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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 external_references(self, ref_list_num):
805
if self._root_node is None:
806
self._get_root_node()
807
if ref_list_num + 1 > self.node_ref_lists:
808
raise ValueError('No ref list %d, index has %d ref lists'
809
% (ref_list_num, self.node_ref_lists))
812
for node in self.iter_all_entries():
814
refs.update(node[3][ref_list_num])
817
def _find_layer_first_and_end(self, offset):
818
"""Find the start/stop nodes for the layer corresponding to offset.
820
:return: (first, end)
821
first is the first node in this layer
822
end is the first node of the next layer
825
for roffset in self._row_offsets:
832
def _get_offsets_to_cached_pages(self):
833
"""Determine what nodes we already have cached."""
834
cached_offsets = set(self._internal_node_cache.keys())
835
cached_offsets.update(self._leaf_node_cache.keys())
836
if self._root_node is not None:
837
cached_offsets.add(0)
838
return cached_offsets
840
def _get_root_node(self):
841
if self._root_node is None:
842
# We may not have a root node yet
843
self._get_internal_nodes([0])
844
return self._root_node
846
def _get_nodes(self, cache, node_indexes):
849
for idx in node_indexes:
850
if idx == 0 and self._root_node is not None:
851
found[0] = self._root_node
854
found[idx] = cache[idx]
859
needed = self._expand_offsets(needed)
860
found.update(self._get_and_cache_nodes(needed))
863
def _get_internal_nodes(self, node_indexes):
864
"""Get a node, from cache or disk.
866
After getting it, the node will be cached.
868
return self._get_nodes(self._internal_node_cache, node_indexes)
870
def _cache_leaf_values(self, nodes):
871
"""Cache directly from key => value, skipping the btree."""
872
if self._leaf_value_cache is not None:
873
for node in nodes.itervalues():
874
for key, value in node.keys.iteritems():
875
if key in self._leaf_value_cache:
876
# Don't add the rest of the keys, we've seen this node
879
self._leaf_value_cache[key] = value
881
def _get_leaf_nodes(self, node_indexes):
882
"""Get a bunch of nodes, from cache or disk."""
883
found = self._get_nodes(self._leaf_node_cache, node_indexes)
884
self._cache_leaf_values(found)
887
def iter_all_entries(self):
888
"""Iterate over all keys within the index.
890
:return: An iterable of (index, key, value) or (index, key, value, reference_lists).
891
The former tuple is used when there are no reference lists in the
892
index, making the API compatible with simple key:value index types.
893
There is no defined order for the result iteration - it will be in
894
the most efficient order for the index.
896
if 'evil' in debug.debug_flags:
897
trace.mutter_callsite(3,
898
"iter_all_entries scales with size of history.")
899
if not self.key_count():
901
if self._row_offsets[-1] == 1:
902
# There is only the root node, and we read that via key_count()
903
if self.node_ref_lists:
904
for key, (value, refs) in sorted(self._root_node.keys.items()):
905
yield (self, key, value, refs)
907
for key, (value, refs) in sorted(self._root_node.keys.items()):
908
yield (self, key, value)
910
start_of_leaves = self._row_offsets[-2]
911
end_of_leaves = self._row_offsets[-1]
912
needed_offsets = range(start_of_leaves, end_of_leaves)
913
if needed_offsets == [0]:
914
# Special case when we only have a root node, as we have already
916
nodes = [(0, self._root_node)]
918
nodes = self._read_nodes(needed_offsets)
919
# We iterate strictly in-order so that we can use this function
920
# for spilling index builds to disk.
921
if self.node_ref_lists:
922
for _, node in nodes:
923
for key, (value, refs) in sorted(node.keys.items()):
924
yield (self, key, value, refs)
926
for _, node in nodes:
927
for key, (value, refs) in sorted(node.keys.items()):
928
yield (self, key, value)
931
def _multi_bisect_right(in_keys, fixed_keys):
932
"""Find the positions where each 'in_key' would fit in fixed_keys.
934
This is equivalent to doing "bisect_right" on each in_key into
937
:param in_keys: A sorted list of keys to match with fixed_keys
938
:param fixed_keys: A sorted list of keys to match against
939
:return: A list of (integer position, [key list]) tuples.
