Mercurial > hg
view mercurial/hook.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> |
---|---|
date | Fri, 13 Apr 2018 11:02:34 -0700 |
parents | bbd240f81ac5 |
children | 483de34f23b1 |
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# hook.py - hook support for mercurial # # Copyright 2007 Matt Mackall <mpm@selenic.com> # # 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 os import sys from .i18n import _ from . import ( demandimport, encoding, error, extensions, pycompat, util, ) from .utils import ( procutil, ) def _pythonhook(ui, repo, htype, hname, funcname, args, throw): '''call python hook. hook is callable object, looked up as name in python module. if callable returns "true", hook fails, else passes. if hook raises exception, treated as hook failure. exception propagates if throw is "true". reason for "true" meaning "hook failed" is so that unmodified commands (e.g. mercurial.commands.update) can be run as hooks without wrappers to convert return values.''' if callable(funcname): obj = funcname funcname = pycompat.sysbytes(obj.__module__ + r"." + obj.__name__) else: d = funcname.rfind('.') if d == -1: raise error.HookLoadError( _('%s hook is invalid: "%s" not in a module') % (hname, funcname)) modname = funcname[:d] oldpaths = sys.path if procutil.mainfrozen(): # binary installs require sys.path manipulation modpath, modfile = os.path.split(modname) if modpath and modfile: sys.path = sys.path[:] + [modpath] modname = modfile with demandimport.deactivated(): try: obj = __import__(pycompat.sysstr(modname)) except (ImportError, SyntaxError): e1 = sys.exc_info() try: # extensions are loaded with hgext_ prefix obj = __import__(r"hgext_%s" % pycompat.sysstr(modname)) except (ImportError, SyntaxError): e2 = sys.exc_info() if ui.tracebackflag: ui.warn(_('exception from first failed import ' 'attempt:\n')) ui.traceback(e1) if ui.tracebackflag: ui.warn(_('exception from second failed import ' 'attempt:\n')) ui.traceback(e2) if not ui.tracebackflag: tracebackhint = _( 'run with --traceback for stack trace') else: tracebackhint = None raise error.HookLoadError( _('%s hook is invalid: import of "%s" failed') % (hname, modname), hint=tracebackhint) sys.path = oldpaths try: for p in funcname.split('.')[1:]: obj = getattr(obj, p) except AttributeError: raise error.HookLoadError( _('%s hook is invalid: "%s" is not defined') % (hname, funcname)) if not callable(obj): raise error.HookLoadError( _('%s hook is invalid: "%s" is not callable') % (hname, funcname)) ui.note(_("calling hook %s: %s\n") % (hname, funcname)) starttime = util.timer() try: r = obj(ui=ui, repo=repo, hooktype=htype, **pycompat.strkwargs(args)) except Exception as exc: if isinstance(exc, error.Abort): ui.warn(_('error: %s hook failed: %s\n') % (hname, exc.args[0])) else: ui.warn(_('error: %s hook raised an exception: ' '%s\n') % (hname, encoding.strtolocal(str(exc)))) if throw: raise if not ui.tracebackflag: ui.warn(_('(run with --traceback for stack trace)\n')) ui.traceback() return True, True finally: duration = util.timer() - starttime ui.log('pythonhook', 'pythonhook-%s: %s finished in %0.2f seconds\n', htype, funcname, duration) if r: if throw: raise error.HookAbort(_('%s hook failed') % hname) ui.warn(_('warning: %s hook failed\n') % hname) return r, False def _exthook(ui, repo, htype, name, cmd, args, throw): ui.note(_("running hook %s: %s\n") % (name, cmd)) starttime = util.timer() env = {} # make in-memory changes visible to external process if repo is not None: tr = repo.currenttransaction() repo.dirstate.write(tr) if tr and tr.writepending(): env['HG_PENDING'] = repo.root env['HG_HOOKTYPE'] = htype env['HG_HOOKNAME'] = name for k, v in args.iteritems(): if callable(v): v = v() if isinstance(v, dict): # make the dictionary element order stable across Python # implementations v = ('{' + ', '.join('%r: %r' % i for