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# Copyright (C) 2005, 2006 by Canonical Ltd
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# Written by Martin Pool.
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# Modified by Johan Rydberg <jrydberg@gnu.org>
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# Modified by Robert Collins <robert.collins@canonical.com>
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# Modified by Aaron Bentley <aaron.bentley@utoronto.ca>
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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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"""Knit versionedfile implementation.
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A knit is a versioned file implementation that supports efficient append only
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lifeless: the data file is made up of "delta records". each delta record has a delta header
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that contains; (1) a version id, (2) the size of the delta (in lines), and (3) the digest of
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the -expanded data- (ie, the delta applied to the parent). the delta also ends with a
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end-marker; simply "end VERSION"
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delta can be line or full contents.a
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... the 8's there are the index number of the annotation.
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version robertc@robertcollins.net-20051003014215-ee2990904cc4c7ad 7 c7d23b2a5bd6ca00e8e266cec0ec228158ee9f9e
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8 e.set('executable', 'yes')
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8 if elt.get('executable') == 'yes':
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8 ie.executable = True
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end robertc@robertcollins.net-20051003014215-ee2990904cc4c7ad
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09:33 < jrydberg> lifeless: each index is made up of a tuple of; version id, options, position, size, parents
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09:33 < jrydberg> lifeless: the parents are currently dictionary compressed
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09:33 < jrydberg> lifeless: (meaning it currently does not support ghosts)
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09:33 < lifeless> right
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09:33 < jrydberg> lifeless: the position and size is the range in the data file
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so the index sequence is the dictionary compressed sequence number used
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in the deltas to provide line annotation
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# 10:16 < lifeless> make partial index writes safe
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# 10:16 < lifeless> implement 'knit.check()' like weave.check()
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# 10:17 < lifeless> record known ghosts so we can detect when they are filled in rather than the current 'reweave
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# move sha1 out of the content so that join is faster at verifying parents
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# record content length ?
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from cStringIO import StringIO
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from itertools import izip, chain
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from bzrlib.errors import FileExists, NoSuchFile, KnitError, \
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InvalidRevisionId, KnitCorrupt, KnitHeaderError, \
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RevisionNotPresent, RevisionAlreadyPresent
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from bzrlib.tuned_gzip import GzipFile
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from bzrlib.trace import mutter
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from bzrlib.osutils import contains_whitespace, contains_linebreaks, \
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from bzrlib.symbol_versioning import DEPRECATED_PARAMETER, deprecated_passed
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from bzrlib.tsort import topo_sort
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from bzrlib.versionedfile import VersionedFile, InterVersionedFile
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# TODO: Split out code specific to this format into an associated object.
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# TODO: Can we put in some kind of value to check that the index and data
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# files belong together?
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# TODO: accommodate binaries, perhaps by storing a byte count
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# TODO: function to check whole file
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# TODO: atomically append data, then measure backwards from the cursor
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# position after writing to work out where it was located. we may need to
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# bypass python file buffering.
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DATA_SUFFIX = '.knit'
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INDEX_SUFFIX = '.kndx'
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class KnitContent(object):
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"""Content of a knit version to which deltas can be applied."""
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def __init__(self, lines):
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def annotate_iter(self):
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"""Yield tuples of (origin, text) for each content line."""
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for origin, text in self._lines:
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"""Return a list of (origin, text) tuples."""
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return list(self.annotate_iter())
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def line_delta_iter(self, new_lines):
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"""Generate line-based delta from this content to new_lines."""
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new_texts = [text for origin, text in new_lines._lines]
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old_texts = [text for origin, text in self._lines]
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s = KnitSequenceMatcher(None, old_texts, new_texts)
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for op in s.get_opcodes():
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# ofrom oto length data
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yield (op[1], op[2], op[4]-op[3], new_lines._lines[op[3]:op[4]])
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def line_delta(self, new_lines):
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return list(self.line_delta_iter(new_lines))
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return [text for origin, text in self._lines]
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return KnitContent(self._lines[:])
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class _KnitFactory(object):
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"""Base factory for creating content objects."""
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def make(self, lines, version):
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num_lines = len(lines)
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return KnitContent(zip([version] * num_lines, lines))
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class KnitAnnotateFactory(_KnitFactory):
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"""Factory for creating annotated Content objects."""
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def parse_fulltext(self, content, version):
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"""Convert fulltext to internal representation
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fulltext content is of the format
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revid(utf8) plaintext\n
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internal representation is of the format:
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decode_utf8 = cache_utf8.decode
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origin, text = line.split(' ', 1)
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lines.append((decode_utf8(origin), text))
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return KnitContent(lines)
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def parse_line_delta_iter(self, lines):
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for result_item in self.parse_line_delta[lines]:
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def parse_line_delta(self, lines, version):
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"""Convert a line based delta into internal representation.
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line delta is in the form of:
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intstart intend intcount
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revid(utf8) newline\n
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internal representation is
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(start, end, count, [1..count tuples (revid, newline)])
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decode_utf8 = cache_utf8.decode
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# walk through the lines parsing.
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start, end, count = [int(n) for n in header.split(',')]
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origin, text = next().split(' ', 1)
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contents.append((decode_utf8(origin), text))
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result.append((start, end, count, contents))
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def lower_fulltext(self, content):
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"""convert a fulltext content record into a serializable form.
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see parse_fulltext which this inverts.
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encode_utf8 = cache_utf8.encode
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return ['%s %s' % (encode_utf8(o), t) for o, t in content._lines]
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def lower_line_delta(self, delta):
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"""convert a delta into a serializable form.
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See parse_line_delta which this inverts.
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encode_utf8 = cache_utf8.encode
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for start, end, c, lines in delta:
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out.append('%d,%d,%d\n' % (start, end, c))
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out.extend(encode_utf8(origin) + ' ' + text
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for origin, text in lines)
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class KnitPlainFactory(_KnitFactory):
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"""Factory for creating plain Content objects."""
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def parse_fulltext(self, content, version):
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"""This parses an unannotated fulltext.
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Note that this is not a noop - the internal representation
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has (versionid, line) - its just a constant versionid.
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return self.make(content, version)
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def parse_line_delta_iter(self, lines, version):
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header = lines.pop(0)
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start, end, c = [int(n) for n in header.split(',')]
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yield start, end, c, zip([version] * c, lines[:c])
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def parse_line_delta(self, lines, version):
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return list(self.parse_line_delta_iter(lines, version))
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def lower_fulltext(self, content):
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return content.text()
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def lower_line_delta(self, delta):
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for start, end, c, lines in delta:
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out.append('%d,%d,%d\n' % (start, end, c))
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out.extend([text for origin, text in lines])
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def make_empty_knit(transport, relpath):
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"""Construct a empty knit at the specified location."""
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k = KnitVersionedFile(transport, relpath, 'w', KnitPlainFactory)
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class KnitVersionedFile(VersionedFile):
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"""Weave-like structure with faster random access.
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A knit stores a number of texts and a summary of the relationships
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between them. Texts are identified by a string version-id. Texts
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are normally stored and retrieved as a series of lines, but can
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also be passed as single strings.
