Re: [PATCH v2 00/11] compactor changes v2

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+From: Tomi Ollila <tomi.ollila@iki.fi>\r
+To: Ben Gamari <bgamari.foss@gmail.com>, David Bremner <david@tethera.net>,\r
+       Jani Nikula <jani@nikula.org>, notmuch@notmuchmail.org\r
+Subject: Re: [PATCH v2 00/11] compactor changes v2\r
+In-Reply-To: <87wqkmhcpm.fsf@gmail.com>\r
+References: <cover.1383481295.git.jani@nikula.org>\r
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+Date: Tue, 05 Nov 2013 22:14:24 +0200\r
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+On Tue, Nov 05 2013, Ben Gamari <bgamari.foss@gmail.com> wrote:\r
+\r
+> Tomi Ollila <tomi.ollila@iki.fi> writes:\r
+>\r
+>>\r
+>> The whole series looks OK to me. The only thing I'm, a bit worried about\r
+>> what happens is I Ctrl-C compaction at any state. Is it possible that I\r
+>> end up with corrupted database ? Someone may accidentally execute\r
+>> notmuch compact -- for example by picking the command from history.\r
+>>\r
+> You should in principle never end up in a situation where the original\r
+> database is corrupted. Xapian's Compactor interface reads from the\r
+> existing database and writes out the compacted database to a new\r
+> directory. The notmuch compact command keeps the original database in\r
+> place until the last possible moment.\r
+>\r
+> When the compacted database is completely constructed it, deletes or\r
+> moves the old database out of the way and then moves the new database\r
+> into place. The worst thing that could happen is that you manage to\r
+> interrupt the process between deleting the old database and moving the\r
+> new one into place (a very small window). In this case you'd simply need\r
+> to move the new database into place manually (although you'd need to\r
+> figure out where the compacted database is located).\r
+\r
+Ah true. I failed to keep the whole picture in mind. Indeed the compactor\r
+first compacts from .notmuch/xapian to .notmuch/xapian.compact (and\r
+finally directory renaming is done in database.cc... (and with directories\r
+we cannot do atomic file update using link()/rename() calls). \r
+(If we wanted to handle this "small window" we could try use 'xapian.compact'\r
+directory in case 'xapian' was nonexistent but... :)\r
+\r
+That understood I'm ok with these pathes (when that oversight fixed).\r
+\r
+>   \r
+> Cheers,\r
+>\r
+> - Ben\r
+\r
+Tomi\r