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# Copyright (C) 2008 Canonical Ltd
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 2 of the License, or
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# (at your option) any later version.
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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from bisect import bisect_right
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from copy import deepcopy
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from bzrlib.index import _OPTION_NODE_REFS, _OPTION_KEY_ELEMENTS, _OPTION_LEN
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from bzrlib.transport import get_transport
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_BTSIGNATURE = "B+Tree Graph Index 2\n"
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_OPTION_ROW_LENGTHS = "row_lengths="
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_LEAF_FLAG = "type=leaf\n"
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_INTERNAL_FLAG = "type=internal\n"
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_INTERNAL_OFFSET = "offset="
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_RESERVED_HEADER_BYTES = 120
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# 4K per page: 4MB - 1000 entries
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_NODE_CACHE_SIZE = 1000
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class _BuilderRow(object):
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"""The stored state accumulated while writing out a row in the index.
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:ivar spool: A temporary file used to accumulate nodes for this row
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:ivar nodes: The count of nodes emitted so far.
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"""Create a _BuilderRow."""
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self.spool = tempfile.TemporaryFile()
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def finish_node(self, pad=True):
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byte_lines, _, padding = self.writer.finish()
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self.spool.write("\x00" * _RESERVED_HEADER_BYTES)
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if not pad and padding:
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skipped_bytes = padding
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self.spool.writelines(byte_lines)
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remainder = (self.spool.tell() + skipped_bytes) % _PAGE_SIZE
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raise AssertionError("incorrect node length: %d, %d"
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% (self.spool.tell(), remainder))
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class _InternalBuilderRow(_BuilderRow):
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"""The stored state accumulated while writing out internal rows."""
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def finish_node(self, pad=True):
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raise AssertionError("Must pad internal nodes only.")
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_BuilderRow.finish_node(self)
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class _LeafBuilderRow(_BuilderRow):
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"""The stored state accumulated while writing out a leaf rows."""
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class BTreeBuilder(index.GraphIndexBuilder):
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"""A Builder for B+Tree based Graph indices.
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The resulting graph has the structure:
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_SIGNATURE OPTIONS NODES
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_SIGNATURE := 'B+Tree Graph Index 1' NEWLINE
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OPTIONS := REF_LISTS KEY_ELEMENTS LENGTH
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REF_LISTS := 'node_ref_lists=' DIGITS NEWLINE
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KEY_ELEMENTS := 'key_elements=' DIGITS NEWLINE
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LENGTH := 'len=' DIGITS NEWLINE
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ROW_LENGTHS := 'row_lengths' DIGITS (COMMA DIGITS)*
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NODES := NODE_COMPRESSED*
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NODE_COMPRESSED:= COMPRESSED_BYTES{4096}
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NODE_RAW := INTERNAL | LEAF
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INTERNAL := INTERNAL_FLAG POINTERS
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LEAF := LEAF_FLAG ROWS
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KEY_ELEMENT := Not-whitespace-utf8
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KEY := KEY_ELEMENT (NULL KEY_ELEMENT)*
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ROW := KEY NULL ABSENT? NULL REFERENCES NULL VALUE NEWLINE
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REFERENCES := REFERENCE_LIST (TAB REFERENCE_LIST){node_ref_lists - 1}
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REFERENCE_LIST := (REFERENCE (CR REFERENCE)*)?
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VALUE := no-newline-no-null-bytes
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def __init__(self, reference_lists=0, key_elements=1, spill_at=100000):
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"""See GraphIndexBuilder.__init__.
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:param spill_at: Optional parameter controlling the maximum number
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of nodes that BTreeBuilder will hold in memory.
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index.GraphIndexBuilder.__init__(self, reference_lists=reference_lists,
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key_elements=key_elements)
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self._spill_at = spill_at
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self._backing_indices = []
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# A map of {key: (node_refs, value)}
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# Indicate it hasn't been built yet
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self._nodes_by_key = None
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self._optimize_for_size = False
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def add_node(self, key, value, references=()):
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"""Add a node to the index.
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If adding the node causes the builder to reach its spill_at threshold,
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disk spilling will be triggered.
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:param key: The key. keys are non-empty tuples containing
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as many whitespace-free utf8 bytestrings as the key length
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defined for this index.
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:param references: An iterable of iterables of keys. Each is a
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reference to another key.
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:param value: The value to associate with the key. It may be any
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bytes as long as it does not contain \0 or \n.
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# we don't care about absent_references
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node_refs, _ = self._check_key_ref_value(key, references, value)
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if key in self._nodes:
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raise errors.BadIndexDuplicateKey(key, self)
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self._nodes[key] = (node_refs, value)
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if self._nodes_by_key is not None and self._key_length > 1:
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self._update_nodes_by_key(key, value, node_refs)
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if len(self._keys) < self._spill_at:
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self._spill_mem_keys_to_disk()
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def _spill_mem_keys_to_disk(self):
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"""Write the in memory keys down to disk to cap memory consumption.
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If we already have some keys written to disk, we will combine them so
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as to preserve the sorted order. The algorithm for combining uses
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powers of two. So on the first spill, write all mem nodes into a
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single index. On the second spill, combine the mem nodes with the nodes
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on disk to create a 2x sized disk index and get rid of the first index.
