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# revlogdeltas.py - Logic around delta computation for revlog
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#
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# Copyright 2005-2007 Matt Mackall <mpm@selenic.com>
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# Copyright 2018 Octobus <contact@octobus.net>
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#
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# This software may be used and distributed according to the terms of the
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# GNU General Public License version 2 or any later version.
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"""Helper class to compute deltas stored inside revlogs"""
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from __future__ import absolute_import
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import collections
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import heapq
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import struct
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# import stuff from node for others to import from revlog
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from ..node import (
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nullrev,
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)
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from ..i18n import _
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from .constants import (
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REVIDX_ISCENSORED,
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REVIDX_RAWTEXT_CHANGING_FLAGS,
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)
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from ..thirdparty import (
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attr,
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)
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from .. import (
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error,
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mdiff,
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)
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RevlogError = error.RevlogError
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CensoredNodeError = error.CensoredNodeError
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# maximum <delta-chain-data>/<revision-text-length> ratio
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LIMIT_DELTA2TEXT = 2
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class _testrevlog(object):
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"""minimalist fake revlog to use in doctests"""
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def __init__(self, data, density=0.5, mingap=0):
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"""data is an list of revision payload boundaries"""
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self._data = data
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self._srdensitythreshold = density
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self._srmingapsize = mingap
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def start(self, rev):
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if rev == 0:
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return 0
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return self._data[rev - 1]
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def end(self, rev):
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return self._data[rev]
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def length(self, rev):
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return self.end(rev) - self.start(rev)
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def __len__(self):
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return len(self._data)
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def slicechunk(revlog, revs, deltainfo=None, targetsize=None):
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"""slice revs to reduce the amount of unrelated data to be read from disk.
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``revs`` is sliced into groups that should be read in one time.
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Assume that revs are sorted.
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The initial chunk is sliced until the overall density (payload/chunks-span
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ratio) is above `revlog._srdensitythreshold`. No gap smaller than
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`revlog._srmingapsize` is skipped.
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If `targetsize` is set, no chunk larger than `targetsize` will be yield.
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For consistency with other slicing choice, this limit won't go lower than
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`revlog._srmingapsize`.
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If individual revisions chunk are larger than this limit, they will still
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be raised individually.
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>>> revlog = _testrevlog([
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... 5, #00 (5)
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... 10, #01 (5)
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... 12, #02 (2)
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... 12, #03 (empty)
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... 27, #04 (15)
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... 31, #05 (4)
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... 31, #06 (empty)
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... 42, #07 (11)
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... 47, #08 (5)
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... 47, #09 (empty)
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... 48, #10 (1)
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... 51, #11 (3)
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... 74, #12 (23)
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... 85, #13 (11)
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... 86, #14 (1)
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... 91, #15 (5)
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... ])
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>>> list(slicechunk(revlog, list(range(16))))
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[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]]
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>>> list(slicechunk(revlog, [0, 15]))
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[[0], [15]]
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>>> list(slicechunk(revlog, [0, 11, 15]))
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[[0], [11], [15]]
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>>> list(slicechunk(revlog, [0, 11, 13, 15]))
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[[0], [11, 13, 15]]
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>>> list(slicechunk(revlog, [1, 2, 3, 5, 8, 10, 11, 14]))
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[[1, 2], [5, 8, 10, 11], [14]]
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Slicing with a maximum chunk size
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>>> list(slicechunk(revlog, [0, 11, 13, 15], targetsize=15))
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[[0], [11], [13], [15]]
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>>> list(slicechunk(revlog, [0, 11, 13, 15], targetsize=20))
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[[0], [11], [13, 15]]
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"""
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if targetsize is not None:
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targetsize = max(targetsize, revlog._srmingapsize)
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# targetsize should not be specified when evaluating delta candidates:
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# * targetsize is used to ensure we stay within specification when reading,
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# * deltainfo is used to pick are good delta chain when writing.
