17
17
"""Core compression logic for compressing streams of related files."""
19
from __future__ import absolute_import
24
from .lazy_import import lazy_import
25
lazy_import(globals(), """
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31
graph as _mod_graph,
37
from bzrlib.btree_index import BTreeBuilder
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from bzrlib.lru_cache import LRUSizeCache
39
from bzrlib.tsort import topo_sort
40
from bzrlib.versionedfile import (
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from breezy.repofmt import pack_repo
40
from breezy.i18n import gettext
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from .btree_index import BTreeBuilder
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from .lru_cache import LRUSizeCache
48
from .versionedfile import (
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51
AbsentContentFactory,
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ChunkedContentFactory,
44
53
FulltextContentFactory,
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VersionedFilesWithFallbacks,
48
57
# Minimum number of uncompressed bytes to try fetch at once when retrieving
49
58
# groupcompress blocks.
52
_USE_LZMA = False and (pylzma is not None)
54
61
# osutils.sha_string('')
55
62
_null_sha1 = 'da39a3ee5e6b4b0d3255bfef95601890afd80709'
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self._content = ''.join(self._content_chunks)
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143
self._content_chunks = None
137
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if self._content is None:
138
if self._z_content is None:
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# We join self._z_content_chunks here, because if we are
146
# decompressing, then it is *very* likely that we have a single
148
if self._z_content_chunks is None:
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raise AssertionError('No content to decompress')
140
if self._z_content == '':
150
z_content = ''.join(self._z_content_chunks)
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152
self._content = ''
142
153
elif self._compressor_name == 'lzma':
143
154
# We don't do partial lzma decomp yet
144
self._content = pylzma.decompress(self._z_content)
156
self._content = pylzma.decompress(z_content)
145
157
elif self._compressor_name == 'zlib':
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# Start a zlib decompressor
147
159
if num_bytes * 4 > self._content_length * 3:
148
160
# If we are requesting more that 3/4ths of the content,
149
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# just extract the whole thing in a single pass
150
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num_bytes = self._content_length
151
self._content = zlib.decompress(self._z_content)
163
self._content = zlib.decompress(z_content)
153
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self._z_content_decompressor = zlib.decompressobj()
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# Seed the decompressor with the uncompressed bytes, so
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# that the rest of the code is simplified
156
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self._content = self._z_content_decompressor.decompress(
157
self._z_content, num_bytes + _ZLIB_DECOMP_WINDOW)
169
z_content, num_bytes + _ZLIB_DECOMP_WINDOW)
158
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if not self._z_content_decompressor.unconsumed_tail:
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self._z_content_decompressor = None
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# XXX: Define some GCCorrupt error ?
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raise AssertionError('Invalid bytes: (%d) != %d + %d' %
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(len(bytes), pos, self._z_content_length))
210
self._z_content = bytes[pos:]
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self._z_content_chunks = (bytes[pos:],)
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def _z_content(self):
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"""Return z_content_chunks as a simple string.
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Meant only to be used by the test suite.
230
if self._z_content_chunks is not None:
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return ''.join(self._z_content_chunks)
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def from_bytes(cls, bytes):
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self._content_length = length
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self._content_chunks = content_chunks
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self._content = None
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self._z_content = None
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self._z_content_chunks = None
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def set_content(self, content):
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"""Set the content of this block."""
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self._content_length = len(content)
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self._content = content
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self._z_content = None
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def _create_z_content_using_lzma(self):
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if self._content_chunks is not None:
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self._content = ''.join(self._content_chunks)
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self._content_chunks = None
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if self._content is None:
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raise AssertionError('Nothing to compress')
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self._z_content = pylzma.compress(self._content)
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self._z_content_length = len(self._z_content)
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def _create_z_content_from_chunks(self):
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self._z_content_chunks = None
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def _create_z_content_from_chunks(self, chunks):
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compressor = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION)
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compressed_chunks = map(compressor.compress, self._content_chunks)
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# Peak in this point is 1 fulltext, 1 compressed text, + zlib overhead
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# (measured peak is maybe 30MB over the above...)
