# Copyright (C) 2008 Canonical Ltd # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA # """B+Tree indices""" import array import bisect from bisect import bisect_right from copy import deepcopy import math import struct import tempfile import zlib from bzrlib import ( chunk_writer, debug, errors, index, lru_cache, osutils, trace, ) from bzrlib.index import _OPTION_NODE_REFS, _OPTION_KEY_ELEMENTS, _OPTION_LEN from bzrlib.transport import get_transport _BTSIGNATURE = "B+Tree Graph Index 2\n" _OPTION_ROW_LENGTHS = "row_lengths=" _LEAF_FLAG = "type=leaf\n" _INTERNAL_FLAG = "type=internal\n" _INTERNAL_OFFSET = "offset=" _RESERVED_HEADER_BYTES = 120 _PAGE_SIZE = 4096 # 4K per page: 4MB - 1000 entries _NODE_CACHE_SIZE = 1000 class _BuilderRow(object): """The stored state accumulated while writing out a row in the index. :ivar spool: A temporary file used to accumulate nodes for this row in the tree. :ivar nodes: The count of nodes emitted so far. """ def __init__(self): """Create a _BuilderRow.""" self.nodes = 0 self.spool = tempfile.TemporaryFile() self.writer = None def finish_node(self, pad=True): byte_lines, _, padding = self.writer.finish() if self.nodes == 0: # padded note: self.spool.write("\x00" * _RESERVED_HEADER_BYTES) skipped_bytes = 0 if not pad and padding: del byte_lines[-1] skipped_bytes = padding self.spool.writelines(byte_lines) remainder = (self.spool.tell() + skipped_bytes) % _PAGE_SIZE if remainder != 0: raise AssertionError("incorrect node length: %d, %d" % (self.spool.tell(), remainder)) self.nodes += 1 self.writer = None class _InternalBuilderRow(_BuilderRow): """The stored state accumulated while writing out internal rows.""" def finish_node(self, pad=True): if not pad: raise AssertionError("Must pad internal nodes only.") _BuilderRow.finish_node(self) class _LeafBuilderRow(_BuilderRow): """The stored state accumulated while writing out a leaf rows.""" class BTreeBuilder(index.GraphIndexBuilder): """A Builder for B+Tree based Graph indices. The resulting graph has the structure: _SIGNATURE OPTIONS NODES _SIGNATURE := 'B+Tree Graph Index 1' NEWLINE OPTIONS := REF_LISTS KEY_ELEMENTS LENGTH REF_LISTS := 'node_ref_lists=' DIGITS NEWLINE KEY_ELEMENTS := 'key_elements=' DIGITS NEWLINE LENGTH := 'len=' DIGITS NEWLINE ROW_LENGTHS := 'row_lengths' DIGITS (COMMA DIGITS)* NODES := NODE_COMPRESSED* NODE_COMPRESSED:= COMPRESSED_BYTES{4096} NODE_RAW := INTERNAL | LEAF INTERNAL := INTERNAL_FLAG POINTERS LEAF := LEAF_FLAG ROWS KEY_ELEMENT := Not-whitespace-utf8 KEY := KEY_ELEMENT (NULL KEY_ELEMENT)* ROWS := ROW* ROW := KEY NULL ABSENT? NULL REFERENCES NULL VALUE NEWLINE ABSENT := 'a' REFERENCES := REFERENCE_LIST (TAB REFERENCE_LIST){node_ref_lists - 1} REFERENCE_LIST := (REFERENCE (CR REFERENCE)*)? REFERENCE := KEY VALUE := no-newline-no-null-bytes """ def __init__(self, reference_lists=0, key_elements=1, spill_at=100000): """See GraphIndexBuilder.__init__. :param spill_at: Optional parameter controlling the maximum number of nodes that BTreeBuilder will hold in memory. """ index.GraphIndexBuilder.__init__(self, reference_lists=reference_lists, key_elements=key_elements) self._spill_at = spill_at self._backing_indices = [] # A map of {key: (node_refs, value)} self._nodes = {} # Indicate it hasn't been built yet self._nodes_by_key = None def add_node(self, key, value, references=()): """Add a node to the index. If adding the node causes the builder to reach its spill_at threshold, disk spilling will be triggered. :param key: The key. keys are non-empty tuples containing as many whitespace-free utf8 bytestrings as the key length defined for this index. :param references: An iterable of iterables of keys. Each is a reference to another key. :param value: The value to associate with the key. It may be any bytes as long as it does not contain \0 or \n. """ # we don't care about absent_references node_refs, _ = self._check_key_ref_value(key, references, value) if key in self._nodes: raise errors.BadIndexDuplicateKey(key, self) self._nodes[key] = (node_refs, value) self._keys.add(key) if self._nodes_by_key is not None and self._key_length > 1: self._update_nodes_by_key(key, value, node_refs) if len(self._keys) < self._spill_at: return self._spill_mem_keys_to_disk() def _spill_mem_keys_to_disk(self): """Write the in memory keys down to disk to