~bzr-pqm/bzr/bzr.dev

# 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()