944
# no pointers in the fixed_keys list, which means everything must
946
return [(0, in_keys)]
948
# TODO: Iterating both lists will generally take M + N steps
949
# Bisecting each key will generally take M * log2 N steps.
950
# If we had an efficient way to compare, we could pick the method
951
# based on which has the fewer number of steps.
952
# There is also the argument that bisect_right is a compiled
953
# function, so there is even more to be gained.
954
# iter_steps = len(in_keys) + len(fixed_keys)
955
# bisect_steps = len(in_keys) * math.log(len(fixed_keys), 2)
956
if len(in_keys) == 1: # Bisect will always be faster for M = 1
957
return [(bisect_right(fixed_keys, in_keys[0]), in_keys)]
958
# elif bisect_steps < iter_steps:
960
# for key in in_keys:
961
# offsets.setdefault(bisect_right(fixed_keys, key),
963
# return [(o, offsets[o]) for o in sorted(offsets)]
964
in_keys_iter = iter(in_keys)
965
fixed_keys_iter = enumerate(fixed_keys)
966
cur_in_key = in_keys_iter.next()
967
cur_fixed_offset, cur_fixed_key = fixed_keys_iter.next()
969
class InputDone(Exception): pass
970
class FixedDone(Exception): pass
975
# TODO: Another possibility is that rather than iterating on each side,
976
# we could use a combination of bisecting and iterating. For
977
# example, while cur_in_key < fixed_key, bisect to find its
978
# point, then iterate all matching keys, then bisect (restricted
979
# to only the remainder) for the next one, etc.
982
if cur_in_key < cur_fixed_key:
984
cur_out = (cur_fixed_offset, cur_keys)
985
output.append(cur_out)
986
while cur_in_key < cur_fixed_key:
987
cur_keys.append(cur_in_key)
989
cur_in_key = in_keys_iter.next()
990
except StopIteration:
992
# At this point cur_in_key must be >= cur_fixed_key
993
# step the cur_fixed_key until we pass the cur key, or walk off
995
while cur_in_key >= cur_fixed_key:
997
cur_fixed_offset, cur_fixed_key = fixed_keys_iter.next()
998
except StopIteration:
1001
# We consumed all of the input, nothing more to do
1004
# There was some input left, but we consumed all of fixed, so we
1005
# have to add one more for the tail
1006
cur_keys = [cur_in_key]
1007
cur_keys.extend(in_keys_iter)
1008
cur_out = (len(fixed_keys), cur_keys)
1009
output.append(cur_out)
1012
def iter_entries(self, keys):
1013
"""Iterate over keys within the index.
1015
:param keys: An iterable providing the keys to be retrieved.
1016
:return: An iterable as per iter_all_entries, but restricted to the
1017
keys supplied. No additional keys will be returned, and every
1018
key supplied that is in the index will be returned.
1020
# 6 seconds spent in miss_torture using the sorted() line.
1021
# Even with out of order disk IO it seems faster not to sort it when
1022
# large queries are being made.
1023
# However, now that we are doing multi-way bisecting, we need the keys
1024
# in sorted order anyway. We could change the multi-way code to not
1025
# require sorted order. (For example, it bisects for the first node,
1026
# does an in-order search until a key comes before the current point,
1027
# which it then bisects for, etc.)
1028
keys = frozenset(keys)
1032
if not self.key_count():
1036
if self._leaf_value_cache is None:
1040
value = self._leaf_value_cache.get(key, None)
1041
if value is not None:
1042
# This key is known not to be here, skip it
1044
if self.node_ref_lists:
1045
yield (self, key, value, refs)
1047
yield (self, key, value)
1049
needed_keys.append(key)
1055
# 6 seconds spent in miss_torture using the sorted() line.
1056
# Even with out of order disk IO it seems faster not to sort it when
1057
# large queries are being made.
1058
needed_keys = sorted(needed_keys)
1060
nodes_and_keys = [(0, needed_keys)]
1062
for row_pos, next_row_start in enumerate(self._row_offsets[1:-1]):
1063
node_indexes = [idx for idx, s_keys in nodes_and_keys]
1064
nodes = self._get_internal_nodes(node_indexes)
1066
next_nodes_and_keys = []
1067
for node_index, sub_keys in nodes_and_keys:
1068
node = nodes[node_index]
1069
positions = self._multi_bisect_right(sub_keys, node.keys)
1070
node_offset = next_row_start + node.offset
1071
next_nodes_and_keys.extend([(node_offset + pos, s_keys)
1072
for pos, s_keys in positions])
1073
nodes_and_keys = next_nodes_and_keys
1074
# We should now be at the _LeafNodes
1075
node_indexes = [idx for idx, s_keys in nodes_and_keys]
1077
# TODO: We may *not* want to always read all the nodes in one
1078
# big go. Consider setting a max size on this.
1080
nodes = self._get_leaf_nodes(node_indexes)
1081
for node_index, sub_keys in nodes_and_keys:
1084
node = nodes[node_index]
1085
for next_sub_key in sub_keys:
1086
if next_sub_key in node.keys:
1087
value, refs = node.keys[next_sub_key]
1088
if self.node_ref_lists:
1089
yield (self, next_sub_key, value, refs)
1091
yield (self, next_sub_key, value)
1093
def iter_entries_prefix(self, keys):
1094
"""Iterate over keys within the index using prefix matching.