cap memory consumption. If we already have some keys written to disk, we will combine them so as to preserve the sorted order. The algorithm for combining uses powers of two. So on the first spill, write all mem nodes into a single index. On the second spill, combine the mem nodes with the nodes on disk to create a 2x sized disk index and get rid of the first index. On the third spill, create a single new disk index, which will contain the mem nodes, and preserve the existing 2x sized index. On the fourth, combine mem with the first and second indexes, creating a new one of size 4x. On the fifth create a single new one, etc. """ iterators_to_combine = [self._iter_mem_nodes()] pos = -1 for pos, backing in enumerate(self._backing_indices): if backing is None: pos -= 1 break iterators_to_combine.append(backing.iter_all_entries()) backing_pos = pos + 1 new_backing_file, size = \ self._write_nodes(self._iter_smallest(iterators_to_combine)) dir_path, base_name = osutils.split(new_backing_file.name) # Note: The transport here isn't strictly needed, because we will use # direct access to the new_backing._file object new_backing = BTreeGraphIndex(get_transport(dir_path), base_name, size) # GC will clean up the file new_backing._file = new_backing_file if len(self._backing_indices) == backing_pos: self._backing_indices.append(None) self._backing_indices[backing_pos] = new_backing for pos in range(backing_pos): self._backing_indices[pos] = None self._keys = set() self._nodes = {} self._nodes_by_key = None def add_nodes(self, nodes): """Add nodes to the index. :param nodes: An iterable of (key, node_refs, value) entries to add. """ if self.reference_lists: for (key, value, node_refs) in nodes: self.add_node(key, value, node_refs) else: for (key, value) in nodes: self.add_node(key, value) def _iter_mem_nodes(self): """Iterate over the nodes held in memory.""" nodes = self._nodes if self.reference_lists: for key in sorted(nodes): references, value = nodes[key] yield self, key, value, references else: for key in sorted(nodes): references, value = nodes[key] yield self, key, value def _iter_smallest(self, iterators_to_combine): if len(iterators_to_combine) == 1: for value in iterators_to_combine[0]: yield value return current_values = [] for iterator in iterators_to_combine: try: current_values.append(iterator.next()) except StopIteration: current_values.append(None) last = None while True: # Decorate candidates with the value to allow 2.4's min to be used. candidates = [(item[1][1], item) for item in enumerate(current_values) if item[1] is not None] if not len(candidates): return selected = min(candidates) # undecorate back to (pos, node) selected = selected[1] if last == selected[1][1]: raise errors.BadIndexDuplicateKey(last, self) last = selected[1][1] # Yield, with self as the index yield (self,) + selected[1][1:] pos = selected[0] try: current_values[pos] = iterators_to_combine[pos].next() except StopIteration: current_values[pos] = None def _add_key(self, string_key, line, rows): """Add a key to the current chunk. :param string_key: The key to add. :param line: The fully serialised key and value. """ if rows[-1].writer is None: # opening a new leaf chunk; for pos, internal_row in enumerate(rows[:-1]): # flesh out any internal nodes that are needed to # preserve the height of the tree if internal_row.writer is None: length = _PAGE_SIZE if internal_row.nodes == 0: length -= _RESERVED_HEADER_BYTES # padded internal_row.writer = chunk_writer.ChunkWriter(length, 0) internal_row.writer.write(_INTERNAL_FLAG) internal_row.writer.write(_INTERNAL_OFFSET + str(rows[pos + 1].nodes) + "\n") # add a new leaf length = _PAGE_SIZE if rows[-1].nodes == 0: length -= _RESERVED_HEADER_BYTES # padded rows[-1].writer = chunk_writer.ChunkWriter(length) rows[-1].writer.write(_LEAF_FLAG) if rows[-1].writer.write(line): # this key did not fit in the node: rows[-1].finish_node() key_line = string_key + "\n" new_row = True for row in reversed(rows[:-1]): # Mark the start of the next node in the node above. If it # doesn't fit then propogate upwards until we find one that # it does fit into. if row.writer.write(key_line): row.finish_node() else: # We've found a node that can handle the pointer. new_row = False break # If we reached the current root without being able to mark the # division point, then we need a new root: if new_row: # We need a new row if 'index' in debug.debug_flags: trace.mutter('Inserting new global row.') new_row = _InternalBuilderRow() reserved_bytes = 0 rows.insert(0, new_row) # This will be padded, hence the -100 new_row.writer = chunk_writer.ChunkWriter( _PAGE_SIZE - _RESERVED_HEADER_BYTES, reserved_bytes) new_row.writer.write(_INTERNAL_FLAG) new_row.writer.write(_INTERNAL_OFFSET + str(rows[1].nodes - 1) + "\n") new_row.writer.write(key_line) self._add_key(string_key, line, rows) def _write_nodes(self, node_iterator): """Write node_iterator out as a B+Tree. :param node_iterator: An iterator of sorted nodes. Each node should match the output given by iter_all_entries. :return: A file handle for a temporary file containing a B+Tree for the nodes. """ # The index rows - rows[0] is the root, rows[1] is the layer under it # etc. rows = [] # forward sorted by key. In future we may consider topological sorting, # at the cost of table scans for direct lookup, or a second index for # direct lookup key_count = 0 # A stack with the number of nodes of each size. 0 is the root node # and must always be 1 (if there are any nodes in the tree). self.row_lengths = [] # Loop over all nodes adding them to the bottom row # (rows[-1]). When we finish a chunk in a row, # propogate the key that didn't fit (comes after the chunk) to the # row above, transitively. for node in node_iterator: if key_count == 0: # First key triggers the first row rows.append(_LeafBuilderRow()) key_count += 1 # TODO: Flattening the node into a string key and a line should # probably be put into a pyrex function. We can do a quick # iter over all the entries to determine the final length, # and then do a single malloc() rather than lots of # intermediate mallocs as we build everything up. # ATM 3 / 13s are spent flattening nodes (10s is compressing) string_key, line = _btree_serializer._flatten_node(node, self.reference_lists) self._add_key(string_key, line, rows) for row in reversed(rows): pad = (type(row) != _LeafBuilderRow) row.finish_node(pad=pad) result = tempfile.NamedTemporaryFile() lines = [_BTSIGNATURE] lines.append(_OPTION_NODE_REFS + str(self.reference_lists) + '\n') lines.append(_OPTION_KEY_ELEMENTS + str(self._key_length) + '\n') lines.append(_OPTION_LEN + str(key_count) + '\n') row_lengths = [row.nodes for row in rows] lines.append(_OPTION_ROW_LENGTHS + ','.join(map(str, row_lengths)) + '\n') result.writelines(lines) position = sum(map(len, lines)) root_row = True if position > _RESERVED_HEADER_BYTES: raise AssertionError("Could not fit the header in the" " reserved space: %d > %d" % (position, _RESERVED_HEADER_BYTES)) # write the rows out: for row in rows: reserved = _RESERVED_HEADER_BYTES # reserved space for first node row.spool.flush() row.spool.seek(0) # copy nodes to the finalised file. # Special case the first node as it may be prefixed node = row.spool.read(_PAGE_SIZE) result.write(node[reserved:]) result.write("\x00" * (reserved - position)) position = 0 # Only the root row actually has an offset copied_len = osutils.pumpfile(row.spool, result) if copied_len != (row.nodes - 1) * _PAGE_SIZE: if type(row) != _LeafBuilderRow: raise AssertionError("Incorrect amount of data copied" " expected: %d, got: %d" % ((row.nodes - 1) * _PAGE_SIZE, copied_len)) result.flush() size = result.tell() result.seek(0) return result, size def finish(self): """Finalise the index. :return: A file handle for a temporary file containing the nodes added to the index. """ return self._write_nodes(self.iter_all_entries())[0] def iter_all_entries(self): """Iterate over all keys within the index :return: An iterable of (index, key, reference_lists, value). There is no defined order for the result iteration - it will be in the most efficient order for the index (in this case dictionary hash order). """ if 'evil' in debug.debug_flags: trace.mutter_callsite(3, "iter_all_entries scales with size of history.") # Doing serial rather than ordered would be faster; but this shouldn't # be getting called routinely anyway. iterators = [self._iter_mem_nodes()] for backing in self._backing_indices: if backing is not None: iterators.append(backing.iter_all_entries()) if len(iterators) == 1: return iterators[0] return self._iter_smallest(iterators) def