 34))))))
+
+;; Test fibers-map with an empty list
+(run-fibers-for-tests
+ (lambda ()
+   (fibers-map identity '())))
+
+;; Test fibers-map with an empty vector
+(run-fibers-for-tests
+ (lambda ()
+   (fibers-map identity #())))
+
+;; Test fibers-map with vectors
+(run-fibers-for-tests
+ (lambda ()
+   (assert-equal
+    1122
+    (apply + (vector->list
+              (fibers-map
+               (lambda (i)
+                 (* 2 i))
+               (list->vector (iota 34))))))))
+
+;; Test fibers-for-each
+(run-fibers-for-tests
+ (lambda ()
+   (fibers-for-each
+    (lambda (i)
+      (* 2 i))
+    (iota 34))))
+
+;; Test fibers-map-with-progress with an empty list
+(run-fibers-for-tests
+ (lambda ()
+   (fibers-map-with-progress
+    identity
+    '(()))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (with-exception-handler
+       (lambda (exn)
+         (unless (and (exception-with-message? exn)
+                      (string=? (exception-message exn)
+                                "foo"))
+           (raise-exception exn)))
+     (lambda ()
+       (fibers-map-with-progress
+        (lambda _
+          (raise-exception
+           (make-exception-with-message "foo")))
+        '((1)))
+
+       (error 'should-not-reach-here))
+     #:unwind? #t)))
+
+(run-fibers-for-tests
+ (lambda ()
+   (with-exception-handler
+       (lambda (exn)
+         (unless (and (exception-with-message? exn)
+                      (string=? (exception-message exn)
+                                "foo"))
+           (raise-exception exn)))
+     (lambda ()
+       (fibers-for-each
+        (lambda (i)
+          (raise-exception
+           (make-exception-with-message "foo")))
+        (iota 2)))
+     #:unwind? #t)))
+
+(run-fibers-for-tests
+ (lambda ()
+   (with-exception-handler
+       (lambda (exn)
+         (unless (and (exception-with-message? exn)
+                      (string=? (exception-message exn)
+                                "foo"))
+           (raise-exception exn)))
+     (lambda ()
+       ((fiberize
+         (lambda (i)
+           (raise-exception
+            (make-exception-with-message "foo"))))
+        1))
+     #:unwind? #t)))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((a 0))
+     (call-with-values
+         (lambda ()
+           (fibers-parallel
+            (begin
+              (sleep 1)
+              1)
+            (begin
+              (set! a 1)
+              2)))
+       (lambda (a b)
+         (assert-equal a 1)
+         (assert-equal b 2)))
+
+     (assert-equal a 1))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((parallelism-limiter (make-parallelism-limiter 2)))
+     (fibers-for-each
+      (lambda _
+        (with-parallelism-limiter
+         parallelism-limiter
+         #f))
+      (iota 50))
+
+     (destroy-parallelism-limiter parallelism-limiter))))
+
+(display "parallelism test finished successfully\n")

tests/promise.scm

@@ -0,0 +1,28 @@
+(use-modules (tests)
+             (fibers)
+             (unit-test)
+             (knots parallelism)
+             (knots promise))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((promises
+          (map (lambda (i)
+                 (fibers-delay
+                  (lambda ()
+                    (* i 2))))
+               (iota 10))))
+
+     (assert-equal
+      #f
+      (fibers-promise-result-available? (car promises)))
+
+     (assert-equal
+      90
+      (apply + (fibers-map fibers-force promises)))
+
+     (assert-equal
+      #t
+      (fibers-promise-result-available? (car promises))))))
+
+(display "promise test finished successfully\n")

tests/queue.scm

@@ -0,0 +1,22 @@
+(use-modules (tests)
+             (fibers)
+             (fibers channels)
+             (unit-test)
+             (knots queue))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((dest-channel
+           (make-channel))
+          (queue-channel
+           (spawn-queueing-fiber dest-channel)))
+
+     (put-message queue-channel 1)
+     (put-message queue-channel 2)
+     (put-message queue-channel 3)
+
+     (assert-equal 1 (get-message dest-channel))
+     (assert-equal 2 (get-message dest-channel))
+     (assert-equal 3 (get-message dest-channel)))))
+
+(display "queue test finished successfully\n")