1096
Prefix matching is applied within the tuple of a key, not to within
1097
the bytestring of each key element. e.g. if you have the keys ('foo',
1098
'bar'), ('foobar', 'gam') and do a prefix search for ('foo', None) then
1099
only the former key is returned.
1101
WARNING: Note that this method currently causes a full index parse
1102
unconditionally (which is reasonably appropriate as it is a means for
1103
thunking many small indices into one larger one and still supplies
1104
iter_all_entries at the thunk layer).
1106
:param keys: An iterable providing the key prefixes to be retrieved.
1107
Each key prefix takes the form of a tuple the length of a key, but
1108
with the last N elements 'None' rather than a regular bytestring.
1109
The first element cannot be 'None'.
1110
:return: An iterable as per iter_all_entries, but restricted to the
1111
keys with a matching prefix to those supplied. No additional keys
1112
will be returned, and every match that is in the index will be
1115
keys = sorted(set(keys))
1118
# Load if needed to check key lengths
1119
if self._key_count is None:
1120
self._get_root_node()
1121
# TODO: only access nodes that can satisfy the prefixes we are looking
1122
# for. For now, to meet API usage (as this function is not used by
1123
# current bzrlib) just suck the entire index and iterate in memory.
1125
if self.node_ref_lists:
1126
if self._key_length == 1:
1127
for _1, key, value, refs in self.iter_all_entries():
1128
nodes[key] = value, refs
1131
for _1, key, value, refs in self.iter_all_entries():
1132
key_value = key, value, refs
1133
# For a key of (foo, bar, baz) create
1134
# _nodes_by_key[foo][bar][baz] = key_value
1135
key_dict = nodes_by_key
1136
for subkey in key[:-1]:
1137
key_dict = key_dict.setdefault(subkey, {})
1138
key_dict[key[-1]] = key_value
1140
if self._key_length == 1:
1141
for _1, key, value in self.iter_all_entries():
1145
for _1, key, value in self.iter_all_entries():
1146
key_value = key, value
1147
# For a key of (foo, bar, baz) create
1148
# _nodes_by_key[foo][bar][baz] = key_value
1149
key_dict = nodes_by_key
1150
for subkey in key[:-1]:
1151
key_dict = key_dict.setdefault(subkey, {})
1152
key_dict[key[-1]] = key_value
1153
if self._key_length == 1:
1157
raise errors.BadIndexKey(key)
1158
if len(key) != self._key_length:
1159
raise errors.BadIndexKey(key)
1161
if self.node_ref_lists:
1162
value, node_refs = nodes[key]
1163
yield self, key, value, node_refs
1165
yield self, key, nodes[key]
1172
raise errors.BadIndexKey(key)
1173
if len(key) != self._key_length:
1174
raise errors.BadIndexKey(key)
1175
# find what it refers to:
1176
key_dict = nodes_by_key
1177
elements = list(key)
1178
# find the subdict whose contents should be returned.
1180
while len(elements) and elements[0] is not None:
1181
key_dict = key_dict[elements[0]]
1184
# a non-existant lookup.
1189
key_dict = dicts.pop(-1)
1190
# can't be empty or would not exist
1191
item, value = key_dict.iteritems().next()
1192
if type(value) == dict:
1194
dicts.extend(key_dict.itervalues())
1197
for value in key_dict.itervalues():
1198
# each value is the key:value:node refs tuple
1200
yield (self, ) + value
1202
# the last thing looked up was a terminal element
1203
yield (self, ) + key_dict
1205
def key_count(self):
1206
"""Return an estimate of the number of keys in this index.
1208
For BTreeGraphIndex the estimate is exact as it is contained in the
1211
if self._key_count is None:
1212
self._get_root_node()
1213
return self._key_count
1215
def _compute_row_offsets(self):
1216
"""Fill out the _row_offsets attribute based on _row_lengths."""
1219
for row in self._row_lengths:
1220
offsets.append(row_offset)
1222
offsets.append(row_offset)
1223
self._row_offsets = offsets
1225
def _parse_header_from_bytes(self, bytes):
1226
"""Parse the header from a region of bytes.
1228
:param bytes: The data to parse.
