root / snf-pithos-backend / pithos / backends / lib / hashfiler / blocker.py @ 11c079c8
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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 hashlib import new as newhasher |
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from binascii import hexlify |
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from fileblocker import FileBlocker |
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def intersect(a, b): |
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""" return the intersection of two lists """
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return list(set(a) & set(b)) |
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def union(a, b): |
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""" return the union of two lists """
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return list(set(a) | set(b)) |
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class Blocker(object): |
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"""Blocker.
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Required constructor parameters: blocksize, blockpath, hashtype.
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Optional blockpool.
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"""
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def __init__(self, **params): |
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self.rblocker = None |
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try:
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if params['blockpool']: |
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from radosblocker import RadosBlocker |
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self.rblocker = RadosBlocker(**params)
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except KeyError: |
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pass
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self.fblocker = FileBlocker(**params)
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self.hashlen = self.fblocker.hashlen |
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def block_hash(self, data): |
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"""Hash a block of data"""
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return self.fblocker.block_hash(data) |
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def block_ping(self, hashes): |
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"""Check hashes for existence and
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return those missing from block storage.
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"""
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r = [] |
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if self.rblocker: |
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r = self.rblocker.block_ping(hashes)
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f = self.fblocker.block_ping(hashes)
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return union(r, f)
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def block_retr(self, hashes): |
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"""Retrieve blocks from storage by their hashes."""
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return self.fblocker.block_retr(hashes) |
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def block_stor(self, blocklist): |
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"""Store a bunch of blocks and return (hashes, missing).
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Hashes is a list of the hashes of the blocks,
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missing is a list of indices in that list indicating
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which blocks were missing from the store.
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"""
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r_missing = [] |
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(hashes, f_missing) = self.fblocker.block_stor(blocklist)
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if self.rblocker: |
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(_, r_missing) = self.rblocker.block_stor(blocklist)
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return (hashes, union(r_missing, f_missing))
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def block_delta(self, blkhash, offset, data): |
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"""Construct and store a new block from a given block
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and a data 'patch' applied at offset. Return:
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(the hash of the new block, if the block already existed)
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"""
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r_hash = None
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r_existed = True
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(f_hash, f_existed) = self.fblocker.block_delta(blkhash, offset, data)
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if self.rblocker: |
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(r_hash, r_existed) = self.rblocker.block_delta(blkhash, offset, data)
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if not r_hash and not f_hash: |
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return None, None |
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if self.rblocker and not r_hash: |
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block = self.fblocker.block_retr((blkhash,))
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if not block: |
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return None, None |
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block = block[0]
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newblock = block[:offset] + data |
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if len(newblock) > blocksize: |
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newblock = newblock[:blocksize] |
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elif len(newblock) < blocksize: |
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newblock += block[len(newblock):]
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r_hash, r_existed = self.rblocker.block_stor((newblock,))
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return f_hash, 1 if r_existed and f_existed else 0 |