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| author | Eric Wong <e@80x24.org> | 2020-08-25 10:23:14 +0000 |
|---|---|---|
| committer | Eric Wong <e@yhbt.net> | 2020-08-26 06:10:58 +0000 |
| commit | 2d41ceaf8f6a084ce650feb17ef56d8bc8e9e51c (patch) | |
| tree | 1c38cd1f682714382f06f9b11df5b1f2e3344537 | |
| parent | 5f6a0d2342323541e44ff2f1e7329053d0263800 (diff) | |
| download | public-inbox-2d41ceaf8f6a084ce650feb17ef56d8bc8e9e51c.tar.gz | |
Unlike DBD::SQLite, the sqlite3(1) CLI does not have a default busy timeout enabled, so it easily times out while acquiring a SHARED lock for read-only queries. We can avoid battery-wasting polling from the SQLite timeout handler by relying on flock(2) as we do in our Perl code. Furthermore, this avoids triggering some locking problems[1] from a long "SELECT COUNT(*) ..." query and reindex. While there may be other SQLite-related parallelism issues[1], this works around one of them by relying on flock(2). [1] https://public-inbox.org/meta/20200825001204.GA840@dcvr/
| -rwxr-xr-x | examples/grok-pull.post_update_hook.sh | 15 |
1 files changed, 14 insertions, 1 deletions
diff --git a/examples/grok-pull.post_update_hook.sh b/examples/grok-pull.post_update_hook.sh index 1f51140f..77489472 100755 --- a/examples/grok-pull.post_update_hook.sh +++ b/examples/grok-pull.post_update_hook.sh @@ -25,11 +25,13 @@ then inbox_dir=$(expr "$full_git_dir" : "$EPOCH2MAIN") inbox_name=$(basename "$inbox_dir") msgmap="$inbox_dir"/msgmap.sqlite3 + inbox_lock="$inbox_dir"/inbox.lock else inbox_fmt=1 inbox_dir="$full_git_dir" inbox_name=$(basename "$inbox_dir" .git) msgmap="$inbox_dir"/public-inbox/msgmap.sqlite3 + inbox_lock="$inbox_dir"/ssoma.lock fi # run public-inbox-init iff unconfigured @@ -118,7 +120,18 @@ esac # don't know what indexlevel a user wants if test -f "$msgmap" then - n=$(echo 'SELECT COUNT(*) FROM msgmap' | sqlite3 -readonly "$msgmap") + # We need to use flock(1) (from util-linux) to avoid timeouts + # and SQLite locking problems. + # FreeBSD has a similar lockf(1) utility, but it unlinks by + # default so we use `-k' to keep the lock on the FS. + FLOCK=flock + case $(uname -s) in + FreeBSD) FLOCK='lockf -k' ;; + # ... other OSes here + esac + + n=$(echo 'SELECT COUNT(*) FROM msgmap' | \ + $FLOCK $inbox_lock sqlite3 -readonly "$msgmap") case $n in 0|'') : v2 inboxes may be init-ed with an empty msgmap |