tests/resource-pool.scm

@@ -0,0 +1,214 @@
+(use-modules (tests)
+             (fibers)
+             (unit-test)
+             (knots parallelism)
+             (knots resource-pool))
+
+(define new-number
+  (let ((val 0))
+    (lambda ()
+      (set! val (1+ val))
+      val)))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-resource-pool
+                         new-number
+                         1)))
+     (assert-true
+      (number?
+       (with-resource-from-pool resource-pool
+           res
+         res)))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-fixed-size-resource-pool
+                         (list 1))))
+     (assert-true
+      (number?
+       (with-resource-from-pool resource-pool
+           res
+         res)))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-resource-pool
+                         new-number
+                         1
+                         #:add-resources-parallelism 1)))
+     (assert-true
+      (number?
+       (with-resource-from-pool resource-pool
+           res
+         res)))
+
+     (destroy-resource-pool resource-pool))))
+
+(let* ((error-constructor
+        (record-constructor &resource-pool-timeout))
+       (err
+        (error-constructor 'foo)))
+  (assert-equal
+   (resource-pool-timeout-error-pool err)
+   'foo))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-resource-pool
+                         new-number
+                         2)))
+     (fibers-for-each
+      (lambda _
+        (with-resource-from-pool resource-pool
+            res
+          res))
+      (iota 20))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-resource-pool
+                         new-number
+                         2
+                         #:destructor
+                         (lambda (res)
+                           #t))))
+     (fibers-for-each
+      (lambda _
+        (with-resource-from-pool resource-pool
+            res
+          res))
+      (iota 20))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-resource-pool
+                         new-number
+                         2
+                         #:idle-seconds 0.5
+                         #:destructor
+                         (lambda (res)
+                           #t))))
+     (fibers-for-each
+      (lambda _
+        (with-resource-from-pool resource-pool
+            res
+          res))
+      (iota 20))
+
+     (let loop ((stats (resource-pool-stats resource-pool
+                                            #:timeout #f)))
+       (unless (= 0 (assq-ref stats 'resources))
+         (sleep 0.1)
+         (loop (resource-pool-stats resource-pool #:timeout #f))))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((counter 0)
+          (resource-pool (make-resource-pool
+                          (lambda ()
+                            (let ((start-val counter))
+                              (sleep 0.05)
+                              (if (= start-val counter)
+                                  (set! counter (+ 1 counter))
+                                  (error "collision detected")))
+                            (new-number))
+                          1)))
+     (fibers-batch-for-each
+      (lambda _
+        (with-resource-from-pool
+            resource-pool res
+          (let ((start-val counter))
+            (sleep 0.05)
+            (if (= start-val counter)
+                (set! counter (+ 1 counter))
+                (error "collision detected")))))
+      20
+      (iota 50))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((counter 0)
+          (resource-pool (make-resource-pool
+                          (lambda ()
+                            (let ((start-val counter))
+                              (sleep 0.05)
+                              (if (= start-val counter)
+                                  (set! counter (+ 1 counter))
+                                  (error "collision detected")))
+                            (new-number))
+                          1
+                          #:default-checkout-timeout 5)))
+     (fibers-batch-for-each
+      (lambda _
+        (with-resource-from-pool
+            resource-pool res
+          (let ((start-val counter))
+            (sleep 0.05)
+            (if (= start-val counter)
+                (set! counter (+ 1 counter))
+                (error "collision detected")))))
+      20
+      (iota 50))
+
+     (destroy-resource-pool resource-pool))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((resource-pool (make-resource-pool
+                         (lambda () #f)
+                         1
+                         #:default-max-waiters 1)))
+     (call-with-resource-from-pool
+         resource-pool
+       (lambda (res)
+
+         ;; 1st waiter
+         (spawn-fiber
+          (lambda ()
+            (with-exception-handler
+                (lambda (exn)
+                  (if (resource-pool-destroyed-error? exn)
+                      #t
+                      (raise-exception exn)))
+              (lambda ()
+                (call-with-resource-from-pool
+                    resource-pool
+                  (lambda (res)
+                    #f)))
+              #:unwind? #t)))
+
+         (while (= 0
+                   (assq-ref
+                    (resource-pool-stats resource-pool #:timeout #f)
+                    'waiters))
+           (sleep 0.1))
+
+         (with-exception-handler
+             (lambda (exn)
+               (if (resource-pool-too-many-waiters-error? exn)
+                   #t
+                   (raise-exception exn)))
+           (lambda ()
+             ;; 2nd waiter
+             (call-with-resource-from-pool
+                 resource-pool
+               (lambda (res)
+                 (error 'should-not-be-reached))))
+           #:unwind? #t)))
+
+     (destroy-resource-pool resource-pool))))
+
+(display "resource-pool test finished successfully\n")