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Lines are stored with the trailing newline (if any) included, to
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avoid special cases for files with no final newline. Lines are
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composed of 8-bit characters, not unicode. The combination of
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these approaches should mean any 'binary' file can be safely
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stored and retrieved.
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def __init__(self, relpath, transport, file_mode=None, access_mode=None,
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factory=None, basis_knit=DEPRECATED_PARAMETER, delta=True,
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"""Construct a knit at location specified by relpath.
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:param create: If not True, only open an existing knit.
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if deprecated_passed(basis_knit):
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warnings.warn("KnitVersionedFile.__(): The basis_knit parameter is"
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" deprecated as of bzr 0.9.",
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DeprecationWarning, stacklevel=2)
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if access_mode is None:
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super(KnitVersionedFile, self).__init__(access_mode)
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assert access_mode in ('r', 'w'), "invalid mode specified %r" % access_mode
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self.transport = transport
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self.filename = relpath
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self.factory = factory or KnitAnnotateFactory()
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self.writable = (access_mode == 'w')
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self._index = _KnitIndex(transport, relpath + INDEX_SUFFIX,
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access_mode, create=create, file_mode=file_mode)
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self._data = _KnitData(transport, relpath + DATA_SUFFIX,
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access_mode, create=create and not len(self), file_mode=file_mode)
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return '%s(%s)' % (self.__class__.__name__,
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self.transport.abspath(self.filename))
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def _add_delta(self, version_id, parents, delta_parent, sha1, noeol, delta):
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"""See VersionedFile._add_delta()."""
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self._check_add(version_id, []) # should we check the lines ?
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self._check_versions_present(parents)
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for parent in parents:
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if not self.has_version(parent):
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ghosts.append(parent)
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present_parents.append(parent)
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if delta_parent is None:
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# reconstitute as full text.
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assert len(delta) == 1 or len(delta) == 0
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assert delta[0][0] == 0
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assert delta[0][1] == 0, delta[0][1]
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return super(KnitVersionedFile, self)._add_delta(version_id,
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options.append('no-eol')
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if delta_parent is not None:
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# determine the current delta chain length.
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# To speed the extract of texts the delta chain is limited
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# to a fixed number of deltas. This should minimize both
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# I/O and the time spend applying deltas.
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delta_parents = [delta_parent]
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parent = delta_parents[0]
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method = self._index.get_method(parent)
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if method == 'fulltext':
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delta_parents = self._index.get_parents(parent)
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if method == 'line-delta':
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# did not find a fulltext in the delta limit.
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# just do a normal insertion.
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return super(KnitVersionedFile, self)._add_delta(version_id,
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options.append('line-delta')
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store_lines = self.factory.lower_line_delta(delta)
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where, size = self._data.add_record(version_id, digest, store_lines)
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self._index.add_version(version_id, options, where, size, parents)
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def _add_raw_records(self, records, data):
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"""Add all the records 'records' with data pre-joined in 'data'.
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:param records: A list of tuples(version_id, options, parents, size).
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:param data: The data for the records. When it is written, the records
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are adjusted to have pos pointing into data by the sum of
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the preceding records sizes.
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pos = self._data.add_raw_record(data)
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for (version_id, options, parents, size) in records:
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index_entries.append((version_id, options, pos+offset,
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if self._data._do_cache:
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self._data._cache[version_id] = data[offset:offset+size]
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self._index.add_versions(index_entries)
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def enable_cache(self):
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"""Start caching data for this knit"""
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self._data.enable_cache()
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def clear_cache(self):
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"""Clear the data cache only."""
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self._data.clear_cache()
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def copy_to(self, name, transport):
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"""See VersionedFile.copy_to()."""
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# copy the current index to a temp index to avoid racing with local
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transport.put_file(name + INDEX_SUFFIX + '.tmp',
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self.transport.get(self._index._filename))
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f = self._data._open_file()
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transport.put_file(name + DATA_SUFFIX, f)
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# move the copied index into place
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transport.move(name + INDEX_SUFFIX + '.tmp', name + INDEX_SUFFIX)
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def create_empty(self, name, transport, mode=None):
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return KnitVersionedFile(name, transport, factory=self.factory,
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delta=self.delta, create=True)
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def _fix_parents(self, version, new_parents):
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"""Fix the parents list for version.
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This is done by appending a new version to the index
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with identical data except for the parents list.
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the parents list must be a superset of the current
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current_values = self._index._cache[version]
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assert set(current_values[4]).difference(set(new_parents)) == set()
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self._index.add_version(version,
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def get_delta(self, version_id):
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"""Get a delta for constructing version from some other version."""
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if not self.has_version(version_id):
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raise RevisionNotPresent(version_id, self.filename)
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parents = self.get_parents(version_id)
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data_pos, data_size = self._index.get_position(version_id)
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data, sha1 = self._data.read_records(((version_id, data_pos, data_size),))[version_id]
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version_idx = self._index.lookup(version_id)
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noeol = 'no-eol' in self._index.get_options(version_id)
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if 'fulltext' == self._index.get_method(version_id):
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new_content = self.factory.parse_fulltext(data, version_idx)
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if parent is not None:
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reference_content = self._get_content(parent)
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old_texts = reference_content.text()
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new_texts = new_content.text()
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delta_seq = KnitSequenceMatcher(None, old_texts, new_texts)
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return parent, sha1, noeol, self._make_line_delta(delta_seq, new_content)
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delta = self.factory.parse_line_delta(data, version_idx)
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return parent, sha1, noeol, delta
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def get_graph_with_ghosts(self):
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"""See VersionedFile.get_graph_with_ghosts()."""
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graph_items = self._index.get_graph()
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return dict(graph_items)
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def get_sha1(self, version_id):
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"""See VersionedFile.get_sha1()."""
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record_map = self._get_record_map([version_id])
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method, content, digest, next = record_map[version_id]
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"""See VersionedFile.get_suffixes()."""
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return [DATA_SUFFIX, INDEX_SUFFIX]
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def has_ghost(self, version_id):
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"""True if there is a ghost reference in the file to version_id."""
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if self.has_version(version_id):
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# optimisable if needed by memoising the _ghosts set.
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items = self._index.get_graph()
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for node, parents in items:
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for parent in parents:
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if parent not in self._index._cache:
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if parent == version_id:
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"""See VersionedFile.versions."""
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return self._index.get_versions()
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def has_version(self, version_id):
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"""See VersionedFile.has_version."""
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return self._index.has_version(version_id)
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__contains__ = has_version
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def _merge_annotations(self, content, parents, parent_texts={},
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delta=None, annotated=None):
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"""Merge annotations for content. This is done by comparing
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the annotations based on changed to the text.
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for parent_id in parents:
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merge_content = self._get_content(parent_id, parent_texts)
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seq = KnitSequenceMatcher(None, merge_content.text(), content.text())
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if delta_seq is None:
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# setup a delta seq to reuse.
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for i, j, n in seq.get_matching_blocks():
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# this appears to copy (origin, text) pairs across to the new
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# content for any line that matches the last-checked parent.
