~bzr-pqm/bzr/bzr.dev

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# Copyright (C) 2005, 2006 Canonical Ltd

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.

# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

from cStringIO import StringIO
import codecs

import bzrlib
from bzrlib.decorators import *
import bzrlib.errors as errors
from bzrlib.errors import LockError, ReadOnlyError
from bzrlib.osutils import file_iterator, safe_unicode
from bzrlib.symbol_versioning import *
from bzrlib.symbol_versioning import deprecated_method, zero_eight
from bzrlib.trace import mutter
import bzrlib.transactions as transactions


class LockableFiles(object):
    """Object representing a set of files locked within the same scope

    _lock_mode
        None, or 'r' or 'w'

    _lock_count
        If _lock_mode is true, a positive count of the number of times the
        lock has been taken *by this process*.  Others may have compatible 
        read locks.

    _lock
        Lock object from bzrlib.lock.
    """

    _lock_mode = None
    _lock_count = None
    _lock = None
    # If set to False (by a plugin, etc) BzrBranch will not set the
    # mode on created files or directories
    _set_file_mode = True
    _set_dir_mode = True

    def __init__(self, transport, lock_name):
        object.__init__(self)
        self._transport = transport
        self.lock_name = lock_name
        self._transaction = None
        self._find_modes()

    def __del__(self):
        if self._lock_mode or self._lock:
            # XXX: This should show something every time, and be suitable for
            # headless operation and embedding
            from warnings import warn
            warn("file group %r was not explicitly unlocked" % self)
            self._lock.unlock()

    def _escape(self, file_or_path):
        if not isinstance(file_or_path, basestring):
            file_or_path = '/'.join(file_or_path)
        if file_or_path == '':
            return u''
        return bzrlib.transport.urlescape(safe_unicode(file_or_path))

    def _find_modes(self):
        """Determine the appropriate modes for files and directories."""
        try:
            st = self._transport.stat('.')
        except errors.TransportNotPossible:
            self._dir_mode = 0755
            self._file_mode = 0644
        else:
            self._dir_mode = st.st_mode & 07777
            # Remove the sticky and execute bits for files
            self._file_mode = self._dir_mode & ~07111
        if not self._set_dir_mode:
            self._dir_mode = None
        if not self._set_file_mode:
            self._file_mode = None

    def controlfilename(self, file_or_path):
        """Return location relative to branch."""
        return self._transport.abspath(self._escape(file_or_path))

    @deprecated_method(zero_eight)
    def controlfile(self, file_or_path, mode='r'):
        """Open a control file for this branch.

        There are two classes of file in a lockable directory: text
        and binary.  binary files are untranslated byte streams.  Text
        control files are stored with Unix newlines and in UTF-8, even
        if the platform or locale defaults are different.

        Such files are not openable in write mode : they are managed via
        put and put_utf8 which atomically replace old versions using
        atomicfile.
        """

        relpath = self._escape(file_or_path)
        #TODO: codecs.open() buffers linewise, so it was overloaded with
        # a much larger buffer, do we need to do the same for getreader/getwriter?
        if mode == 'rb': 
            return self.get(relpath)
        elif mode == 'wb':
            raise BzrError("Branch.controlfile(mode='wb') is not supported, use put[_utf8]")
        elif mode == 'r':
            return self.get_utf8(relpath)
        elif mode == 'w':
            raise BzrError("Branch.controlfile(mode='w') is not supported, use put[_utf8]")
        else:
            raise BzrError("invalid controlfile mode %r" % mode)

    @needs_read_lock
    def get(self, relpath):
        """Get a file as a bytestream."""
        relpath = self._escape(relpath)
        return self._transport.get(relpath)

    @needs_read_lock
    def get_utf8(self, relpath):
        """Get a file as a unicode stream."""
        relpath = self._escape(relpath)
        # DO NOT introduce an errors=replace here.
        return codecs.getreader('utf-8')(self._transport.get(relpath))

    @needs_write_lock
    def put(self, path, file):
        """Write a file.
        
        :param path: The path to put the file, relative to the .bzr control
                     directory
        :param f: A file-like or string object whose contents should be copied.
        """
        self._transport.put(self._escape(path), file, mode=self._file_mode)

    @needs_write_lock
    def put_utf8(self, path, a_string):
        """Write a string, encoding as utf-8.

        :param path: The path to put the string, relative to the transport root.
        :param string: A file-like or string object whose contents should be copied.
        """
        # IterableFile would not be needed if Transport.put took iterables
        # instead of files.  ADHB 2005-12-25
        # RBC 20060103 surely its not needed anyway, with codecs transcode
        # file support ?
        # JAM 20060103 We definitely don't want encode(..., 'replace')
        # these are valuable files which should have exact contents.
        if not isinstance(a_string, basestring):
            raise errors.BzrBadParameterNotString(a_string)
        self.put(path, StringIO(a_string.encode('utf-8')))

    def lock_write(self):
        # mutter("lock write: %s (%s)", self, self._lock_count)
        # TODO: Upgrade locking to support using a Transport,
        # and potentially a remote locking protocol
        if self._lock_mode:
            if self._lock_mode != 'w':
                raise ReadOnlyError(self)
            self._lock_count += 1
        else:
            self._lock = self._transport.lock_write(
                    self._escape(self.lock_name))
            self._lock_mode = 'w'
            self._lock_count = 1
            self._set_transaction(transactions.PassThroughTransaction())

    def lock_read(self):
        # mutter("lock read: %s (%s)", self, self._lock_count)
        if self._lock_mode:
            assert self._lock_mode in ('r', 'w'), \
                   "invalid lock mode %r" % self._lock_mode
            self._lock_count += 1
        else:
            self._lock = self._transport.lock_read(
                    self._escape(self.lock_name))
            self._lock_mode = 'r'
            self._lock_count = 1
            self._set_transaction(transactions.ReadOnlyTransaction())
            # 5K may be excessive, but hey, its a knob.
            self.get_transaction().set_cache_size(5000)
                        
    def unlock(self):
        # mutter("unlock: %s (%s)", self, self._lock_count)
        if not self._lock_mode:
            raise errors.BranchNotLocked(self)
        if self._lock_count > 1:
            self._lock_count -= 1
        else:
            self._finish_transaction()
            self._lock.unlock()
            self._lock = None
            self._lock_mode = self._lock_count = None

    def get_transaction(self):
        """Return the current active transaction.

        If no transaction is active, this returns a passthrough object
        for which all data is immediately flushed and no caching happens.
        """
        if self._transaction is None:
            return transactions.PassThroughTransaction()
        else:
            return self._transaction

    def _set_transaction(self, new_transaction):
        """Set a new active transaction."""
        if self._transaction is not None:
            raise errors.LockError('Branch %s is in a transaction already.' %
                                   self)
        self._transaction = new_transaction

    def _finish_transaction(self):
        """Exit the current transaction."""
        if self._transaction is None:
            raise errors.LockError('Branch %s is not in a transaction' %
                                   self)
        transaction = self._transaction
        self._transaction = None
        transaction.finish()