386
341
self.row_lengths = []
387
342
# Loop over all nodes adding them to the bottom row
388
343
# (rows[-1]). When we finish a chunk in a row,
389
# propagate the key that didn't fit (comes after the chunk) to the
344
# propogate the key that didn't fit (comes after the chunk) to the
390
345
# row above, transitively.
391
346
for node in node_iterator:
392
347
if key_count == 0:
393
348
# First key triggers the first row
394
349
rows.append(_LeafBuilderRow())
351
# TODO: Flattening the node into a string key and a line should
352
# probably be put into a pyrex function. We can do a quick
353
# iter over all the entries to determine the final length,
354
# and then do a single malloc() rather than lots of
355
# intermediate mallocs as we build everything up.
356
# ATM 3 / 13s are spent flattening nodes (10s is compressing)
396
357
string_key, line = _btree_serializer._flatten_node(node,
397
358
self.reference_lists)
398
self._add_key(string_key, line, rows, allow_optimize=allow_optimize)
359
self._add_key(string_key, line, rows)
399
360
for row in reversed(rows):
400
361
pad = (type(row) != _LeafBuilderRow)
401
362
row.finish_node(pad=pad)
363
result = tempfile.NamedTemporaryFile()
402
364
lines = [_BTSIGNATURE]
403
365
lines.append(_OPTION_NODE_REFS + str(self.reference_lists) + '\n')
404
366
lines.append(_OPTION_KEY_ELEMENTS + str(self._key_length) + '\n')
405
367
lines.append(_OPTION_LEN + str(key_count) + '\n')
406
368
row_lengths = [row.nodes for row in rows]
407
369
lines.append(_OPTION_ROW_LENGTHS + ','.join(map(str, row_lengths)) + '\n')
408
if row_lengths and row_lengths[-1] > 1:
409
result = tempfile.NamedTemporaryFile(prefix='bzr-index-')
411
result = cStringIO.StringIO()
412
370
result.writelines(lines)
413
371
position = sum(map(len, lines))
609
552
For InMemoryGraphIndex the estimate is exact.
611
return len(self._nodes) + sum(backing.key_count() for backing in
554
return len(self._keys) + sum(backing.key_count() for backing in
612
555
self._backing_indices if backing is not None)
614
557
def validate(self):
615
558
"""In memory index's have no known corruption at the moment."""
618
class _LeafNode(dict):
561
class _LeafNode(object):
619
562
"""A leaf node for a serialised B+Tree index."""
621
__slots__ = ('min_key', 'max_key', '_keys')
623
564
def __init__(self, bytes, key_length, ref_list_length):
624
565
"""Parse bytes to create a leaf node object."""
625
566
# splitlines mangles the \r delimiters.. don't use it.
626
key_list = _btree_serializer._parse_leaf_lines(bytes,
627
key_length, ref_list_length)
629
self.min_key = key_list[0][0]
630
self.max_key = key_list[-1][0]
632
self.min_key = self.max_key = None
633
super(_LeafNode, self).__init__(key_list)
634
self._keys = dict(self)
637
"""Return a sorted list of (key, (value, refs)) items"""
643
"""Return a sorted list of all keys."""
567
self.keys = dict(_btree_serializer._parse_leaf_lines(bytes,
568
key_length, ref_list_length))
649
571
class _InternalNode(object):
650
572
"""An internal node for a serialised B+Tree index."""
652
__slots__ = ('keys', 'offset')
654
574
def __init__(self, bytes):
655
575
"""Parse bytes to create an internal node object."""
656
576
# splitlines mangles the \r delimiters.. don't use it.
685
603
the initial read (to read the root node header) can be done
686
604
without over-reading even on empty indices, and on small indices
687
605
allows single-IO to read the entire index.
688
:param unlimited_cache: If set to True, then instead of using an
689
LRUCache with size _NODE_CACHE_SIZE, we will use a dict and always
690
cache all leaf nodes.
691
:param offset: The start of the btree index data isn't byte 0 of the
692
file. Instead it starts at some point later.
