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from cStringIO import StringIO
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from bzrlib.decorators import *
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import bzrlib.errors as errors
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from bzrlib.errors import BzrError
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from bzrlib.errors import LockError, ReadOnlyError
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from bzrlib.osutils import file_iterator, safe_unicode
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from bzrlib.symbol_versioning import *
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from bzrlib.trace import mutter, note
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from bzrlib.symbol_versioning import deprecated_method, zero_eight
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from bzrlib.trace import mutter
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import bzrlib.transactions as transactions
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import bzrlib.urlutils as urlutils
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# XXX: The tracking here of lock counts and whether the lock is held is
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# somewhat redundant with what's done in LockDir; the main difference is that
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# LockableFiles permits reentrancy.
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class LockableFiles(object):
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"""Object representing a set of related files locked within the same scope.
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These files are used by a WorkingTree, Repository or Branch, and should
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generally only be touched by that object.
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LockableFiles also provides some policy on top of Transport for encoding
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control files as utf-8.
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LockableFiles manage a lock count and can be locked repeatedly by
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a single caller. (The underlying lock implementation generally does not
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Instances of this class are often called control_files.
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This object builds on top of a Transport, which is used to actually write
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the files to disk, and an OSLock or LockDir, which controls how access to
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the files is controlled. The particular type of locking used is set when
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the object is constructed. In older formats OSLocks are used everywhere.
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in newer formats a LockDir is used for Repositories and Branches, and
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OSLocks for the local filesystem.
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"""Object representing a set of files locked within the same scope
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If _lock_mode is true, a positive count of the number of times the
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lock has been taken *by this process*. Others may have compatible
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Lock object from bzrlib.lock.
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# _lock_mode: None, or 'r' or 'w'
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# _lock_count: If _lock_mode is true, a positive count of the number of
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# times the lock has been taken *by this process*.
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# If set to False (by a plugin, etc) BzrBranch will not set the
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# mode on created files or directories
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_set_file_mode = True
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_set_dir_mode = True
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def __init__(self, transport, lock_name, lock_class):
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"""Create a LockableFiles group
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:param transport: Transport pointing to the directory holding the
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control files and lock.
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:param lock_name: Name of the lock guarding these files.
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:param lock_class: Class of lock strategy to use: typically
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either LockDir or TransportLock.
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def __init__(self, transport, lock_name):
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self._transport = transport
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self.lock_name = lock_name
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self._transaction = None
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self._lock_mode = None
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esc_name = self._escape(lock_name)
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self._lock = lock_class(transport, esc_name,
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file_modebits=self._file_mode,
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dir_modebits=self._dir_mode)
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def create_lock(self):
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This should normally be called only when the LockableFiles directory
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is first created on disk.
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self._lock.create(mode=self._dir_mode)
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return '%s(%r)' % (self.__class__.__name__,
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return 'LockableFiles(%s, %s)' % (self.lock_name, self._transport.base)
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def __del__(self):
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if self._lock_mode or self._lock:
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# XXX: This should show something every time, and be suitable for
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# headless operation and embedding
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from warnings import warn
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warn("file group %r was not explicitly unlocked" % self)
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self._lock.unlock()
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def break_lock(self):
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"""Break the lock of this lockable files group if it is held.
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The current ui factory will be used to prompt for user conformation.
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self._lock.break_lock()
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def _escape(self, file_or_path):
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if not isinstance(file_or_path, basestring):
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file_or_path = '/'.join(file_or_path)
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if file_or_path == '':
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return urlutils.escape(safe_unicode(file_or_path))
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return bzrlib.transport.urlescape(safe_unicode(file_or_path))
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def _find_modes(self):
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"""Determine the appropriate modes for files and directories."""
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self.put(path, StringIO(a_string.encode('utf-8')))
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def lock_write(self):
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# mutter("lock write: %s (%s)", self, self._lock_count)
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mutter("lock write: %s (%s)", self, self._lock_count)
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# TODO: Upgrade locking to support using a Transport,
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# and potentially a remote locking protocol
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if self._lock_mode:
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if self._lock_mode != 'w' or not self.get_transaction().writeable():
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raise errors.ReadOnlyError(self)
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if self._lock_mode != 'w':
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raise ReadOnlyError("can't upgrade to a write lock from %r" %
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self._lock_count += 1
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self._lock.lock_write()
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#note('write locking %s', self)
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#traceback.print_stack()
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self._lock = self._transport.lock_write(
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self._escape(self.lock_name))
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self._lock_mode = 'w'
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self._lock_count = 1
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self._set_transaction(transactions.WriteTransaction())
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self._set_transaction(transactions.PassThroughTransaction())
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def lock_read(self):
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# mutter("lock read: %s (%s)", self, self._lock_count)
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mutter("lock read: %s (%s)", self, self._lock_count)
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if self._lock_mode:
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assert self._lock_mode in ('r', 'w'), \
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"invalid lock mode %r" % self._lock_mode
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self._lock_count += 1
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self._lock.lock_read()
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#note('read locking %s', self)
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#traceback.print_stack()
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self._lock = self._transport.lock_read(
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self._escape(self.lock_name))
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self._lock_mode = 'r'
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self._lock_count = 1
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self._set_transaction(transactions.ReadOnlyTransaction())
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self.get_transaction().set_cache_size(5000)
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def unlock(self):
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# mutter("unlock: %s (%s)", self, self._lock_count)
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mutter("unlock: %s (%s)", self, self._lock_count)
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if not self._lock_mode:
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raise errors.LockNotHeld(self)
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raise LockError('branch %r is not locked' % (self))
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if self._lock_count > 1:
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self._lock_count -= 1
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#note('unlocking %s', self)
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#traceback.print_stack()
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self._finish_transaction()
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self._lock_mode = self._lock_count = None
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"""Return true if this LockableFiles group is locked"""
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return self._lock_count >= 1
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def get_physical_lock_status(self):
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"""Return physical lock status.
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Returns true if a lock is held on the transport. If no lock is held, or
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the underlying locking mechanism does not support querying lock
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status, false is returned.
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return self._lock.peek() is not None
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except NotImplementedError:
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self._lock_mode = self._lock_count = None
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def get_transaction(self):
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"""Return the current active transaction.
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transaction = self._transaction
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self._transaction = None
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transaction.finish()
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class TransportLock(object):
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"""Locking method which uses transport-dependent locks.
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On the local filesystem these transform into OS-managed locks.
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These do not guard against concurrent access via different
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This is suitable for use only in WorkingTrees (which are at present
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def __init__(self, transport, escaped_name, file_modebits, dir_modebits):
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self._transport = transport
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self._escaped_name = escaped_name
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self._file_modebits = file_modebits
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self._dir_modebits = dir_modebits
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def break_lock(self):
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raise NotImplementedError(self.break_lock)
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def lock_write(self):
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self._lock = self._transport.lock_write(self._escaped_name)
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self._lock = self._transport.lock_read(self._escaped_name)
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raise NotImplementedError()
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def create(self, mode=None):
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"""Create lock mechanism"""
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# for old-style locks, create the file now
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self._transport.put(self._escaped_name, StringIO(),
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mode=self._file_modebits)
added
removed
bzrlib/lockable_files.py
