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https://github.com/tahoe-lafs/tahoe-lafs.git
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361 lines
13 KiB
Python
361 lines
13 KiB
Python
import os, re, weakref, stat, struct
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from foolscap import Referenceable
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from twisted.application import service
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from twisted.internet import defer
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from zope.interface import implements
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from allmydata.interfaces import RIStorageServer, RIBucketWriter, \
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RIBucketReader, IStorageBucketWriter, IStorageBucketReader
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from allmydata import interfaces
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from allmydata.util import fileutil, idlib
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from allmydata.util.assertutil import precondition
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# store/
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# store/incoming # temp dirs named $STORAGEINDEX/$SHARENUM which will be moved to store/$STORAGEINDEX/$SHARENUM on success
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# store/$STORAGEINDEX
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# store/$STORAGEINDEX/$SHARENUM
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# store/$STORAGEINDEX/$SHARENUM/blocksize
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# store/$STORAGEINDEX/$SHARENUM/data
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# store/$STORAGEINDEX/$SHARENUM/blockhashes
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# store/$STORAGEINDEX/$SHARENUM/sharehashtree
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# $SHARENUM matches this regex:
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NUM_RE=re.compile("[0-9]*")
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class BucketWriter(Referenceable):
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implements(RIBucketWriter)
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def __init__(self, ss, incominghome, finalhome, size):
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self.ss = ss
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self.incominghome = incominghome
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self.finalhome = finalhome
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self._size = size
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self.closed = False
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# touch the file, so later callers will see that we're working on it
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f = open(self.incominghome, 'ab')
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f.close()
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def allocated_size(self):
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return self._size
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def remote_write(self, offset, data):
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precondition(not self.closed)
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precondition(offset >= 0)
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precondition(offset+len(data) <= self._size)
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f = open(self.incominghome, 'ab')
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f.seek(offset)
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f.write(data)
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f.close()
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def remote_close(self):
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precondition(not self.closed)
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fileutil.rename(self.incominghome, self.finalhome)
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self.closed = True
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filelen = os.stat(self.finalhome)[stat.ST_SIZE]
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self.ss.bucket_writer_closed(self, filelen)
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class BucketReader(Referenceable):
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implements(RIBucketReader)
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def __init__(self, home):
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self.home = home
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def remote_read(self, offset, length):
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f = open(self.home, 'rb')
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f.seek(offset)
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return f.read(length)
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class StorageServer(service.MultiService, Referenceable):
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implements(RIStorageServer)
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name = 'storageserver'
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def __init__(self, storedir, sizelimit=None):
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service.MultiService.__init__(self)
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fileutil.make_dirs(storedir)
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self.storedir = storedir
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self.sizelimit = sizelimit
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self.incomingdir = os.path.join(storedir, 'incoming')
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self._clean_incomplete()
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fileutil.make_dirs(self.incomingdir)
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self._active_writers = weakref.WeakKeyDictionary()
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self.measure_size()
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def _clean_incomplete(self):
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fileutil.rm_dir(self.incomingdir)
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def measure_size(self):
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self.consumed = fileutil.du(self.storedir)
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def allocated_size(self):
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space = self.consumed
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for bw in self._active_writers:
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space += bw.allocated_size()
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return space
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def remote_allocate_buckets(self, storage_index, sharenums, sharesize,
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canary):
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alreadygot = set()
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bucketwriters = {} # k: shnum, v: BucketWriter
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si_s = idlib.b2a(storage_index)
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space_per_bucket = sharesize
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no_limits = self.sizelimit is None
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yes_limits = not no_limits
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if yes_limits:
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remaining_space = self.sizelimit - self.allocated_size()
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for shnum in sharenums:
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incominghome = os.path.join(self.incomingdir, si_s, "%d" % shnum)
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finalhome = os.path.join(self.storedir, si_s, "%d" % shnum)
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if os.path.exists(incominghome) or os.path.exists(finalhome):
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alreadygot.add(shnum)
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elif no_limits or remaining_space >= space_per_bucket:
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fileutil.make_dirs(os.path.join(self.incomingdir, si_s))
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bw = BucketWriter(self, incominghome, finalhome,
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space_per_bucket)
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bucketwriters[shnum] = bw
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self._active_writers[bw] = 1
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if yes_limits:
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remaining_space -= space_per_bucket
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else:
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# not enough space to accept this bucket
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pass
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if bucketwriters:
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fileutil.make_dirs(os.path.join(self.storedir, si_s))
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return alreadygot, bucketwriters
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def bucket_writer_closed(self, bw, consumed_size):
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self.consumed += consumed_size
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del self._active_writers[bw]
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def remote_get_buckets(self, storage_index):
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bucketreaders = {} # k: sharenum, v: BucketReader
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storagedir = os.path.join(self.storedir, idlib.b2a(storage_index))
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try:
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for f in os.listdir(storagedir):
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if NUM_RE.match(f):
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br = BucketReader(os.path.join(storagedir, f))
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bucketreaders[int(f)] = br
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except OSError:
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# Commonly caused by there being no buckets at all.