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# FIXME: save the sequence control data for delta compression
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# against the most relevant parent rather than rediffing.
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content._lines[j:j+n] = merge_content._lines[i:i+n]
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reference_content = self._get_content(parents[0], parent_texts)
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new_texts = content.text()
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old_texts = reference_content.text()
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delta_seq = KnitSequenceMatcher(None, old_texts, new_texts)
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return self._make_line_delta(delta_seq, content)
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def _make_line_delta(self, delta_seq, new_content):
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"""Generate a line delta from delta_seq and new_content."""
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for op in delta_seq.get_opcodes():
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diff_hunks.append((op[1], op[2], op[4]-op[3], new_content._lines[op[3]:op[4]]))
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def _get_components_positions(self, version_ids):
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"""Produce a map of position data for the components of versions.
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This data is intended to be used for retrieving the knit records.
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A dict of version_id to (method, data_pos, data_size, next) is
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method is the way referenced data should be applied.
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data_pos is the position of the data in the knit.
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data_size is the size of the data in the knit.
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next is the build-parent of the version, or None for fulltexts.
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for version_id in version_ids:
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while cursor is not None and cursor not in component_data:
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method = self._index.get_method(cursor)
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if method == 'fulltext':
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next = self.get_parents(cursor)[0]
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data_pos, data_size = self._index.get_position(cursor)
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component_data[cursor] = (method, data_pos, data_size, next)
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return component_data
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def _get_content(self, version_id, parent_texts={}):
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"""Returns a content object that makes up the specified
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if not self.has_version(version_id):
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raise RevisionNotPresent(version_id, self.filename)
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cached_version = parent_texts.get(version_id, None)
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if cached_version is not None:
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return cached_version
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text_map, contents_map = self._get_content_maps([version_id])
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return contents_map[version_id]
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def _check_versions_present(self, version_ids):
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"""Check that all specified versions are present."""
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version_ids = set(version_ids)
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for r in list(version_ids):
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if self._index.has_version(r):
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version_ids.remove(r)
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raise RevisionNotPresent(list(version_ids)[0], self.filename)
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def _add_lines_with_ghosts(self, version_id, parents, lines, parent_texts):
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"""See VersionedFile.add_lines_with_ghosts()."""
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self._check_add(version_id, lines)
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return self._add(version_id, lines[:], parents, self.delta, parent_texts)
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def _add_lines(self, version_id, parents, lines, parent_texts):
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"""See VersionedFile.add_lines."""
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self._check_add(version_id, lines)
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self._check_versions_present(parents)
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return self._add(version_id, lines[:], parents, self.delta, parent_texts)
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def _check_add(self, version_id, lines):
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"""check that version_id and lines are safe to add."""
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assert self.writable, "knit is not opened for write"
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### FIXME escape. RBC 20060228
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if contains_whitespace(version_id):
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raise InvalidRevisionId(version_id, self.filename)
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if self.has_version(version_id):
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raise RevisionAlreadyPresent(version_id, self.filename)
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self._check_lines_not_unicode(lines)
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self._check_lines_are_lines(lines)
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def _add(self, version_id, lines, parents, delta, parent_texts):
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"""Add a set of lines on top of version specified by parents.
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If delta is true, compress the text as a line-delta against
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Any versions not present will be converted into ghosts.
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# 461 0 6546.0390 43.9100 bzrlib.knit:489(_add)
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# +400 0 889.4890 418.9790 +bzrlib.knit:192(lower_fulltext)
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# +461 0 1364.8070 108.8030 +bzrlib.knit:996(add_record)
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# +461 0 193.3940 41.5720 +bzrlib.knit:898(add_version)
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# +461 0 134.0590 18.3810 +bzrlib.osutils:361(sha_strings)
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# +461 0 36.3420 15.4540 +bzrlib.knit:146(make)
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# +1383 0 8.0370 8.0370 +<len>
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# +61 0 13.5770 7.9190 +bzrlib.knit:199(lower_line_delta)
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# +61 0 963.3470 7.8740 +bzrlib.knit:427(_get_content)
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# +61 0 973.9950 5.2950 +bzrlib.knit:136(line_delta)
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# +61 0 1918.1800 5.2640 +bzrlib.knit:359(_merge_annotations)
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if parent_texts is None:
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for parent in parents:
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if not self.has_version(parent):
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ghosts.append(parent)
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present_parents.append(parent)
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if delta and not len(present_parents):
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digest = sha_strings(lines)
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if lines[-1][-1] != '\n':
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options.append('no-eol')
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lines[-1] = lines[-1] + '\n'
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if len(present_parents) and delta:
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# To speed the extract of texts the delta chain is limited
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# to a fixed number of deltas. This should minimize both
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# I/O and the time spend applying deltas.
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delta_parents = present_parents
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parent = delta_parents[0]
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method = self._index.get_method(parent)
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if method == 'fulltext':
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delta_parents = self._index.get_parents(parent)
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if method == 'line-delta':
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lines = self.factory.make(lines, version_id)
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if delta or (self.factory.annotated and len(present_parents) > 0):
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# Merge annotations from parent texts if so is needed.
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delta_hunks = self._merge_annotations(lines, present_parents, parent_texts,
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delta, self.factory.annotated)
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options.append('line-delta')
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store_lines = self.factory.lower_line_delta(delta_hunks)
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options.append('fulltext')
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store_lines = self.factory.lower_fulltext(lines)
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where, size = self._data.add_record(version_id, digest, store_lines)
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self._index.add_version(version_id, options, where, size, parents)
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def check(self, progress_bar=None):
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"""See VersionedFile.check()."""
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def _clone_text(self, new_version_id, old_version_id, parents):
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"""See VersionedFile.clone_text()."""
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# FIXME RBC 20060228 make fast by only inserting an index with null
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self.add_lines(new_version_id, parents, self.get_lines(old_version_id))
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def get_lines(self, version_id):
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"""See VersionedFile.get_lines()."""
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return self.get_line_list([version_id])[0]
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def _get_record_map(self, version_ids):
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"""Produce a dictionary of knit records.
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The keys are version_ids, the values are tuples of (method, content,
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method is the way the content should be applied.
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content is a KnitContent object.
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digest is the SHA1 digest of this version id after all steps are done
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next is the build-parent of the version, i.e. the leftmost ancestor.
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If the method is fulltext, next will be None.
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position_map = self._get_components_positions(version_ids)
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# c = component_id, m = method, p = position, s = size, n = next
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records = [(c, p, s) for c, (m, p, s, n) in position_map.iteritems()]
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for component_id, content, digest in \
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self._data.read_records_iter(records):
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method, position, size, next = position_map[component_id]
718
record_map[component_id] = method, content, digest, next
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def get_text(self, version_id):
723
"""See VersionedFile.get_text"""
724
return self.get_texts([version_id])[0]
726
def get_texts(self, version_ids):
727
return [''.join(l) for l in self.get_line_list(version_ids)]
729
def get_line_list(self, version_ids):
730
"""Return the texts of listed versions as a list of strings."""
