/brz/remove-bazaar

# 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

"""

Stores are the main data-storage mechanism for Bazaar-NG.

A store is a simple write-once container indexed by a universally

unique ID.

"""

import os, tempfile, types, osutils, gzip, errno

from stat import ST_SIZE

from StringIO import StringIO

from bzrlib.errors import BzrError

from bzrlib.trace import mutter

import bzrlib.ui

from bzrlib.remotebranch import get_url

######################################################################

# stores

class StoreError(Exception):

    pass

class Store(object):

    """An abstract 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.

    >>> st = ImmutableScratchStore()

    >>> 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 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 fid in self:

            count += 1

            total += self._item_size(fid)

        return count, total

class ImmutableStore(Store):

    """Store that stores files on disk.

    TODO: Atomic add by writing to a temporary file and renaming.

    TODO: Guard against the same thing being stored twice, compressed and

          uncompressed during copy_multi_immutable - the window is for a

          matching store with some crack code that lets it offer a 

          non gz FOO and then a fz FOO.

    In bzr 0.0.5 and earlier, files within the store were marked

    readonly on disk.  This is no longer done but existing stores need

    to be accomodated.

    """

    def __init__(self, basedir):

        super(ImmutableStore, self).__init__()

        self._basedir = basedir

    def _path(self, entry_id):

        if not isinstance(entry_id, basestring):

            raise TypeError(type(entry_id))

        if '\\' in entry_id or '/' in entry_id:

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

        return os.path.join(self._basedir, entry_id)

    def __repr__(self):

        return "%s(%r)" % (self.__class__.__name__, self._basedir)

    def add(self, f, fileid, compressed=True):

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

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

        # FIXME: Only works on files that will fit in memory

        from bzrlib.atomicfile import AtomicFile

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

        if isinstance(f, types.StringTypes):

            content = f

        else:

            content = f.read()

        p = self._path(fileid)

        if os.access(p, os.F_OK) or os.access(p + '.gz', os.F_OK):

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

        fn = p

        if compressed:

            fn = fn + '.gz'

        af = AtomicFile(fn, 'wb')

        try:

            if compressed:

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

                gf.write(content)

                gf.close()

            else:

                af.write(content)

            af.commit()

        finally:

            af.close()

    def copy_multi(self, other, ids, permit_failure=False):

        """Copy texts for ids from other into self.

        If an id is present in self, it is skipped.

        Returns (count_copied, failed), where failed is a collection of ids

        that could not be copied.

        """

        pb = bzrlib.ui.ui_factory.progress_bar()

        pb.update('preparing to copy')

        to_copy = [id for id in ids if id not in self]

        if isinstance(other, ImmutableStore):

            return self.copy_multi_immutable(other, to_copy, pb)

        count = 0

        failed = set()

        for id in to_copy:

            count += 1

            pb.update('copy', count, len(to_copy))

            if not permit_failure:

                self.add(other[id], id)

            else:

                try:

                    entry = other[id]

                except IndexError:

                    failed.add(id)

                    continue

                self.add(entry, id)

        if not permit_failure:

            assert count == len(to_copy)

        pb.clear()

        return count, failed

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

        from shutil import copyfile

        count = 0

        failed = set()

        for id in to_copy:

            p = self._path(id)

            other_p = other._path(id)

            try:

                copyfile(other_p, p)

            except IOError, e:

                if e.errno == errno.ENOENT:

                    if not permit_failure:

                        copyfile(other_p+".gz", p+".gz")

                    else:

                        try:

                            copyfile(other_p+".gz", p+".gz")

                        except IOError, e:

                            if e.errno == errno.ENOENT:

                                failed.add(id)

                            else:

                                raise

                else:

                    raise

            count += 1

            pb.update('copy', count, len(to_copy))

        assert count == len(to_copy)

        pb.clear()

        return count, failed

    def __contains__(self, fileid):

        """"""

        p = self._path(fileid)

        return (os.access(p, os.R_OK)

                or os.access(p + '.gz', os.R_OK))

    def _item_size(self, fid):

        p = self._path(fid)

        try:

            return os.stat(p)[ST_SIZE]

        except OSError:

            return os.stat(p + '.gz')[ST_SIZE]

    def __iter__(self):

        for f in os.listdir(self._basedir):

            if f[-3:] == '.gz':

                # TODO: case-insensitive?

                yield f[:-3]

            else:

                yield f

    def __len__(self):

        return len(os.listdir(self._basedir))

    def __getitem__(self, fileid):

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

        p = self._path(fileid)

        try:

            return gzip.GzipFile(p + '.gz', 'rb')

        except IOError, e:

            if e.errno != errno.ENOENT:

                raise

        try:

            return file(p, 'rb')

        except IOError, e:

            if e.errno != errno.ENOENT:

                raise

        raise IndexError(fileid)

class ImmutableScratchStore(ImmutableStore):

    """Self-destructing test subclass of ImmutableStore.

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

 Obviously you should not put anything precious in it.

    """

    def __init__(self):

        super(ImmutableScratchStore, self).__init__(tempfile.mkdtemp())

    def __del__(self):

        for f in os.listdir(self._basedir):

            fpath = os.path.join(self._basedir, f)

            # needed on windows, and maybe some other filesystems

            os.chmod(fpath, 0600)

            os.remove(fpath)

        os.rmdir(self._basedir)

        mutter("%r destroyed" % self)

class ImmutableMemoryStore(Store):

    """A memory only store."""

    def __init__(self):

        super(ImmutableMemoryStore, self).__init__()

        self._contents = {}

    def add(self, stream, fileid, compressed=True):

        if self._contents.has_key(fileid):

            raise StoreError("fileid %s already in the store" % fileid)

        self._contents[fileid] = stream.read()

    def __getitem__(self, fileid):

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

        if not self._contents.has_key(fileid):

            raise IndexError

        return StringIO(self._contents[fileid])

    def _item_size(self, fileid):

        return len(self._contents[fileid])

    def __iter__(self):

        return iter(self._contents.keys())

class RemoteStore(object):

    def __init__(self, baseurl):

        self._baseurl = baseurl

    def _path(self, name):

        if '/' in name:

            raise ValueError('invalid store id', name)

        return self._baseurl + '/' + name

    def __getitem__(self, fileid):

        p = self._path(fileid)

        try:

            return get_url(p, compressed=True)

        except:

            raise KeyError(fileid)

class CachedStore:

    """A store that caches data locally, to avoid repeated downloads.

    The precacache method should be used to avoid server round-trips for

    every piece of data.

    """

    def __init__(self, store, cache_dir):

        self.source_store = store

        self.cache_store = ImmutableStore(cache_dir)

    def __getitem__(self, id):

        mutter("Cache add %s" % id)

        if id not in self.cache_store:

            self.cache_store.add(self.source_store[id], id)

        return self.cache_store[id]

    def prefetch(self, ids):

        """Copy a series of ids into the cache, before they are used.

        For remote stores that support pipelining or async downloads, this can

        increase speed considerably.

        """

        mutter("Prefetch of ids %s" % ",".join(ids))

        self.cache_store.copy_multi(self.source_store, ids)