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On the third spill, create a single new disk index, which will contain
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the mem nodes, and preserve the existing 2x sized index. On the fourth,
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combine mem with the first and second indexes, creating a new one of
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size 4x. On the fifth create a single new one, etc.
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iterators_to_combine = [self._iter_mem_nodes()]
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for pos, backing in enumerate(self._backing_indices):
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iterators_to_combine.append(backing.iter_all_entries())
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backing_pos = pos + 1
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new_backing_file, size = \
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self._write_nodes(self._iter_smallest(iterators_to_combine))
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dir_path, base_name = osutils.split(new_backing_file.name)
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# Note: The transport here isn't strictly needed, because we will use
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# direct access to the new_backing._file object
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new_backing = BTreeGraphIndex(get_transport(dir_path),
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# GC will clean up the file
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new_backing._file = new_backing_file
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if len(self._backing_indices) == backing_pos:
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self._backing_indices.append(None)
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self._backing_indices[backing_pos] = new_backing
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for pos in range(backing_pos):
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self._backing_indices[pos] = None
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self._nodes_by_key = None
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def add_nodes(self, nodes):
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"""Add nodes to the index.
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:param nodes: An iterable of (key, node_refs, value) entries to add.
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if self.reference_lists:
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for (key, value, node_refs) in nodes:
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self.add_node(key, value, node_refs)
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for (key, value) in nodes:
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self.add_node(key, value)
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def _iter_mem_nodes(self):
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"""Iterate over the nodes held in memory."""
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if self.reference_lists:
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for key in sorted(nodes):
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references, value = nodes[key]
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yield self, key, value, references
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for key in sorted(nodes):
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references, value = nodes[key]
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yield self, key, value
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def _iter_smallest(self, iterators_to_combine):
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if len(iterators_to_combine) == 1:
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for value in iterators_to_combine[0]:
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for iterator in iterators_to_combine:
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current_values.append(iterator.next())
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except StopIteration:
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current_values.append(None)
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# Decorate candidates with the value to allow 2.4's min to be used.
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candidates = [(item[1][1], item) for item
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in enumerate(current_values) if item[1] is not None]
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if not len(candidates):
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selected = min(candidates)
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# undecorate back to (pos, node)
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selected = selected[1]
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if last == selected[1][1]:
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raise errors.BadIndexDuplicateKey(last, self)
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last = selected[1][1]
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# Yield, with self as the index
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yield (self,) + selected[1][1:]
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current_values[pos] = iterators_to_combine[pos].next()
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except StopIteration:
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current_values[pos] = None
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def _add_key(self, string_key, line, rows):
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"""Add a key to the current chunk.
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:param string_key: The key to add.
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:param line: The fully serialised key and value.
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if rows[-1].writer is None:
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# opening a new leaf chunk;
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for pos, internal_row in enumerate(rows[:-1]):
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# flesh out any internal nodes that are needed to
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# preserve the height of the tree
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if internal_row.writer is None:
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if internal_row.nodes == 0:
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length -= _RESERVED_HEADER_BYTES # padded
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internal_row.writer = chunk_writer.ChunkWriter(length, 0,
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optimize_for_size=self._optimize_for_size)
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internal_row.writer.write(_INTERNAL_FLAG)
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internal_row.writer.write(_INTERNAL_OFFSET +
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str(rows[pos + 1].nodes) + "\n")
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if rows[-1].nodes == 0:
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length -= _RESERVED_HEADER_BYTES # padded
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rows[-1].writer = chunk_writer.ChunkWriter(length,
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optimize_for_size=self._optimize_for_size)
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rows[-1].writer.write(_LEAF_FLAG)
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if rows[-1].writer.write(line):
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# this key did not fit in the node:
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rows[-1].finish_node()
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key_line = string_key + "\n"
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for row in reversed(rows[:-1]):
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# Mark the start of the next node in the node above. If it
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# doesn't fit then propogate upwards until we find one that
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if row.writer.write(key_line):
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# We've found a node that can handle the pointer.
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# If we reached the current root without being able to mark the
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# division point, then we need a new root:
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if 'index' in debug.debug_flags:
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trace.mutter('Inserting new global row.')
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new_row = _InternalBuilderRow()
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rows.insert(0, new_row)
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# This will be padded, hence the -100
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new_row.writer = chunk_writer.ChunkWriter(
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_PAGE_SIZE - _RESERVED_HEADER_BYTES,
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optimize_for_size=self._optimize_for_size)
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new_row.writer.write(_INTERNAL_FLAG)
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new_row.writer.write(_INTERNAL_OFFSET +
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str(rows[1].nodes - 1) + "\n")
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new_row.writer.write(key_line)
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self._add_key(string_key, line, rows)
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def _write_nodes(self, node_iterator):
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"""Write node_iterator out as a B+Tree.
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:param node_iterator: An iterator of sorted nodes. Each node should
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match the output given by iter_all_entries.
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:return: A file handle for a temporary file containing a B+Tree for
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# The index rows - rows[0] is the root, rows[1] is the layer under it
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# forward sorted by key. In future we may consider topological sorting,
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# at the cost of table scans for direct lookup, or a second index for
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# A stack with the number of nodes of each size. 0 is the root node
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# and must always be 1 (if there are any nodes in the tree).
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self.row_lengths = []
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# Loop over all nodes adding them to the bottom row
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# (rows[-1]). When we finish a chunk in a row,
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# propogate the key that didn't fit (comes after the chunk) to the
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# row above, transitively.