731
text_map, content_map = self._get_content_maps(version_ids)
732
return [text_map[v] for v in version_ids]
734
def _get_content_maps(self, version_ids):
735
"""Produce maps of text and KnitContents
737
:return: (text_map, content_map) where text_map contains the texts for
738
the requested versions and content_map contains the KnitContents.
739
Both dicts take version_ids as their keys.
741
for version_id in version_ids:
742
if not self.has_version(version_id):
743
raise RevisionNotPresent(version_id, self.filename)
744
record_map = self._get_record_map(version_ids)
749
for version_id in version_ids:
752
while cursor is not None:
753
method, data, digest, next = record_map[cursor]
754
components.append((cursor, method, data, digest))
755
if cursor in content_map:
760
for component_id, method, data, digest in reversed(components):
761
if component_id in content_map:
762
content = content_map[component_id]
764
version_idx = self._index.lookup(component_id)
765
if method == 'fulltext':
766
assert content is None
767
content = self.factory.parse_fulltext(data, version_idx)
768
elif method == 'line-delta':
769
delta = self.factory.parse_line_delta(data[:],
771
content = content.copy()
772
content._lines = self._apply_delta(content._lines,
774
content_map[component_id] = content
776
if 'no-eol' in self._index.get_options(version_id):
777
content = content.copy()
778
line = content._lines[-1][1].rstrip('\n')
779
content._lines[-1] = (content._lines[-1][0], line)
780
final_content[version_id] = content
782
# digest here is the digest from the last applied component.
783
text = content.text()
784
if sha_strings(text) != digest:
785
raise KnitCorrupt(self.filename,
786
'sha-1 does not match %s' % version_id)
788
text_map[version_id] = text
789
return text_map, final_content
791
def iter_lines_added_or_present_in_versions(self, version_ids=None):
792
"""See VersionedFile.iter_lines_added_or_present_in_versions()."""
793
if version_ids is None:
794
version_ids = self.versions()
795
# we don't care about inclusions, the caller cares.
796
# but we need to setup a list of records to visit.
797
# we need version_id, position, length
798
version_id_records = []
799
requested_versions = list(version_ids)
800
# filter for available versions
801
for version_id in requested_versions:
802
if not self.has_version(version_id):
803
raise RevisionNotPresent(version_id, self.filename)
804
# get a in-component-order queue:
806
for version_id in self.versions():
807
if version_id in requested_versions:
808
version_ids.append(version_id)
809
data_pos, length = self._index.get_position(version_id)
810
version_id_records.append((version_id, data_pos, length))
812
pb = bzrlib.ui.ui_factory.nested_progress_bar()
814
total = len(version_id_records)
816
pb.update('Walking content.', count, total)
817
for version_id, data, sha_value in \
818
self._data.read_records_iter(version_id_records):
819
pb.update('Walking content.', count, total)
820
method = self._index.get_method(version_id)
821
version_idx = self._index.lookup(version_id)
822
assert method in ('fulltext', 'line-delta')
823
if method == 'fulltext':
824
content = self.factory.parse_fulltext(data, version_idx)
825
for line in content.text():
828
delta = self.factory.parse_line_delta(data, version_idx)
829
for start, end, count, lines in delta:
830
for origin, line in lines:
833
pb.update('Walking content.', total, total)
836
pb.update('Walking content.', total, total)
840
def num_versions(self):
841
"""See VersionedFile.num_versions()."""
842
return self._index.num_versions()
844
__len__ = num_versions
846
def annotate_iter(self, version_id):
847
"""See VersionedFile.annotate_iter."""
848
content = self._get_content(version_id)
849
for origin, text in content.annotate_iter():
852
def get_parents(self, version_id):
853
"""See VersionedFile.get_parents."""
856
# 52554 calls in 1264 872 internal down from 3674
858
return self._index.get_parents(version_id)
860
raise RevisionNotPresent(version_id, self.filename)
862
def get_parents_with_ghosts(self, version_id):
863
"""See VersionedFile.get_parents."""
865
return self._index.get_parents_with_ghosts(version_id)
867
raise RevisionNotPresent(version_id, self.filename)
869
def get_ancestry(self, versions):
870
"""See VersionedFile.get_ancestry."""
871
if isinstance(versions, basestring):
872
versions = [versions]
875
self._check_versions_present(versions)
876
return self._index.get_ancestry(versions)
878
def get_ancestry_with_ghosts(self, versions):
879
"""See VersionedFile.get_ancestry_with_ghosts."""
880
if isinstance(versions, basestring):
881
versions = [versions]
884
self._check_versions_present(versions)
885
return self._index.get_ancestry_with_ghosts(versions)
887
#@deprecated_method(zero_eight)
888
def walk(self, version_ids):
889
"""See VersionedFile.walk."""
890
# We take the short path here, and extract all relevant texts
891
# and put them in a weave and let that do all the work. Far
892
# from optimal, but is much simpler.
893
# FIXME RB 20060228 this really is inefficient!
894
from bzrlib.weave import Weave
896
w = Weave(self.filename)
897
ancestry = self.get_ancestry(version_ids)
898
sorted_graph = topo_sort(self._index.get_graph())
899
version_list = [vid for vid in sorted_graph if vid in ancestry]
901
for version_id in version_list:
902
lines = self.get_lines(version_id)
903
w.add_lines(version_id, self.get_parents(version_id), lines)
905
for lineno, insert_id, dset, line in w.walk(version_ids):
906
yield lineno, insert_id, dset, line
908
def plan_merge(self, ver_a, ver_b):
909
"""See VersionedFile.plan_merge."""
910
ancestors_b = set(self.get_ancestry(ver_b))
911
def status_a(revision, text):
912
if revision in ancestors_b:
913
return 'killed-b', text
917
ancestors_a = set(self.get_ancestry(ver_a))
918
def status_b(revision, text):
919
if revision in ancestors_a:
920
return 'killed-a', text
924
annotated_a = self.annotate(ver_a)
925
annotated_b = self.annotate(ver_b)
926
plain_a = [t for (a, t) in annotated_a]
927
plain_b = [t for (a, t) in annotated_b]
928
blocks = KnitSequenceMatcher(None, plain_a, plain_b).get_matching_blocks()
931
for ai, bi, l in blocks:
932
# process all mismatched sections
933
# (last mismatched section is handled because blocks always
934
# includes a 0-length last block)
935
for revision, text in annotated_a[a_cur:ai]:
936
yield status_a(revision, text)
937
for revision, text in annotated_b[b_cur:bi]:
938
yield status_b(revision, text)
940
# and now the matched section
943
for text_a, text_b in zip(plain_a[ai:a_cur], plain_b[bi:b_cur]):
944
assert text_a == text_b
945
yield "unchanged", text_a
948
class _KnitComponentFile(object):
949
"""One of the files used to implement a knit database"""
951
def __init__(self, transport, filename, mode, file_mode=None):
952
self._transport = transport
953
self._filename = filename
955
self._file_mode=file_mode
957
def write_header(self):
958
if self._transport.append(self._filename, StringIO(self.HEADER),
959
mode=self._file_mode):
960
raise KnitCorrupt(self._filename, 'misaligned after writing header')
962
def check_header(self, fp):
964
if line != self.HEADER:
965
raise KnitHeaderError(badline=line)
968
"""Commit is a nop."""
