Synnefo

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from hashlib import new as newhasher

from binascii import hexlify

import os, re

from context_archipelago import ArchipelagoObject, file_sync_read_chunks

from archipelago.common import (

    Request,

    xseg_reply_info,

    string_at,

    )

from pithos.workers import glue, monkey

monkey.patch_Request()

from pithos.api.settings import BACKEND_ARCHIPELAGO_CONF

class ArchipelagoBlocker(object):

    """Blocker.

       Required constructor parameters: blocksize, hashtype.

    """

    blocksize = None

    blockpool = None

    hashtype = None

    def __init__(self, **params):

        cfg = {}

        bcfg = open(BACKEND_ARCHIPELAGO_CONF).read()

        cfg['blockerb'] = re.search('\'blockerb_port\'\s*:\s*\d+',

                bcfg).group(0).split(':')[1]

        blocksize = params['blocksize']

        hashtype = params['hashtype']

        try:

            hasher = newhasher(hashtype)

        except ValueError:

            msg = "Variable hashtype '%s' is not available from hashlib"

            raise ValueError(msg % (hashtype,))

        hasher.update("")

        emptyhash = hasher.digest()

        self.blocksize = blocksize

        self.ioctx_pool = glue.WorkerGlue().ioctx_pool

        self.dst_port = int(cfg['blockerb'])

        self.hashtype = hashtype

        self.hashlen = len(emptyhash)

        self.emptyhash = emptyhash

    def _pad(self, block):

        return block + ('\x00' * (self.blocksize - len(block)))

    def _get_rear_block(self, blkhash, create=0):

        name = hexlify(blkhash)

        return ArchipelagoObject(name, self.ioctx_pool,self.dst_port,create)

    def _check_rear_block(self, blkhash):

        filename = hexlify(blkhash)

        ioctx = self.ioctx_pool.pool_get()

        req = Request.get_info_request(ioctx,self.dst_port,filename)

        req.submit()

        req.wait()

        ret = req.success()

        req.put()

        self.ioctx_pool.pool_put(ioctx)

        if ret:

            return True

        else:

            return False

    def block_hash(self, data):

        """Hash a block of data"""

        hasher = newhasher(self.hashtype)

        hasher.update(data.rstrip('\x00'))

        return hasher.digest()

    def block_ping(self, hashes):

        """Check hashes for existence and

           return those missing from block storage.

        """

        notfound = []

        append = notfound.append

        for h in hashes:

            if h not in notfound and not self._check_rear_block(h):

                append(h)

        return notfound

    def block_retr(self, hashes):

        """Retrieve blocks from storage by their hashes."""

        blocksize = self.blocksize

        blocks = []

        append = blocks.append

        block = None

        for h in hashes:

            if h == self.emptyhash:

                append(self._pad(''))

                continue

            with self._get_rear_block(h, 0) as rbl:

                if not rbl:

                    break

                for block in rbl.sync_read_chunks(blocksize, 1, 0):

                    break  # there should be just one block there

            if not block:

                break

            append(self._pad(block))

        return blocks

    def block_retr_archipelago(self, hashes):

        """Retrieve blocks from storage by their hashes"""

        blocks = []

        append = blocks.append

        block = None

        ioctx = self.ioctx_pool.pool_get()

        archip_emptyhash = hexlify(self.emptyhash)

        for h in hashes:

            if h == archip_emptyhash:

                append(self._pad(''))

                continue

            req = Request.get_info_request(ioctx, self.dst_port, h)

            req.submit()

            req.wait()

            ret = req.success()

            if ret:

                info = req.get_data(_type=xseg_reply_info)

                size = info.contents.size

                req.put()

                req_data = Request.get_read_request(ioctx, self.dst_port, h,

                                                    size=size)

                req_data.submit()

                req_data.wait()

                ret_data = req_data.success()

                if ret_data:

                    append(self._pad(string_at(req_data.get_data(), size)))

                    req_data.put()

                else:

                    req_data.put()

                    self.ioctx_pool.put(ioctx)

                    raise Exception("Cannot retrieve Archipelago data.")

            else:

                req.put()

                self.ioctx_pool.pool_put(ioctx)

                raise Exception("Bad block file.")

        self.ioctx_pool.pool_put(ioctx)

        return blocks

    def block_stor(self, blocklist):

        """Store a bunch of blocks and return (hashes, missing).

           Hashes is a list of the hashes of the blocks,

           missing is a list of indices in that list indicating

           which blocks were missing from the store.

        """

        block_hash = self.block_hash

        hashlist = [block_hash(b) for b in blocklist]

        missing = [i for i, h in enumerate(hashlist) if not

                   self._check_rear_block(h)]

        for i in missing:

            with self._get_rear_block(hashlist[i], 1) as rbl:

                rbl.sync_write(blocklist[i])  # XXX: verify?

        return hashlist, missing

    def block_delta(self, blkhash, offset, data):

        """Construct and store a new block from a given block

           and a data 'patch' applied at offset. Return:

           (the hash of the new block, if the block already existed)

        """

        blocksize = self.blocksize

        if offset >= blocksize or not data:

            return None, None

        block = self.block_retr((blkhash,))

        if not block:

            return None, None

        block = block[0]

        newblock = block[:offset] + data

        if len(newblock) > blocksize:

            newblock = newblock[:blocksize]

        elif len(newblock) < blocksize:

            newblock += block[len(newblock):]

        h, a = self.block_stor((newblock,))

        return h[0], 1 if a else 0

    def block_hash_file(self, archipelagoobject):

        """Return the list of hashes (hashes map)

           for the blocks in a buffered file.

           Helper method, does not affect store.

        """

        hashes = []

        append = hashes.append

        block_hash = self.block_hash

        for block in file_sync_read_chunks(archipelagoobject, self.blocksize, 1, 0):

            append(block_hash(block))

        return hashes

    def block_stor_file(self, archipelagoobject):

        """Read blocks from buffered file object and store them. Return:

           (bytes read, list of hashes, list of hashes that were missing)

        """

        blocksize = self.blocksize

        block_stor = self.block_stor

        hashlist = []

        hextend = hashlist.extend

        storedlist = []

        sextend = storedlist.extend

        lastsize = 0

        for block in file_sync_read_chunks(archipelagoobject, blocksize, 1, 0):

            hl, sl = block_stor((block,))

            hextend(hl)

            sextend(sl)

            lastsize = len(block)

        size = (len(hashlist) - 1) * blocksize + lastsize if hashlist else 0

        return size, hashlist, storedlist