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for node in node_iterator:
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# First key triggers the first row
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rows.append(_LeafBuilderRow())
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string_key, line = _btree_serializer._flatten_node(node,
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self.reference_lists)
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self._add_key(string_key, line, rows)
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for row in reversed(rows):
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pad = (type(row) != _LeafBuilderRow)
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row.finish_node(pad=pad)
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result = tempfile.NamedTemporaryFile()
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lines = [_BTSIGNATURE]
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lines.append(_OPTION_NODE_REFS + str(self.reference_lists) + '\n')
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lines.append(_OPTION_KEY_ELEMENTS + str(self._key_length) + '\n')
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lines.append(_OPTION_LEN + str(key_count) + '\n')
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row_lengths = [row.nodes for row in rows]
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lines.append(_OPTION_ROW_LENGTHS + ','.join(map(str, row_lengths)) + '\n')
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result.writelines(lines)
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position = sum(map(len, lines))
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if position > _RESERVED_HEADER_BYTES:
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raise AssertionError("Could not fit the header in the"
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" reserved space: %d > %d"
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% (position, _RESERVED_HEADER_BYTES))
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# write the rows out:
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reserved = _RESERVED_HEADER_BYTES # reserved space for first node
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# copy nodes to the finalised file.
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# Special case the first node as it may be prefixed
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node = row.spool.read(_PAGE_SIZE)
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result.write(node[reserved:])
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result.write("\x00" * (reserved - position))
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position = 0 # Only the root row actually has an offset
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copied_len = osutils.pumpfile(row.spool, result)
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if copied_len != (row.nodes - 1) * _PAGE_SIZE:
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if type(row) != _LeafBuilderRow:
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raise AssertionError("Incorrect amount of data copied"
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" expected: %d, got: %d"
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% ((row.nodes - 1) * _PAGE_SIZE,
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"""Finalise the index.
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:return: A file handle for a temporary file containing the nodes added
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return self._write_nodes(self.iter_all_entries())[0]
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def iter_all_entries(self):
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"""Iterate over all keys within the index
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:return: An iterable of (index, key, reference_lists, value). There is no
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defined order for the result iteration - it will be in the most
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efficient order for the index (in this case dictionary hash order).
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if 'evil' in debug.debug_flags:
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trace.mutter_callsite(3,
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"iter_all_entries scales with size of history.")
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# Doing serial rather than ordered would be faster; but this shouldn't
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# be getting called routinely anyway.
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iterators = [self._iter_mem_nodes()]
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for backing in self._backing_indices:
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if backing is not None:
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iterators.append(backing.iter_all_entries())
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if len(iterators) == 1:
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return self._iter_smallest(iterators)
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def iter_entries(self, keys):
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"""Iterate over keys within the index.
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:param keys: An iterable providing the keys to be retrieved.
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:return: An iterable of (index, key, value, reference_lists). There is no
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defined order for the result iteration - it will be in the most
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efficient order for the index (keys iteration order in this case).
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local_keys = keys.intersection(self._keys)
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if self.reference_lists:
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for key in local_keys:
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node = self._nodes[key]
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yield self, key, node[1], node[0]
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for key in local_keys:
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node = self._nodes[key]
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yield self, key, node[1]
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# Find things that are in backing indices that have not been handled
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if not self._backing_indices:
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return # We won't find anything there either
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# Remove all of the keys that we found locally
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keys.difference_update(local_keys)
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for backing in self._backing_indices:
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for node in backing.iter_entries(keys):
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yield (self,) + node[1:]
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def iter_entries_prefix(self, keys):
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"""Iterate over keys within the index using prefix matching.
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Prefix matching is applied within the tuple of a key, not to within
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the bytestring of each key element. e.g. if you have the keys ('foo',
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'bar'), ('foobar', 'gam') and do a prefix search for ('foo', None) then
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only the former key is returned.
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:param keys: An iterable providing the key prefixes to be retrieved.
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Each key prefix takes the form of a tuple the length of a key, but
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with the last N elements 'None' rather than a regular bytestring.
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The first element cannot be 'None'.
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:return: An iterable as per iter_all_entries, but restricted to the
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keys with a matching prefix to those supplied. No additional keys
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will be returned, and every match that is in the index will be
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# XXX: To much duplication with the GraphIndex class; consider finding
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# a good place to pull out the actual common logic.
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for backing in self._backing_indices:
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for node in backing.iter_entries_prefix(keys):
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yield (self,) + node[1:]
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if self._key_length == 1:
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raise errors.BadIndexKey(key)
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if len(key) != self._key_length:
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raise errors.BadIndexKey(key)
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node = self._nodes[key]
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if self.reference_lists:
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yield self, key, node[1], node[0]
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yield self, key, node[1]
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raise errors.BadIndexKey(key)
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if len(key) != self._key_length:
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raise errors.BadIndexKey(key)
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# find what it refers to:
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key_dict = self._get_nodes_by_key()
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# find the subdict to return
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while len(elements) and elements[0] is not None:
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key_dict = key_dict[elements[0]]
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# a non-existant lookup.
