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view tests/bruterebase.py @ 37631:2f626233859b
wireproto: implement batching on peer executor interface
This is a bit more complicated than non-batch requests because we
need to buffer sends until the last request arrives *and* we need
to support resolving futures as data arrives from the remote.
In a classical concurrent.futures executor model, the future
"starts" as soon as it is submitted. However, we have nothing to
start until the last command is submitted.
If we did nothing, calling result() would deadlock, since the future
hasn't "started." So in the case where we queue the command, we return
a special future type whose result() will trigger sendcommands().
This eliminates the deadlock potential. It also serves as a check
against callers who may be calling result() prematurely, as it will
prevent any subsequent callcommands() from working. This behavior
is slightly annoying and a bit restrictive. But it's the world
that half duplex connections forces on us.
In order to support streaming responses, we were previously using
a generator. But with a futures-based API, we're using futures
and not generators. So in order to get streaming, we need a
background thread to read data from the server.
The approach taken in this patch is to leverage the ThreadPoolExecutor
from concurrent.futures for managing a background thread. We create
an executor and future that resolves when all response data is
processed (or an error occurs). When exiting the context manager,
we wait on that background reading before returning.
I was hoping we could manually spin up a threading.Thread and this
would be simple. But I ran into a few deadlocks when implementing.
After looking at the source code to concurrent.futures, I figured
it would just be easier to use a ThreadPoolExecutor than implement
all the code needed to manually manage a thread.
To prove this works, a use of the batch API in discovery has been
updated.
Differential Revision: https://phab.mercurial-scm.org/D3269
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Fri, 13 Apr 2018 11:02:34 -0700 |
parents | 3b98ffd2dde3 |
children | 337d6e0fd9c9 |
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# bruterebase.py - brute force rebase testing # # Copyright 2017 Facebook, Inc. # # 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 from mercurial import ( error, registrar, revsetlang, ) from hgext import rebase try: xrange except NameError: xrange = range cmdtable = {} command = registrar.command(cmdtable) @command(b'debugbruterebase') def debugbruterebase(ui, repo, source, dest): """for every non-empty subset of source, run rebase -r subset -d dest Print one line summary for each subset. Assume obsstore is enabled. """ srevs = list(repo.revs(source)) with repo.wlock(), repo.lock(): repolen = len(repo) cl = repo.changelog def getdesc(rev): result = cl.changelogrevision(rev).description if rev >= repolen: result += b"'" return result for i in xrange(1, 2 ** len(srevs)): subset = [rev for j, rev in enumerate(srevs) if i & (1 << j) != 0] spec = revsetlang.formatspec(b'%ld', subset) tr = repo.transaction(b'rebase') tr.report = lambda x: 0 # hide "transaction abort" ui.pushbuffer() try: rebase.rebase(ui, repo, dest=dest, rev=[spec]) except error.Abort as ex: summary = b'ABORT: %s' % ex except Exception as ex: summary = b'CRASH: %s' % ex else: # short summary about new nodes cl = repo.changelog descs = [] for rev in xrange(repolen, len(repo)): desc = b'%s:' % getdesc(rev) for prev in cl.parentrevs(rev): if prev > -1: desc += getdesc(prev) descs.append(desc) descs.sort() summary = b' '.join(descs) ui.popbuffer() repo.vfs.tryunlink(b'rebasestate') subsetdesc = b''.join(getdesc(rev) for rev in subset) ui.write((b'%s: %s\n') % (subsetdesc.rjust(len(srevs)), summary)) tr.abort()