~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005 by Canonical Development 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

"""

An implementation the primary storage type CompressedTextStore.

This store keeps compressed versions of the full text. It does not

do any sort of delta compression.

"""

import os, tempfile, gzip

import bzrlib.store

from bzrlib.store import hash_prefix

from bzrlib.trace import mutter

from bzrlib.errors import BzrError, FileExists

from StringIO import StringIO

from stat import ST_SIZE

class CompressedTextStore(bzrlib.store.TransportStore):

    """Store that holds files indexed by unique names.

    Files can be added, but not modified once they are in.  Typically

    the hash is used as the name, or something else known to be unique,

    such as a UUID.

    Files are stored gzip compressed, with no delta compression.

    >>> st = ScratchCompressedTextStore()

    >>> st.add(StringIO('hello'), 'aa')

    >>> 'aa' in st

    True

    >>> 'foo' in st

    False

    You are not allowed to add an id that is already present.

    Entries can be retrieved as files, which may then be read.

    >>> st.add(StringIO('goodbye'), '123123')

    >>> st['123123'].read()

    'goodbye'

    """

    def __init__(self, transport, prefixed=False):

        super(CompressedTextStore, self).__init__(transport)

        self._prefixed = prefixed

    def _check_fileid(self, fileid):

        if '\\' in fileid or '/' in fileid:

            raise ValueError("invalid store id %r" % fileid)

    def _relpath(self, fileid):

        self._check_fileid(fileid)

        if self._prefixed:

            return hash_prefix(fileid) + fileid + ".gz"

        else:

            return fileid + ".gz"

    def add(self, f, fileid):

        """Add contents of a file into the store.

        f -- An open file, or file-like object."""

        # TODO: implement an add_multi which can do some of it's

        #       own piplelining, and possible take advantage of

        #       transport.put_multi(). The problem is that

        #       entries potentially need to be compressed as they

        #       are received, which implies translation, which

        #       means it isn't as straightforward as we would like.

        from cStringIO import StringIO

        from bzrlib.osutils import pumpfile

        mutter("add store entry %r" % (fileid))

        if isinstance(f, basestring):

            f = StringIO(f)

        fn = self._relpath(fileid)

        if self._transport.has(fn):

            raise BzrError("store %r already contains id %r" % (self._transport.base, fileid))

        if self._prefixed:

            try:

                self._transport.mkdir(hash_prefix(fileid))

            except FileExists:

                pass

        sio = StringIO()

        gf = gzip.GzipFile(mode='wb', fileobj=sio)

        # if pumpfile handles files that don't fit in ram,

        # so will this function

        if isinstance(f, basestring):

            gf.write(f)

        else:

            pumpfile(f, gf)

        gf.close()

        sio.seek(0)

        self._transport.put(fn, sio)

    def _do_copy(self, other, to_copy, pb, permit_failure=False):

        if isinstance(other, CompressedTextStore):

            return self._copy_multi_text(other, to_copy, pb,

                    permit_failure=permit_failure)

        return super(CompressedTextStore, self)._do_copy(other, to_copy,

                pb, permit_failure=permit_failure)

    def _copy_multi_text(self, other, to_copy, pb,

            permit_failure=False):

        # Because of _transport, we can no longer assume

        # that they are on the same filesystem, we can, however

        # assume that we only need to copy the exact bytes,

        # we don't need to process the files.

        failed = set()

        if permit_failure:

            new_to_copy = set()

            for fileid, has in zip(to_copy, other.has(to_copy)):

                if has:

                    new_to_copy.add(fileid)

                else:

                    failed.add(fileid)

            to_copy = new_to_copy

            #mutter('_copy_multi_text copying %s, failed %s' % (to_copy, failed))

        paths = [self._relpath(fileid) for fileid in to_copy]

        count = other._transport.copy_to(paths, self._transport, pb=pb)

        assert count == len(to_copy)

        return count, failed

    def __contains__(self, fileid):

        """"""

        fn = self._relpath(fileid)

        return self._transport.has(fn)

    def has(self, fileids, pb=None):

        """Return True/False for each entry in fileids.

        :param fileids: A List or generator yielding file ids.

        :return: A generator or list returning True/False for each entry.

        """

        relpaths = (self._relpath(fid) for fid in fileids)

        return self._transport.has_multi(relpaths, pb=pb)

    def get(self, fileids, permit_failure=False, pb=None):

        """Return a set of files, one for each requested entry.

        TODO: Write some tests to make sure that permit_failure is

              handled correctly.

        TODO: What should the exception be for a missing file?

              KeyError, or NoSuchFile?

        """

        # This next code gets a bit hairy because it can allow

        # to not request a file which doesn't seem to exist.

        # Also, the same fileid may be requested twice, so we

        # can't just build up a map.

        rel_paths = [self._relpath(fid) for fid in fileids]

        is_requested = []

        #mutter('CompressedTextStore.get(permit_failure=%s)' % permit_failure)

        if permit_failure:

            existing_paths = []

            for path, has in zip(rel_paths,

                    self._transport.has_multi(rel_paths)):

                if has:

                    existing_paths.append(path)

                    is_requested.append(True)

                else:

                    is_requested.append(False)

            #mutter('Retrieving %s out of %s' % (existing_paths, rel_paths))

        else:

            #mutter('Retrieving all %s' % (rel_paths, ))

            existing_paths = rel_paths

            is_requested = [True for x in rel_paths]

        count = 0

        for f in self._transport.get_multi(existing_paths, pb=pb):

            assert count < len(is_requested)

            while not is_requested[count]:

                yield None

                count += 1

            if hasattr(f, 'tell'):

                yield gzip.GzipFile(mode='rb', fileobj=f)

            else:

                from cStringIO import StringIO

                sio = StringIO(f.read())

                yield gzip.GzipFile(mode='rb', fileobj=sio)

            count += 1

        while count < len(is_requested):

            yield None

            count += 1

    def __iter__(self):

        for relpath, st in self._iter_relpaths():

            if relpath.endswith(".gz"):

                yield os.path.basename(relpath)[:-3]

            else:

                yield os.path.basename(relpath)

    def __len__(self):

        return len(list(self._iter_relpath()))

    def __getitem__(self, fileid):

        """Returns a file reading from a particular entry."""

        f = super(CompressedTextStore, self).__getitem__(fileid)

        # gzip.GzipFile.read() requires a tell() function

        # but some transports return objects that cannot seek

        # so buffer them in a StringIO instead

        if hasattr(f, 'tell'):

            return gzip.GzipFile(mode='rb', fileobj=f)

        else:

            from cStringIO import StringIO

            sio = StringIO(f.read())

            return gzip.GzipFile(mode='rb', fileobj=sio)

    def total_size(self):

        """Return (count, bytes)

        This is the (compressed) size stored on disk, not the size of

        the content."""

        total = 0

        count = 0

        for relpath, st in self._iter_relpaths():

            count += 1

            total += st[ST_SIZE]

        return count, total

class ScratchCompressedTextStore(CompressedTextStore):

    """Self-destructing test subclass of CompressedTextStore.

    The Store only exists for the lifetime of the Python object.

    Obviously you should not put anything precious in it.

    """

    def __init__(self):

        from transport import transport

        t = transport(tempfile.mkdtemp())

        super(ScratchCompressedTextStore, self).__init__(t)

    def __del__(self):

        self._transport.delete_multi(self._transport.list_dir('.'))

        os.rmdir(self._transport.base)

        mutter("%r destroyed" % self)