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key_dict = dicts.pop(-1)
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# can't be empty or would not exist
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item, value = key_dict.iteritems().next()
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if type(value) == dict:
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dicts.extend(key_dict.itervalues())
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for value in key_dict.itervalues():
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yield (self, ) + value
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yield (self, ) + key_dict
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def _get_nodes_by_key(self):
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if self._nodes_by_key is None:
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if self.reference_lists:
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for key, (references, value) in self._nodes.iteritems():
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key_dict = nodes_by_key
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for subkey in key[:-1]:
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key_dict = key_dict.setdefault(subkey, {})
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key_dict[key[-1]] = key, value, references
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for key, (references, value) in self._nodes.iteritems():
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key_dict = nodes_by_key
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for subkey in key[:-1]:
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key_dict = key_dict.setdefault(subkey, {})
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key_dict[key[-1]] = key, value
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self._nodes_by_key = nodes_by_key
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return self._nodes_by_key
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"""Return an estimate of the number of keys in this index.
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For InMemoryGraphIndex the estimate is exact.
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return len(self._keys) + sum(backing.key_count() for backing in
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self._backing_indices if backing is not None)
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"""In memory index's have no known corruption at the moment."""
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class _LeafNode(object):
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"""A leaf node for a serialised B+Tree index."""
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def __init__(self, bytes, key_length, ref_list_length):
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"""Parse bytes to create a leaf node object."""
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# splitlines mangles the \r delimiters.. don't use it.
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self.keys = dict(_btree_serializer._parse_leaf_lines(bytes,
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key_length, ref_list_length))
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class _InternalNode(object):
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"""An internal node for a serialised B+Tree index."""
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def __init__(self, bytes):
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"""Parse bytes to create an internal node object."""
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# splitlines mangles the \r delimiters.. don't use it.
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self.keys = self._parse_lines(bytes.split('\n'))
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def _parse_lines(self, lines):
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self.offset = int(lines[1][7:])
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for line in lines[2:]:
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nodes.append(tuple(line.split('\0')))
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class BTreeGraphIndex(object):
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"""Access to nodes via the standard GraphIndex interface for B+Tree's.
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Individual nodes are held in a LRU cache. This holds the root node in
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memory except when very large walks are done.
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def __init__(self, transport, name, size):
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"""Create a B+Tree index object on the index name.
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:param transport: The transport to read data for the index from.
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:param name: The file name of the index on transport.
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:param size: Optional size of the index in bytes. This allows
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compatibility with the GraphIndex API, as well as ensuring that
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the initial read (to read the root node header) can be done
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without over-reading even on empty indices, and on small indices
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allows single-IO to read the entire index.
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self._transport = transport
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self._recommended_pages = self._compute_recommended_pages()
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self._root_node = None
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# Default max size is 100,000 leave values
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self._leaf_value_cache = None # lru_cache.LRUCache(100*1000)
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self._leaf_node_cache = lru_cache.LRUCache(_NODE_CACHE_SIZE)
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self._internal_node_cache = lru_cache.LRUCache()
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self._key_count = None
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self._row_lengths = None
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self._row_offsets = None # Start of each row, [-1] is the end
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def __eq__(self, other):
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"""Equal when self and other were created with the same parameters."""
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type(self) == type(other) and
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self._transport == other._transport and
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self._name == other._name and
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self._size == other._size)
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def __ne__(self, other):
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return not self.__eq__(other)
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def _get_and_cache_nodes(self, nodes):
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"""Read nodes and cache them in the lru.
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The nodes list supplied is sorted and then read from disk, each node
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being inserted it into the _node_cache.
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Note: Asking for more nodes than the _node_cache can contain will
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result in some of the results being immediately discarded, to prevent
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this an assertion is raised if more nodes are asked for than are
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:return: A dict of {node_pos: node}
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start_of_leaves = None
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for node_pos, node in self._read_nodes(sorted(nodes)):
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if node_pos == 0: # Special case
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self._root_node = node
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if start_of_leaves is None:
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start_of_leaves = self._row_offsets[-2]
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if node_pos < start_of_leaves:
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self._internal_node_cache.add(node_pos, node)
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self._leaf_node_cache.add(node_pos, node)
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found[node_pos] = node
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def _compute_recommended_pages(self):
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"""Convert transport's recommended_page_size into btree pages.
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recommended_page_size is in bytes, we want to know how many _PAGE_SIZE
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pages fit in that length.
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recommended_read = self._transport.recommended_page_size()
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recommended_pages = int(math.ceil(recommended_read /
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return recommended_pages
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def _compute_total_pages_in_index(self):
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"""How many pages are in the index.
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If we have read the header we will use the value stored there.
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Otherwise it will be computed based on the length of the index.
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if self._size is None:
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raise AssertionError('_compute_total_pages_in_index should not be'
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' called when self._size is None')
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if self._root_node is not None:
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# This is the number of pages as defined by the header
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return self._row_offsets[-1]
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# This is the number of pages as defined by the size of the index. They
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# should be indentical.
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total_pages = int(math.ceil(self._size / float(_PAGE_SIZE)))
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def _expand_offsets(self, offsets):
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"""Find extra pages to download.
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The idea is that we always want to make big-enough requests (like 64kB
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for http), so that we don't waste round trips. So given the entries
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that we already have cached and the new pages being downloaded figure
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out what other pages we might want to read.
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See also doc/developers/btree_index_prefetch.txt for more details.