iter_entries(self, keys): """Iterate over keys within the index. :param keys: An iterable providing the keys to be retrieved. :return: An iterable of (index, key, value, reference_lists). There is no defined order for the result iteration - it will be in the most efficient order for the index (keys iteration order in this case). """ keys = set(keys) if self.reference_lists: for key in keys.intersection(self._keys): node = self._nodes[key] yield self, key, node[1], node[0] else: for key in keys.intersection(self._keys): node = self._nodes[key] yield self, key, node[1] keys.difference_update(self._keys) for backing in self._backing_indices: if backing is None: continue if not keys: return for node in backing.iter_entries(keys): keys.remove(node[1]) yield (self,) + node[1:] def iter_entries_prefix(self, keys): """Iterate over keys within the index using prefix matching. Prefix matching is applied within the tuple of a key, not to within the bytestring of each key element. e.g. if you have the keys ('foo', 'bar'), ('foobar', 'gam') and do a prefix search for ('foo', None) then only the former key is returned. :param keys: An iterable providing the key prefixes to be retrieved. Each key prefix takes the form of a tuple the length of a key, but with the last N elements 'None' rather than a regular bytestring. The first element cannot be 'None'. :return: An iterable as per iter_all_entries, but restricted to the keys with a matching prefix to those supplied. No additional keys will be returned, and every match that is in the index will be returned. """ # XXX: To much duplication with the GraphIndex class; consider finding # a good place to pull out the actual common logic. keys = set(keys) if not keys: return for backing in self._backing_indices: if backing is None: continue for node in backing.iter_entries_prefix(keys): yield (self,) + node[1:] if self._key_length == 1: for key in keys: # sanity check if key[0] is None: raise errors.BadIndexKey(key) if len(key) != self._key_length: raise errors.BadIndexKey(key) try: node = self._nodes[key] except KeyError: continue if self.reference_lists: yield self, key, node[1], node[0] else: yield self, key, node[1] return for key in keys: # sanity check if key[0] is None: raise errors.BadIndexKey(key) if len(key) != self._key_length: raise errors.BadIndexKey(key) # find what it refers to: key_dict = self._get_nodes_by_key() elements = list(key) # find the subdict to return try: while len(elements) and elements[0] is not None: key_dict = key_dict[elements[0]] elements.pop(0) except KeyError: # a non-existant lookup. continue if len(elements): dicts = [key_dict] while dicts: key_dict = dicts.pop(-1) # can't be empty or would not exist item, value = key_dict.iteritems().next() if type(value) == dict: # push keys dicts.extend(key_dict.itervalues()) else: # yield keys for value in key_dict.itervalues(): yield (self, ) + value else: yield (self, ) + key_dict def _get_nodes_by_key(self): if self._nodes_by_key is None: nodes_by_key = {} if self.reference_lists: for key, (references, value) in self._nodes.iteritems(): key_dict = nodes_by_key for subkey in key[:-1]: key_dict = key_dict.setdefault(subkey, {}) key_dict[key[-1]] = key, value, references else: for key, (references, value) in self._nodes.iteritems(): key_dict = nodes_by_key for subkey in key[:-1]: key_dict = key_dict.setdefault(subkey, {}) key_dict[key[-1]] = key, value self._nodes_by_key = nodes_by_key return self._nodes_by_key def key_count(self): """Return an estimate of the number of keys in this index. For InMemoryGraphIndex the estimate is exact. """ return len(self._keys) + sum(backing.key_count() for backing in self._backing_indices if backing is not None) def validate(self): """In memory index's have no known corruption at the moment.""" class _LeafNode(object): """A leaf node for a serialised B+Tree index.""" def __init__(self, bytes, key_length, ref_list_length): """Parse bytes to create a leaf node object.""" # splitlines mangles the \r delimiters.. don't use it. self.keys = dict(_btree_serializer._parse_leaf_lines(bytes, key_length, ref_list_length)) class _InternalNode(object): """An internal node for a serialised B+Tree index.""" def __init__(self, bytes): """Parse bytes to create an internal node object.""" # splitlines mangles the \r delimiters.. don't