root / pithos / backends / lib / hashfiler / mapper.py @ 6f4bce7b
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# Copyright 2011 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.path import realpath, join, exists, isdir |
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from os import makedirs, unlink |
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from errno import ENOENT |
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from context_file import ContextFile |
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class Mapper(object): |
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"""Mapper.
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Required contstructor 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" % (mappath,)) |
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self.mappath = mappath
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def get_rear_map(self, name, create=0): |
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name = join(self.mappath, hex(int(name))) |
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return ContextFile(name, create)
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def delete_rear_map(self, name): |
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name = join(self.mappath, hex(int(name))) |
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try:
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unlink(name) |
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return 1 |
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except OSError, e: |
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if e.errno != ENOENT:
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raise
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return 0 |
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def map_retr(self, name, 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(name, 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, name, hashes=(), blkoff=0, create=1): |
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"""Store hashes in the given hashes map, replacing the old ones."""
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namelen = self.namelen
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with self.get_rear_map(name, 1) as rmap: |
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rmap.sync_write_chunks(namelen, blkoff, hashes, None)
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# def map_copy(self, src, dst):
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# """Copy a hashes map to another one, replacing it."""
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# with self.get_rear_map(src, 0) as rmap:
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# if rmap:
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# rmap.copy_to(dst)
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def map_remv(self, name): |
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"""Remove a hashes map. Returns true if the map was found and removed."""
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return self.delete_rear_map(name) |
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