694
607
self._transport = transport
695
608
self._name = name
696
609
self._size = size
697
610
self._file = None
698
self._recommended_pages = self._compute_recommended_pages()
611
self._page_size = transport.recommended_page_size()
699
612
self._root_node = None
700
self._base_offset = offset
701
self._leaf_factory = _LeafNode
702
613
# Default max size is 100,000 leave values
703
614
self._leaf_value_cache = None # lru_cache.LRUCache(100*1000)
705
self._leaf_node_cache = {}
706
self._internal_node_cache = {}
708
self._leaf_node_cache = lru_cache.LRUCache(_NODE_CACHE_SIZE)
709
# We use a FIFO here just to prevent possible blowout. However, a
710
# 300k record btree has only 3k leaf nodes, and only 20 internal
711
# nodes. A value of 100 scales to ~100*100*100 = 1M records.
712
self._internal_node_cache = fifo_cache.FIFOCache(100)
615
self._leaf_node_cache = lru_cache.LRUCache(_NODE_CACHE_SIZE)
616
self._internal_node_cache = lru_cache.LRUCache()
713
617
self._key_count = None
714
618
self._row_lengths = None
715
619
self._row_offsets = None # Start of each row, [-1] is the end
739
651
:return: A dict of {node_pos: node}
653
if len(nodes) > cache._max_cache:
654
trace.mutter('Requesting %s > %s nodes, not all will be cached',
655
len(nodes), cache._max_cache)
742
start_of_leaves = None
743
657
for node_pos, node in self._read_nodes(sorted(nodes)):
744
658
if node_pos == 0: # Special case
745
659
self._root_node = node
747
if start_of_leaves is None:
748
start_of_leaves = self._row_offsets[-2]
749
if node_pos < start_of_leaves:
750
self._internal_node_cache[node_pos] = node
752
self._leaf_node_cache[node_pos] = node
661
cache.add(node_pos, node)
753
662
found[node_pos] = node
756
def _compute_recommended_pages(self):
757
"""Convert transport's recommended_page_size into btree pages.
759
recommended_page_size is in bytes, we want to know how many _PAGE_SIZE
760
pages fit in that length.
762
recommended_read = self._transport.recommended_page_size()
763
recommended_pages = int(math.ceil(recommended_read /
765
return recommended_pages
767
def _compute_total_pages_in_index(self):
768
"""How many pages are in the index.
770
If we have read the header we will use the value stored there.
771
Otherwise it will be computed based on the length of the index.
773
if self._size is None:
774
raise AssertionError('_compute_total_pages_in_index should not be'
775
' called when self._size is None')
776
if self._root_node is not None:
777
# This is the number of pages as defined by the header
778
return self._row_offsets[-1]
779
# This is the number of pages as defined by the size of the index. They
780
# should be indentical.
781
total_pages = int(math.ceil(self._size / float(_PAGE_SIZE)))
784
def _expand_offsets(self, offsets):
785
"""Find extra pages to download.
787
The idea is that we always want to make big-enough requests (like 64kB
788
for http), so that we don't waste round trips. So given the entries
789
that we already have cached and the new pages being downloaded figure
790
out what other pages we might want to read.
792
See also doc/developers/btree_index_prefetch.txt for more details.
794
:param offsets: The offsets to be read
795
:return: A list of offsets to download
797
if 'index' in debug.debug_flags:
798
trace.mutter('expanding: %s\toffsets: %s', self._name, offsets)
800
if len(offsets) >= self._recommended_pages:
801
# Don't add more, we are already requesting more than enough
802
if 'index' in debug.debug_flags:
803
trace.mutter(' not expanding large request (%s >= %s)',
804
len(offsets), self._recommended_pages)
806
if self._size is None:
807
# Don't try anything, because we don't know where the file ends
808
if 'index' in debug.debug_flags:
809
trace.mutter(' not expanding without knowing index size')
811
total_pages = self._compute_total_pages_in_index()
812
cached_offsets = self._get_offsets_to_cached_pages()
813
# If reading recommended_pages would read the rest of the index, just
815
if total_pages - len(cached_offsets) <= self._recommended_pages:
816
# Read whatever is left
818
expanded = [x for x in xrange(total_pages)
819
if x not in cached_offsets]
821
expanded = range(total_pages)
822
if 'index' in debug.debug_flags:
823
trace.mutter(' reading all unread pages: %s', expanded)
826
if self._root_node is None:
827
# ATM on the first read of the root node of a large index, we don't
828
# bother pre-reading any other pages. This is because the
829
# likelyhood of actually reading interesting pages is very low.
830
# See doc/developers/btree_index_prefetch.txt for a discussion, and
831
# a possible implementation when we are guessing that the second
832
# layer index is small
833
final_offsets = offsets
835
tree_depth = len(self._row_lengths)
836
if len(cached_offsets) < tree_depth and len(offsets) == 1:
837
# We haven't read enough to justify expansion
838
# If we are only going to read the root node, and 1 leaf node,
839
# then it isn't worth expanding our request. Once we've read at
840
# least 2 nodes, then we are probably doing a search, and we
841
# start expanding our requests.
842
if 'index' in debug.debug_flags:
843
trace.mutter(' not expanding on first reads')
845
final_offsets = self._expand_to_neighbors(offsets, cached_offsets,
848
final_offsets = sorted(final_offsets)
849
if 'index' in debug.debug_flags:
850
trace.mutter('expanded: %s', final_offsets)
853
def _expand_to_neighbors(self, offsets, cached_offsets, total_pages):
854
"""Expand requests to neighbors until we have enough pages.
856
This is called from _expand_offsets after policy has determined that we
858
We only want to expand requests within a given layer. We cheat a little
859
bit and assume all requests will be in the same layer. This is true
860
given the current design, but if it changes this algorithm may perform
863
:param offsets: requested offsets
864
:param cached_offsets: offsets for pages we currently have cached
865
:return: A set() of offsets after expansion
867
final_offsets = set(offsets)
869
new_tips = set(final_offsets)
870
while len(final_offsets) < self._recommended_pages and new_tips:
874
first, end = self._find_layer_first_and_end(pos)
877
and previous not in cached_offsets
878
and previous not in final_offsets
879
and previous >= first):
880
next_tips.add(previous)
882
if (after < total_pages
883
and after not in cached_offsets
884
and after not in final_offsets
887
# This would keep us from going bigger than
888
# recommended_pages by only expanding the first offsets.
889
# However, if we are making a 'wide' request, it is
890
# reasonable to expand all points equally.
891
# if len(final_offsets) > recommended_pages:
893
final_offsets.update(next_tips)
897
def clear_cache(self):
898
"""Clear out any cached/memoized values.
900
This can be called at any time, but generally it is used when we have
901
extracted some information, but don't expect to be requesting any more
904
# Note that we don't touch self._root_node or self._internal_node_cache
905
# We don't expect either of those to be big, and it can save
906
# round-trips in the future. We may re-evaluate this if InternalNode
907
# memory starts to be an issue.
908
self._leaf_node_cache.clear()
910
def external_references(self, ref_list_num):
911
if self._root_node is None:
912
self._get_root_node()
913
if ref_list_num + 1 > self.node_ref_lists:
914
raise ValueError('No ref list %d, index has %d ref lists'
915
% (ref_list_num, self.node_ref_lists))
918
for node in self.iter_all_entries():
920
refs.update(node[3][ref_list_num])
923
def _find_layer_first_and_end(self, offset):
924
"""Find the start/stop nodes for the layer corresponding to offset.
926
:return: (first, end)
927
first is the first node in this layer
928
end is the first node of the next layer
931
for roffset in self._row_offsets:
938
def _get_offsets_to_cached_pages(self):
939
"""Determine what nodes we already have cached."""
940
cached_offsets = set(self._internal_node_cache.keys())
941
cached_offsets.update(self._leaf_node_cache.keys())
942
if self._root_node is not None:
943
cached_offsets.add(0)
944
return cached_offsets
946
def _get_root_node(self):
947
if self._root_node is None:
948
# We may not have a root node yet
949
self._get_internal_nodes([0])
950
return self._root_node
952
665
def _get_nodes(self, cache, node_indexes):
1004
710
"iter_all_entries scales with size of history.")
