Mercurial > hg
view mercurial/repocache.py @ 42522:d29db0a0c4eb
update: fix spurious unclean status bug shown by previous commit
The crux of the problem is:
- the dirstate is corrupted (the sizes/dates are assigned to the wrong files)
- because when worker.worker is used with a return value (batchget in
merge.py here), the return value when worker.worker effectively parallelizes
is permuted
- this is because worker.worker's partition of input and combination of output
values are not inverses of one another: it split [1,2,3,4,5,6] into
[[1,3,5],[2,4,6]], but combines that into [1,3,5,2,4,6].
Given that worker.worker doesn't call its function argument on contiguous
chunks on the input arguments, sticking with lists means we'd need to
know the relation between the inputs of worker.worker function argument
(for instance, requiring that every input element is mapped to exactly
one output element). It seems better to instead switch return values to
dicts, which can combined reliably with a straighforward restriction.
Differential Revision: https://phab.mercurial-scm.org/D6581
author | Valentin Gatien-Baron <valentin.gatienbaron@gmail.com> |
---|---|
date | Thu, 27 Jun 2019 11:39:35 +0200 |
parents | dcac24ec935b |
children | 2372284d9457 |
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# repocache.py - in-memory repository cache for long-running services # # Copyright 2018 Yuya Nishihara <yuya@tcha.org> # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. from __future__ import absolute_import import collections import gc import threading from . import ( error, hg, obsolete, scmutil, util, ) class repoloader(object): """Load repositories in background thread This is designed for a forking server. A cached repo cannot be obtained until the server fork()s a worker and the loader thread stops. """ def __init__(self, ui, maxlen): self._ui = ui.copy() self._cache = util.lrucachedict(max=maxlen) # use deque and Event instead of Queue since deque can discard # old items to keep at most maxlen items. self._inqueue = collections.deque(maxlen=maxlen) self._accepting = False self._newentry = threading.Event() self._thread = None def start(self): assert not self._thread if self._inqueue.maxlen == 0: # no need to spawn loader thread as the cache is disabled return self._accepting = True self._thread = threading.Thread(target=self._mainloop) self._thread.start() def stop(self): if not self._thread: return self._accepting = False self._newentry.set() self._thread.join() self._thread = None self._cache.clear() self._inqueue.clear() def load(self, path): """Request to load the specified repository in background""" self._inqueue.append(path) self._newentry.set() def get(self, path): """Return a cached repo if available This function must be called after fork(), where the loader thread is stopped. Otherwise, the returned repo might be updated by the loader thread. """ if self._thread and self._thread.is_alive(): raise error.ProgrammingError(b'cannot obtain cached repo while ' b'loader is active') return self._cache.peek(path, None) def _mainloop(self): while self._accepting: # Avoid heavy GC after fork(), which would cancel the benefit of # COW. We assume that GIL is acquired while GC is underway in the # loader thread. If that isn't true, we might have to move # gc.collect() to the main thread so that fork() would never stop # the thread where GC is in progress. gc.collect() self._newentry.wait() while self._accepting: self._newentry.clear() try: path = self._inqueue.popleft() except IndexError: break scmutil.callcatch(self._ui, lambda: self._load(path)) def _load(self, path): start = util.timer() # TODO: repo should be recreated if storage configuration changed try: # pop before loading so inconsistent state wouldn't be exposed repo = self._cache.pop(path) except KeyError: repo = hg.repository(self._ui, path).unfiltered() _warmupcache(repo) repo.ui.log(b'repocache', b'loaded repo into cache: %s (in %.3fs)\n', path, util.timer() - start) self._cache.insert(path, repo) # TODO: think about proper API of preloading cache def _warmupcache(repo): repo.invalidateall() repo.changelog repo.obsstore._all repo.obsstore.successors repo.obsstore.predecessors repo.obsstore.children for name in obsolete.cachefuncs: obsolete.getrevs(repo, name) repo._phasecache.loadphaserevs(repo) # TODO: think about proper API of attaching preloaded attributes def copycache(srcrepo, destrepo): """Copy cached attributes from srcrepo to destrepo""" destfilecache = destrepo._filecache srcfilecache = srcrepo._filecache if 'changelog' in srcfilecache: destfilecache['changelog'] = ce = srcfilecache['changelog'] ce.obj.opener = ce.obj._realopener = destrepo.svfs if 'obsstore' in srcfilecache: destfilecache['obsstore'] = ce = srcfilecache['obsstore'] ce.obj.svfs = destrepo.svfs if '_phasecache' in srcfilecache: destfilecache['_phasecache'] = ce = srcfilecache['_phasecache'] ce.obj.opener = destrepo.svfs