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(), """
30
31
graph as _mod_graph,
37
from bzrlib.btree_index import BTreeBuilder
38
from bzrlib.lru_cache import LRUSizeCache
39
from bzrlib.tsort import topo_sort
40
from bzrlib.versionedfile import (
39
from breezy.repofmt import pack_repo
40
from breezy.i18n import gettext
43
from .btree_index import BTreeBuilder
44
from .lru_cache import LRUSizeCache
49
from .versionedfile import (
42
52
AbsentContentFactory,
43
53
ChunkedContentFactory,
44
54
FulltextContentFactory,
55
VersionedFilesWithFallbacks,
48
58
# Minimum number of uncompressed bytes to try fetch at once when retrieving
49
59
# groupcompress blocks.
52
_USE_LZMA = False and (pylzma is not None)
54
62
# osutils.sha_string('')
55
63
_null_sha1 = 'da39a3ee5e6b4b0d3255bfef95601890afd80709'
135
143
self._content = ''.join(self._content_chunks)
136
144
self._content_chunks = None
137
145
if self._content is None:
138
if self._z_content is None:
146
# We join self._z_content_chunks here, because if we are
147
# decompressing, then it is *very* likely that we have a single
149
if self._z_content_chunks is None:
139
150
raise AssertionError('No content to decompress')
140
if self._z_content == '':
151
z_content = ''.join(self._z_content_chunks)
141
153
self._content = ''
142
154
elif self._compressor_name == 'lzma':
143
155
# We don't do partial lzma decomp yet
144
self._content = pylzma.decompress(self._z_content)
157
self._content = pylzma.decompress(z_content)
145
158
elif self._compressor_name == 'zlib':
146
159
# Start a zlib decompressor
147
160
if num_bytes * 4 > self._content_length * 3:
148
161
# If we are requesting more that 3/4ths of the content,
149
162
# just extract the whole thing in a single pass
150
163
num_bytes = self._content_length
151
self._content = zlib.decompress(self._z_content)
164
self._content = zlib.decompress(z_content)
153
166
self._z_content_decompressor = zlib.decompressobj()
154
167
# Seed the decompressor with the uncompressed bytes, so
155
168
# that the rest of the code is simplified
156
169
self._content = self._z_content_decompressor.decompress(
157
self._z_content, num_bytes + _ZLIB_DECOMP_WINDOW)
170
z_content, num_bytes + _ZLIB_DECOMP_WINDOW)
158
171
if not self._z_content_decompressor.unconsumed_tail:
159
172
self._z_content_decompressor = None
207
220
# XXX: Define some GCCorrupt error ?
208
221
raise AssertionError('Invalid bytes: (%d) != %d + %d' %
209
222
(len(bytes), pos, self._z_content_length))
210
self._z_content = bytes[pos:]
223
self._z_content_chunks = (bytes[pos:],)
226
def _z_content(self):
227
"""Return z_content_chunks as a simple string.
229
Meant only to be used by the test suite.
231
if self._z_content_chunks is not None:
232
return ''.join(self._z_content_chunks)
213
236
def from_bytes(cls, bytes):
269
292
self._content_length = length
270
293
self._content_chunks = content_chunks
271
294
self._content = None
272
self._z_content = None
295
self._z_content_chunks = None
274
297
def set_content(self, content):
275
298
"""Set the content of this block."""