use it. self.keys = self._parse_lines(bytes.split('\n')) def _parse_lines(self, lines): nodes = [] self.offset = int(lines[1][7:]) for line in lines[2:]: if line == '': break nodes.append(tuple(line.split('\0'))) return nodes class BTreeGraphIndex(object): """Access to nodes via the standard GraphIndex interface for B+Tree's. Individual nodes are held in a LRU cache. This holds the root node in memory except when very large walks are done. """ def __init__(self, transport, name, size): """Create a B+Tree index object on the index name. :param transport: The transport to read data for the index from. :param name: The file name of the index on transport. :param size: Optional size of the index in bytes. This allows compatibility with the GraphIndex API, as well as ensuring that the initial read (to read the root node header) can be done without over-reading even on empty indices, and on small indices allows single-IO to read the entire index. """ self._transport = transport self._name = name self._size = size self._file = None self._page_size = transport.recommended_page_size() self._root_node = None # Default max size is 100,000 leave values self._leaf_value_cache = None # lru_cache.LRUCache(100*1000) self._leaf_node_cache = lru_cache.LRUCache(_NODE_CACHE_SIZE) self._internal_node_cache = lru_cache.LRUCache() self._key_count = None self._row_lengths = None self._row_offsets = None # Start of each row, [-1] is the end def __eq__(self, other): """Equal when self and other were created with the same parameters.""" return ( type(self) == type(other) and self._transport == other._transport and self._name == other._name and self._size == other._size) def __ne__(self, other): return not self.__eq__(other) def _get_root_node(self): if self._root_node is None: # We may not have a root node yet nodes = list(self._read_nodes([0])) if len(nodes): self._root_node = nodes[0][1] return self._root_node def _cache_nodes(self, nodes, cache): """Read nodes and cache them in the lru. The nodes list supplied is sorted and then read from disk, each node being inserted it into the _node_cache. Note: Asking for more nodes than the _node_cache can contain will result in some of the results being immediately discarded, to prevent this an assertion is raised if more nodes are asked for than are cachable. :return: A dict of {node_pos: node} """ if len(nodes) > cache._max_cache: trace.mutter('Requesting %s > %s nodes, not all will be cached', len(nodes), cache._max_cache) found = {} for node_pos, node in self._read_nodes(sorted(nodes)): if node_pos == 0: # Special case self._root_node = node else: cache.add(node_pos, node) found[node_pos] = node return found def _get_nodes(self, cache, node_indexes): found = {} needed = [] for idx in node_indexes: if idx == 0 and self._root_node is not None: found[0] = self._root_node continue try: found[idx] = cache[idx] except KeyError: needed.append(idx) found.update(self._cache_nodes(needed, cache)) return found def _get_internal_nodes(self, node_indexes): """Get a node, from cache or disk. After getting it, the node will be cached. """ return self._get_nodes(self._internal_node_cache, node_indexes) def _get_leaf_nodes(self, node_indexes): """Get a bunch of nodes, from cache or disk.""" found = self._get_nodes(self._leaf_node_cache, node_indexes) if self._leaf_value_cache is not None: for node in found.itervalues(): for key, value in node.keys.iteritems(): if key in self._leaf_value_cache: # Don't add the rest of the keys, we've seen this node # before. break self._leaf_value_cache[key] = value return found def iter_all_entries(self): """Iterate over all keys within the index. :return: An iterable of (index, key, value) or (index, key, value, reference_lists). The former tuple is used when there are no reference lists in the index, making the API compatible with simple key:value index types. There is no defined order for the result iteration - it will be in the most efficient order for the index. """ if 'evil' in debug.debug_flags: trace.mutter_callsite(3, "iter_all_entries scales with size of history.") if not self.key_count(): return start_of_leaves = self._row_offsets[-2] end_of_leaves = self._row_offsets[-1] needed_nodes = range(start_of_leaves, end_of_leaves) # We iterate strictly in-order so that we can use this function # for