971
return '%s(%s)' % (self.__class__.__name__, self._filename)
974
class _KnitIndex(_KnitComponentFile):
975
"""Manages knit index file.
977
The index is already kept in memory and read on startup, to enable
978
fast lookups of revision information. The cursor of the index
979
file is always pointing to the end, making it easy to append
982
_cache is a cache for fast mapping from version id to a Index
985
_history is a cache for fast mapping from indexes to version ids.
987
The index data format is dictionary compressed when it comes to
988
parent references; a index entry may only have parents that with a
989
lover index number. As a result, the index is topological sorted.
991
Duplicate entries may be written to the index for a single version id
992
if this is done then the latter one completely replaces the former:
993
this allows updates to correct version and parent information.
994
Note that the two entries may share the delta, and that successive
995
annotations and references MUST point to the first entry.
997
The index file on disc contains a header, followed by one line per knit
998
record. The same revision can be present in an index file more than once.
999
The first occurrence gets assigned a sequence number starting from 0.
1001
The format of a single line is
1002
REVISION_ID FLAGS BYTE_OFFSET LENGTH( PARENT_ID|PARENT_SEQUENCE_ID)* :\n
1003
REVISION_ID is a utf8-encoded revision id
1004
FLAGS is a comma separated list of flags about the record. Values include
1005
no-eol, line-delta, fulltext.
1006
BYTE_OFFSET is the ascii representation of the byte offset in the data file
1007
that the the compressed data starts at.
1008
LENGTH is the ascii representation of the length of the data file.
1009
PARENT_ID a utf-8 revision id prefixed by a '.' that is a parent of
1011
PARENT_SEQUENCE_ID the ascii representation of the sequence number of a
1012
revision id already in the knit that is a parent of REVISION_ID.
1013
The ' :' marker is the end of record marker.
1016
when a write is interrupted to the index file, it will result in a line that
1017
does not end in ' :'. If the ' :' is not present at the end of a line, or at
1018
the end of the file, then the record that is missing it will be ignored by
1021
When writing new records to the index file, the data is preceded by '\n'
1022
to ensure that records always start on new lines even if the last write was
1023
interrupted. As a result its normal for the last line in the index to be
1024
missing a trailing newline. One can be added with no harmful effects.
1027
HEADER = "# bzr knit index 8\n"
1029
# speed of knit parsing went from 280 ms to 280 ms with slots addition.
1030
# __slots__ = ['_cache', '_history', '_transport', '_filename']
1032
def _cache_version(self, version_id, options, pos, size, parents):
1033
"""Cache a version record in the history array and index cache.
1035
This is inlined into __init__ for performance. KEEP IN SYNC.
1036
(It saves 60ms, 25% of the __init__ overhead on local 4000 record
1039
# only want the _history index to reference the 1st index entry
1041
if version_id not in self._cache:
1042
index = len(self._history)
1043
self._history.append(version_id)
1045
index = self._cache[version_id][5]
1046
self._cache[version_id] = (version_id,
1053
def __init__(self, transport, filename, mode, create=False, file_mode=None):
1054
_KnitComponentFile.__init__(self, transport, filename, mode, file_mode)
1056
# position in _history is the 'official' index for a revision
1057
# but the values may have come from a newer entry.
1058
# so - wc -l of a knit index is != the number of unique names
1061
pb = bzrlib.ui.ui_factory.nested_progress_bar()
1066
pb.update('read knit index', count, total)
1067
fp = self._transport.get(self._filename)
1069
self.check_header(fp)
1070
# readlines reads the whole file at once:
1071
# bad for transports like http, good for local disk
1072
# we save 60 ms doing this one change (
1073
# from calling readline each time to calling
1075
# probably what we want for nice behaviour on
1076
# http is a incremental readlines that yields, or
1077
# a check for local vs non local indexes,
1078
for l in fp.readlines():
1080
if len(rec) < 5 or rec[-1] != ':':
1082
# FIXME: in the future we should determine if its a
1083
# short write - and ignore it
1084
# or a different failure, and raise. RBC 20060407
1088
#pb.update('read knit index', count, total)
1089
# See self._parse_parents
1091
for value in rec[4:-1]:
1093
# uncompressed reference
1094
parents.append(value[1:])
1096
# this is 15/4000ms faster than isinstance,
1098
# this function is called thousands of times a
1099
# second so small variations add up.
1100
assert value.__class__ is str
1101
parents.append(self._history[int(value)])
1102
# end self._parse_parents
1103
# self._cache_version(rec[0],
1104
# rec[1].split(','),
1108
# --- self._cache_version
1109
# only want the _history index to reference the 1st
1110
# index entry for version_id
1112
if version_id not in self._cache:
1113
index = len(self._history)
1114
self._history.append(version_id)
1116
index = self._cache[version_id][5]
1117
self._cache[version_id] = (version_id,
1123
# --- self._cache_version
1126
except NoSuchFile, e:
1127
if mode != 'w' or not create:
1131
pb.update('read knit index', total, total)
1134
def _parse_parents(self, compressed_parents):
1135
"""convert a list of string parent values into version ids.
1137
ints are looked up in the index.
1138
.FOO values are ghosts and converted in to FOO.
1140
NOTE: the function is retained here for clarity, and for possible
1141
use in partial index reads. However bulk processing now has
1142
it inlined in __init__ for inner-loop optimisation.
1145
for value in compressed_parents:
1146
if value[-1] == '.':
1147
# uncompressed reference
1148
result.append(value[1:])
1150
# this is 15/4000ms faster than isinstance,
1151
# this function is called thousands of times a
1152
# second so small variations add up.
1153
assert value.__class__ is str
1154
result.append(self._history[int(value)])
1157
def get_graph(self):
1159
for version_id, index in self._cache.iteritems():
1160
graph.append((version_id, index[4]))
1163
def get_ancestry(self, versions):
1164
"""See VersionedFile.get_ancestry."""
1165
# get a graph of all the mentioned versions:
1167
pending = set(versions)
1169
version = pending.pop()
1170
parents = self._cache[version][4]
1171
# got the parents ok
1173
parents = [parent for parent in parents if parent in self._cache]
1174
for parent in parents:
1175
# if not completed and not a ghost
1176
if parent not in graph:
1178
graph[version] = parents
1179
return topo_sort(graph.items())
1181
def get_ancestry_with_ghosts(self, versions):
1182
"""See VersionedFile.get_ancestry_with_ghosts."""