276
299
self._content_length = len(content)
277
300
self._content = content
278
self._z_content = None
280
def _create_z_content_using_lzma(self):
281
if self._content_chunks is not None:
282
self._content = ''.join(self._content_chunks)
283
self._content_chunks = None
284
if self._content is None:
285
raise AssertionError('Nothing to compress')
286
self._z_content = pylzma.compress(self._content)
287
self._z_content_length = len(self._z_content)
289
def _create_z_content_from_chunks(self):
301
self._z_content_chunks = None
303
def _create_z_content_from_chunks(self, chunks):
290
304
compressor = zlib.compressobj(zlib.Z_DEFAULT_COMPRESSION)
291
compressed_chunks = map(compressor.compress, self._content_chunks)
305
# Peak in this point is 1 fulltext, 1 compressed text, + zlib overhead
306
# (measured peak is maybe 30MB over the above...)
307
compressed_chunks = list(map(compressor.compress, chunks))
292
308
compressed_chunks.append(compressor.flush())
293
self._z_content = ''.join(compressed_chunks)
294
self._z_content_length = len(self._z_content)
309
# Ignore empty chunks
310
self._z_content_chunks = [c for c in compressed_chunks if c]
311
self._z_content_length = sum(map(len, self._z_content_chunks))
296
313
def _create_z_content(self):
297
if self._z_content is not None:
300
self._create_z_content_using_lzma()
314
if self._z_content_chunks is not None:
302
316
if self._content_chunks is not None:
303
self._create_z_content_from_chunks()
305
self._z_content = zlib.compress(self._content)
306
self._z_content_length = len(self._z_content)
317
chunks = self._content_chunks
319
chunks = (self._content,)
320
self._create_z_content_from_chunks(chunks)
323
"""Create the byte stream as a series of 'chunks'"""
324
self._create_z_content()
325
header = self.GCB_HEADER
326
chunks = ['%s%d\n%d\n'
327
% (header, self._z_content_length, self._content_length),
329
chunks.extend(self._z_content_chunks)
330
total_len = sum(map(len, chunks))
331
return total_len, chunks
308
333
def to_bytes(self):
309
334
"""Encode the information into a byte stream."""
310
self._create_z_content()
312
header = self.GCB_LZ_HEADER
314
header = self.GCB_HEADER
316
'%d\n%d\n' % (self._z_content_length, self._content_length),
335
total_len, chunks = self.to_chunks()
319
336
return ''.join(chunks)
321
338
def _dump(self, include_text=False):
435
452
# Grab and cache the raw bytes for this entry
436
453
# and break the ref-cycle with _manager since we don't need it
438
self._manager._prepare_for_extract()
456
self._manager._prepare_for_extract()
457
except zlib.error as value:
458
raise errors.DecompressCorruption("zlib: " + str(value))
439
459
block = self._manager._block
440
460
self._bytes = block.extract(self.key, self._start, self._end)
441
461
# There are code paths that first extract as fulltext, and then
460
480
_full_enough_block_size = 3*1024*1024 # size at which we won't repack
461
481
_full_enough_mixed_block_size = 2*768*1024 # 1.5MB
463
def __init__(self, block):
483
def __init__(self, block, get_compressor_settings=None):
464
484
self._block = block
465
485
# We need to preserve the ordering
466
486
self._factories = []
467
487
self._last_byte = 0
488
self._get_settings = get_compressor_settings
489
self._compressor_settings = None
491
def _get_compressor_settings(self):
492
if self._compressor_settings is not None:
493
return self._compressor_settings
495
if self._get_settings is not None:
496
settings = self._get_settings()
498
vf = GroupCompressVersionedFiles
499
settings = vf._DEFAULT_COMPRESSOR_SETTINGS
500
self._compressor_settings = settings
501
return self._compressor_settings
469
503
def add_factory(self, key, parents, start, end):
470
504
if not self._factories:
503
537
new_block.set_content(self._block._content[:last_byte])
504
538
self._block = new_block
540
def _make_group_compressor(self):
541
return GroupCompressor(self._get_compressor_settings())
506
543
def _rebuild_block(self):
507
544
"""Create a new GroupCompressBlock with only the referenced texts."""