1229
:return: An offset, data tuple such as readv yields, for the unparsed
1230
data. (which may be of length 0).
1232
signature = bytes[0:len(self._signature())]
1233
if not signature == self._signature():
1234
raise errors.BadIndexFormatSignature(self._name, BTreeGraphIndex)
1235
lines = bytes[len(self._signature()):].splitlines()
1236
options_line = lines[0]
1237
if not options_line.startswith(_OPTION_NODE_REFS):
1238
raise errors.BadIndexOptions(self)
1240
self.node_ref_lists = int(options_line[len(_OPTION_NODE_REFS):])
1242
raise errors.BadIndexOptions(self)
1243
options_line = lines[1]
1244
if not options_line.startswith(_OPTION_KEY_ELEMENTS):
1245
raise errors.BadIndexOptions(self)
1247
self._key_length = int(options_line[len(_OPTION_KEY_ELEMENTS):])
1249
raise errors.BadIndexOptions(self)
1250
options_line = lines[2]
1251
if not options_line.startswith(_OPTION_LEN):
1252
raise errors.BadIndexOptions(self)
1254
self._key_count = int(options_line[len(_OPTION_LEN):])
1256
raise errors.BadIndexOptions(self)
1257
options_line = lines[3]
1258
if not options_line.startswith(_OPTION_ROW_LENGTHS):
1259
raise errors.BadIndexOptions(self)
1261
self._row_lengths = map(int, [length for length in
1262
options_line[len(_OPTION_ROW_LENGTHS):].split(',')
1265
raise errors.BadIndexOptions(self)
1266
self._compute_row_offsets()
1268
# calculate the bytes we have processed
1269
header_end = (len(signature) + sum(map(len, lines[0:4])) + 4)
1270
return header_end, bytes[header_end:]
1272
def _read_nodes(self, nodes):
1273
"""Read some nodes from disk into the LRU cache.
1275
This performs a readv to get the node data into memory, and parses each
1276
node, then yields it to the caller. The nodes are requested in the
1277
supplied order. If possible doing sort() on the list before requesting
1278
a read may improve performance.
1280
:param nodes: The nodes to read. 0 - first node, 1 - second node etc.
1283
# may be the byte string of the whole file
1285
# list of (offset, length) regions of the file that should, evenually
1286
# be read in to data_ranges, either from 'bytes' or from the transport
1289
offset = index * _PAGE_SIZE
1292
# Root node - special case
1294
size = min(_PAGE_SIZE, self._size)
1296
# The only case where we don't know the size, is for very
1297
# small indexes. So we read the whole thing
1298
bytes = self._transport.get_bytes(self._name)
1299
self._size = len(bytes)
1300
# the whole thing should be parsed out of 'bytes'
1301
ranges.append((0, len(bytes)))
1304
if offset > self._size:
1305
raise AssertionError('tried to read past the end'
1306
' of the file %s > %s'
1307
% (offset, self._size))
1308
size = min(size, self._size - offset)
1309
ranges.append((offset, size))
1312
elif bytes is not None:
1313
# already have the whole file
1314
data_ranges = [(start, bytes[start:start+_PAGE_SIZE])
1315
for start in xrange(0, len(bytes), _PAGE_SIZE)]
1316
elif self._file is None:
1317
data_ranges = self._transport.readv(self._name, ranges)
1320
for offset, size in ranges:
1321
self._file.seek(offset)
1322
data_ranges.append((offset, self._file.read(size)))
1323
for offset, data in data_ranges:
1325
# extract the header
1326
offset, data = self._parse_header_from_bytes(data)
1329
bytes = zlib.decompress(data)
1330
if bytes.startswith(_LEAF_FLAG):
1331
node = _LeafNode(bytes, self._key_length, self.node_ref_lists)
1332
elif bytes.startswith(_INTERNAL_FLAG):
1333
node = _InternalNode(bytes)
1335
raise AssertionError("Unknown node type for %r" % bytes)
1336
yield offset / _PAGE_SIZE, node
1338
def _signature(self):
1339
"""The file signature for this index type."""
1343
"""Validate that everything in the index can be accessed."""
1344
# just read and parse every node.
1345
self._get_root_node()
1346
if len(self._row_lengths) > 1:
1347
start_node = self._row_offsets[1]
1349
# We shouldn't be reading anything anyway
1351
node_end = self._row_offsets[-1]
1352
for node in self._read_nodes(range(start_node, node_end)):
1357
from bzrlib import _btree_serializer_c as _btree_serializer
1359
from bzrlib import _btree_serializer_py as _btree_serializer
added
removed
bzrlib/btree_index.py
