database: Serialize all database accesses in a thread.

Fixes <https://bugs.gnu.org/32234>.

* bin/cuirass.in (main): Keep only one WITH-DATABASE call around all fibers.
Remove all DB arguments.
* src/cuirass/base.scm (evaluate, update-build-statuses!, spawn-builds,
handle-build-event, build-packages): Remove all DB arguments.
(clear-build-queue, cancel-old-builds): Wrap in WITH-DB-CRITICAL-SECTION,
remove all DB arguments.
(restart-builds): Remove the NON-BLOCKING call, remove all DB arguments.
(process-specs): Remove all DB arguments, remove the WITH-DATABASE call.
* src/cuirass/database.scm (%db-channel): New parameter.
(with-db-critical-section): New macro.
(db-add-input, db-add-specification, db-get-inputs, db-get-specifications,
db-add-evaluation, db-add-build, db-update-build-status!, db-get-outputs,
db-get-builds, db-get-build, db-get-pending-derivations, db-get-stamp,
db-add-stamp, db-get-evaluations, db-get-evaluations-build-summary,
db-get-evaluations-id-min, db-get-evaluations-id-max, db-get-builds-min,
db-get-builds-max): Wrap in WITH-DB-CRITICAL-SECTION, remove all DB arguments.
(with-database): Wrap BODY in PARAMETERIZE form that sets %DB-CHANNEL to the
channel returned by MAKE-CRITICAL-SECTION.
* src/cuirass/http.scm (handle-build-request, handle-builds-request): Remove
all DB arguments.
(url-handler): Remove all DB arguments, remove the DB-CHANNEL state, remove
the WITH-CRITICAL-SECTION calls.
(run-cuirass-server): Remove the DB arguments, remove the
MAKE-CRITICAL-SECTION call.
* src/cuirass/utils.scm (make-critical-section): Replace SPAWN-FIBER with
CALL-WITH-NEW-THREAD.  Wrap body in PARAMETERIZE form that clears
CURRENT-FIBER.
* tests/database.scm (with-temporary-database, "db-add-specification",
"db-add-build", "db-update-build-status!", "db-get-builds",
"db-get-pending-derivations"): Remove the DB arguments.
("db-init"): Set the %DB-CHANNEL parameter to the channel returned by
MAKE-CRITICAL-SECTION, and return #t.
("database"): Set %DB-CHANNEL to #f during cleanup.
* tests/http.scm ("db-init"): Set the %DB-CHANNEL parameter to the channel
returned by MAKE-CRITICAL-SECTION, and return #t.
("cuirass-run", "fill-db"): Remove the DB arguments.
("http"): Set %DB-CHANNEL to #f during cleanup.

1 files changed, 12 insertions, 11 deletions

diff --git a/src/cuirass/utils.scm b/src/cuirass/utils.scm
index 6083890..48e797c 100644
--- a/src/cuirass/utils.scm
+++ b/src/cuirass/utils.scm
@@ -103,17 +103,18 @@ then be passed to 'join-critical-section', which will ensure sequential
 ordering.  ARGS are the arguments of the critical section.
 
 Critical sections are implemented by passing the procedure to execute to a
-dedicated fiber."
-  (let ((channel (make-channel)))
-    (spawn-fiber
-     (lambda ()
-       (parameterize ((%critical-section-args args))
-         (let loop ()
-           (match (get-message channel)
-             (((? channel? reply) . (? procedure? proc))
-              (put-message reply (apply proc args))))
-           (loop)))))
-    channel))
+dedicated thread."
+  (parameterize (((@@ (fibers internal) current-fiber) #f))
+    (let ((channel (make-channel)))
+      (call-with-new-thread
+       (lambda ()
+         (parameterize ((%critical-section-args args))
+           (let loop ()
+             (match (get-message channel)
+               (((? channel? reply) . (? procedure? proc))
+                (put-message reply (apply proc args))))
+             (loop)))))
+      channel)))
 
 (define (call-with-critical-section channel proc)
   "Send PROC to the critical section through CHANNEL.  Return the result of