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compressed_chunks = list(map(compressor.compress, chunks))
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compressed_chunks.append(compressor.flush())
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self._z_content = ''.join(compressed_chunks)
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self._z_content_length = len(self._z_content)
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# Ignore empty chunks
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self._z_content_chunks = [c for c in compressed_chunks if c]
310
self._z_content_length = sum(map(len, self._z_content_chunks))
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def _create_z_content(self):
297
if self._z_content is not None:
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self._create_z_content_using_lzma()
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if self._z_content_chunks is not None:
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if self._content_chunks is not None:
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self._create_z_content_from_chunks()
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self._z_content = zlib.compress(self._content)
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self._z_content_length = len(self._z_content)
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chunks = self._content_chunks
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chunks = (self._content,)
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self._create_z_content_from_chunks(chunks)
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"""Create the byte stream as a series of 'chunks'"""
323
self._create_z_content()
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header = self.GCB_HEADER
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chunks = ['%s%d\n%d\n'
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% (header, self._z_content_length, self._content_length),
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chunks.extend(self._z_content_chunks)
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total_len = sum(map(len, chunks))
330
return total_len, chunks
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def to_bytes(self):
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"""Encode the information into a byte stream."""
310
self._create_z_content()
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header = self.GCB_LZ_HEADER
314
header = self.GCB_HEADER
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'%d\n%d\n' % (self._z_content_length, self._content_length),
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total_len, chunks = self.to_chunks()
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return ''.join(chunks)
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def _dump(self, include_text=False):
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# Grab and cache the raw bytes for this entry
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# and break the ref-cycle with _manager since we don't need it
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self._manager._prepare_for_extract()
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self._manager._prepare_for_extract()
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except zlib.error as value:
457
raise errors.DecompressCorruption("zlib: " + str(value))
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block = self._manager._block
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self._bytes = block.extract(self.key, self._start, self._end)
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# There are code paths that first extract as fulltext, and then
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_full_enough_block_size = 3*1024*1024 # size at which we won't repack
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_full_enough_mixed_block_size = 2*768*1024 # 1.5MB
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def __init__(self, block):
482
def __init__(self, block, get_compressor_settings=None):
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self._block = block
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# We need to preserve the ordering
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self._factories = []
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self._last_byte = 0
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self._get_settings = get_compressor_settings
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self._compressor_settings = None
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def _get_compressor_settings(self):
491
if self._compressor_settings is not None:
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return self._compressor_settings
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if self._get_settings is not None:
495
settings = self._get_settings()
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vf = GroupCompressVersionedFiles
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settings = vf._DEFAULT_COMPRESSOR_SETTINGS
499
self._compressor_settings = settings
500
return self._compressor_settings
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def add_factory(self, key, parents, start, end):
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if not self._factories:
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new_block.set_content(self._block._content[:last_byte])
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self._block = new_block
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def _make_group_compressor(self):
540
return GroupCompressor(self._get_compressor_settings())
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def _rebuild_block(self):
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"""Create a new GroupCompressBlock with only the referenced texts."""
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compressor = GroupCompressor()
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compressor = self._make_group_compressor()
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tstart = time.time()
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old_length = self._block._content_length
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# block? It seems hard to come up with a method that it would
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# expand, since we do full compression again. Perhaps based on a
525
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# request that ends up poorly ordered?
562
# TODO: If the content would have expanded, then we would want to
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# handle a case where we need to split the block.
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# Now that we have a user-tweakable option
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# (max_bytes_to_index), it is possible that one person set it
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# to a very low value, causing poor compression.
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delta = time.time() - tstart
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self._block = new_block
528
569
trace.mutter('creating new compressed block on-the-fly in %.3fs'
679
720
z_header_bytes = zlib.compress(header_bytes)
681
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z_header_bytes_len = len(z_header_bytes)
682
block_bytes = self._block.to_bytes()
723
block_bytes_len, block_chunks = self._block.to_chunks()
683
724
lines.append('%d\n%d\n%d\n' % (z_header_bytes_len, header_bytes_len,
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726
lines.append(z_header_bytes)
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lines.append(block_bytes)
687
del z_header_bytes, block_bytes
727
lines.extend(block_chunks)
728
del z_header_bytes, block_chunks
729
# TODO: This is a point where we will double the memory consumption. To
730
# avoid this, we probably have to switch to a 'chunked' api
688
731
return ''.join(lines)
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734
def from_bytes(cls, bytes):
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# TODO: This does extra string copying, probably better to do it a
736
# different way. At a minimum this creates 2 copies of the
694
738
(storage_kind, z_header_len, header_len,
695
739
block_len, rest) = bytes.split('\n', 4)