508
compressor = GroupCompressor()
545
compressor = self._make_group_compressor()
509
546
tstart = time.time()
510
547
old_length = self._block._content_length
523
560
# block? It seems hard to come up with a method that it would
524
561
# expand, since we do full compression again. Perhaps based on a
525
562
# request that ends up poorly ordered?
563
# TODO: If the content would have expanded, then we would want to
564
# handle a case where we need to split the block.
565
# Now that we have a user-tweakable option
566
# (max_bytes_to_index), it is possible that one person set it
567
# to a very low value, causing poor compression.
526
568
delta = time.time() - tstart
527
569
self._block = new_block
528
570
trace.mutter('creating new compressed block on-the-fly in %.3fs'
679
721
z_header_bytes = zlib.compress(header_bytes)
681
723
z_header_bytes_len = len(z_header_bytes)
682
block_bytes = self._block.to_bytes()
724
block_bytes_len, block_chunks = self._block.to_chunks()
683
725
lines.append('%d\n%d\n%d\n' % (z_header_bytes_len, header_bytes_len,
685
727
lines.append(z_header_bytes)
686
lines.append(block_bytes)
687
del z_header_bytes, block_bytes
728
lines.extend(block_chunks)
729
del z_header_bytes, block_chunks
730
# TODO: This is a point where we will double the memory consumption. To
731
# avoid this, we probably have to switch to a 'chunked' api
688
732
return ''.join(lines)
691
735
def from_bytes(cls, bytes):
692
736
# TODO: This does extra string copying, probably better to do it a
737
# different way. At a minimum this creates 2 copies of the
694
739
(storage_kind, z_header_len, header_len,
695
740
block_len, rest) = bytes.split('\n', 4)
855
904
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.
859
# 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
863
# cost of increased complexity within this code. 2x is still <<
864
# 3x the size of the largest file, so we are doing ok.
865
906
self._block.set_chunked_content(self.chunks, self.endpoint)
866
907
self.chunks = None
867
908
self._delta_index = None
886
927
class PythonGroupCompressor(_CommonGroupCompressor):
929
def __init__(self, settings=None):
889
930
"""Create a GroupCompressor.
891
932
Used only if the pyrex version is not available.
893
super(PythonGroupCompressor, self).__init__()
934
super(PythonGroupCompressor, self).__init__(settings)
894
935
self._delta_index = LinesDeltaIndex([])
895
936
# The actual content is managed by LinesDeltaIndex
896
937
self.chunks = self._delta_index.lines
934
975
It contains code very similar to SequenceMatcher because of having a similar
935
976
task. However some key differences apply:
936
- there is no junk, we want a minimal edit not a human readable diff.
937
- 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
978
* there is no junk, we want a minimal edit not a human readable diff.
979
* we don't filter very common lines (because we don't know where a good
980
range will start, and after the first text we want to be emitting minmal
982
* we chain the left side, not the right side
983
* we incrementally update the adjacency matrix as new lines are provided.
984
* we look for matches in all of the left side, so the routine which does
985
the analagous task of find_longest_match does not need to filter on the
948
super(PyrexGroupCompressor, self).__init__()
949
self._delta_index = DeltaIndex()
989
def __init__(self, settings=None):
990
super(PyrexGroupCompressor, self).__init__(settings)
991
max_bytes_to_index = self._settings.get('max_bytes_to_index', 0)
992
self._delta_index = DeltaIndex(max_bytes_to_index=max_bytes_to_index)
951
994
def _compress(self, key, bytes, max_delta_size, soft=False):
952
995
"""see _CommonGroupCompressor._compress"""
1027
1070
index = _GCGraphIndex(graph_index, lambda:True, parents=parents,
1028
1071
add_callback=graph_index.add_nodes,
1029
1072
inconsistency_fatal=inconsistency_fatal)
1030
access = knit._DirectPackAccess({})
1073
access = pack_repo._DirectPackAccess({})
1031
1074
access.set_writer(writer, graph_index, (transport, 'newpack'))
1032
1075
result = GroupCompressVersionedFiles(index, access, delta)
1033
1076
result.stream = stream
1044
1087
class _BatchingBlockFetcher(object):
1045
1088
"""Fetch group compress blocks in batches.
