Mercurial > hg
view mercurial/lock.py @ 24956:48583a1e44f3
treemanifest: set requires at repo creation time, ignore config after
The very next changeset will start writing one revlog per directory
when tree manifests are enabled. That is backwards incompatible, so it
requires .hg/requires to be updated. Just like with generaldelta, we
want to update .hg/requires only when the repo is created. Updating
..hg/requires is bad for repos on shared disk. Instead, those who do
want to upgrade a repo to using treemanifest (or manifestv2, etc) can
run
hg clone --config experimental.treemanifest repo clone
which will create a new repo with the requirement set. Unlike the case
of e.g. generaldelta, it will not rewrite the changesets, since tree
manifests hash differently.
author | Martin von Zweigbergk <martinvonz@google.com> |
---|---|
date | Tue, 05 May 2015 08:40:59 -0700 |
parents | f484be02bd35 |
children | 328739ea70c3 |
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. import util, error import errno, os, socket, time import warnings 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, file, timeout=-1, releasefn=None, desc=None): self.vfs = vfs self.f = file self.held = 0 self.timeout = timeout self.releasefn = releasefn self.desc = desc self.postrelease = [] self.pid = os.getpid() self.delay = self.lock() 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 lock(self): timeout = self.timeout while True: try: self.trylock() return self.timeout - timeout except error.LockHeld, 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 = socket.gethostname() lockname = '%s:%s' % (lock._host, self.pid) while not self.held: try: self.vfs.makelock(lockname, self.f) self.held = 1 except (OSError, IOError), why: if why.errno == errno.EEXIST: locker = self.testlock() 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) 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. """ try: locker = self.vfs.readlock(self.f) except (OSError, IOError), why: if why.errno == errno.ENOENT: return None raise try: host, pid = locker.split(":", 1) except ValueError: return locker if host != lock._host: return locker try: pid = int(pid) except ValueError: return locker if util.testpid(pid): return locker # if locker dead, break lock. must do this with another lock # held, or can race and break valid lock. try: l = lock(self.vfs, self.f + '.break', timeout=0) self.vfs.unlink(self.f) l.release() except error.LockError: return locker def release(self): """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 os.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 for callback in self.postrelease: callback() def release(*locks): for lock in locks: if lock is not None: lock.release()