Re: notmuch dump: taking write-lock to protect from concurrent (cronned) notmuch...

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+From: Mark Walters <markwalters1009@gmail.com>\r
+To: Maarten Aertsen <sagi-notmuch@rtsn.nl>, notmuch@notmuchmail.org\r
+Subject: Re: notmuch dump: taking write-lock to protect from concurrent\r
+       (cronned) notmuch new?\r
+In-Reply-To: <20140606080354.28047.77393@kardo.rtsn.nl>\r
+References: <20140606080354.28047.77393@kardo.rtsn.nl>\r
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+\r
+\r
+On Fri, 06 Jun 2014, Maarten Aertsen <sagi-notmuch@rtsn.nl> wrote:\r
+> Hi everyone,\r
+>\r
+> (summary of IRC-conversation just now)\r
+> I did:\r
+>   - run notmuch new (and afew -t) in cron, every two minutes\r
+>   - run notmuch dump in cron, every 12 hours\r
+>\r
+> I expected:\r
+>   - notmuch dump to complete, possibly causing notmuch new to fail in the meantime\r
+>\r
+> I observed:\r
+>   - notmuch dump terminating with:\r
+> "terminate called after throwing an instance of 'Xapian::DatabaseModifiedError'"\r
+>\r
+> mjw1009 suggested to change NOTMUCH_DATABASE_MODE_READ_ONLY on line\r
+> 215 of notmuch-dump.c to NOTMUCH_DATABASE_MODE_READ_WRITE\r
+>\r
+> I'm wondering if this hits enough people to motivate the addition of a\r
+> command line switch (or perhaps even a change in default behaviour?)\r
+\r
+I think this is a clear bug but the fix is a little unclear. The above\r
+fix works but it breaks one of the tests: "unicode message-ids" in\r
+T150-tagging.sh.\r
+\r
+I think the problem is that it does \r
+notmuch dump | sed... | notmuch restore\r
+\r
+and if we open the dump read-write the restore will fail.\r
+\r
+We can obviously fix the test, but I don't know if anyone is using a\r
+pipe of this sort in their scripts. If this a likely problem then we\r
+could offer a --no-lock option (which keeps the behaviour as now)\r
+\r
+What do people think?\r
+\r
+Best wishes\r
+\r
+Mark\r
+\r