1005
711
if not self.key_count():
1007
if self._row_offsets[-1] == 1:
1008
# There is only the root node, and we read that via key_count()
1009
if self.node_ref_lists:
1010
for key, (value, refs) in self._root_node.all_items():
1011
yield (self, key, value, refs)
1013
for key, (value, refs) in self._root_node.all_items():
1014
yield (self, key, value)
1016
713
start_of_leaves = self._row_offsets[-2]
1017
714
end_of_leaves = self._row_offsets[-1]
1018
needed_offsets = range(start_of_leaves, end_of_leaves)
1019
if needed_offsets == [0]:
1020
# Special case when we only have a root node, as we have already
1022
nodes = [(0, self._root_node)]
1024
nodes = self._read_nodes(needed_offsets)
715
needed_nodes = range(start_of_leaves, end_of_leaves)
1025
716
# We iterate strictly in-order so that we can use this function
1026
717
# for spilling index builds to disk.
1027
718
if self.node_ref_lists:
1028
for _, node in nodes:
1029
for key, (value, refs) in node.all_items():
719
for _, node in self._read_nodes(needed_nodes):
720
for key, (value, refs) in sorted(node.keys.items()):
1030
721
yield (self, key, value, refs)
1032
for _, node in nodes:
1033
for key, (value, refs) in node.all_items():
723
for _, node in self._read_nodes(needed_nodes):
724
for key, (value, refs) in sorted(node.keys.items()):
1034
725
yield (self, key, value)
1115
806
output.append(cur_out)
1118
def _walk_through_internal_nodes(self, keys):
1119
"""Take the given set of keys, and find the corresponding LeafNodes.
1121
:param keys: An unsorted iterable of keys to search for
1122
:return: (nodes, index_and_keys)
1123
nodes is a dict mapping {index: LeafNode}
1124
keys_at_index is a list of tuples of [(index, [keys for Leaf])]
1126
# 6 seconds spent in miss_torture using the sorted() line.
1127
# Even with out of order disk IO it seems faster not to sort it when
1128
# large queries are being made.
1129
keys_at_index = [(0, sorted(keys))]
1131
for row_pos, next_row_start in enumerate(self._row_offsets[1:-1]):
1132
node_indexes = [idx for idx, s_keys in keys_at_index]
1133
nodes = self._get_internal_nodes(node_indexes)
1135
next_nodes_and_keys = []
1136
for node_index, sub_keys in keys_at_index:
1137
node = nodes[node_index]
1138
positions = self._multi_bisect_right(sub_keys, node.keys)
1139
node_offset = next_row_start + node.offset
1140
next_nodes_and_keys.extend([(node_offset + pos, s_keys)
1141
for pos, s_keys in positions])
1142
keys_at_index = next_nodes_and_keys
1143
# We should now be at the _LeafNodes
1144
node_indexes = [idx for idx, s_keys in keys_at_index]
1146
# TODO: We may *not* want to always read all the nodes in one
1147
# big go. Consider setting a max size on this.
1148
nodes = self._get_leaf_nodes(node_indexes)
1149
return nodes, keys_at_index
1151
809
def iter_entries(self, keys):
1152
810
"""Iterate over keys within the index.
1191
849
needed_keys = keys
1192
850
if not needed_keys:
1194
nodes, nodes_and_keys = self._walk_through_internal_nodes(needed_keys)
852
# 6 seconds spent in miss_torture using the sorted() line.
853
# Even with out of order disk IO it seems faster not to sort it when
854
# large queries are being made.
855
needed_keys = sorted(needed_keys)
857
nodes_and_keys = [(0, needed_keys)]
859
for row_pos, next_row_start in enumerate(self._row_offsets[1:-1]):
860
node_indexes = [idx for idx, s_keys in nodes_and_keys]
861
nodes = self._get_internal_nodes(node_indexes)
863
next_nodes_and_keys = []
864
for node_index, sub_keys in nodes_and_keys:
865
node = nodes[node_index]
866
positions = self._multi_bisect_right(sub_keys, node.keys)
867
node_offset = next_row_start + node.offset
868
next_nodes_and_keys.extend([(node_offset + pos, s_keys)
869
for pos, s_keys in positions])
870
nodes_and_keys = next_nodes_and_keys
871
# We should now be at the _LeafNodes
872
node_indexes = [idx for idx, s_keys in nodes_and_keys]
