git_cache: Remove locks
These aren't in use, and the original problem they were
meant to solve has been solved at the gclient.py layer
using resource locking:
https://codereview.chromium.org/2049583003
Bug: 773008
Change-Id: I6609f39d7f15604e0bb3d742a41c4f9fec87a57a
Reviewed-on: https://chromium-review.googlesource.com/707728
Reviewed-by: Aaron Gable <agable@chromium.org>
Reviewed-by: Robbie Iannucci <iannucci@chromium.org>
Commit-Queue: Ryan Tseng <hinoka@chromium.org>
diff --git a/git_cache.py b/git_cache.py
index 20b8445..3229202 100755
--- a/git_cache.py
+++ b/git_cache.py
@@ -35,9 +35,6 @@
class WinErr(Exception):
pass
-class LockError(Exception):
- pass
-
class ClobberNeeded(Exception):
pass
@@ -77,122 +74,11 @@
sleep_time *= 2
-class Lockfile(object):
- """Class to represent a cross-platform process-specific lockfile."""
-
- def __init__(self, path, timeout=0):
- self.path = os.path.abspath(path)
- self.timeout = timeout
- self.lockfile = self.path + ".lock"
- self.pid = os.getpid()
-
- def _read_pid(self):
- """Read the pid stored in the lockfile.
-
- Note: This method is potentially racy. By the time it returns the lockfile
- may have been unlocked, removed, or stolen by some other process.
- """
- try:
- with open(self.lockfile, 'r') as f:
- pid = int(f.readline().strip())
- except (IOError, ValueError):
- pid = None
- return pid
-
- def _make_lockfile(self):
- """Safely creates a lockfile containing the current pid."""
- open_flags = (os.O_CREAT | os.O_EXCL | os.O_WRONLY)
- fd = os.open(self.lockfile, open_flags, 0o644)
- f = os.fdopen(fd, 'w')
- print(self.pid, file=f)
- f.close()
-
- def _remove_lockfile(self):
- """Delete the lockfile. Complains (implicitly) if it doesn't exist.
-
- See gclient_utils.py:rmtree docstring for more explanation on the
- windows case.
- """
- if sys.platform == 'win32':
- lockfile = os.path.normcase(self.lockfile)
-
- def delete():
- exitcode = subprocess.call(['cmd.exe', '/c',
- 'del', '/f', '/q', lockfile])
- if exitcode != 0:
- raise LockError('Failed to remove lock: %s' % (lockfile,))
- exponential_backoff_retry(
- delete,
- excs=(LockError,),
- name='del [%s]' % (lockfile,))
- else:
- os.remove(self.lockfile)
-
- def lock(self):
- """Acquire the lock.
-
- This will block with a deadline of self.timeout seconds.
- """
- elapsed = 0
- while True:
- try:
- self._make_lockfile()
- return
- except OSError as e:
- if elapsed < self.timeout:
- sleep_time = max(10, min(3, self.timeout - elapsed))
- logging.info('Could not create git cache lockfile; '
- 'will retry after sleep(%d).', sleep_time);
- elapsed += sleep_time
- time.sleep(sleep_time)
- continue
- if e.errno == errno.EEXIST:
- raise LockError("%s is already locked" % self.path)
- else:
- raise LockError("Failed to create %s (err %s)" % (self.path, e.errno))
-
- def unlock(self):
- """Release the lock."""
- try:
- if not self.is_locked():
- raise LockError("%s is not locked" % self.path)
- if not self.i_am_locking():
- raise LockError("%s is locked, but not by me" % self.path)
- self._remove_lockfile()
- except WinErr:
- # Windows is unreliable when it comes to file locking. YMMV.
- pass
-
- def break_lock(self):
- """Remove the lock, even if it was created by someone else."""
- try:
- self._remove_lockfile()
- return True
- except OSError as exc:
- if exc.errno == errno.ENOENT:
- return False
- else:
- raise
-
- def is_locked(self):
- """Test if the file is locked by anyone.