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903
After calling this, the compressor should no longer be used
857
# TODO: this causes us to 'bloat' to 2x the size of content in the
858
# group. This has an impact for 'commit' of large objects.
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# One possibility is to use self._content_chunks, and be lazy and
860
# only fill out self._content as a full string when we actually
861
# need it. That would at least drop the peak memory consumption
862
# for 'commit' down to ~1x the size of the largest file, at a
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# cost of increased complexity within this code. 2x is still <<
864
# 3x the size of the largest file, so we are doing ok.
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self._block.set_chunked_content(self.chunks, self.endpoint)
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self.chunks = None
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self._delta_index = None
886
926
class PythonGroupCompressor(_CommonGroupCompressor):
928
def __init__(self, settings=None):
889
929
"""Create a GroupCompressor.
891
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Used only if the pyrex version is not available.
893
super(PythonGroupCompressor, self).__init__()
933
super(PythonGroupCompressor, self).__init__(settings)
894
934
self._delta_index = LinesDeltaIndex([])
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# The actual content is managed by LinesDeltaIndex
896
936
self.chunks = self._delta_index.lines
934
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It contains code very similar to SequenceMatcher because of having a similar
935
975
task. However some key differences apply:
936
- there is no junk, we want a minimal edit not a human readable diff.
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- we don't filter very common lines (because we don't know where a good
938
range will start, and after the first text we want to be emitting minmal
940
- we chain the left side, not the right side
941
- we incrementally update the adjacency matrix as new lines are provided.
942
- we look for matches in all of the left side, so the routine which does
943
the analagous task of find_longest_match does not need to filter on the
977
* there is no junk, we want a minimal edit not a human readable diff.
978
* we don't filter very common lines (because we don't know where a good
979
range will start, and after the first text we want to be emitting minmal
981
* we chain the left side, not the right side
982
* we incrementally update the adjacency matrix as new lines are provided.
983
* we look for matches in all of the left side, so the routine which does
984
the analagous task of find_longest_match does not need to filter on the
948
super(PyrexGroupCompressor, self).__init__()
949
self._delta_index = DeltaIndex()
988
def __init__(self, settings=None):
989
super(PyrexGroupCompressor, self).__init__(settings)
990
max_bytes_to_index = self._settings.get('max_bytes_to_index', 0)
991
self._delta_index = DeltaIndex(max_bytes_to_index=max_bytes_to_index)
951
993
def _compress(self, key, bytes, max_delta_size, soft=False):
952
994
"""see _CommonGroupCompressor._compress"""
1027
1069
index = _GCGraphIndex(graph_index, lambda:True, parents=parents,
1028
1070
add_callback=graph_index.add_nodes,
1029
1071
inconsistency_fatal=inconsistency_fatal)
1030
access = knit._DirectPackAccess({})
1072
access = pack_repo._DirectPackAccess({})
1031
1073
access.set_writer(writer, graph_index, (transport, 'newpack'))
1032
1074
result = GroupCompressVersionedFiles(index, access, delta)
1033
1075
result.stream = stream
1044
1086
class _BatchingBlockFetcher(object):
1045
1087
"""Fetch group compress blocks in batches.
1047
1089
:ivar total_bytes: int of expected number of bytes needed to fetch the
1048
1090
currently pending batch.
1051
def __init__(self, gcvf, locations):
1093
def __init__(self, gcvf, locations, get_compressor_settings=None):
1052
1094
self.gcvf = gcvf
1053
1095
self.locations = locations
1102
1145
def yield_factories(self, full_flush=False):
1103
1146
"""Yield factories for keys added since the last yield. They will be
1104
1147
returned in the order they were added via add_key.
