From 0a2558aabfefd6800fe74c24e5aff2b0d47cc5e2 Mon Sep 17 00:00:00 2001 From: Guilhem Moulin Date: Mon, 11 Nov 2019 00:39:09 +0100 Subject: Avoid sending large UID EXPUNGE|FETCH|STORE and APPEND commands. UID EXPUNGE|FETCH|STORE commands are now split into multiple (sequential) commands when their set representation exceeds 4096 bytes in size. Without splitting logic set representations could grow arbitrarily large, and exceed the server's maximum command size. This adds roundtrips which could be eliminated by pipelining, but it's unlikely to make any difference in typical synchronization work. While set representations seem to remain small in practice, they might grow significantly if many non-contiguous UIDs were flagged and/or expunged, and later synchronized at once. Furthermore, for MULTIAPPEND-capable servers, the number of messages is limited to 128 per APPEND command (also subject to a combined literal size of 1MiB like before). These numbers are currently not configurable. They're intentionally lower than Dovecot's default maximum command size (64k) in order to avoid a deadlock situation after sending 8k-long commands under COMPRESS=DEFLATE: https://dovecot.org/pipermail/dovecot/2019-November/117522.html . --- Changelog | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'Changelog') diff --git a/Changelog b/Changelog index 763a7a1..f0c9e50 100644 --- a/Changelog +++ b/Changelog @@ -94,6 +94,17 @@ interimap (0.5) upstream; FETCH response was received. - libinterimap: push_flag_updates(): don't ignores received updates (by another client) to a superset of the desigred flag list. + - libinterimap: avoid sending large UID EXPUNGE|FETCH|STORE commands as + they might exceed the server's max acceptable command size; these + commands are now split into multiple (sequential) commands when their + set representation exceeds 4096 bytes in size. Performance could be + improved by pipelining but given the scope of this software + (synchronization) it's unlikely to make any difference in practice. + This is a also a workaround for a bug in Dovecot 2.3.4: + https://dovecot.org/pipermail/dovecot/2019-November/117522.html + - interimap: for the reason explained above, limit number of messages + to 128 per APPEND command (only on servers advertizing MULTIAPPEND, + for other servers the number remains 1). -- Guilhem Moulin Fri, 10 May 2019 00:58:14 +0200 -- cgit v1.2.3