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:param offsets: The offsets to be read
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:return: A list of offsets to download
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if 'index' in debug.debug_flags:
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trace.mutter('expanding: %s\toffsets: %s', self._name, offsets)
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if len(offsets) >= self._recommended_pages:
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# Don't add more, we are already requesting more than enough
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if 'index' in debug.debug_flags:
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trace.mutter(' not expanding large request (%s >= %s)',
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len(offsets), self._recommended_pages)
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if self._size is None:
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# Don't try anything, because we don't know where the file ends
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if 'index' in debug.debug_flags:
716
trace.mutter(' not expanding without knowing index size')
718
total_pages = self._compute_total_pages_in_index()
719
cached_offsets = self._get_offsets_to_cached_pages()
720
# If reading recommended_pages would read the rest of the index, just
722
if total_pages - len(cached_offsets) <= self._recommended_pages:
723
# Read whatever is left
725
expanded = [x for x in xrange(total_pages)
726
if x not in cached_offsets]
728
expanded = range(total_pages)
729
if 'index' in debug.debug_flags:
730
trace.mutter(' reading all unread pages: %s', expanded)
733
if self._root_node is None:
734
# ATM on the first read of the root node of a large index, we don't
735
# bother pre-reading any other pages. This is because the
736
# likelyhood of actually reading interesting pages is very low.
737
# See doc/developers/btree_index_prefetch.txt for a discussion, and
738
# a possible implementation when we are guessing that the second
739
# layer index is small
740
final_offsets = offsets
742
tree_depth = len(self._row_lengths)
743
if len(cached_offsets) < tree_depth and len(offsets) == 1:
744
# We haven't read enough to justify expansion
745
# If we are only going to read the root node, and 1 leaf node,
746
# then it isn't worth expanding our request. Once we've read at
747
# least 2 nodes, then we are probably doing a search, and we
748
# start expanding our requests.
749
if 'index' in debug.debug_flags:
750
trace.mutter(' not expanding on first reads')
752
final_offsets = self._expand_to_neighbors(offsets, cached_offsets,
755
final_offsets = sorted(final_offsets)
756
if 'index' in debug.debug_flags:
757
trace.mutter('expanded: %s', final_offsets)
760
def _expand_to_neighbors(self, offsets, cached_offsets, total_pages):
761
"""Expand requests to neighbors until we have enough pages.
763
This is called from _expand_offsets after policy has determined that we
765
We only want to expand requests within a given layer. We cheat a little
766
bit and assume all requests will be in the same layer. This is true
767
given the current design, but if it changes this algorithm may perform
770
:param offsets: requested offsets
771
:param cached_offsets: offsets for pages we currently have cached
772
:return: A set() of offsets after expansion
774
final_offsets = set(offsets)
776
new_tips = set(final_offsets)
777
while len(final_offsets) < self._recommended_pages and new_tips:
781
first, end = self._find_layer_first_and_end(pos)
784
and previous not in cached_offsets
785
and previous not in final_offsets
786
and previous >= first):
787
next_tips.add(previous)
789
if (after < total_pages
790
and after not in cached_offsets
791
and after not in final_offsets
794
# This would keep us from going bigger than
795
# recommended_pages by only expanding the first offsets.
796
# However, if we are making a 'wide' request, it is
797
# reasonable to expand all points equally.
798
# if len(final_offsets) > recommended_pages:
800
final_offsets.update(next_tips)
804
def _find_layer_first_and_end(self, offset):
805
"""Find the start/stop nodes for the layer corresponding to offset.
807
:return: (first, end)
808
first is the first node in this layer
809
end is the first node of the next layer
812
for roffset in self._row_offsets:
819
def _get_offsets_to_cached_pages(self):
820
"""Determine what nodes we already have cached."""
821
cached_offsets = set(self._internal_node_cache.keys())
822
cached_offsets.update(self._leaf_node_cache.keys())
823
if self._root_node is not None:
824
cached_offsets.add(0)
825
return cached_offsets
827
def _get_root_node(self):
828
if self._root_node is None:
829
# We may not have a root node yet
830
self._get_internal_nodes([0])
831
return self._root_node
833
def _get_nodes(self, cache, node_indexes):
836
for idx in node_indexes:
837
if idx == 0 and self._root_node is not None:
838
found[0] = self._root_node
841
found[idx] = cache[idx]
846
needed = self._expand_offsets(needed)
847
found.update(self._get_and_cache_nodes(needed))
850
def _get_internal_nodes(self, node_indexes):
851
"""Get a node, from cache or disk.
853
After getting it, the node will be cached.
855
return self._get_nodes(self._internal_node_cache, node_indexes)
857
def _cache_leaf_values(self, nodes):
858
"""Cache directly from key => value, skipping the btree."""
859
if self._leaf_value_cache is not None:
860
for node in nodes.itervalues():
861
for key, value in node.keys.iteritems():
862
if key in self._leaf_value_cache:
863
# Don't add the rest of the keys, we've seen this node
866
self._leaf_value_cache[key] = value
868
def _get_leaf_nodes(self, node_indexes):
869
"""Get a bunch of nodes, from cache or disk."""
870
found = self._get_nodes(self._leaf_node_cache, node_indexes)
871
self._cache_leaf_values(found)
874
def iter_all_entries(self):
875
"""Iterate over all keys within the index.