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pass
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return bucketreaders
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"""
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Share data is written into a single file. At the start of the file, there is
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a series of four-byte big-endian offset values, which indicate where each
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section starts. Each offset is measured from the beginning of the file.
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0x00: segment size
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0x04: offset of data (=00 00 00 1c)
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0x08: offset of plaintext_hash_tree
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0x0c: offset of crypttext_hash_tree
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0x10: offset of block_hashes
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0x14: offset of share_hashes
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0x18: offset of uri_extension_length + uri_extension
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0x1c: start of data
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start of plaintext_hash_tree
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start of crypttext_hash_tree
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start of block_hashes
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start of share_hashes
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each share_hash is written as a two-byte (big-endian) hashnum
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followed by the 32-byte SHA-256 hash. We only store the hashes
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necessary to validate the share hash root
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start of uri_extension_length (four-byte big-endian value)
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start of uri_extension
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"""
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class WriteBucketProxy:
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implements(IStorageBucketWriter)
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def __init__(self, rref, data_size, segment_size, num_segments,
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num_share_hashes):
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self._rref = rref
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self._segment_size = segment_size
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HASH_SIZE = interfaces.HASH_SIZE
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self._segment_hash_size = (2*num_segments - 1) * HASH_SIZE
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# how many share hashes are included in each share? This will be
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# about ln2(num_shares).
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self._share_hash_size = num_share_hashes * (2+HASH_SIZE)
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offsets = self._offsets = {}
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x = 0x1c
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offsets['data'] = x
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x += data_size
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offsets['plaintext_hash_tree'] = x
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x += self._segment_hash_size
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offsets['crypttext_hash_tree'] = x
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x += self._segment_hash_size
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offsets['block_hashes'] = x
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x += self._segment_hash_size
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offsets['share_hashes'] = x
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x += self._share_hash_size
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offsets['uri_extension'] = x
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offset_data = struct.pack(">LLLLLLL",
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segment_size,
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offsets['data'],
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offsets['plaintext_hash_tree'],
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offsets['crypttext_hash_tree'],
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offsets['block_hashes'],
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offsets['share_hashes'],
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offsets['uri_extension']
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)
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assert len(offset_data) == 7*4
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self._offset_data = offset_data
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def start(self):
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return self._write(0, self._offset_data)
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def put_block(self, segmentnum, data):
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offset = self._offsets['data'] + segmentnum * self._segment_size
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assert offset + len(data) <= self._offsets['uri_extension']
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assert isinstance(data, str)
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if segmentnum < self._segment_size-1:
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assert len(data) == self._segment_size
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else:
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assert len(data) <= self._segment_size
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return self._write(offset, data)
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def put_plaintext_hashes(self, hashes):
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offset = self._offsets['plaintext_hash_tree']
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assert isinstance(hashes, list)
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data = "".join(hashes)
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assert len(data) == self._segment_hash_size
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assert offset + len(data) <= self._offsets['crypttext_hash_tree']
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return self._write(offset, data)
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def put_crypttext_hashes(self, hashes):
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offset = self._offsets['crypttext_hash_tree']
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assert isinstance(hashes, list)
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data = "".join(hashes)
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assert len(data) == self._segment_hash_size
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assert offset + len(data) <= self._offsets['block_hashes']
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return self._write(offset, data)
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def put_block_hashes(self, blockhashes):
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offset = self._offsets['block_hashes']
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assert isinstance(blockhashes, list)
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data = "".join(blockhashes)
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assert len(data) == self._segment_hash_size
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assert offset + len(data) <= self._offsets['share_hashes']
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return self._write(offset, data)
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def put_share_hashes(self, sharehashes):
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# sharehashes is a list of (index, hash) tuples, so they get stored