i in sorted(v.iteritems())) + '}') env['HG_' + k.upper()] = v if repo: cwd = repo.root else: cwd = pycompat.getcwd() r = ui.system(cmd, environ=env, cwd=cwd, blockedtag='exthook-%s' % (name,)) duration = util.timer() - starttime ui.log('exthook', 'exthook-%s: %s finished in %0.2f seconds\n', name, cmd, duration) if r: desc = procutil.explainexit(r) if throw: raise error.HookAbort(_('%s hook %s') % (name, desc)) ui.warn(_('warning: %s hook %s\n') % (name, desc)) return r # represent an untrusted hook command _fromuntrusted = object() def _allhooks(ui): """return a list of (hook-id, cmd) pairs sorted by priority""" hooks = _hookitems(ui) # Be careful in this section, propagating the real commands from untrusted # sources would create a security vulnerability, make sure anything altered # in that section uses "_fromuntrusted" as its command. untrustedhooks = _hookitems(ui, _untrusted=True) for name, value in untrustedhooks.items(): trustedvalue = hooks.get(name, (None, None, name, _fromuntrusted)) if value != trustedvalue: (lp, lo, lk, lv) = trustedvalue hooks[name] = (lp, lo, lk, _fromuntrusted) # (end of the security sensitive section) return [(k, v) for p, o, k, v in sorted(hooks.values())] def _hookitems(ui, _untrusted=False): """return all hooks items ready to be sorted""" hooks = {} for name, cmd in ui.configitems('hooks', untrusted=_untrusted): if not name.startswith('priority'): priority = ui.configint('hooks', 'priority.%s' % name, 0) hooks[name] = (-priority, len(hooks), name, cmd) return hooks _redirect = False def redirect(state): global _redirect _redirect = state def hashook(ui, htype): """return True if a hook is configured for 'htype'""" if not ui.callhooks: return False for hname, cmd in _allhooks(ui): if hname.split('.')[0] == htype and cmd: return True return False def hook(ui, repo, htype, throw=False, **args): if not ui.callhooks: return False hooks = [] for hname, cmd in _allhooks(ui): if hname.split('.')[0] == htype and cmd: hooks.append((hname, cmd)) res = runhooks(ui, repo, htype, hooks, throw=throw, **args) r = False for hname, cmd in hooks: r = res[hname][0] or r return r def runhooks(ui, repo, htype, hooks, throw=False, **args): args = pycompat.byteskwargs(args) res = {} oldstdout = -1 try: for hname, cmd in hooks: if oldstdout == -1 and _redirect: try: stdoutno = procutil.stdout.fileno() stderrno = procutil.stderr.fileno() # temporarily redirect stdout to stderr, if possible if stdoutno >= 0 and stderrno >= 0: procutil.stdout.flush() oldstdout = os.dup(stdoutno) os.dup2(stderrno, stdoutno) except (OSError, AttributeError): # files seem to be bogus, give up on redirecting (WSGI, etc) pass if cmd is _fromuntrusted: if throw: raise error.HookAbort( _('untrusted hook %s not executed') % hname, hint = _("see 'hg help config.trusted'")) ui.warn(_('warning: untrusted hook %s not executed\n') % hname) r = 1 raised = False elif callable(cmd): r, raised = _pythonhook(ui, repo, htype, hname, cmd, args, throw) elif cmd.startswith('python:'): if cmd.count(':') >= 2: path, cmd = cmd[7:].rsplit(':', 1) path = util.expandpath(path) if repo: path = os.path.join(repo.root, path) try: mod = extensions.loadpath(path, 'hghook.%s' % hname) except Exception: ui.write(_("loading %s hook failed:\n") % hname) raise hookfn = getattr(mod, cmd) else: hookfn = cmd[7:].strip() r, raised = _pythonhook(ui, repo, htype, hname, hookfn, args, throw) else: r = _exthook(ui, repo, htype, hname, cmd, args, throw) raised = False res[hname] = r, raised finally: # The stderr is fully buffered on Windows when connected to a pipe. # A forcible flush is required to make small stderr data in the # remote side available to the client immediately. procutil.stderr.flush() if _redirect and oldstdout >= 0: procutil.stdout.flush() # write hook output to stderr fd os.dup2(oldstdout, stdoutno) os.close(oldstdout) return res