tests/thread-pool.scm

@@ -0,0 +1,88 @@
+(use-modules (tests)
+             (srfi srfi-71)
+             (fibers)
+             (unit-test)
+             (knots)
+             (knots thread-pool))
+
+(let ((thread-pool
+       (make-fixed-size-thread-pool 2)))
+
+  (assert-equal
+   (call-with-thread
+    thread-pool
+    (lambda ()
+      4))
+   4))
+
+(let ((thread-pool
+       (make-fixed-size-thread-pool
+        2
+        #:thread-initializer (const '(2)))))
+
+  (assert-equal
+   (call-with-thread
+    thread-pool
+    (lambda (num)
+      (* 2 num)))
+   4))
+
+(let ((thread-pool
+       (make-fixed-size-thread-pool 2)))
+
+  (assert-equal
+   #t
+   (with-exception-handler
+       (lambda (exn)
+         (knots-exception? exn))
+     (lambda ()
+       (call-with-thread
+        thread-pool
+        (lambda ()
+          (+ 1 'a))))
+     #:unwind? #t)))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((thread-pool
+          (make-thread-pool 2)))
+
+     (assert-equal
+      (call-with-thread
+       thread-pool
+       (lambda ()
+         4))
+      4))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((thread-pool
+          (make-thread-pool
+           2
+           #:thread-initializer (const '(2)))))
+
+     (assert-equal
+      (call-with-thread
+       thread-pool
+       (lambda (num)
+         (* 2 num)))
+      4))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let ((thread-pool
+          (make-thread-pool 2)))
+
+     (assert-equal
+      #t
+      (with-exception-handler
+          (lambda (exn)
+            (knots-exception? exn))
+        (lambda ()
+          (call-with-thread
+           thread-pool
+           (lambda ()
+             (+ 1 'a))))
+        #:unwind? #t)))))
+
+(display "thread-pool test finished successfully\n")

tests/timeout.scm

@@ -0,0 +1,22 @@
+(use-modules (tests)
+             (fibers)
+             (unit-test)
+             (knots timeout))
+
+(run-fibers-for-tests
+ (lambda ()
+   (assert-equal
+    1
+    (with-fibers-timeout
+     (const 1)
+     #:timeout 10))
+
+   (assert-equal
+    2
+    (with-fibers-timeout
+     (lambda ()
+       (sleep 10))
+     #:timeout 0.1
+     #:on-timeout (const 2)))))
+
+(display "timeout test finished successfully\n")

