Mercurial > hg
view mercurial/lock.py @ 46018:8b0a3ff5ed12
statprof: separate functions and "line", assume 4 digit line numbers
Previously, the profile output looked like this (I've removed many lines that
are mostly inconsequential):
```
| 100.0% 0.02s hg: <module> line 43: dispatch.run()
| 100.0% 0.02s dispatch.py: run line 115: status = dispatch(req)
| 100.0% 0.02s dispatch.py: _runcatchfunc line 432: return _dispatch(req)
\ 50.0% 0.01s dispatch.py: _dispatch line 1228: return runcommand(
| 50.0% 0.01s dispatch.py: runcommand line 883: ret = _runcommand(ui, optio...
| 50.0% 0.01s dispatch.py: _runcommand line 1240: return cmdfunc()
| 50.0% 0.01s localrepo.py: __getitem__ line 1670: quick_access = self._quick_...
| 50.0% 0.01s localrepo.py: _quick_access_changeidline 1650: return self._quick_access_c...
| 50.0% 0.01s localrepo.py: __get__ line 179: return getattr(unfi, self.n...
| 50.0% 0.01s util.py: __get__ line 1747: result = self.func(obj)
| 50.0% 0.01s localrepo.py: _quick_access_changeid_wcline 1611: cl = self.unfiltered().chan...
| 50.0% 0.01s localrepo.py: __get__ line 110: return super(_basefilecache...
| 50.0% 0.01s util.py: __getattribute__line 245: self.__spec__.loader.exec_m...
| 50.0% 0.01s <frozen importlib._bootstrap_external>: exec_moduleline 783:
| 50.0% 0.01s <frozen importlib._bootstrap>: _call_with_frames_removedline 219:
| 50.0% 0.01s changelog.py: <module> line 376: class changelog(revlog.revl...
| 50.0% 0.01s util.py: __getattribute__line 245: self.__spec__.loader.exec_m...
| 50.0% 0.01s <frozen importlib._bootstrap_external>: exec_moduleline 779:
| 50.0% 0.01s <frozen importlib._bootstrap_external>: get_codeline 868:
| 50.0% 0.01s <frozen importlib._bootstrap_external>: path_statsline 1012:
| 50.0% 0.01s <frozen importlib._bootstrap_external>: _path_statline 87:
```
This has a few problems, though I'm only addressing some of them.
1. If the stuff before "line ###" is long, there's no separation between the
function name and the "line" string.
2. If the stuff before "line ###" is really long, there's excessive separation
between the "line" string and the line number.
3. We frequently have 4-digit line numbers, the code on the right wasn't
dynamically indented and ended up quite messy looking.
To solve these problems, I've added a ", " prefix before "line" iff it would
otherwise not have any separation such as spaces. I've added a 'max' so that we
never use a negative width (which is the cause of problem #2 above), and I've
added a default assumption of 4 digit line numbers (but again using a 'max' so
this shouldn't cause problems if we go beyond that.
With these changes, it now looks like this:
```
| 100.0% 0.02s hg: <module> line 43: dispatch.run()
| 100.0% 0.02s dispatch.py: run line 115: status = dispatch(req)
| 100.0% 0.02s dispatch.py: _runcatchfunc line 432: return _dispatch(req)
\ 50.0% 0.01s dispatch.py: _dispatch line 1228: return runcommand(
| 50.0% 0.01s dispatch.py: runcommand line 883: ret = _runcommand(ui, optio...
| 50.0% 0.01s dispatch.py: _runcommand line 1240: return cmdfunc()
| 50.0% 0.01s localrepo.py: __getitem__ line 1670: quick_access = self._quick_...
| 50.0% 0.01s localrepo.py: _quick_access_changeid, line 1650: return self._quick_access_c...
| 50.0% 0.01s localrepo.py: __get__ line 179: return getattr(unfi, self.n...
| 50.0% 0.01s util.py: __get__ line 1747: result = self.func(obj)
| 50.0% 0.01s localrepo.py: _quick_access_changeid_wc, line 1611: cl = self.unfiltered().chan...
| 50.0% 0.01s localrepo.py: __get__ line 110: return super(_basefilecache...
| 50.0% 0.01s util.py: __getattribute__, line 245: self.__spec__.loader.exec_m...
| 50.0% 0.01s <frozen importlib._bootstrap_external>: exec_module, line 783:
| 50.0% 0.01s <frozen importlib._bootstrap>: _call_with_frames_removed, line 219:
| 50.0% 0.01s changelog.py: <module> line 376: class changelog(revlog.revl...
| 50.0% 0.01s util.py: __getattribute__, line 245: self.__spec__.loader.exec_m...
