From 38b36570132f8463cc763256aeab7613656278e6 Mon Sep 17 00:00:00 2001
From: Christopher Baines <mail@cbaines.net>
Date: Mon, 28 Nov 2022 10:26:46 +0000
Subject: [PATCH] Use advisory locks to avoid deadlocks during data deletion

In the case where multiple data deleting processes end up running at the same
time.
---
 guix-data-service/data-deletion.scm | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/guix-data-service/data-deletion.scm b/guix-data-service/data-deletion.scm
index e4762c9..6794bea 100644
--- a/guix-data-service/data-deletion.scm
+++ b/guix-data-service/data-deletion.scm
@@ -206,6 +206,10 @@ WHERE id IN (
   (with-postgresql-transaction
    conn
    (lambda (conn)
+     (obtain-advisory-transaction-lock
+      conn
+      'delete-revisions-from-branch)
+
      (delete-from-git-commits conn)
      (delete-jobs conn)
 
@@ -538,6 +542,10 @@ WHERE NOT EXISTS (
                          (with-postgresql-transaction
                           conn
                           (lambda (conn)
+                            (obtain-advisory-transaction-lock
+                             conn
+                             'delete-unreferenced-derivations)
+
                             (exec-query
                              conn
                              "