877
:return: An iterable of (index, key, value) or (index, key, value, reference_lists).
878
The former tuple is used when there are no reference lists in the
879
index, making the API compatible with simple key:value index types.
880
There is no defined order for the result iteration - it will be in
881
the most efficient order for the index.
883
if 'evil' in debug.debug_flags:
884
trace.mutter_callsite(3,
885
"iter_all_entries scales with size of history.")
886
if not self.key_count():
888
if self._row_offsets[-1] == 1:
889
# There is only the root node, and we read that via key_count()
890
if self.node_ref_lists:
891
for key, (value, refs) in sorted(self._root_node.keys.items()):
892
yield (self, key, value, refs)
894
for key, (value, refs) in sorted(self._root_node.keys.items()):
895
yield (self, key, value)
897
start_of_leaves = self._row_offsets[-2]
898
end_of_leaves = self._row_offsets[-1]
899
needed_offsets = range(start_of_leaves, end_of_leaves)
900
if needed_offsets == [0]:
901
# Special case when we only have a root node, as we have already
903
nodes = [(0, self._root_node)]
905
nodes = self._read_nodes(needed_offsets)
906
# We iterate strictly in-order so that we can use this function
907
# for spilling index builds to disk.
908
if self.node_ref_lists:
909
for _, node in nodes:
910
for key, (value, refs) in sorted(node.keys.items()):
911
yield (self, key, value, refs)
913
for _, node in nodes:
914
for key, (value, refs) in sorted(node.keys.items()):
915
yield (self, key, value)
918
def _multi_bisect_right(in_keys, fixed_keys):
919
"""Find the positions where each 'in_key' would fit in fixed_keys.
921
This is equivalent to doing "bisect_right" on each in_key into
924
:param in_keys: A sorted list of keys to match with fixed_keys
925
:param fixed_keys: A sorted list of keys to match against
926
:return: A list of (integer position, [key list]) tuples.
931
# no pointers in the fixed_keys list, which means everything must
933
return [(0, in_keys)]
935
# TODO: Iterating both lists will generally take M + N steps
936
# Bisecting each key will generally take M * log2 N steps.
937
# If we had an efficient way to compare, we could pick the method
938
# based on which has the fewer number of steps.
939
# There is also the argument that bisect_right is a compiled
940
# function, so there is even more to be gained.
941
# iter_steps = len(in_keys) + len(fixed_keys)
942
# bisect_steps = len(in_keys) * math.log(len(fixed_keys), 2)
943
if len(in_keys) == 1: # Bisect will always be faster for M = 1
944
return [(bisect_right(fixed_keys, in_keys[0]), in_keys)]
945
# elif bisect_steps < iter_steps:
947
# for key in in_keys:
948
# offsets.setdefault(bisect_right(fixed_keys, key),
950
# return [(o, offsets[o]) for o in sorted(offsets)]
951
in_keys_iter = iter(in_keys)
952
fixed_keys_iter = enumerate(fixed_keys)
953
cur_in_key = in_keys_iter.next()
954
cur_fixed_offset, cur_fixed_key = fixed_keys_iter.next()
956
class InputDone(Exception): pass
957
class FixedDone(Exception): pass
962
# TODO: Another possibility is that rather than iterating on each side,
963
# we could use a combination of bisecting and iterating. For
964
# example, while cur_in_key < fixed_key, bisect to find its
965
# point, then iterate all matching keys, then bisect (restricted
966
# to only the remainder) for the next one, etc.
969
if cur_in_key < cur_fixed_key:
971
cur_out = (cur_fixed_offset, cur_keys)
972
output.append(cur_out)
973
while cur_in_key < cur_fixed_key:
974
cur_keys.append(cur_in_key)
976
cur_in_key = in_keys_iter.next()
977
except StopIteration:
979
# At this point cur_in_key must be >= cur_fixed_key
980
# step the cur_fixed_key until we pass the cur key, or walk off
982
while cur_in_key >= cur_fixed_key:
984
cur_fixed_offset, cur_fixed_key = fixed_keys_iter.next()
985
except StopIteration:
988
# We consumed all of the input, nothing more to do
991
# There was some input left, but we consumed all of fixed, so we
992
# have to add one more for the tail
993
cur_keys = [cur_in_key]
994
cur_keys.extend(in_keys_iter)
995
cur_out = (len(fixed_keys), cur_keys)
996
output.append(cur_out)
999
def iter_entries(self, keys):
1000
"""Iterate over keys within the index.
1002
:param keys: An iterable providing the keys to be retrieved.
1003
:return: An iterable as per iter_all_entries, but restricted to the
1004
keys supplied. No additional keys will be returned, and every
1005
key supplied that is in the index will be returned.