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# as 2+32=34 bytes each
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offset = self._offsets['share_hashes']
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assert isinstance(sharehashes, list)
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data = "".join([struct.pack(">H", hashnum) + hashvalue
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for hashnum,hashvalue in sharehashes])
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assert len(data) == self._share_hash_size
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assert offset + len(data) <= self._offsets['uri_extension']
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return self._write(offset, data)
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def put_uri_extension(self, data):
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offset = self._offsets['uri_extension']
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assert isinstance(data, str)
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length = struct.pack(">L", len(data))
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return self._write(offset, length+data)
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def _write(self, offset, data):
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# TODO: for small shares, buffer the writes and do just a single call
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return self._rref.callRemote("write", offset, data)
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def close(self):
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return self._rref.callRemote("close")
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class ReadBucketProxy:
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implements(IStorageBucketReader)
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def __init__(self, rref):
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self._rref = rref
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def startIfNecessary(self):
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if self._started:
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return defer.succeed(self)
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d = self.start()
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d.addCallback(lambda res: self)
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return d
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def start(self):
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# TODO: for small shares, read the whole bucket in start()
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d = self._read(0, 7*4)
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self._offsets = {}
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def _got_offsets(data):
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self._segment_size = struct.unpack(">L", data[0:4])[0]
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x = 4
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for field in ( 'data',
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'plaintext_hash_tree',
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'crypttext_hash_tree',
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'block_hashes',
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'share_hashes',
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'uri_extension' ):
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offset = struct.unpack(">L", data[x:x+4])[0]
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x += 4
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self._offsets[field] = offset
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d.addCallback(_got_offsets)
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return d
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def get_block(self, blocknum):
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offset = self._offsets['data'] + blocknum * self._segment_size
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return self._read(offset, self._segment_size)
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def _str2l(self, s):
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""" split string (pulled from storage) into a list of blockids """
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return [ s[i:i+interfaces.HASH_SIZE]
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for i in range(0, len(s), interfaces.HASH_SIZE) ]
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def get_plaintext_hashes(self):
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offset = self._offsets['plaintext_hash_tree']
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size = self._offsets['crypttext_hash_tree'] - offset
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d = self._read(offset, size)
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d.addCallback(self._str2l)
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return d
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def get_crypttext_hashes(self):
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offset = self._offsets['crypttext_hash_tree']
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size = self._offsets['block_hashes'] - offset
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d = self._read(offset, size)
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d.addCallback(self._str2l)
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return d
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def get_block_hashes(self):
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offset = self._offsets['block_hashes']
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size = self._offsets['share_hashes'] - offset
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d = self._read(offset, size)
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d.addCallback(self._str2l)
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return d
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def get_share_hashes(self):
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offset = self._offsets['share_hashes']
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size = self._offsets['uri_extension'] - offset
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HASH_SIZE = interfaces.HASH_SIZE
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assert size % (2+HASH_SIZE) == 0
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d = self._read(offset, size)
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def _unpack_share_hashes(data):
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assert len(data) == size
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hashes = []
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for i in range(0, size, 2+HASH_SIZE):
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hashnum = struct.unpack(">H", data[i:i+2])[0]
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hashvalue = data[i+2:i+2+HASH_SIZE]
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hashes.append( (hashnum, hashvalue) )
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return hashes
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d.addCallback(_unpack_share_hashes)
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return d
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def get_uri_extension(self):
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offset = self._offsets['uri_extension']
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d = self._read(offset, 4)
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def _got_length(data):
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length = struct.unpack(">L", data)[0]
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return self._read(offset+4, length)
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d.addCallback(_got_length)
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return d
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def _read(self, offset, length):
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return self._rref.callRemote("read", offset, length)
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