[PATCH] forbid atomic transactions on writable, upgradable databases

diff --git a/a1/69847ddd3df62b3acda20e1275430e331569b0 b/a1/69847ddd3df62b3acda20e1275430e331569b0
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+Sender: Steven <stebalien@gmail.com>\r
+From: Steven Allen <steven@stebalien.com>\r
+To: notmuch@notmuchmail.org\r
+Cc: Steven Allen <steven@stebalien.com>\r
+Subject: [PATCH] forbid atomic transactions on writable, upgradable databases\r
+Date: Sun, 25 Oct 2015 17:30:39 -0400\r
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+We can't (but currently do) allow upgrades within transactions because\r
+upgrades need their own transactions. We don't want to re-use the\r
+current transaction because bailing out of an upgrade would mean loosing\r
+all previous changes (because our "atomic" transactions don't commit\r
+before hand). This gives us two options:\r
+\r
+1. Fail at the beginning of upgrade (tell the user to end the\r
+   transaction, upgrade, and start over).\r
+2. Don't allow the user to start the transaction.\r
+\r
+I went with the latter because:\r
+\r
+1. There is no reason to call `begin_atomic` unless you intend to to\r
+   write to the database and anyone intending to write to the database\r
+   should upgrade it first.\r
+2. This means that nothing inside an atomic transaction can ever fail\r
+   with NOTMUCH_STATUS_UPGRADE_REQUIRED.\r
+---\r
+ lib/database.cc | 3 +++\r
+ 1 file changed, 3 insertions(+)\r
+\r
+diff --git a/lib/database.cc b/lib/database.cc\r
+index 5e86955..3b342f1 100644\r
+--- a/lib/database.cc\r
++++ b/lib/database.cc\r
+@@ -1635,6 +1635,9 @@ notmuch_database_begin_atomic (notmuch_database_t *notmuch)\r
+       notmuch->atomic_nesting > 0)\r
+       goto DONE;\r
+ \r
++      if (notmuch_database_needs_upgrade(notmuch))\r
++              return NOTMUCH_STATUS_UPGRADE_REQUIRED;\r
++\r
+     try {\r
+       (static_cast <Xapian::WritableDatabase *> (notmuch->xapian_db))->begin_transaction (false);\r
+     } catch (const Xapian::Error &error) {\r
+-- \r
+2.6.2\r
+\r