874
# TODO: We may *not* want to always read all the nodes in one
875
# big go. Consider setting a max size on this.
877
nodes = self._get_leaf_nodes(node_indexes)
1195
878
for node_index, sub_keys in nodes_and_keys:
1196
879
if not sub_keys:
1198
881
node = nodes[node_index]
1199
882
for next_sub_key in sub_keys:
1200
if next_sub_key in node:
1201
value, refs = node[next_sub_key]
883
if next_sub_key in node.keys:
884
value, refs = node.keys[next_sub_key]
1202
885
if self.node_ref_lists:
1203
886
yield (self, next_sub_key, value, refs)
1205
888
yield (self, next_sub_key, value)
1207
def _find_ancestors(self, keys, ref_list_num, parent_map, missing_keys):
1208
"""Find the parent_map information for the set of keys.
1210
This populates the parent_map dict and missing_keys set based on the
1211
queried keys. It also can fill out an arbitrary number of parents that
1212
it finds while searching for the supplied keys.
1214
It is unlikely that you want to call this directly. See
1215
"CombinedGraphIndex.find_ancestry()" for a more appropriate API.
1217
:param keys: A keys whose ancestry we want to return
1218
Every key will either end up in 'parent_map' or 'missing_keys'.
1219
:param ref_list_num: This index in the ref_lists is the parents we
1221
:param parent_map: {key: parent_keys} for keys that are present in this
1222
index. This may contain more entries than were in 'keys', that are
1223
reachable ancestors of the keys requested.
1224
:param missing_keys: keys which are known to be missing in this index.
1225
This may include parents that were not directly requested, but we
1226
were able to determine that they are not present in this index.
1227
:return: search_keys parents that were found but not queried to know
1228
if they are missing or present. Callers can re-query this index for
1229
those keys, and they will be placed into parent_map or missing_keys
1231
if not self.key_count():
1232
# We use key_count() to trigger reading the root node and
1233
# determining info about this BTreeGraphIndex
1234
# If we don't have any keys, then everything is missing
1235
missing_keys.update(keys)
1237
if ref_list_num >= self.node_ref_lists:
1238
raise ValueError('No ref list %d, index has %d ref lists'
1239
% (ref_list_num, self.node_ref_lists))
1241
# The main trick we are trying to accomplish is that when we find a
1242
# key listing its parents, we expect that the parent key is also likely
1243
# to sit on the same page. Allowing us to expand parents quickly
1244
# without suffering the full stack of bisecting, etc.
1245
nodes, nodes_and_keys = self._walk_through_internal_nodes(keys)
1247
# These are parent keys which could not be immediately resolved on the
1248
# page where the child was present. Note that we may already be
1249
# searching for that key, and it may actually be present [or known
1250
# missing] on one of the other pages we are reading.
1252
# We could try searching for them in the immediate previous or next
1253
# page. If they occur "later" we could put them in a pending lookup
1254
# set, and then for each node we read thereafter we could check to
1255
# see if they are present.
1256
# However, we don't know the impact of keeping this list of things
1257
# that I'm going to search for every node I come across from here on
1259
# It doesn't handle the case when the parent key is missing on a
1260
# page that we *don't* read. So we already have to handle being
1261
# re-entrant for that.
1262
# Since most keys contain a date string, they are more likely to be
1263
# found earlier in the file than later, but we would know that right
1264
# away (key < min_key), and wouldn't keep searching it on every other
1265
# page that we read.
1266
# Mostly, it is an idea, one which should be benchmarked.
1267
parents_not_on_page = set()
1269
for node_index, sub_keys in nodes_and_keys:
1272
# sub_keys is all of the keys we are looking for that should exist
1273
# on this page, if they aren't here, then they won't be found
1274
node = nodes[node_index]
1275
parents_to_check = set()
1276
for next_sub_key in sub_keys:
1277
if next_sub_key not in node:
1278
# This one is just not present in the index at all
1279
missing_keys.add(next_sub_key)
1281
value, refs = node[next_sub_key]
1282
parent_keys = refs[ref_list_num]
1283
parent_map[next_sub_key] = parent_keys
1284
parents_to_check.update(parent_keys)
1285
# Don't look for things we've already found
1286
parents_to_check = parents_to_check.difference(parent_map)
1287
# this can be used to test the benefit of having the check loop
1289
# parents_not_on_page.update(parents_to_check)
1291
while parents_to_check:
1292
next_parents_to_check = set()
1293
for key in parents_to_check:
1295
value, refs = node[key]
1296
parent_keys = refs[ref_list_num]
1297
parent_map[key] = parent_keys
1298
next_parents_to_check.update(parent_keys)
