Mercurial > hg
view mercurial/lock.py @ 22196:23fe278bde43
largefiles: keep largefiles from colliding with normal one during linear merge
Before this patch, linear merging of modified or newly added largefile
causes unexpected result, if (1) largefile collides with same name
normal one in the target revision and (2) "local" largefile is chosen,
even though branch merging between such revisions doesn't.
Expected result of such linear merging is:
(1) (not yet recorded) largefile is kept in the working directory
(2) largefile is marked as (re-)"added"
(3) colliding normal file is marked as "removed"
But actual result is:
(1) largefile in the working directory is unlinked
(2) largefile is marked as "normal" (so treated as "missing")
(3) the dirstate entry for colliding normal file is just dropped
(1) is very serious, because there is no way to restore temporarily
modified largefiles.
(3) prevents the next commit from adding the manifest with correct
"removal of (normal) file" information for newly created changeset.
The root cause of this problem is putting "lfile" into "actions['r']"
in linear-merging case. At liner merging, "actions['r']" causes:
- unlinking "target file" in the working directory, but "lfile" as
"target file" is also largefile itself in this case
- dropping the dirstate entry for target file
"actions['f']" (= "forget") does only the latter, and this is reason
why this patch doesn't choose putting "lfile" into it instead of
"actions['r']".
This patch newly introduces action "lfmr" (LargeFiles: Mark as
Removed) to mark colliding normal file as "removed" without unlinking
it.
This patch uses "hg debugdirstate" instead of "hg status" in test,
because:
- choosing "local largefile" hides "removed" status of "remote
normal file" in "hg status" output, and
- "hg status" for "large2" in this case has another problem fixed in
the subsequent patch
author | FUJIWARA Katsunori <foozy@lares.dti.ne.jp> |
---|---|
date | Fri, 15 Aug 2014 20:28:51 +0900 |
parents | c697b70f295f |
children | f484be02bd35 |
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# 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 if self.releasefn: self.releasefn() 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()