GNU bug report logs - #32209
Cuirass: Use SQLite in Multi-thread mode

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Clément Lassieur <clement <at> lassieur.org>
To: guix-patches <at> gnu.org
Subject: [PATCH] database: Use SQLite in Multi-thread mode.
Date: Thu, 19 Jul 2018 12:54:57 +0200

This disables mutexing on database connection and prepared statement objects,
thus making us responsible for serializing access to database connections and
prepared statements.  It may result in a performance improvement.

* src/cuirass/database.scm (db-init, db-open): Pass the SQLITE_OPEN_NOMUTEX
flag to SQLITE-OPEN.
---
 src/cuirass/database.scm | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/src/cuirass/database.scm b/src/cuirass/database.scm
index a84d0fa..6bf3bc4 100644
--- a/src/cuirass/database.scm
+++ b/src/cuirass/database.scm
@@ -195,7 +195,8 @@ database object."
     (format (current-error-port) "Removing leftover database ~a~%" db-name)
     (delete-file db-name))
   (let ((db (sqlite-open db-name (logior SQLITE_OPEN_CREATE
-                                         SQLITE_OPEN_READWRITE))))
+                                         SQLITE_OPEN_READWRITE
+                                         SQLITE_OPEN_NOMUTEX))))
     (db-load db schema)
     (db-set-schema-version db (latest-db-schema-version))
     db))
@@ -222,7 +223,9 @@ database object."
   ;; avoid SQLITE_LOCKED errors when we have several readers:
   ;; <https://www.sqlite.org/wal.html>.
   (set-db-options (if (file-exists? db)
-                      (db-upgrade (sqlite-open db SQLITE_OPEN_READWRITE))
+                      (db-upgrade
+                       (sqlite-open db (logior SQLITE_OPEN_READWRITE
+                                               SQLITE_OPEN_NOMUTEX)))
                       (db-init db))))
 
 (define (db-close db)
-- 
2.18.0

Message #14 received at 32209 <at> debbugs.gnu.org (full text, mbox):

From: ludo <at> gnu.org (Ludovic Courtès)
To: Clément Lassieur <clement <at> lassieur.org>
Cc: 32209 <at> debbugs.gnu.org
Subject: Re: [bug#32209] [PATCH] database: Use SQLite in Multi-thread mode.
Date: Fri, 20 Jul 2018 14:55:12 +0200

Hello!

Clément Lassieur <clement <at> lassieur.org> skribis:

> This disables mutexing on database connection and prepared statement objects,
> thus making us responsible for serializing access to database connections and
> prepared statements.  It may result in a performance improvement.
>
> * src/cuirass/database.scm (db-init, db-open): Pass the SQLITE_OPEN_NOMUTEX
> flag to SQLITE-OPEN.

Could you copy (part of) the paragraph above as a comment above the
‘sqlite-open’ call in ‘db-open’?

Then I guess you can go ahead and push!

Thank you,
Ludo’.

Message #19 received at 32209-done <at> debbugs.gnu.org (full text, mbox):

From: Clément Lassieur <clement <at> lassieur.org>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: 32209-done <at> debbugs.gnu.org
Subject: Re: [bug#32209] [PATCH] database: Use SQLite in Multi-thread mode.
Date: Fri, 20 Jul 2018 15:23:28 +0200

Ludovic Courtès <ludo <at> gnu.org> writes:

> Hello!
>
> Clément Lassieur <clement <at> lassieur.org> skribis:
>
>> This disables mutexing on database connection and prepared statement objects,
>> thus making us responsible for serializing access to database connections and
>> prepared statements.  It may result in a performance improvement.
>>
>> * src/cuirass/database.scm (db-init, db-open): Pass the SQLITE_OPEN_NOMUTEX
>> flag to SQLITE-OPEN.
>
> Could you copy (part of) the paragraph above as a comment above the
> ‘sqlite-open’ call in ‘db-open’?

Done, and pushed.  Thanks!

Clément

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