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# Copyright 2011-2012 GRNET S.A. All rights reserved.
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#
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# Redistribution and use in source and binary forms, with or
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# without modification, are permitted provided that the following
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# conditions are met:
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#
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#   1. Redistributions of source code must retain the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer.
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#
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#   2. Redistributions in binary form must reproduce the above
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#      copyright notice, this list of conditions and the following
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#      disclaimer in the documentation and/or other materials
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#      provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
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# OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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# PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
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# CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
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# USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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# AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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# LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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#
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# The views and conclusions contained in the software and
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# documentation are those of the authors and should not be
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# interpreted as representing official policies, either expressed
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# or implied, of GRNET S.A.
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from os import makedirs
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from os.path import isdir, realpath, exists, join
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from binascii import hexlify
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from context_file import ContextFile
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class FileMapper(object):
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    """Mapper.
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       Required constructor parameters: mappath, namelen.
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    """
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    mappath = None
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    namelen = None
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    def __init__(self, **params):
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        self.params = params
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        self.namelen = params['namelen']
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        mappath = realpath(params['mappath'])
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        if not isdir(mappath):
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            if not exists(mappath):
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                makedirs(mappath)
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            else:
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                raise ValueError("Variable mappath '%s' is not a directory" %
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                                 (mappath,))
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        self.mappath = mappath
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    def _get_rear_map(self, maphash, create=0):
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        filename = hexlify(maphash)
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        dir = join(self.mappath, filename[0:2], filename[2:4], filename[4:6])
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        if not exists(dir):
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            makedirs(dir)
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        name = join(dir, filename)
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        return ContextFile(name, create)
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    def _check_rear_map(self, maphash):
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        filename = hexlify(maphash)
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        dir = join(self.mappath, filename[0:2], filename[2:4], filename[4:6])
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        name = join(dir, filename)
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        return exists(name)
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    def map_retr(self, maphash, blkoff=0, nr=100000000000000):
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        """Return as a list, part of the hashes map of an object
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           at the given block offset.
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           By default, return the whole hashes map.
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        """
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        namelen = self.namelen
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        hashes = ()
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        with self._get_rear_map(maphash, 0) as rmap:
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            if rmap:
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                hashes = list(rmap.sync_read_chunks(namelen, nr, blkoff))
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        return hashes
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    def map_stor(self, maphash, hashes=(), blkoff=0, create=1):
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        """Store hashes in the given hashes map."""
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        namelen = self.namelen
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        if self._check_rear_map(maphash):
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            return
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        with self._get_rear_map(maphash, 1) as rmap:
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            rmap.sync_write_chunks(namelen, blkoff, hashes, None)