1106
1149
:param full_flush: by default, some results may not be returned in case
1107
1150
they can be part of the next batch. If full_flush is True, then
1108
1151
all results are returned.
1136
1179
memos_to_get_stack.pop()
1138
1181
block = self.batch_memos[read_memo]
1139
self.manager = _LazyGroupContentManager(block)
1182
self.manager = _LazyGroupContentManager(block,
1183
get_compressor_settings=self._get_compressor_settings)
1140
1184
self.last_read_memo = read_memo
1141
1185
start, end = index_memo[3:5]
1142
1186
self.manager.add_factory(key, parents, start, end)
1149
1193
self.total_bytes = 0
1152
class GroupCompressVersionedFiles(VersionedFiles):
1196
class GroupCompressVersionedFiles(VersionedFilesWithFallbacks):
1153
1197
"""A group-compress based VersionedFiles implementation."""
1155
def __init__(self, index, access, delta=True, _unadded_refs=None):
1199
# This controls how the GroupCompress DeltaIndex works. Basically, we
1200
# compute hash pointers into the source blocks (so hash(text) => text).
1201
# However each of these references costs some memory in trade against a
1202
# more accurate match result. For very large files, they either are
1203
# pre-compressed and change in bulk whenever they change, or change in just
1204
# local blocks. Either way, 'improved resolution' is not very helpful,
1205
# versus running out of memory trying to track everything. The default max
1206
# gives 100% sampling of a 1MB file.
1207
_DEFAULT_MAX_BYTES_TO_INDEX = 1024 * 1024
1208
_DEFAULT_COMPRESSOR_SETTINGS = {'max_bytes_to_index':
1209
_DEFAULT_MAX_BYTES_TO_INDEX}
1211
def __init__(self, index, access, delta=True, _unadded_refs=None,
1156
1213
"""Create a GroupCompressVersionedFiles object.
1158
1215
:param index: The index object storing access and graph data.
1159
1216
:param access: The access object storing raw data.
1160
1217
:param delta: Whether to delta compress or just entropy compress.
1161
1218
:param _unadded_refs: private parameter, don't use.
1219
:param _group_cache: private parameter, don't use.
1163
1221
self._index = index
1164
1222
self._access = access
1166
1224
if _unadded_refs is None:
1167
1225
_unadded_refs = {}
1168
1226
self._unadded_refs = _unadded_refs
1169
self._group_cache = LRUSizeCache(max_size=50*1024*1024)
1170
self._fallback_vfs = []
1227
if _group_cache is None:
1228
_group_cache = LRUSizeCache(max_size=50*1024*1024)
1229
self._group_cache = _group_cache
1230
self._immediate_fallback_vfs = []
1231
self._max_bytes_to_index = None
1172
1233
def without_fallbacks(self):
1173
1234
"""Return a clone of this object without any fallbacks configured."""
1174
1235
return GroupCompressVersionedFiles(self._index, self._access,
1175
self._delta, _unadded_refs=dict(self._unadded_refs))
1236
self._delta, _unadded_refs=dict(self._unadded_refs),
1237
_group_cache=self._group_cache)
1177
1239
def add_lines(self, key, parents, lines, parent_texts=None,
1178
1240
left_matching_blocks=None, nostore_sha=None, random_id=False,
1182
1244
:param key: The key tuple of the text to add.
1183
1245
:param parents: The parents key tuples of the text to add.
1184
1246
:param lines: A list of lines. Each line must be a bytestring. And all
1185
of them except the last must be terminated with \n and contain no
1186
other \n's. The last line may either contain no \n's or a single
1187
terminating \n. If the lines list does meet this constraint the add
1188
routine may error or may succeed - but you will be unable to read
1189
the data back accurately. (Checking the lines have been split
1247
of them except the last must be terminated with \\n and contain no
1248
other \\n's. The last line may either contain no \\n's or a single
1249
terminating \\n. If the lines list does meet this constraint the
1250
add routine may error or may succeed - but you will be unable to
1251
read the data back accurately. (Checking the lines have been split
1190
1252
correctly is expensive and extremely unlikely to catch bugs so it
1191
1253
is not done at runtime unless check_content is True.)
