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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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"""Stores are the main data-storage mechanism for Bazaar-NG.
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A store is a simple write-once container indexed by a universally
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unique ID, which is typically the SHA-1 of the content."""
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__copyright__ = "Copyright (C) 2005 Canonical Ltd."
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__author__ = "Martin Pool <mbp@canonical.com>"
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import os, tempfile, types, osutils, gzip, errno
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from stat import ST_SIZE
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from StringIO import StringIO
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from trace import mutter
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######################################################################
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class StoreError(Exception):
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"""Store that holds files indexed by unique names.
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Files can be added, but not modified once they are in. Typically
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the hash is used as the name, or something else known to be unique,
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>>> st = ImmutableScratchStore()
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>>> st.add(StringIO('hello'), 'aa')
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You are not allowed to add an id that is already present.
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Entries can be retrieved as files, which may then be read.
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>>> st.add(StringIO('goodbye'), '123123')
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>>> st['123123'].read()
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TODO: Atomic add by writing to a temporary file and renaming.
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TODO: Perhaps automatically transform to/from XML in a method?
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Would just need to tell the constructor what class to
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TODO: Even within a simple disk store like this, we could
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gzip the files. But since many are less than one disk
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block, that might not help a lot.
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def __init__(self, basedir):
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"""ImmutableStore constructor."""
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self._basedir = basedir
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return os.path.join(self._basedir, id)
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return "%s(%r)" % (self.__class__.__name__, self._basedir)
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def add(self, f, fileid, compressed=True):
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"""Add contents of a file into the store.
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f -- An open file, or file-like object."""
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# FIXME: Only works on smallish files
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# TODO: Can be optimized by copying at the same time as
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mutter("add store entry %r" % (fileid))
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if isinstance(f, types.StringTypes):
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p = self._path(fileid)
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if os.access(p, os.F_OK) or os.access(p + '.gz', os.F_OK):
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bailout("store %r already contains id %r" % (self._basedir, fileid))
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f = gzip.GzipFile(p + '.gz', 'wb')
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os.chmod(p + '.gz', 0444)
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def __contains__(self, fileid):
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p = self._path(fileid)
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return (os.access(p, os.R_OK)
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or os.access(p + '.gz', os.R_OK))
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# TODO: Guard against the same thing being stored twice, compressed and uncompresse
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for f in os.listdir(self._basedir):
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# TODO: case-insensitive?
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return len(os.listdir(self._basedir))
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def __getitem__(self, fileid):
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"""Returns a file reading from a particular entry."""
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p = self._path(fileid)
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return gzip.GzipFile(p + '.gz', 'rb')
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if e.errno == errno.ENOENT:
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def total_size(self):
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"""Return (count, bytes)
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This is the (compressed) size stored on disk, not the size of
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total += os.stat(p)[ST_SIZE]
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total += os.stat(p + '.gz')[ST_SIZE]
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class ImmutableScratchStore(ImmutableStore):
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"""Self-destructing test subclass of ImmutableStore.
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The Store only exists for the lifetime of the Python object.
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Obviously you should not put anything precious in it.
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ImmutableStore.__init__(self, tempfile.mkdtemp())
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for f in os.listdir(self._basedir):
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fpath = os.path.join(self._basedir, f)
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# needed on windows, and maybe some other filesystems
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os.chmod(fpath, 0600)
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os.rmdir(self._basedir)
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mutter("%r destroyed" % self)
added
removed
bzrlib/store.py