1047
1090
:ivar total_bytes: int of expected number of bytes needed to fetch the
1048
1091
currently pending batch.
1051
def __init__(self, gcvf, locations):
1094
def __init__(self, gcvf, locations, get_compressor_settings=None):
1052
1095
self.gcvf = gcvf
1053
1096
self.locations = locations
1102
1146
def yield_factories(self, full_flush=False):
1103
1147
"""Yield factories for keys added since the last yield. They will be
1104
1148
returned in the order they were added via add_key.
1106
1150
:param full_flush: by default, some results may not be returned in case
1107
1151
they can be part of the next batch. If full_flush is True, then
1108
1152
all results are returned.
1136
1180
memos_to_get_stack.pop()
1138
1182
block = self.batch_memos[read_memo]
1139
self.manager = _LazyGroupContentManager(block)
1183
self.manager = _LazyGroupContentManager(block,
1184
get_compressor_settings=self._get_compressor_settings)
1140
1185
self.last_read_memo = read_memo
1141
1186
start, end = index_memo[3:5]
1142
1187
self.manager.add_factory(key, parents, start, end)
1149
1194
self.total_bytes = 0
1152
class GroupCompressVersionedFiles(VersionedFiles):
1197
class GroupCompressVersionedFiles(VersionedFilesWithFallbacks):
1153
1198
"""A group-compress based VersionedFiles implementation."""
1155
def __init__(self, index, access, delta=True, _unadded_refs=None):
1200
# This controls how the GroupCompress DeltaIndex works. Basically, we
1201
# compute hash pointers into the source blocks (so hash(text) => text).
1202
# However each of these references costs some memory in trade against a
1203
# more accurate match result. For very large files, they either are
1204
# pre-compressed and change in bulk whenever they change, or change in just
1205
# local blocks. Either way, 'improved resolution' is not very helpful,
1206
# versus running out of memory trying to track everything. The default max
1207
# gives 100% sampling of a 1MB file.
1208
_DEFAULT_MAX_BYTES_TO_INDEX = 1024 * 1024
1209
_DEFAULT_COMPRESSOR_SETTINGS = {'max_bytes_to_index':
1210
_DEFAULT_MAX_BYTES_TO_INDEX}
1212
def __init__(self, index, access, delta=True, _unadded_refs=None,
1156
1214
"""Create a GroupCompressVersionedFiles object.
1158
1216
:param index: The index object storing access and graph data.
1159
1217
:param access: The access object storing raw data.
1160
1218
:param delta: Whether to delta compress or just entropy compress.
1161
1219
:param _unadded_refs: private parameter, don't use.
1220
:param _group_cache: private parameter, don't use.
1163
1222
self._index = index
1164
1223
self._access = access
1166
1225
if _unadded_refs is None:
1167
1226
_unadded_refs = {}
1168
1227
self._unadded_refs = _unadded_refs
1169
self._group_cache = LRUSizeCache(max_size=50*1024*1024)
1170
self._fallback_vfs = []
1228
if _group_cache is None:
1229
_group_cache = LRUSizeCache(max_size=50*1024*1024)
1230
self._group_cache = _group_cache
1231
self._immediate_fallback_vfs = []
1232
self._max_bytes_to_index = None
1172
1234
def without_fallbacks(self):
1173
1235
"""Return a clone of this object without any fallbacks configured."""
1174
1236
return GroupCompressVersionedFiles(self._index, self._access,
1175
self._delta, _unadded_refs=dict(self._unadded_refs))
1237
self._delta, _unadded_refs=dict(self._unadded_refs),
1238
_group_cache=self._group_cache)
1177
1240
def add_lines(self, key, parents, lines, parent_texts=None,
1178
1241
left_matching_blocks=None, nostore_sha=None, random_id=False,
1182
1245
:param key: The key tuple of the text to add.