1183
# get a graph of all the mentioned versions:
1185
pending = set(versions)
1187
version = pending.pop()
1189
parents = self._cache[version][4]
1195
# got the parents ok
1196
for parent in parents:
1197
if parent not in graph:
1199
graph[version] = parents
1200
return topo_sort(graph.items())
1202
def num_versions(self):
1203
return len(self._history)
1205
__len__ = num_versions
1207
def get_versions(self):
1208
return self._history
1210
def idx_to_name(self, idx):
1211
return self._history[idx]
1213
def lookup(self, version_id):
1214
assert version_id in self._cache
1215
return self._cache[version_id][5]
1217
def _version_list_to_index(self, versions):
1218
encode_utf8 = cache_utf8.encode
1220
for version in versions:
1221
if version in self._cache:
1222
# -- inlined lookup() --
1223
result_list.append(str(self._cache[version][5]))
1224
# -- end lookup () --
1226
result_list.append('.' + encode_utf8(version))
1227
return ' '.join(result_list)
1229
def add_version(self, version_id, options, pos, size, parents):
1230
"""Add a version record to the index."""
1231
self.add_versions(((version_id, options, pos, size, parents),))
1233
def add_versions(self, versions):
1234
"""Add multiple versions to the index.
1236
:param versions: a list of tuples:
1237
(version_id, options, pos, size, parents).
1240
encode_utf8 = cache_utf8.encode
1241
for version_id, options, pos, size, parents in versions:
1242
line = "\n%s %s %s %s %s :" % (encode_utf8(version_id),
1246
self._version_list_to_index(parents))
1247
assert isinstance(line, str), \
1248
'content must be utf-8 encoded: %r' % (line,)
1250
self._transport.append(self._filename, StringIO(''.join(lines)))
1251
# cache after writing, so that a failed write leads to missing cache
1252
# entries not extra ones. XXX TODO: RBC 20060502 in the event of a
1253
# failure, reload the index or flush it or some such, to prevent
1254
# writing records that did complete twice.
1255
for version_id, options, pos, size, parents in versions:
1256
self._cache_version(version_id, options, pos, size, parents)
1258
def has_version(self, version_id):
1259
"""True if the version is in the index."""
1260
return (version_id in self._cache)
1262
def get_position(self, version_id):
1263
"""Return data position and size of specified version."""
1264
return (self._cache[version_id][2], \
1265
self._cache[version_id][3])
1267
def get_method(self, version_id):
1268
"""Return compression method of specified version."""
1269
options = self._cache[version_id][1]
1270
if 'fulltext' in options:
1273
assert 'line-delta' in options
1276
def get_options(self, version_id):
1277
return self._cache[version_id][1]
1279
def get_parents(self, version_id):
1280
"""Return parents of specified version ignoring ghosts."""
1281
return [parent for parent in self._cache[version_id][4]
1282
if parent in self._cache]
1284
def get_parents_with_ghosts(self, version_id):
1285
"""Return parents of specified version with ghosts."""
1286
return self._cache[version_id][4]
1288
def check_versions_present(self, version_ids):
1289
"""Check that all specified versions are present."""
1290
version_ids = set(version_ids)
1291
for version_id in list(version_ids):
1292
if version_id in self._cache:
1293
version_ids.remove(version_id)
1295
raise RevisionNotPresent(list(version_ids)[0], self.filename)
1298
class _KnitData(_KnitComponentFile):
1299
"""Contents of the knit data file"""
1301
HEADER = "# bzr knit data 8\n"
1303
def __init__(self, transport, filename, mode, create=False, file_mode=None):
1304
_KnitComponentFile.__init__(self, transport, filename, mode)
1305
self._checked = False
1306
# TODO: jam 20060713 conceptually, this could spill to disk
1307
# if the cached size gets larger than a certain amount
1308
# but it complicates the model a bit, so for now just use
1309
# a simple dictionary
1311
self._do_cache = False
1313
self._transport.put_bytes(self._filename, '', mode=file_mode)
1315
def enable_cache(self):
1316
"""Enable caching of reads."""
1317
self._do_cache = True
1319
def clear_cache(self):
1320
"""Clear the record cache."""
1321
self._do_cache = False
1324
def _open_file(self):
1326
return self._transport.get(self._filename)
1331
def _record_to_data(self, version_id, digest, lines):
1332
"""Convert version_id, digest, lines into a raw data block.
1334
:return: (len, a StringIO instance with the raw data ready to read.)
1337
data_file = GzipFile(None, mode='wb', fileobj=sio)
1339
version_id_utf8 = cache_utf8.encode(version_id)
1340
data_file.writelines(chain(
1341
["version %s %d %s\n" % (version_id_utf8,
1345
["end %s\n" % version_id_utf8]))
1352
def add_raw_record(self, raw_data):
1353
"""Append a prepared record to the data file.
1355
:return: the offset in the data file raw_data was written.
1357
assert isinstance(raw_data, str), 'data must be plain bytes'
1358
return self._transport.append(self._filename, StringIO(raw_data))
1360
def add_record(self, version_id, digest, lines):
1361
"""Write new text record to disk. Returns the position in the
1362
file where it was written."""
1363
size, sio = self._record_to_data(version_id, digest, lines)
1365
start_pos = self._transport.append(self._filename, sio)
1367
self._cache[version_id] = sio.getvalue()
1368
return start_pos, size
1370
def _parse_record_header(self, version_id, raw_data):
1371
"""Parse a record header for consistency.
1373
:return: the header and the decompressor stream.
1374
as (stream, header_record)
1376
df = GzipFile(mode='rb', fileobj=StringIO(raw_data))
1377
rec = df.readline().split()
1379
raise KnitCorrupt(self._filename, 'unexpected number of elements in record header')
1380
if cache_utf8.decode(rec[1]) != version_id:
1381
raise KnitCorrupt(self._filename,
1382
'unexpected version, wanted %r, got %r' % (
1383
version_id, rec[1]))
1386
def _parse_record(self, version_id, data):
1388
# 4168 calls in 2880 217 internal
1389
# 4168 calls to _parse_record_header in 2121
1390
# 4168 calls to readlines in 330
1391
df, rec = self._parse_record_header(version_id, data)
1392
record_contents = df.readlines()
1393
l = record_contents.pop()
1394
assert len(record_contents) == int(rec[2])
1395
if l != 'end %s\n' % cache_utf8.encode(version_id):
1396
raise KnitCorrupt(self._filename, 'unexpected version end line %r, wanted %r'
1399
return record_contents, rec[3]
1401
def read_records_iter_raw(self, records):
1402
"""Read text records from data file and yield raw data.
1404
This unpacks enough of the text record to validate the id is
1405
as expected but thats all.
1407
# setup an iterator of the external records:
1408
# uses readv so nice and fast we hope.
1410
# grab the disk data needed.
1412
# Don't check _cache if it is empty
1413
needed_offsets = [(pos, size) for version_id, pos, size
1415
if version_id not in self._cache]
1417
needed_offsets = [(pos, size) for version_id, pos, size
1420
raw_records = self._transport.readv(self._filename, needed_offsets)
1423
for version_id, pos, size in records:
1424
if version_id in self._cache:
1425
# This data has already been validated
1426
data = self._cache[version_id]
1428
pos, data = raw_records.next()
1430
self._cache[version_id] = data
1432
# validate the header
1433
df, rec = self._parse_record_header(version_id, data)
1435
yield version_id, data
1437
def read_records_iter(self, records):
1438
"""Read text records from data file and yield result.