spilling index builds to disk. if self.node_ref_lists: for _, node in self._read_nodes(needed_nodes): for key, (value, refs) in sorted(node.keys.items()): yield (self, key, value, refs) else: for _, node in self._read_nodes(needed_nodes): for key, (value, refs) in sorted(node.keys.items()): yield (self, key, value) @staticmethod def _multi_bisect_right(in_keys, fixed_keys): """Find the positions where each 'in_key' would fit in fixed_keys. This is equivalent to doing "bisect_right" on each in_key into fixed_keys :param in_keys: A sorted list of keys to match with fixed_keys :param fixed_keys: A sorted list of keys to match against :return: A list of (integer position, [key list]) tuples. """ if not in_keys: return [] if not fixed_keys: # no pointers in the fixed_keys list, which means everything must # fall to the left. return [(0, in_keys)] # TODO: Iterating both lists will generally take M + N steps # Bisecting each key will generally take M * log2 N steps. # If we had an efficient way to compare, we could pick the method # based on which has the fewer number of steps. # There is also the argument that bisect_right is a compiled # function, so there is even more to be gained. # iter_steps = len(in_keys) + len(fixed_keys) # bisect_steps = len(in_keys) * math.log(len(fixed_keys), 2) if len(in_keys) == 1: # Bisect will always be faster for M = 1 return [(bisect_right(fixed_keys, in_keys[0]), in_keys)] # elif bisect_steps < iter_steps: # offsets = {} # for key in in_keys: # offsets.setdefault(bisect_right(fixed_keys, key), # []).append(key) # return [(o, offsets[o]) for o in sorted(offsets)] in_keys_iter = iter(in_keys) fixed_keys_iter = enumerate(fixed_keys) cur_in_key = in_keys_iter.next() cur_fixed_offset, cur_fixed_key = fixed_keys_iter.next() class InputDone(Exception): pass class FixedDone(Exception): pass output = [] cur_out = [] # TODO: Another possibility is that rather than iterating on each side, # we could use a combination of bisecting and iterating. For # example, while cur_in_key < fixed_key, bisect to find its # point, then iterate all matching keys, then bisect (restricted # to only the remainder) for the next one, etc. try: while True: if cur_in_key < cur_fixed_key: cur_keys = [] cur_out = (cur_fixed_offset, cur_keys) output.append(cur_out) while cur_in_key < cur_fixed_key: cur_keys.append(cur_in_key) try: cur_in_key = in_keys_iter.next() except StopIteration: raise InputDone # At this point cur_in_key must be >= cur_fixed_key # step the cur_fixed_key until we pass the cur key, or walk off # the end while cur_in_key >= cur_fixed_key: try: cur_fixed_offset, cur_fixed_key = fixed_keys_iter.next() except StopIteration: raise FixedDone except InputDone: # We consumed all of the input, nothing more to do pass except FixedDone: # There was some input left, but we consumed all of fixed, so we # have to add one more for the tail cur_keys = [cur_in_key] cur_keys.extend(in_keys_iter) cur_out = (len(fixed_keys), cur_keys) output.append(cur_out) return output def iter_entries(self, keys): """Iterate over keys within the index. :param keys: An iterable providing the keys to be retrieved. :return: An iterable as per iter_all_entries, but restricted to the keys supplied. No additional keys will be returned, and every key supplied that is in the index will be returned. """ # 6 seconds spent in miss_torture using the sorted() line. # Even with out of order disk IO it seems faster not to sort it when # large queries are being made. # However, now that we are doing multi-way bisecting, we need the keys # in sorted order anyway. We could change the multi-way code to not # require sorted order. (For example, it bisects for the first node, # does an in-order search until a key comes before the current point, # which it then bisects for, etc.) keys = frozenset(keys) if not keys: return if not self.key_count(): return needed_keys = [] if self._leaf_value_cache is None: needed_keys = keys else: for key in keys: value = self._leaf_value_cache.get(key, None) if value is not None: # This key is known not to be here, skip it value, refs = value if self.node_ref_lists: yield (self, key, value, refs) else: yield (self, key, value) else: needed_keys.append(key) last_key = None needed_keys = keys if not needed_keys: return # 6 seconds spent in miss_torture using