1183
1246
:param parents: The parents key tuples of the text to add.
1184
1247
: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
1248
of them except the last must be terminated with \\n and contain no
1249
other \\n's. The last line may either contain no \\n's or a single
1250
terminating \\n. If the lines list does meet this constraint the
1251
add routine may error or may succeed - but you will be unable to
1252
read the data back accurately. (Checking the lines have been split
1190
1253
correctly is expensive and extremely unlikely to catch bugs so it
1191
1254
is not done at runtime unless check_content is True.)
1192
1255
:param parent_texts: An optional dictionary containing the opaque
1287
1350
self._check_lines_not_unicode(lines)
1288
1351
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
1353
def get_parent_map(self, keys):
1307
1354
"""Get a map of the graph parents of keys.
1366
1413
yield read_memo, cached[read_memo]
1367
1414
except KeyError:
1368
1415
# Read the block, and cache it.
1369
zdata = raw_records.next()
1416
zdata = next(raw_records)
1370
1417
block = GroupCompressBlock.from_bytes(zdata)
1371
1418
self._group_cache[read_memo] = block
1372
1419
cached[read_memo] = block
1447
1494
The returned objects should be in the order defined by 'ordering',
1448
1495
which can weave between different sources.
1449
1497
:param ordering: Must be one of 'topological' or 'groupcompress'
1450
1498
:return: List of [(source, [keys])] tuples, such that all keys are in
1451
1499
the defined order, regardless of source.
1453
1501
if ordering == 'topological':
1454
present_keys = topo_sort(parent_map)
1502
present_keys = tsort.topo_sort(parent_map)
1456
1504
# ordering == 'groupcompress'
1457
1505
# XXX: This only optimizes for the target ordering. We may need
1546
1594
# - we encounter an unadded ref, or
1547
1595
# - we run out of keys, or
1548
1596
# - the total bytes to retrieve for this batch > BATCH_SIZE
1549
batcher = _BatchingBlockFetcher(self, locations)
1597
batcher = _BatchingBlockFetcher(self, locations,
1598
get_compressor_settings=self._get_compressor_settings)
1550
1599
for source, keys in source_keys:
1551
1600
if source is self:
1552
1601
for key in keys:
1598
1647
for _ in self._insert_record_stream(stream, random_id=False):
1650
def _get_compressor_settings(self):
1651
if self._max_bytes_to_index is None:
1652
# TODO: VersionedFiles don't know about their containing
1653
# repository, so they don't have much of an idea about their
1654
# location. So for now, this is only a global option.
1655
c = config.GlobalConfig()
1656
val = c.get_user_option('bzr.groupcompress.max_bytes_to_index')
1660
except ValueError as e:
1661
trace.warning('Value for '
1662
'"bzr.groupcompress.max_bytes_to_index"'
1663
' %r is not an integer'
1667
val = self._DEFAULT_MAX_BYTES_TO_INDEX
1668
self._max_bytes_to_index = val
1669
return {'max_bytes_to_index': self._max_bytes_to_index}
1671
def _make_group_compressor(self):
1672
return GroupCompressor(self._get_compressor_settings())
1601
1674
def _insert_record_stream(self, stream, random_id=False, nostore_sha=None,
1602
1675
reuse_blocks=True):
1603
1676
"""Internal core to insert a record stream into this container.