-
- Note: This method is potentially racy. By the time it returns the lockfile
- may have been unlocked, removed, or stolen by some other process.
- """
- return os.path.exists(self.lockfile)
-
- def i_am_locking(self):
- """Test if the file is locked by this process."""
- return self.is_locked() and self.pid == self._read_pid()
-
-
class Mirror(object):
git_exe = 'git.bat' if sys.platform.startswith('win') else 'git'
gsutil_exe = os.path.join(
os.path.dirname(os.path.abspath(__file__)), 'gsutil.py')
- cachepath_lock = threading.Lock()
@staticmethod
def parse_fetch_spec(spec):
@@ -254,23 +140,21 @@
@classmethod
def SetCachePath(cls, cachepath):
- with cls.cachepath_lock:
- setattr(cls, 'cachepath', cachepath)
+ setattr(cls, 'cachepath', cachepath)
@classmethod
def GetCachePath(cls):
- with cls.cachepath_lock:
- if not hasattr(cls, 'cachepath'):
- try:
- cachepath = subprocess.check_output(
- [cls.git_exe, 'config', '--global', 'cache.cachepath']).strip()
- except subprocess.CalledProcessError:
- cachepath = None
- if not cachepath:
- raise RuntimeError(
- 'No global cache.cachepath git configuration found.')
- setattr(cls, 'cachepath', cachepath)
- return getattr(cls, 'cachepath')
+ if not hasattr(cls, 'cachepath'):
+ try:
+ cachepath = subprocess.check_output(
+ [cls.git_exe, 'config', '--global', 'cache.cachepath']).strip()
+ except subprocess.CalledProcessError:
+ cachepath = None
+ if not cachepath:
+ raise RuntimeError(
+ 'No global cache.cachepath git configuration found.')
+ setattr(cls, 'cachepath', cachepath)
+ return getattr(cls, 'cachepath')
def Rename(self, src, dst):
# This is somehow racy on Windows.
@@ -487,17 +371,12 @@
raise ClobberNeeded() # Corrupted cache.
logging.warn('Fetch of %s failed' % spec)
- def populate(self, depth=None, shallow=False, bootstrap=False,
- verbose=False, ignore_lock=False, lock_timeout=0):
+ def populate(self, depth=None, shallow=False, bootstrap=False, verbose=False):
assert self.GetCachePath()
if shallow and not depth:
depth = 10000
gclient_utils.safe_makedirs(self.GetCachePath())
- lockfile = Lockfile(self.mirror_path, lock_timeout)
- if not ignore_lock:
- lockfile.lock()
-
tempdir = None
try:
tempdir = self._ensure_bootstrapped(depth, bootstrap)
@@ -515,8 +394,6 @@
if os.path.exists(self.mirror_path):
gclient_utils.rmtree(self.mirror_path)
self.Rename(tempdir, self.mirror_path)
- if not ignore_lock:
- lockfile.unlock()
def update_bootstrap(self, prune=False):
# The files are named <git number>.zip
@@ -557,45 +434,6 @@
except OSError:
logging.warn('Unable to delete temporary pack file %s' % f)
- @classmethod
- def BreakLocks(cls, path):
- did_unlock = False
- lf = Lockfile(path)
- if lf.break_lock():
- did_unlock = True
- # Look for lock files that might have been left behind by an interrupted
- # git process.