| 50.0% 0.01s <frozen importlib._bootstrap_external>: exec_module, line 779:
| 50.0% 0.01s <frozen importlib._bootstrap_external>: get_code, line 868:
| 50.0% 0.01s <frozen importlib._bootstrap_external>: path_stats, line 1012:
| 50.0% 0.01s <frozen importlib._bootstrap_external>: _path_stat, line 87:
```
Differential Revision: https://phab.mercurial-scm.org/D9511
author | Kyle Lippincott <spectral@google.com> |
---|---|
date | Wed, 02 Dec 2020 12:33:51 -0800 |
parents | 89a2afe31e82 |
children | d4ba4d51f85f |
line wrap: on
line source
# lock.py - simple advisory locking scheme for mercurial # # Copyright 2005, 2006 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 contextlib import errno import os import signal import socket import time import warnings from .i18n import _ from .pycompat import getattr from . import ( encoding, error, pycompat, util, ) from .utils import procutil def _getlockprefix(): """Return a string which is used to differentiate pid namespaces It's useful to detect "dead" processes and remove stale locks with confidence. Typically it's just hostname. On modern linux, we include an extra Linux-specific pid namespace identifier. """ result = encoding.strtolocal(socket.gethostname()) if pycompat.sysplatform.startswith(b'linux'): try: result += b'/%x' % os.stat(b'/proc/self/ns/pid').st_ino except OSError as ex: if ex.errno not in (errno.ENOENT, errno.EACCES, errno.ENOTDIR): raise return result @contextlib.contextmanager def _delayedinterrupt(): """Block signal interrupt while doing something critical This makes sure that the code block wrapped by this context manager won't be interrupted. For Windows developers: It appears not possible to guard time.sleep() from CTRL_C_EVENT, so please don't use time.sleep() to test if this is working. """ assertedsigs = [] blocked = False orighandlers = {} def raiseinterrupt(num): if num == getattr(signal, 'SIGINT', None) or num == getattr( signal, 'CTRL_C_EVENT', None ): raise KeyboardInterrupt else: raise error.SignalInterrupt def catchterm(num, frame): if blocked: assertedsigs.append(num) else: raiseinterrupt(num) try: # save handlers first so they can be restored even if a setup is # interrupted between signal.signal() and orighandlers[] =. for name in [ b'CTRL_C_EVENT', b'SIGINT', b'SIGBREAK', b'SIGHUP', b'SIGTERM', ]: num = getattr(signal, name, None) if num and num not in orighandlers: orighandlers[num] = signal.getsignal(num) try: for num in orighandlers: signal.signal(num, catchterm) except ValueError: pass # in a thread? no luck blocked = True yield finally: # no simple way to reliably restore all signal handlers because # any loops, recursive function calls, except blocks, etc. can be # interrupted. so instead, make catchterm() raise interrupt. blocked = False try: for num, handler in orighandlers.items(): signal.signal(num, handler) except ValueError: pass # in a thread? # re-raise interrupt exception if any, which may be shadowed by a new # interrupt occurred while re-raising the first one if assertedsigs: raiseinterrupt(assertedsigs[0]) def trylock(ui, vfs, lockname, timeout, warntimeout, *args, **kwargs): """return an acquired lock or raise an a LockHeld exception This function is responsible to issue warnings and or debug messages about the held lock while trying to acquires it.""" def printwarning(printer, locker): """issue the usual "waiting on lock" message through any channel""" # show more details for new-style locks if b':' in locker: host, pid = locker.split(b":", 1) msg = _( b"waiting for lock on %s held by process %r on host %r\n" ) % ( pycompat.bytestr(l.desc), pycompat.bytestr(pid), pycompat.bytestr(host), ) else: msg = _(b"waiting for lock on %s held by %r\n") % ( l.desc, pycompat.bytestr(locker), ) printer(msg) l = lock(vfs, lockname, 0, *args, dolock=False, **kwargs) debugidx = 0 if (warntimeout and timeout) else -1 warningidx = 0 if not timeout: warningidx = -1 elif warntimeout: warningidx = warntimeout delay = 0 while True: try: l._trylock() break except error.LockHeld as inst: if delay == debugidx: printwarning(ui.debug, inst.locker) if delay == warningidx: printwarning(ui.warn, inst.locker) if timeout <= delay: raise error.LockHeld( errno.ETIMEDOUT, inst.filename, l.desc, inst.locker ) time.sleep(1) delay += 1 l.delay = delay if l.delay: if 0 <= warningidx <= l.delay: ui.warn(_(b"got lock after %d seconds\n") % l.delay) else: ui.debug(b"got lock after %d seconds\n" % l.delay) if l.acquirefn: l.acquirefn() return l class lock(object): """An advisory lock held by one process to control access to a set of files. Non-cooperating processes or incorrectly written scripts