1627
1700
# This will go up to fulltexts for gc to gc fetching, which isn't
1629
self._compressor = GroupCompressor()
1702
self._compressor = self._make_group_compressor()
1630
1703
self._unadded_refs = {}
1631
1704
keys_to_add = []
1633
bytes = self._compressor.flush().to_bytes()
1634
self._compressor = GroupCompressor()
1706
bytes_len, chunks = self._compressor.flush().to_chunks()
1707
self._compressor = self._make_group_compressor()
1708
# Note: At this point we still have 1 copy of the fulltext (in
1709
# record and the var 'bytes'), and this generates 2 copies of
1710
# the compressed text (one for bytes, one in chunks)
1711
# TODO: Push 'chunks' down into the _access api, so that we don't
1712
# have to double compressed memory here
1713
# TODO: Figure out how to indicate that we would be happy to free
1714
# the fulltext content at this point. Note that sometimes we
1715
# will want it later (streaming CHK pages), but most of the
1716
# time we won't (everything else)
1717
bytes = ''.join(chunks)
1635
1719
index, start, length = self._access.add_raw_records(
1636
1720
[(None, len(bytes))], bytes)[0]
1656
1740
raise errors.RevisionNotPresent(record.key, self)
1658
1742
if record.key in inserted_keys:
1659
trace.note('Insert claimed random_id=True,'
1660
' but then inserted %r two times', record.key)
1743
trace.note(gettext('Insert claimed random_id=True,'
1744
' but then inserted %r two times'), record.key)
1662
1746
inserted_keys.add(record.key)
1663
1747
if reuse_blocks:
1802
1886
"""See VersionedFiles.keys."""
1803
1887
if 'evil' in debug.debug_flags:
1804
1888
trace.mutter_callsite(2, "keys scales with size of history")
1805
sources = [self._index] + self._fallback_vfs
1889
sources = [self._index] + self._immediate_fallback_vfs
1807
1891
for source in sources:
1808
1892
result.update(source.keys())
1896
class _GCBuildDetails(object):
1897
"""A blob of data about the build details.
1899
This stores the minimal data, which then allows compatibility with the old
1900
api, without taking as much memory.
1903
__slots__ = ('_index', '_group_start', '_group_end', '_basis_end',
1904
'_delta_end', '_parents')
1907
compression_parent = None
1909
def __init__(self, parents, position_info):
1910
self._parents = parents
1911
(self._index, self._group_start, self._group_end, self._basis_end,
1912
self._delta_end) = position_info
1915
return '%s(%s, %s)' % (self.__class__.__name__,
1916
self.index_memo, self._parents)
1919
def index_memo(self):
1920
return (self._index, self._group_start, self._group_end,
1921
self._basis_end, self._delta_end)
1924
def record_details(self):
1925
return static_tuple.StaticTuple(self.method, None)
1927
def __getitem__(self, offset):
1928
"""Compatibility thunk to act like a tuple."""
1930
return self.index_memo
1932
return self.compression_parent # Always None
1934
return self._parents
1936
return self.record_details
1938
raise IndexError('offset out of range')
1812
1944
class _GCGraphIndex(object):
1813
1945
"""Mapper from GroupCompressVersionedFiles needs into GraphIndex storage."""
1817
1949
inconsistency_fatal=True, track_new_keys=False):
1818
1950
"""Construct a _GCGraphIndex on a graph_index.
1820
:param graph_index: An implementation of bzrlib.index.GraphIndex.
1952
:param graph_index: An implementation of breezy.index.GraphIndex.
1821
1953
:param is_locked: A callback, returns True if the index is locked and
1823
1955
:param parents: If True, record knits parents, if not do not record
1989
2121
:param keys: An iterable of keys.
1990
2122
:return: A dict of key:
1991
2123
(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
2125
* index_memo: opaque structure to pass to read_records to extract
2127
* compression_parent: Content that this record is built upon, may
2129
* parents: Logical parents of this node
2130
* record_details: extra information about the content which needs
2131
to be passed to Factory.parse_record
2003
2133
self._check_read()
2033
2162
# each, or about 7MB. Note that it might be even more when you consider
2034
2163
# how PyInt is allocated in separate slabs. And you can't return a slab
2035
2164
# 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
2165
# a LIFO when re-using PyInt slots, which might cause more
2037
2166
# fragmentation.
2038
2167
start = int(bits[0])
2039
2168
start = self._int_cache.setdefault(start, start)
added
removed
breezy/groupcompress.py