tests/web-server.scm

@@ -0,0 +1,236 @@
+(use-modules (srfi srfi-71)
+             (rnrs bytevectors)
+             (ice-9 binary-ports)
+             (ice-9 textual-ports)
+             (tests)
+             (fibers)
+             (fibers channels)
+             (unit-test)
+             (web uri)
+             (web client)
+             (web request)
+             (web response)
+             (knots web-server)
+             (knots non-blocking))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              (values '((content-type . (text/plain)))
+                      "Hello, World!"))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (assert-equal
+      200
+      (response-code
+       (http-get
+        uri
+        #:port (non-blocking-open-socket-for-uri uri)))))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              "Hello, World!")
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (assert-equal
+      500
+      (response-code
+       (http-get
+        uri
+        #:port (non-blocking-open-socket-for-uri uri)))))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              (values '((content-type . (text/plain))
+                        (content-length . 3))
+                      (lambda (port)
+                        (display "foo" port))))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (let ((response
+            body
+            (http-get
+             uri
+             #:port (non-blocking-open-socket-for-uri uri))))
+       (assert-equal
+        "foo"
+        body)))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              (values '((content-type . (text/plain
+                                         (charset . "utf-8"))))
+                      (lambda (port)
+                        (display "☺" port))))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (let ((response
+            body
+            (http-get
+             uri
+             #:port (non-blocking-open-socket-for-uri uri))))
+       (assert-equal
+        "☺"
+        body)))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              (values '((content-type . (text/plain
+                                         (charset . "utf-8")))
+                        (content-length . 3))
+                      (lambda (port)
+                        (display "☺" port))))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (let ((response
+            body
+            (http-get
+             uri
+             ;; TODO Remove once using Guile 3.0.10
+             #:streaming? #t
+             #:port (non-blocking-open-socket-for-uri uri))))
+       (assert-equal
+        "☺"
+        (utf8->string
+         (get-bytevector-n body 3)))))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((web-server
+           (run-knots-web-server
+            (lambda (request)
+              (if (string=? (utf8->string
+                             (read-request-body/knots request))
+                            "☺")
+                  (values (build-response #:code 200)
+                          "")
+                  (values (build-response #:code 500)
+                          "")))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (let ((response
+            body
+            (http-post
+             uri
+             #:body "☺"
+             #:port (non-blocking-open-socket-for-uri uri))))
+       (assert-equal
+        200
+        (response-code response))))))
+
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((channel (make-channel))
+          (web-server
+           (run-knots-web-server
+            (lambda (request)
+              (with-exception-handler
+                  (lambda (exn)
+                    (put-message channel exn))
+                (lambda ()
+                  (read-request-body/knots request))
+                #:unwind? #t))
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (let* ((port (non-blocking-open-socket-for-uri uri))
+            (request
+             (build-request
+              uri
+              #:method 'POST
+              #:version '(1 . 1)
+              #:headers `((connection close)
+                          (content-length . 20)
+                          (Content-Type . "application/octet-stream"))
+              #:port port)))
+
+       (set-port-encoding! port "ISO-8859-1")
+       (let ((request (write-request request port)))
+         (display "12")
+         (force-output port)
+
+         (close-port port)))
+
+     (assert-true
+      (request-body-ended-prematurely-error?
+       (get-message channel))))))
+
+;; Test handling of exceptions when writing the response to a client
+(run-fibers-for-tests
+ (lambda ()
+   (let* ((exception-handled-sucecssfully-channel
+           (make-channel))
+          (port-closed-channel (make-channel))
+          (web-server
+           (run-knots-web-server
+            (lambda (request)
+              ;; TODO Not sure why buffering makes a difference here
+              (setvbuf (request-port request) 'none)
+              (get-message port-closed-channel)
+              (values '((content-type . (text/plain)))
+                      "Hello, World!"))
+            #:write-response-exception-handler
+            (lambda (exn request)
+              (spawn-fiber
+               (lambda ()
+                 (put-message exception-handled-sucecssfully-channel
+                              #t)))
+              #f)
+            #:port 0)) ;; Bind to any port
+          (port
+           (web-server-port web-server))
+          (uri
+           (build-uri 'http #:host "127.0.0.1" #:port port)))
+
+     (let ((request-port (non-blocking-open-socket-for-uri uri)))
+       (write-request
+        (build-request uri)
+        request-port)
+       (close-port request-port))
+     (put-message port-closed-channel #t)
+
+     (assert-equal (get-message exception-handled-sucecssfully-channel)
+                   #t))))
+
+(display "web-server test finished successfully\n")