cbaines/guix-data-service
1
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

Rework the shortlived PostgreSQL specific connection channel

Browse source 
In to a generic thing more like (ice-9 futures). Including copying some bits
from the (ice-9 threads) module and adapting them to work with this fibers
approach, rather than futures. The advantage being that using fibers channels
doesn't block the threads being used by fibers, whereas futures would.
This commit is contained in:
Christopher Baines 2020-10-03 21:32:46 +01:00
parent 18b6dd9e6d
commit e2e55c69de
4 changed files with 112 additions and 106 deletions
Download patch file Download diff file Expand all files Collapse all files

95
guix-data-service/database.scm
View file

@ -20,9 +20,6 @@
#:use-module (ice-9 match)
#:use-module (ice-9 threads)
#:use-module (squee)
#:use-module (fibers)
#:use-module (fibers channels)
#:use-module (fibers conditions)
#:use-module (guix-data-service config)
#:export (with-postgresql-connection
@ -136,98 +133,6 @@
(f conn)))))
(define* (make-postgresql-connection-channel name
#:key
(statement-timeout #f)
(threads 2))
(parameterize (((@@ (fibers internal) current-fiber) #f))
(let ((channel (make-channel)))
(for-each
(lambda _
(call-with-new-thread
(lambda ()
(with-postgresql-connection
name
(lambda (conn)
(let loop ()
(match (get-message channel)
(((? channel? reply) f (? boolean? allways-rollback?))
(put-message
reply
(with-exception-handler
(lambda (exn)
(cons 'worker-thread-error exn))
(lambda ()
(with-exception-handler
(lambda (exn)
(simple-format
(current-error-port)
"postgresql connection thread: exception: ~A\n"
exn)
(backtrace)
(raise-exception exn))
(lambda ()
(call-with-values
(lambda ()
(with-postgresql-transaction
conn
(lambda (conn)
(f conn))))
(lambda vals vals)))))
#:unwind? #t))
(loop))
(((? channel? reply) . (? list? args))
(put-message
reply
(with-exception-handler
(lambda (exn)
(cons 'worker-thread-error exn))
(lambda ()
(with-exception-handler
(lambda (exn)
(simple-format
(current-error-port)
"postgresql connection thread: exception: ~A\n"
exn)
(backtrace)
(raise-exception exn))
(lambda ()
(call-with-values
(lambda ()
(apply exec-query
conn
args))
(lambda vals vals)))))
#:unwind? #t))
(loop))
(_ #f))))
#:statement-timeout statement-timeout))))
(iota threads))
channel)))
(define (close-postgresql-connection-channel channel)
(put-message channel #f))
(define (exec-query/through-channel channel . args)
(let ((reply (make-channel)))
(put-message channel (cons reply args))
(match (get-message reply)
(('worker-thread-error . exn)
(raise-exception exn))
(result
(apply values result)))))
(define* (with-postgresql-transaction/through-channel channel
f
#:key always-rollback?)
(let ((reply (make-channel)))
(put-message channel (list reply f always-rollback?))
(match (get-message reply)
(('worker-thread-error . exn)
(raise-exception exn))
(result
(apply values result)))))
(define* (with-postgresql-transaction conn f
#:key always-rollback?)
(exec-query conn "BEGIN;")