commandserver: add IPC channel to teach repository path on command finished
The idea is to load recently-used repositories first in the master process,
and fork(). The forked worker can reuse a warm repository if it's preloaded.
There are a couple of ways of in-memory repository caching. They have pros
and cons:
a. "preload by master"
pros: can use a single cache dict, maximizing cache hit rate
cons: need to reload a repo in master process (because worker process
dies per command)
b. "prefork"
pros: can cache a repo without reloading (as worker processes persist)
cons: lower cache hit rate since each worker has to maintain its own cache
c. "shared memory" (or separate key-value store server)
pros: no need to reload a repo in master process, ideally
cons: need to serialize objects to sharable form
Since my primary goal is to get rid of the cost of loading obsstore without
massive rewrites, (c) doesn't work. (b) isn't ideal since it would require
much more SDRAMs than (a). So I take (a).
The idea credits to Jun Wu.
[This file is here for historical purposes, all recent contributors
should appear in the changelog directly]
Andrea Arcangeli <andrea at suse.de>
Thomas Arendsen Hein <thomas at intevation.de>
Goffredo Baroncelli <kreijack at libero.it>
Muli Ben-Yehuda <mulix at mulix.org>
Mikael Berthe <mikael at lilotux.net>
Benoit Boissinot <bboissin at gmail.com>
Brendan Cully <brendan at kublai.com>
Vincent Danjean <vdanjean.ml at free.fr>
Jake Edge <jake at edge2.net>
Michael Fetterman <michael.fetterman at intel.com>
Edouard Gomez <ed.gomez at free.fr>
Eric Hopper <hopper at omnifarious.org>
Alecs King <alecsk at gmail.com>
Volker Kleinfeld <Volker.Kleinfeld at gmx.de>
Vadim Lebedev <vadim at mbdsys.com>
Christopher Li <hg at chrisli.org>
Chris Mason <mason at suse.com>
Colin McMillen <mcmillen at cs.cmu.edu>
Wojciech Milkowski <wmilkowski at interia.pl>
Chad Netzer <chad.netzer at gmail.com>
Bryan O'Sullivan <bos at serpentine.com>
Vicent Seguí Pascual <vseguip at gmail.com>
Sean Perry <shaleh at speakeasy.net>
Nguyen Anh Quynh <aquynh at gmail.com>
Ollivier Robert <roberto at keltia.freenix.fr>
Alexander Schremmer <alex at alexanderweb.de>
Arun Sharma <arun at sharma-home.net>
Josef "Jeff" Sipek <jeffpc at optonline.net>
Kevin Smith <yarcs at qualitycode.com>
TK Soh <teekaysoh at yahoo.com>
Radoslaw Szkodzinski <astralstorm at gorzow.mm.pl>
Samuel Tardieu <sam at rfc1149.net>
K Thananchayan <thananck at yahoo.com>
Andrew Thompson <andrewkt at aktzero.com>
Michael S. Tsirkin <mst at mellanox.co.il>
Rafael Villar Burke <pachi at mmn-arquitectos.com>
Tristan Wibberley <tristan at wibberley.org>
Mark Williamson <mark.williamson at cl.cam.ac.uk>