can ignore Mercurial's locking scheme and stomp all over the repository, so don't do that. Typically used via localrepository.lock() to lock the repository store (.hg/store/) or localrepository.wlock() to lock everything else under .hg/.""" # lock is symlink on platforms that support it, file on others. # symlink is used because create of directory entry and contents # are atomic even over nfs. # old-style lock: symlink to pid # new-style lock: symlink to hostname:pid _host = None def __init__( self, vfs, fname, timeout=-1, releasefn=None, acquirefn=None, desc=None, signalsafe=True, dolock=True, ): self.vfs = vfs self.f = fname self.held = 0 self.timeout = timeout self.releasefn = releasefn self.acquirefn = acquirefn self.desc = desc if signalsafe: self._maybedelayedinterrupt = _delayedinterrupt else: self._maybedelayedinterrupt = util.nullcontextmanager self.postrelease = [] self.pid = self._getpid() if dolock: self.delay = self.lock() if self.acquirefn: self.acquirefn() def __enter__(self): return self def __exit__(self, exc_type, exc_value, exc_tb): success = all(a is None for a in (exc_type, exc_value, exc_tb)) self.release(success=success) def __del__(self): if self.held: warnings.warn( "use lock.release instead of del lock", category=DeprecationWarning, stacklevel=2, ) # ensure the lock will be removed # even if recursive locking did occur self.held = 1 self.release() def _getpid(self): # wrapper around procutil.getpid() to make testing easier return procutil.getpid() def lock(self): timeout = self.timeout while True: try: self._trylock() return self.timeout - timeout except error.LockHeld as inst: if timeout != 0: time.sleep(1) if timeout > 0: timeout -= 1 continue raise error.LockHeld( errno.ETIMEDOUT, inst.filename, self.desc, inst.locker ) def _trylock(self): if self.held: self.held += 1 return if lock._host is None: lock._host = _getlockprefix() lockname = b'%s:%d' % (lock._host, self.pid) retry = 5 while not self.held and retry: retry -= 1 try: with self._maybedelayedinterrupt(): self.vfs.makelock(lockname, self.f) self.held = 1 except (OSError, IOError) as why: if why.errno == errno.EEXIST: locker = self._readlock() if locker is None: continue locker = self._testlock(locker) if locker is not None: raise error.LockHeld( errno.EAGAIN, self.vfs.join(self.f), self.desc, locker, ) else: raise error.LockUnavailable( why.errno, why.strerror, why.filename, self.desc ) if not self.held: # use empty locker to mean "busy for frequent lock/unlock # by many processes" raise error.LockHeld( errno.EAGAIN, self.vfs.join(self.f), self.desc, b"" ) def _readlock(self): """read lock and return its value Returns None if no lock exists, pid for old-style locks, and host:pid for new-style locks. """ try: return self.vfs.readlock(self.f) except (OSError, IOError) as why: if why.errno == errno.ENOENT: return None raise def _lockshouldbebroken(self, locker): if locker is None: return False try: host, pid = locker.split(b":", 1) except ValueError: return False if host != lock._host: return False try: pid = int(pid) except ValueError: return False if procutil.testpid(pid): return False return True def _testlock(self, locker): if not self._lockshouldbebroken(locker): return locker # if locker dead, break lock. must do this with another lock # held, or can race and break valid lock. try: with lock(self.vfs, self.f + b'.break', timeout=0): locker = self._readlock() if not self._lockshouldbebroken(locker): return locker self.vfs.unlink(self.f) except error.LockError: return locker def testlock(self): """return id of locker if lock is valid, else None. If old-style lock, we cannot tell what machine locker is on. with new-style lock, if locker is on this machine, we can see if locker is alive. If locker is on this machine but not alive, we can safely break lock. The lock file is only deleted when None is returned. """ locker = self._readlock() return self._testlock(locker) def release(self, success=True): """release the lock and execute callback function if any If the lock has been acquired multiple times, the actual release is delayed to the last release call.""" if self.held > 1: self.held -= 1 elif self.held == 1: self.held = 0 if self._getpid() != self.pid: # we forked, and are not the parent return try: if self.releasefn: self.releasefn() finally: try: self.vfs.unlink(self.f) except OSError: pass # The postrelease functions typically assume the lock is not held # at all. for callback in self.postrelease: callback(success) # Prevent double usage and help clear cycles. self.postrelease = None def release(*locks): for lock in locks: if lock is not None: lock.release()