1440
The result will be returned in whatever is the fastest to read.
1441
Not by the order requested. Also, multiple requests for the same
1442
record will only yield 1 response.
1443
:param records: A list of (version_id, pos, len) entries
1444
:return: Yields (version_id, contents, digest) in the order
1445
read, not the order requested
1451
# Skip records we have alread seen
1452
yielded_records = set()
1453
needed_records = set()
1454
for record in records:
1455
if record[0] in self._cache:
1456
if record[0] in yielded_records:
1458
yielded_records.add(record[0])
1459
data = self._cache[record[0]]
1460
content, digest = self._parse_record(record[0], data)
1461
yield (record[0], content, digest)
1463
needed_records.add(record)
1464
needed_records = sorted(needed_records, key=operator.itemgetter(1))
1466
needed_records = sorted(set(records), key=operator.itemgetter(1))
1468
if not needed_records:
1471
# The transport optimizes the fetching as well
1472
# (ie, reads continuous ranges.)
1473
readv_response = self._transport.readv(self._filename,
1474
[(pos, size) for version_id, pos, size in needed_records])
1476
for (version_id, pos, size), (pos, data) in \
1477
izip(iter(needed_records), readv_response):
1478
content, digest = self._parse_record(version_id, data)
1480
self._cache[version_id] = data
1481
yield version_id, content, digest
1483
def read_records(self, records):
1484
"""Read records into a dictionary."""
1486
for record_id, content, digest in \
1487
self.read_records_iter(records):
1488
components[record_id] = (content, digest)
1492
class InterKnit(InterVersionedFile):
1493
"""Optimised code paths for knit to knit operations."""
1495
_matching_file_from_factory = KnitVersionedFile
1496
_matching_file_to_factory = KnitVersionedFile
1499
def is_compatible(source, target):
1500
"""Be compatible with knits. """
1502
return (isinstance(source, KnitVersionedFile) and
1503
isinstance(target, KnitVersionedFile))
1504
except AttributeError:
1507
def join(self, pb=None, msg=None, version_ids=None, ignore_missing=False):
1508
"""See InterVersionedFile.join."""
1509
assert isinstance(self.source, KnitVersionedFile)
1510
assert isinstance(self.target, KnitVersionedFile)
1512
version_ids = self._get_source_version_ids(version_ids, ignore_missing)
1517
pb = bzrlib.ui.ui_factory.nested_progress_bar()
1519
version_ids = list(version_ids)
1520
if None in version_ids:
1521
version_ids.remove(None)
1523
self.source_ancestry = set(self.source.get_ancestry(version_ids))
1524
this_versions = set(self.target._index.get_versions())
1525
needed_versions = self.source_ancestry - this_versions
1526
cross_check_versions = self.source_ancestry.intersection(this_versions)
1527
mismatched_versions = set()
1528
for version in cross_check_versions:
1529
# scan to include needed parents.
1530
n1 = set(self.target.get_parents_with_ghosts(version))
1531
n2 = set(self.source.get_parents_with_ghosts(version))
1533
# FIXME TEST this check for cycles being introduced works
1534
# the logic is we have a cycle if in our graph we are an
1535
# ancestor of any of the n2 revisions.
1541
parent_ancestors = self.source.get_ancestry(parent)
1542
if version in parent_ancestors:
1543
raise errors.GraphCycleError([parent, version])
1544
# ensure this parent will be available later.
1545
new_parents = n2.difference(n1)
1546
needed_versions.update(new_parents.difference(this_versions))
1547
mismatched_versions.add(version)
1549
if not needed_versions and not mismatched_versions:
1551
full_list = topo_sort(self.source.get_graph())
1553
version_list = [i for i in full_list if (not self.target.has_version(i)
1554
and i in needed_versions)]
1558
copy_queue_records = []
1560
for version_id in version_list:
1561
options = self.source._index.get_options(version_id)
1562
parents = self.source._index.get_parents_with_ghosts(version_id)
1563
# check that its will be a consistent copy:
1564
for parent in parents:
1565
# if source has the parent, we must :
1566
# * already have it or
1567
# * have it scheduled already
1568
# otherwise we don't care
1569
assert (self.target.has_version(parent) or
1570
parent in copy_set or
1571
not self.source.has_version(parent))
1572
data_pos, data_size = self.source._index.get_position(version_id)
1573
copy_queue_records.append((version_id, data_pos, data_size))
1574
copy_queue.append((version_id, options, parents))
1575
copy_set.add(version_id)
1577
# data suck the join:
1579
total = len(version_list)
1582
for (version_id, raw_data), \
1583
(version_id2, options, parents) in \
1584
izip(self.source._data.read_records_iter_raw(copy_queue_records),
1586
assert version_id == version_id2, 'logic error, inconsistent results'
1588
pb.update("Joining knit", count, total)
1589
raw_records.append((version_id, options, parents, len(raw_data)))
1590
raw_datum.append(raw_data)
1591
self.target._add_raw_records(raw_records, ''.join(raw_datum))
1593
for version in mismatched_versions:
1594
# FIXME RBC 20060309 is this needed?
1595
n1 = set(self.target.get_parents_with_ghosts(version))
1596
n2 = set(self.source.get_parents_with_ghosts(version))
1597
# write a combined record to our history preserving the current
1598
# parents as first in the list
1599
new_parents = self.target.get_parents_with_ghosts(version) + list(n2.difference(n1))
1600
self.target.fix_parents(version, new_parents)
1606
InterVersionedFile.register_optimiser(InterKnit)
1609
class WeaveToKnit(InterVersionedFile):
1610
"""Optimised code paths for weave to knit operations."""
1612
_matching_file_from_factory = bzrlib.weave.WeaveFile
1613
_matching_file_to_factory = KnitVersionedFile
1616
def is_compatible(source, target):
1617
"""Be compatible with weaves to knits."""
1619
return (isinstance(source, bzrlib.weave.Weave) and
1620
isinstance(target, KnitVersionedFile))
1621
except AttributeError:
1624
def join(self, pb=None, msg=None, version_ids=None, ignore_missing=False):
1625
"""See InterVersionedFile.join."""