1192
1254
:param parent_texts: An optional dictionary containing the opaque
1287
1349
self._check_lines_not_unicode(lines)
1288
1350
self._check_lines_are_lines(lines)
1290
def get_known_graph_ancestry(self, keys):
1291
"""Get a KnownGraph instance with the ancestry of keys."""
1292
# Note that this is identical to
1293
# KnitVersionedFiles.get_known_graph_ancestry, but they don't share
1295
parent_map, missing_keys = self._index.find_ancestry(keys)
1296
for fallback in self._fallback_vfs:
1297
if not missing_keys:
1299
(f_parent_map, f_missing_keys) = fallback._index.find_ancestry(
1301
parent_map.update(f_parent_map)
1302
missing_keys = f_missing_keys
1303
kg = _mod_graph.KnownGraph(parent_map)
1306
1352
def get_parent_map(self, keys):
1307
1353
"""Get a map of the graph parents of keys.
1366
1412
yield read_memo, cached[read_memo]
1367
1413
except KeyError:
1368
1414
# Read the block, and cache it.
1369
zdata = raw_records.next()
1415
zdata = next(raw_records)
1370
1416
block = GroupCompressBlock.from_bytes(zdata)
1371
1417
self._group_cache[read_memo] = block
1372
1418
cached[read_memo] = block
1447
1493
The returned objects should be in the order defined by 'ordering',
1448
1494
which can weave between different sources.
1449
1496
:param ordering: Must be one of 'topological' or 'groupcompress'
1450
1497
:return: List of [(source, [keys])] tuples, such that all keys are in
1451
1498
the defined order, regardless of source.
1453
1500
if ordering == 'topological':
1454
present_keys = topo_sort(parent_map)
1501
present_keys = tsort.topo_sort(parent_map)
1456
1503
# ordering == 'groupcompress'
1457
1504
# XXX: This only optimizes for the target ordering. We may need
1546
1593
# - we encounter an unadded ref, or
1547
1594
# - we run out of keys, or
1548
1595
# - the total bytes to retrieve for this batch > BATCH_SIZE
1549
batcher = _BatchingBlockFetcher(self, locations)
1596
batcher = _BatchingBlockFetcher(self, locations,
1597
get_compressor_settings=self._get_compressor_settings)
1550
1598
for source, keys in source_keys:
1551
1599
if source is self:
1552
1600
for key in keys:
1598
1646
for _ in self._insert_record_stream(stream, random_id=False):
1649
def _get_compressor_settings(self):
1650
if self._max_bytes_to_index is None:
1651
# TODO: VersionedFiles don't know about their containing
1652
# repository, so they don't have much of an idea about their
1653
# location. So for now, this is only a global option.
1654
c = config.GlobalConfig()
1655
val = c.get_user_option('bzr.groupcompress.max_bytes_to_index')
1659
except ValueError as e:
1660
trace.warning('Value for '
1661
'"bzr.groupcompress.max_bytes_to_index"'
1662
' %r is not an integer'
1666
val = self._DEFAULT_MAX_BYTES_TO_INDEX
1667
self._max_bytes_to_index = val
1668
return {'max_bytes_to_index': self._max_bytes_to_index}
1670
def _make_group_compressor(self):
1671
return GroupCompressor(self._get_compressor_settings())
1601
1673
def _insert_record_stream(self, stream, random_id=False, nostore_sha=None,
1602
1674
reuse_blocks=True):
1603
1675
"""Internal core to insert a record stream into this container.