1007
# 6 seconds spent in miss_torture using the sorted() line.
1008
# Even with out of order disk IO it seems faster not to sort it when
1009
# large queries are being made.
1010
# However, now that we are doing multi-way bisecting, we need the keys
1011
# in sorted order anyway. We could change the multi-way code to not
1012
# require sorted order. (For example, it bisects for the first node,
1013
# does an in-order search until a key comes before the current point,
1014
# which it then bisects for, etc.)
1015
keys = frozenset(keys)
1019
if not self.key_count():
1023
if self._leaf_value_cache is None:
1027
value = self._leaf_value_cache.get(key, None)
1028
if value is not None:
1029
# This key is known not to be here, skip it
1031
if self.node_ref_lists:
1032
yield (self, key, value, refs)
1034
yield (self, key, value)
1036
needed_keys.append(key)
1042
# 6 seconds spent in miss_torture using the sorted() line.
1043
# Even with out of order disk IO it seems faster not to sort it when
1044
# large queries are being made.
1045
needed_keys = sorted(needed_keys)
1047
nodes_and_keys = [(0, needed_keys)]
1049
for row_pos, next_row_start in enumerate(self._row_offsets[1:-1]):
1050
node_indexes = [idx for idx, s_keys in nodes_and_keys]
1051
nodes = self._get_internal_nodes(node_indexes)
1053
next_nodes_and_keys = []
1054
for node_index, sub_keys in nodes_and_keys:
1055
node = nodes[node_index]
1056
positions = self._multi_bisect_right(sub_keys, node.keys)
1057
node_offset = next_row_start + node.offset
1058
next_nodes_and_keys.extend([(node_offset + pos, s_keys)
1059
for pos, s_keys in positions])
1060
nodes_and_keys = next_nodes_and_keys
1061
# We should now be at the _LeafNodes
1062
node_indexes = [idx for idx, s_keys in nodes_and_keys]
1064
# TODO: We may *not* want to always read all the nodes in one
1065
# big go. Consider setting a max size on this.
1067
nodes = self._get_leaf_nodes(node_indexes)
1068
for node_index, sub_keys in nodes_and_keys:
1071
node = nodes[node_index]
1072
for next_sub_key in sub_keys:
1073
if next_sub_key in node.keys:
1074
value, refs = node.keys[next_sub_key]
1075
if self.node_ref_lists:
1076
yield (self, next_sub_key, value, refs)
1078
yield (self, next_sub_key, value)
1080
def iter_entries_prefix(self, keys):
1081
"""Iterate over keys within the index using prefix matching.
1083
Prefix matching is applied within the tuple of a key, not to within
1084
the bytestring of each key element. e.g. if you have the keys ('foo',
1085
'bar'), ('foobar', 'gam') and do a prefix search for ('foo', None) then
1086
only the former key is returned.
1088
WARNING: Note that this method currently causes a full index parse
1089
unconditionally (which is reasonably appropriate as it is a means for
1090
thunking many small indices into one larger one and still supplies
1091
iter_all_entries at the thunk layer).
1093
:param keys: An iterable providing the key prefixes to be retrieved.
1094
Each key prefix takes the form of a tuple the length of a key, but
1095
with the last N elements 'None' rather than a regular bytestring.
1096
The first element cannot be 'None'.
1097
:return: An iterable as per iter_all_entries, but restricted to the
1098
keys with a matching prefix to those supplied. No additional keys
1099
will be returned, and every match that is in the index will be
1102
keys = sorted(set(keys))
1105
# Load if needed to check key lengths
1106
if self._key_count is None:
1107
self._get_root_node()
1108
# TODO: only access nodes that can satisfy the prefixes we are looking
1109
# for. For now, to meet API usage (as this function is not used by
1110
# current bzrlib) just suck the entire index and iterate in memory.
1112
if self.node_ref_lists:
1113
if self._key_length == 1:
1114
for _1, key, value, refs in self.iter_all_entries():
1115
nodes[key] = value, refs
1118
for _1, key, value, refs in self.iter_all_entries():
1119
key_value = key, value, refs
1120
# For a key of (foo, bar, baz) create
1121
# _nodes_by_key[foo][bar][baz] = key_value
1122
key_dict = nodes_by_key
1123
for subkey in key[:-1]:
1124
key_dict = key_dict.setdefault(subkey, {})
1125
key_dict[key[-1]] = key_value
1127
if self._key_length == 1:
1128
for _1, key, value in self.iter_all_entries():
1132
for _1, key, value in self.iter_all_entries():
1133
key_value = key, value
1134
# For a key of (foo, bar, baz) create
1135
# _nodes_by_key[foo][bar][baz] = key_value
1136
key_dict = nodes_by_key
1137
for subkey in key[:-1]:
1138
key_dict = key_dict.setdefault(subkey, {})
1139
key_dict[key[-1]] = key_value
1140
if self._key_length == 1:
1144
raise errors.BadIndexKey(key)
1145
if len(key) != self._key_length:
1146
raise errors.BadIndexKey(key)
1148
if self.node_ref_lists:
1149
value, node_refs = nodes[key]
1150
yield self, key, value, node_refs
1152
yield self, key, nodes[key]
1159
raise errors.BadIndexKey(key)
1160
if len(key) != self._key_length:
1161
raise errors.BadIndexKey(key)
1162
# find what it refers to:
1163
key_dict = nodes_by_key
1164
elements = list(key)
1165
# find the subdict whose contents should be returned.
1167
while len(elements) and elements[0] is not None:
1168
key_dict = key_dict[elements[0]]
1171
# a non-existant lookup.
1176
key_dict = dicts.pop(-1)
1177
# can't be empty or would not exist
1178
item, value = key_dict.iteritems().next()
1179
if type(value) == dict:
1181
dicts.extend(key_dict.itervalues())
1184
for value in key_dict.itervalues():
1185
# each value is the key:value:node refs tuple
1187
yield (self, ) + value
1189
# the last thing looked up was a terminal element
1190
yield (self, ) + key_dict
1192
def key_count(self):
1193
"""Return an estimate of the number of keys in this index.