1626
assert isinstance(self.source, bzrlib.weave.Weave)
1627
assert isinstance(self.target, KnitVersionedFile)
1629
version_ids = self._get_source_version_ids(version_ids, ignore_missing)
1634
pb = bzrlib.ui.ui_factory.nested_progress_bar()
1636
version_ids = list(version_ids)
1638
self.source_ancestry = set(self.source.get_ancestry(version_ids))
1639
this_versions = set(self.target._index.get_versions())
1640
needed_versions = self.source_ancestry - this_versions
1641
cross_check_versions = self.source_ancestry.intersection(this_versions)
1642
mismatched_versions = set()
1643
for version in cross_check_versions:
1644
# scan to include needed parents.
1645
n1 = set(self.target.get_parents_with_ghosts(version))
1646
n2 = set(self.source.get_parents(version))
1647
# if all of n2's parents are in n1, then its fine.
1648
if n2.difference(n1):
1649
# FIXME TEST this check for cycles being introduced works
1650
# the logic is we have a cycle if in our graph we are an
1651
# ancestor of any of the n2 revisions.
1657
parent_ancestors = self.source.get_ancestry(parent)
1658
if version in parent_ancestors:
1659
raise errors.GraphCycleError([parent, version])
1660
# ensure this parent will be available later.
1661
new_parents = n2.difference(n1)
1662
needed_versions.update(new_parents.difference(this_versions))
1663
mismatched_versions.add(version)
1665
if not needed_versions and not mismatched_versions:
1667
full_list = topo_sort(self.source.get_graph())
1669
version_list = [i for i in full_list if (not self.target.has_version(i)
1670
and i in needed_versions)]
1674
total = len(version_list)
1675
for version_id in version_list:
1676
pb.update("Converting to knit", count, total)
1677
parents = self.source.get_parents(version_id)
1678
# check that its will be a consistent copy:
1679
for parent in parents:
1680
# if source has the parent, we must already have it
1681
assert (self.target.has_version(parent))
1682
self.target.add_lines(
1683
version_id, parents, self.source.get_lines(version_id))
1686
for version in mismatched_versions:
1687
# FIXME RBC 20060309 is this needed?
1688
n1 = set(self.target.get_parents_with_ghosts(version))
1689
n2 = set(self.source.get_parents(version))
1690
# write a combined record to our history preserving the current
1691
# parents as first in the list
1692
new_parents = self.target.get_parents_with_ghosts(version) + list(n2.difference(n1))
1693
self.target.fix_parents(version, new_parents)
1699
InterVersionedFile.register_optimiser(WeaveToKnit)
1702
class KnitSequenceMatcher(difflib.SequenceMatcher):
1703
"""Knit tuned sequence matcher.
1705
This is based on profiling of difflib which indicated some improvements
1706
for our usage pattern.
1709
def find_longest_match(self, alo, ahi, blo, bhi):
1710
"""Find longest matching block in a[alo:ahi] and b[blo:bhi].
1712
If isjunk is not defined:
1714
Return (i,j,k) such that a[i:i+k] is equal to b[j:j+k], where
1715
alo <= i <= i+k <= ahi
1716
blo <= j <= j+k <= bhi
1717
and for all (i',j',k') meeting those conditions,
1720
and if i == i', j <= j'
1722
In other words, of all maximal matching blocks, return one that
1723
starts earliest in a, and of all those maximal matching blocks that
1724
start earliest in a, return the one that starts earliest in b.
1726
>>> s = SequenceMatcher(None, " abcd", "abcd abcd")
1727
>>> s.find_longest_match(0, 5, 0, 9)
1730
If isjunk is defined, first the longest matching block is
1731
determined as above, but with the additional restriction that no
1732
junk element appears in the block. Then that block is extended as
1733
far as possible by matching (only) junk elements on both sides. So
1734
the resulting block never matches on junk except as identical junk
1735
happens to be adjacent to an "interesting" match.
1737
Here's the same example as before, but considering blanks to be
1738
junk. That prevents " abcd" from matching the " abcd" at the tail
1739
end of the second sequence directly. Instead only the "abcd" can
1740
match, and matches the leftmost "abcd" in the second sequence:
1742
>>> s = SequenceMatcher(lambda x: x==" ", " abcd", "abcd abcd")
1743
>>> s.find_longest_match(0, 5, 0, 9)
1746
If no blocks match, return (alo, blo, 0).
1748
>>> s = SequenceMatcher(None, "ab", "c")
1749
>>> s.find_longest_match(0, 2, 0, 1)
1753
# CAUTION: stripping common prefix or suffix would be incorrect.
1757
# Longest matching block is "ab", but if common prefix is
1758
# stripped, it's "a" (tied with "b"). UNIX(tm) diff does so
1759
# strip, so ends up claiming that ab is changed to acab by
1760
# inserting "ca" in the middle. That's minimal but unintuitive:
1761
# "it's obvious" that someone inserted "ac" at the front.
1762
# Windiff ends up at the same place as diff, but by pairing up
1763
# the unique 'b's and then matching the first two 'a's.
1765
a, b, b2j, isbjunk = self.a, self.b, self.b2j, self.isbjunk
1766
besti, bestj, bestsize = alo, blo, 0
1767
# find longest junk-free match
1768
# during an iteration of the loop, j2len[j] = length of longest
1769
# junk-free match ending with a[i-1] and b[j]
1773
for i in xrange(alo, ahi):
1774
# look at all instances of a[i] in b; note that because
1775
# b2j has no junk keys, the loop is skipped if a[i] is junk
1776
j2lenget = j2len.get
1779
# changing b2j.get(a[i], nothing) to a try:KeyError pair produced the
1780
# following improvement
1781
# 704 0 4650.5320 2620.7410 bzrlib.knit:1336(find_longest_match)
1782
# +326674 0 1655.1210 1655.1210 +<method 'get' of 'dict' objects>
1783
# +76519 0 374.6700 374.6700 +<method 'has_key' of 'dict' objects>
1785
# 704 0 3733.2820 2209.6520 bzrlib.knit:1336(find_longest_match)
1786
# +211400 0 1147.3520 1147.3520 +<method 'get' of 'dict' objects>
1787
# +76519 0 376.2780 376.2780 +<method 'has_key' of 'dict' objects>
1799
k = newj2len[j] = 1 + j2lenget(-1 + j, 0)
1801
besti, bestj, bestsize = 1 + i-k, 1 + j-k, k
1804
# Extend the best by non-junk elements on each end. In particular,
1805
# "popular" non-junk elements aren't in b2j, which greatly speeds
1806
# the inner loop above, but also means "the best" match so far
1807
# doesn't contain any junk *or* popular non-junk elements.
1808
while besti > alo and bestj > blo and \
1809
not isbjunk(b[bestj-1]) and \
1810
a[besti-1] == b[bestj-1]:
1811
besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
1812
while besti+bestsize < ahi and bestj+bestsize < bhi and \
1813
not isbjunk(b[bestj+bestsize]) and \
1814
a[besti+bestsize] == b[bestj+bestsize]:
1817
# Now that we have a wholly interesting match (albeit possibly
1818
# empty!), we may as well suck up the matching junk on each
1819
# side of it too. Can't think of a good reason not to, and it
1820
# saves post-processing the (possibly considerable) expense of
1821
# figuring out what to do with it. In the case of an empty
1822
# interesting match, this is clearly the right thing to do,
1823
# because no other kind of match is possible in the regions.
1824
while besti > alo and bestj > blo and \
1825
isbjunk(b[bestj-1]) and \
1826
a[besti-1] == b[bestj-1]:
1827
besti, bestj, bestsize = besti-1, bestj-1, bestsize+1
1828
while besti+bestsize < ahi and bestj+bestsize < bhi and \
1829
isbjunk(b[bestj+bestsize]) and \
1830
a[besti+bestsize] == b[bestj+bestsize]:
1831
bestsize = bestsize + 1
1833
return besti, bestj, bestsize
added
removed
bzrlib/knit.py