1627
1699
# This will go up to fulltexts for gc to gc fetching, which isn't
1629
self._compressor = GroupCompressor()
1701
self._compressor = self._make_group_compressor()
1630
1702
self._unadded_refs = {}
1631
1703
keys_to_add = []
1633
bytes = self._compressor.flush().to_bytes()
1634
self._compressor = GroupCompressor()
1705
bytes_len, chunks = self._compressor.flush().to_chunks()
1706
self._compressor = self._make_group_compressor()
1707
# Note: At this point we still have 1 copy of the fulltext (in
1708
# record and the var 'bytes'), and this generates 2 copies of
1709
# the compressed text (one for bytes, one in chunks)
1710
# TODO: Push 'chunks' down into the _access api, so that we don't
1711
# have to double compressed memory here
1712
# TODO: Figure out how to indicate that we would be happy to free
1713
# the fulltext content at this point. Note that sometimes we
1714
# will want it later (streaming CHK pages), but most of the
1715
# time we won't (everything else)
1716
bytes = ''.join(chunks)
1635
1718
index, start, length = self._access.add_raw_records(
1636
1719
[(None, len(bytes))], bytes)[0]
1656
1739
raise errors.RevisionNotPresent(record.key, self)
1658
1741
if record.key in inserted_keys:
1659
trace.note('Insert claimed random_id=True,'
1660
' but then inserted %r two times', record.key)
1742
trace.note(gettext('Insert claimed random_id=True,'
1743
' but then inserted %r two times'), record.key)
1662
1745
inserted_keys.add(record.key)
1663
1746
if reuse_blocks:
1802
1885
"""See VersionedFiles.keys."""
1803
1886
if 'evil' in debug.debug_flags:
1804
1887
trace.mutter_callsite(2, "keys scales with size of history")
1805
sources = [self._index] + self._fallback_vfs
1888
sources = [self._index] + self._immediate_fallback_vfs
1807
1890
for source in sources:
1808
1891
result.update(source.keys())
1895
class _GCBuildDetails(object):
1896
"""A blob of data about the build details.
1898
This stores the minimal data, which then allows compatibility with the old
1899
api, without taking as much memory.
1902
__slots__ = ('_index', '_group_start', '_group_end', '_basis_end',
1903
'_delta_end', '_parents')
1906
compression_parent = None
1908
def __init__(self, parents, position_info):
1909
self._parents = parents
1910
(self._index, self._group_start, self._group_end, self._basis_end,
1911
self._delta_end) = position_info
1914
return '%s(%s, %s)' % (self.__class__.__name__,
1915
self.index_memo, self._parents)
1918
def index_memo(self):
1919
return (self._index, self._group_start, self._group_end,
1920
self._basis_end, self._delta_end)
1923
def record_details(self):
1924
return static_tuple.StaticTuple(self.method, None)
1926
def __getitem__(self, offset):
1927
"""Compatibility thunk to act like a tuple."""
1929
return self.index_memo
1931
return self.compression_parent # Always None
1933
return self._parents
1935
return self.record_details
1937
raise IndexError('offset out of range')
1812
1943
class _GCGraphIndex(object):
1813
1944
"""Mapper from GroupCompressVersionedFiles needs into GraphIndex storage."""
1817
1948
inconsistency_fatal=True, track_new_keys=False):
1818
1949
"""Construct a _GCGraphIndex on a graph_index.
1820
:param graph_index: An implementation of bzrlib.index.GraphIndex.
1951
:param graph_index: An implementation of breezy.index.GraphIndex.
1821
1952
:param is_locked: A callback, returns True if the index is locked and
1823
1954
:param parents: If True, record knits parents, if not do not record
1989
2120
:param keys: An iterable of keys.
1990
2121
:return: A dict of key:
1991
2122
(index_memo, compression_parent, parents, record_details).
1993
opaque structure to pass to read_records to extract the raw
1996
Content that this record is built upon, may be None
1998
Logical parents of this node
2000
extra information about the content which needs to be passed to
2001
Factory.parse_record
2124
* index_memo: opaque structure to pass to read_records to extract
2126
* compression_parent: Content that this record is built upon, may
2128
* parents: Logical parents of this node
2129
* record_details: extra information about the content which needs
2130
to be passed to Factory.parse_record
2003
2132
self._check_read()
2033
2161
# each, or about 7MB. Note that it might be even more when you consider
2034
2162
# how PyInt is allocated in separate slabs. And you can't return a slab
2035
2163
# to the OS if even 1 int on it is in use. Note though that Python uses
2036
# a LIFO when re-using PyInt slots, which probably causes more
2164
# a LIFO when re-using PyInt slots, which might cause more
2037
2165
# fragmentation.
2038
2166
start = int(bits[0])
2039
2167
start = self._int_cache.setdefault(start, start)
added
removed
breezy/groupcompress.py