the sorted() line. # Even with out of order disk IO it seems faster not to sort it when # large queries are being made. needed_keys = sorted(needed_keys) nodes_and_keys = [(0, needed_keys)] for row_pos, next_row_start in enumerate(self._row_offsets[1:-1]): node_indexes = [idx for idx, s_keys in nodes_and_keys] nodes = self._get_internal_nodes(node_indexes) next_nodes_and_keys = [] for node_index, sub_keys in nodes_and_keys: node = nodes[node_index] positions = self._multi_bisect_right(sub_keys, node.keys) node_offset = next_row_start + node.offset next_nodes_and_keys.extend([(node_offset + pos, s_keys) for pos, s_keys in positions]) nodes_and_keys = next_nodes_and_keys # We should now be at the _LeafNodes node_indexes = [idx for idx, s_keys in nodes_and_keys] # TODO: We may *not* want to always read all the nodes in one # big go. Consider setting a max size on this. nodes = self._get_leaf_nodes(node_indexes) for node_index, sub_keys in nodes_and_keys: if not sub_keys: continue node = nodes[node_index] for next_sub_key in sub_keys: if next_sub_key in node.keys: value, refs = node.keys[next_sub_key] if self.node_ref_lists: yield (self, next_sub_key, value, refs) else: yield (self, next_sub_key, value) def iter_entries_prefix(self, keys): """Iterate over keys within the index using prefix matching. Prefix matching is applied within the tuple of a key, not to within the bytestring of each key element. e.g. if you have the keys ('foo', 'bar'), ('foobar', 'gam') and do a prefix search for ('foo', None) then only the former key is returned. WARNING: Note that this method currently causes a full index parse unconditionally (which is reasonably appropriate as it is a means for thunking many small indices into one larger one and still supplies iter_all_entries at the thunk layer). :param keys: An iterable providing the key prefixes to be retrieved. Each key prefix takes the form of a tuple the length of a key, but with the last N elements 'None' rather than a regular bytestring. The first element cannot be 'None'. :return: An iterable as per iter_all_entries, but restricted to the keys with a matching prefix to those supplied. No additional keys will be returned, and every match that is in the index will be returned. """ keys = sorted(set(keys)) if not keys: return # Load if needed to check key lengths if self._key_count is None: self._get_root_node() # TODO: only access nodes that can satisfy the prefixes we are looking # for. For now, to meet API usage (as this function is not used by # current bzrlib) just suck the entire index and iterate in memory. nodes = {} if self.node_ref_lists: if self._key_length == 1: for _1, key, value, refs in self.iter_all_entries(): nodes[key] = value, refs else: nodes_by_key = {} for _1, key, value, refs in self.iter_all_entries(): key_value = key, value, refs # For a key of (foo, bar, baz) create # _nodes_by_key[foo][bar][baz] = key_value key_dict = nodes_by_key for subkey in key[:-1]: key_dict = key_dict.setdefault(subkey, {}) key_dict[key[-1]] = key_value else: if self._key_length == 1: for _1, key, value in self.iter_all_entries(): nodes[key] = value else: nodes_by_key = {} for _1, key, value in self.iter_all_entries(): key_value = key, value # For a key of (foo, bar, baz) create # _nodes_by_key[foo][bar][baz] = key_value key_dict = nodes_by_key for subkey in key[:-1]: key_dict = key_dict.setdefault(subkey, {}) key_dict[key[-1]] = key_value if self._key_length == 1: for key in keys: # sanity check if key[0] is None: raise errors.BadIndexKey(key) if len(key) != self._key_length: raise errors.BadIndexKey(key) try: if self.node_ref_lists: value, node_refs = nodes[key] yield self, key, value, node_refs else: yield self, key, nodes[key] except KeyError: pass return for key in keys: # sanity check if key[0] is None: raise errors.BadIndexKey(key) if len(key) != self._key_length: raise errors.BadIndexKey(key) # find what it refers to: key_dict = nodes_by_key elements = list(key) # find the subdict whose contents should be returned. try: while len(elements) and elements[0] is not None: key_dict = key_dict[elements[0]] elements.pop(0) except KeyError: # a non-existant lookup. continue if len(elements): dicts = [key_dict] while dicts: key_dict = dicts.pop(-1) # can't be empty or would not exist item, value = key_dict.iteritems().next() if