1300
# This parent either is genuinely missing, or should be
1301
# found on another page. Perf test whether it is better
1302
# to check if this node should fit on this page or not.
1303
# in the 'everything-in-one-pack' scenario, this *not*
1304
# doing the check is 237ms vs 243ms.
1305
# So slightly better, but I assume the standard 'lots
1306
# of packs' is going to show a reasonable improvement
1307
# from the check, because it avoids 'going around
1308
# again' for everything that is in another index
1309
# parents_not_on_page.add(key)
1310
# Missing for some reason
1311
if key < node.min_key:
1312
# in the case of bzr.dev, 3.4k/5.3k misses are
1313
# 'earlier' misses (65%)
1314
parents_not_on_page.add(key)
1315
elif key > node.max_key:
1316
# This parent key would be present on a different
1318
parents_not_on_page.add(key)
1320
# assert key != node.min_key and key != node.max_key
1321
# If it was going to be present, it would be on
1322
# *this* page, so mark it missing.
1323
missing_keys.add(key)
1324
parents_to_check = next_parents_to_check.difference(parent_map)
1325
# Might want to do another .difference() from missing_keys
1326
# parents_not_on_page could have been found on a different page, or be
1327
# known to be missing. So cull out everything that has already been
1329
search_keys = parents_not_on_page.difference(
1330
parent_map).difference(missing_keys)
1333
890
def iter_entries_prefix(self, keys):
1334
891
"""Iterate over keys within the index using prefix matching.
1513
1066
"""Read some nodes from disk into the LRU cache.
1515
1068
This performs a readv to get the node data into memory, and parses each
1516
node, then yields it to the caller. The nodes are requested in the
1069
node, the yields it to the caller. The nodes are requested in the
1517
1070
supplied order. If possible doing sort() on the list before requesting
1518
1071
a read may improve performance.
1520
1073
:param nodes: The nodes to read. 0 - first node, 1 - second node etc.
1523
# may be the byte string of the whole file
1525
# list of (offset, length) regions of the file that should, evenually
1526
# be read in to data_ranges, either from 'bytes' or from the transport
1528
base_offset = self._base_offset
1529
1077
for index in nodes:
1530
offset = (index * _PAGE_SIZE)
1078
offset = index * _PAGE_SIZE
1531
1079
size = _PAGE_SIZE
1533
1081
# Root node - special case
1535
1083
size = min(_PAGE_SIZE, self._size)
1537
# The only case where we don't know the size, is for very
1538
# small indexes. So we read the whole thing
1539
bytes = self._transport.get_bytes(self._name)
1540
num_bytes = len(bytes)
1541
self._size = num_bytes - base_offset
1542
# the whole thing should be parsed out of 'bytes'
1543
ranges = [(start, min(_PAGE_SIZE, num_bytes - start))
1544
for start in xrange(base_offset, num_bytes, _PAGE_SIZE)]
1085
stream = self._transport.get(self._name)
1086
start = stream.read(_PAGE_SIZE)
1087
# Avoid doing this again
1088
self._size = len(start)
1089
size = min(_PAGE_SIZE, self._size)
1547
if offset > self._size:
1548
raise AssertionError('tried to read past the end'
1549
' of the file %s > %s'
1550
% (offset, self._size))
1551
1091
size = min(size, self._size - offset)
1552
ranges.append((base_offset + offset, size))
1092
ranges.append((offset, size))
1555
elif bytes is not None:
1556
# already have the whole file
1557
data_ranges = [(start, bytes[start:start+size])
1558
for start, size in ranges]
1559
elif self._file is None:
1095
if self._file is None:
1560
1096
data_ranges = self._transport.readv(self._name, ranges)
1562
1098
data_ranges = []
added
removed
bzrlib/btree_index.py