- lf = os.path.join(path, 'config.lock')
- if os.path.exists(lf):
- os.remove(lf)
- did_unlock = True
- cls.DeleteTmpPackFiles(path)
- return did_unlock
-
- def unlock(self):
- return self.BreakLocks(self.mirror_path)
-
- @classmethod
- def UnlockAll(cls):
- cachepath = cls.GetCachePath()
- if not cachepath:
- return
- dirlist = os.listdir(cachepath)
- repo_dirs = set([os.path.join(cachepath, path) for path in dirlist
- if os.path.isdir(os.path.join(cachepath, path))])
- for dirent in dirlist:
- if dirent.startswith('_cache_tmp') or dirent.startswith('tmp'):
- gclient_utils.rm_file_or_tree(os.path.join(cachepath, dirent))
- elif (dirent.endswith('.lock') and
- os.path.isfile(os.path.join(cachepath, dirent))):
- repo_dirs.add(os.path.join(cachepath, dirent[:-5]))
-
- unlocked_repos = []
- for repo_dir in repo_dirs:
- if cls.BreakLocks(repo_dir):
- unlocked_repos.append(repo_dir)
-
- return unlocked_repos
@subcommand.usage('[url of repo to check for caching]')
def CMDexists(parser, args):
@@ -647,9 +485,6 @@
parser.add_option('--no_bootstrap', '--no-bootstrap',
action='store_true',
help='Don\'t bootstrap from Google Storage')
- parser.add_option('--ignore_locks', '--ignore-locks',
- action='store_true',
- help='Don\'t try to lock repository')
options, args = parser.parse_args(args)
if not len(args) == 1:
@@ -661,8 +496,6 @@
'verbose': options.verbose,
'shallow': options.shallow,
'bootstrap': not options.no_bootstrap,
- 'ignore_lock': options.ignore_locks,
- 'lock_timeout': options.timeout,
}
if options.depth:
kwargs['depth'] = options.depth
@@ -707,7 +540,7 @@
if git_dir.startswith(cachepath):
mirror = Mirror.FromPath(git_dir)
mirror.populate(
- bootstrap=not options.no_bootstrap, lock_timeout=options.timeout)
+ bootstrap=not options.no_bootstrap,)
return 0
for remote in remotes:
remote_url = subprocess.check_output(
@@ -717,44 +550,11 @@
mirror.print = lambda *args: None
print('Updating git cache...')
mirror.populate(
- bootstrap=not options.no_bootstrap, lock_timeout=options.timeout)
+ bootstrap=not options.no_bootstrap)
subprocess.check_call([Mirror.git_exe, 'fetch', remote])
return 0
-@subcommand.usage('[url of repo to unlock, or -a|--all]')
-def CMDunlock(parser, args):
- """Unlock one or all repos if their lock files are still around."""
- parser.add_option('--force', '-f', action='store_true',
- help='Actually perform the action')
- parser.add_option('--all', '-a', action='store_true',
- help='Unlock all repository caches')
- options, args = parser.parse_args(args)
- if len(args) > 1 or (len(args) == 0 and not options.all):
- parser.error('git cache unlock takes exactly one repo url, or --all')
-
- if not options.force:
- cachepath = Mirror.GetCachePath()
- lockfiles = [os.path.join(cachepath, path)
- for path in os.listdir(cachepath)
- if path.endswith('.lock') and os.path.isfile(path)]
- parser.error('git cache unlock requires -f|--force to do anything. '
- 'Refusing to unlock the following repo caches: '
- ', '.join(lockfiles))
-
- unlocked_repos = []
- if options.all:
- unlocked_repos.extend(Mirror.UnlockAll())
- else:
- m = Mirror(args[0])
- if m.unlock():
- unlocked_repos.append(m.mirror_path)
-
- if unlocked_repos:
- logging.info('Broke locks on these caches:\n %s' % '\n '.join(
- unlocked_repos))
-
-
class OptionParser(optparse.OptionParser):
"""Wrapper class for OptionParser to handle global options."""
@@ -766,8 +566,6 @@
help='Increase verbosity (can be passed multiple times)')
self.add_option('-q', '--quiet', action='store_true',
help='Suppress all extraneous output')
- self.add_option('--timeout', type='int', default=0,
- help='Timeout for acquiring cache lock, in seconds')
def parse_args(self, args=None, values=None):
options, args = optparse.OptionParser.parse_args(self, args, values)