type(value) == dict: # push keys dicts.extend(key_dict.itervalues()) else: # yield keys for value in key_dict.itervalues(): # each value is the key:value:node refs tuple # ready to yield. yield (self, ) + value else: # the last thing looked up was a terminal element yield (self, ) + key_dict def key_count(self): """Return an estimate of the number of keys in this index. For BTreeGraphIndex the estimate is exact as it is contained in the header. """ if self._key_count is None: self._get_root_node() return self._key_count def _parse_header_from_bytes(self, bytes): """Parse the header from a region of bytes. :param bytes: The data to parse. :return: An offset, data tuple such as readv yields, for the unparsed data. (which may be of length 0). """ signature = bytes[0:len(self._signature())] if not signature == self._signature(): raise errors.BadIndexFormatSignature(self._name, BTreeGraphIndex) lines = bytes[len(self._signature()):].splitlines() options_line = lines[0] if not options_line.startswith(_OPTION_NODE_REFS): raise errors.BadIndexOptions(self) try: self.node_ref_lists = int(options_line[len(_OPTION_NODE_REFS):]) except ValueError: raise errors.BadIndexOptions(self) options_line = lines[1] if not options_line.startswith(_OPTION_KEY_ELEMENTS): raise errors.BadIndexOptions(self) try: self._key_length = int(options_line[len(_OPTION_KEY_ELEMENTS):]) except ValueError: raise errors.BadIndexOptions(self) options_line = lines[2] if not options_line.startswith(_OPTION_LEN): raise errors.BadIndexOptions(self) try: self._key_count = int(options_line[len(_OPTION_LEN):]) except ValueError: raise errors.BadIndexOptions(self) options_line = lines[3] if not options_line.startswith(_OPTION_ROW_LENGTHS): raise errors.BadIndexOptions(self) try: self._row_lengths = map(int, [length for length in options_line[len(_OPTION_ROW_LENGTHS):].split(',') if len(length)]) except ValueError: raise errors.BadIndexOptions(self) offsets = [] row_offset = 0 for row in self._row_lengths: offsets.append(row_offset) row_offset += row offsets.append(row_offset) self._row_offsets = offsets # calculate the bytes we have processed header_end = (len(signature) + sum(map(len, lines[0:4])) + 4) return header_end, bytes[header_end:] def _read_nodes(self, nodes): """Read some nodes from disk into the LRU cache. This performs a readv to get the node data into memory, and parses each node, the yields it to the caller. The nodes are requested in the supplied order. If possible doing sort() on the list before requesting a read may improve performance. :param nodes: The nodes to read. 0 - first node, 1 - second node etc. :return: None """ ranges = [] for index in nodes: offset = index * _PAGE_SIZE size = _PAGE_SIZE if index == 0: # Root node - special case if self._size: size = min(_PAGE_SIZE, self._size) else: stream = self._transport.get(self._name) start = stream.read(_PAGE_SIZE) # Avoid doing this again self._size = len(start) size = min(_PAGE_SIZE, self._size) else: size = min(size, self._size - offset) ranges.append((offset, size)) if not ranges: return if self._file is None: data_ranges = self._transport.readv(self._name, ranges) else: data_ranges = [] for offset, size in ranges: self._file.seek(offset) data_ranges.append((offset, self._file.read(size))) for offset, data in data_ranges: if offset == 0: # extract the header offset, data = self._parse_header_from_bytes(data) if len(data) == 0: continue bytes = zlib.decompress(data) if bytes.startswith(_LEAF_FLAG): node = _LeafNode(bytes, self._key_length, self.node_ref_lists) elif bytes.startswith(_INTERNAL_FLAG): node = _InternalNode(bytes) else: raise AssertionError("Unknown node type for %r" % bytes) yield offset / _PAGE_SIZE, node def _signature(self): """The file signature for this index type.""" return _BTSIGNATURE def validate(self): """Validate that everything in the index can be accessed.""" # just read and parse every node. self._get_root_node() if len(self._row_lengths) > 1: start_node = self._row_offsets[1] else: # We shouldn't be reading anything anyway start_node = 1 node_end = self._row_offsets[-1] for node in self._read_nodes(range(start_node, node_end)): pass try: from bzrlib import _btree_serializer_c as _btree_serializer except ImportError: from bzrlib import _btree_serializer_py as _btree_serializer