1195
For BTreeGraphIndex the estimate is exact as it is contained in the
1198
if self._key_count is None:
1199
self._get_root_node()
1200
return self._key_count
1202
def _compute_row_offsets(self):
1203
"""Fill out the _row_offsets attribute based on _row_lengths."""
1206
for row in self._row_lengths:
1207
offsets.append(row_offset)
1209
offsets.append(row_offset)
1210
self._row_offsets = offsets
1212
def _parse_header_from_bytes(self, bytes):
1213
"""Parse the header from a region of bytes.
1215
:param bytes: The data to parse.
1216
:return: An offset, data tuple such as readv yields, for the unparsed
1217
data. (which may be of length 0).
1219
signature = bytes[0:len(self._signature())]
1220
if not signature == self._signature():
1221
raise errors.BadIndexFormatSignature(self._name, BTreeGraphIndex)
1222
lines = bytes[len(self._signature()):].splitlines()
1223
options_line = lines[0]
1224
if not options_line.startswith(_OPTION_NODE_REFS):
1225
raise errors.BadIndexOptions(self)
1227
self.node_ref_lists = int(options_line[len(_OPTION_NODE_REFS):])
1229
raise errors.BadIndexOptions(self)
1230
options_line = lines[1]
1231
if not options_line.startswith(_OPTION_KEY_ELEMENTS):
1232
raise errors.BadIndexOptions(self)
1234
self._key_length = int(options_line[len(_OPTION_KEY_ELEMENTS):])
1236
raise errors.BadIndexOptions(self)
1237
options_line = lines[2]
1238
if not options_line.startswith(_OPTION_LEN):
1239
raise errors.BadIndexOptions(self)
1241
self._key_count = int(options_line[len(_OPTION_LEN):])
1243
raise errors.BadIndexOptions(self)
1244
options_line = lines[3]
1245
if not options_line.startswith(_OPTION_ROW_LENGTHS):
1246
raise errors.BadIndexOptions(self)
1248
self._row_lengths = map(int, [length for length in
1249
options_line[len(_OPTION_ROW_LENGTHS):].split(',')
1252
raise errors.BadIndexOptions(self)
1253
self._compute_row_offsets()
1255
# calculate the bytes we have processed
1256
header_end = (len(signature) + sum(map(len, lines[0:4])) + 4)
1257
return header_end, bytes[header_end:]
1259
def _read_nodes(self, nodes):
1260
"""Read some nodes from disk into the LRU cache.
1262
This performs a readv to get the node data into memory, and parses each
1263
node, then yields it to the caller. The nodes are requested in the
1264
supplied order. If possible doing sort() on the list before requesting
1265
a read may improve performance.
1267
:param nodes: The nodes to read. 0 - first node, 1 - second node etc.
1270
# may be the byte string of the whole file
1272
# list of (offset, length) regions of the file that should, evenually
1273
# be read in to data_ranges, either from 'bytes' or from the transport
1276
offset = index * _PAGE_SIZE
1279
# Root node - special case
1281
size = min(_PAGE_SIZE, self._size)
1283
# The only case where we don't know the size, is for very
1284
# small indexes. So we read the whole thing
1285
bytes = self._transport.get_bytes(self._name)
1286
self._size = len(bytes)
1287
# the whole thing should be parsed out of 'bytes'
1288
ranges.append((0, len(bytes)))
1291
if offset > self._size:
1292
raise AssertionError('tried to read past the end'
1293
' of the file %s > %s'
1294
% (offset, self._size))
1295
size = min(size, self._size - offset)
1296
ranges.append((offset, size))
1299
elif bytes is not None:
1300
# already have the whole file
1301
data_ranges = [(start, bytes[start:start+_PAGE_SIZE])
1302
for start in xrange(0, len(bytes), _PAGE_SIZE)]
1303
elif self._file is None:
1304
data_ranges = self._transport.readv(self._name, ranges)
1307
for offset, size in ranges:
1308
self._file.seek(offset)
1309
data_ranges.append((offset, self._file.read(size)))
1310
for offset, data in data_ranges:
1312
# extract the header
1313
offset, data = self._parse_header_from_bytes(data)
1316
bytes = zlib.decompress(data)
1317
if bytes.startswith(_LEAF_FLAG):
1318
node = _LeafNode(bytes, self._key_length, self.node_ref_lists)
1319
elif bytes.startswith(_INTERNAL_FLAG):
1320
node = _InternalNode(bytes)
1322
raise AssertionError("Unknown node type for %r" % bytes)
1323
yield offset / _PAGE_SIZE, node
1325
def _signature(self):
1326
"""The file signature for this index type."""
1330
"""Validate that everything in the index can be accessed."""
1331
# just read and parse every node.
1332
self._get_root_node()
1333
if len(self._row_lengths) > 1:
1334
start_node = self._row_offsets[1]
1336
# We shouldn't be reading anything anyway
1338
node_end = self._row_offsets[-1]
1339
for node in self._read_nodes(range(start_node, node_end)):
1344
from bzrlib import _btree_serializer_c as _btree_serializer
1346
from bzrlib import _btree_serializer_py as _btree_serializer
added
removed
bzrlib/btree_index.py