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if not (deltainfo is None or targetsize is None):
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msg = 'cannot use `targetsize` with a `deltainfo`'
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raise error.ProgrammingError(msg)
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for chunk in _slicechunktodensity(revlog, revs,
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deltainfo,
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revlog._srdensitythreshold,
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revlog._srmingapsize):
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for subchunk in _slicechunktosize(revlog, chunk, targetsize):
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yield subchunk
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def _slicechunktosize(revlog, revs, targetsize=None):
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"""slice revs to match the target size
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This is intended to be used on chunk that density slicing selected by that
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are still too large compared to the read garantee of revlog. This might
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happens when "minimal gap size" interrupted the slicing or when chain are
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built in a way that create large blocks next to each other.
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>>> revlog = _testrevlog([
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... 3, #0 (3)
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... 5, #1 (2)
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... 6, #2 (1)
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... 8, #3 (2)
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... 8, #4 (empty)
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... 11, #5 (3)
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... 12, #6 (1)
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... 13, #7 (1)
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... 14, #8 (1)
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... ])
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Cases where chunk is already small enough
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>>> list(_slicechunktosize(revlog, [0], 3))
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[[0]]
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>>> list(_slicechunktosize(revlog, [6, 7], 3))
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[[6, 7]]
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>>> list(_slicechunktosize(revlog, [0], None))
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[[0]]
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>>> list(_slicechunktosize(revlog, [6, 7], None))
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[[6, 7]]
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cases where we need actual slicing
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>>> list(_slicechunktosize(revlog, [0, 1], 3))
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[[0], [1]]
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>>> list(_slicechunktosize(revlog, [1, 3], 3))
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[[1], [3]]
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>>> list(_slicechunktosize(revlog, [1, 2, 3], 3))
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[[1, 2], [3]]
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>>> list(_slicechunktosize(revlog, [3, 5], 3))
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[[3], [5]]
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>>> list(_slicechunktosize(revlog, [3, 4, 5], 3))
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[[3], [5]]
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>>> list(_slicechunktosize(revlog, [5, 6, 7, 8], 3))
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[[5], [6, 7, 8]]
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>>> list(_slicechunktosize(revlog, [0, 1, 2, 3, 4, 5, 6, 7, 8], 3))
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[[0], [1, 2], [3], [5], [6, 7, 8]]
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Case with too large individual chunk (must return valid chunk)
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>>> list(_slicechunktosize(revlog, [0, 1], 2))
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[[0], [1]]
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>>> list(_slicechunktosize(revlog, [1, 3], 1))
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[[1], [3]]
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>>> list(_slicechunktosize(revlog, [3, 4, 5], 2))
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[[3], [5]]
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"""
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assert targetsize is None or 0 <= targetsize
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if targetsize is None or segmentspan(revlog, revs) <= targetsize:
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yield revs
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return
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startrevidx = 0
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startdata = revlog.start(revs[0])
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endrevidx = 0
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iterrevs = enumerate(revs)
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next(iterrevs) # skip first rev.
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for idx, r in iterrevs:
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span = revlog.end(r) - startdata
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if span <= targetsize:
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endrevidx = idx
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else:
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chunk = _trimchunk(revlog, revs, startrevidx, endrevidx + 1)
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if chunk:
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yield chunk
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startrevidx = idx
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startdata = revlog.start(r)
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endrevidx = idx
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yield _trimchunk(revlog, revs, startrevidx)
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def _slicechunktodensity(revlog, revs, deltainfo=None, targetdensity=0.5,
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mingapsize=0):
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"""slice revs to reduce the amount of unrelated data to be read from disk.
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``revs`` is sliced into groups that should be read in one time.
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Assume that revs are sorted.
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``deltainfo`` is a _deltainfo instance of a revision that we would append
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to the top of the revlog.
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The initial chunk is sliced until the overall density (payload/chunks-span
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ratio) is above `targetdensity`. No gap smaller than `mingapsize` is
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skipped.
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>>> revlog = _testrevlog([
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... 5, #00 (5)
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... 10, #01 (5)
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... 12, #02 (2)
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... 12, #03 (empty)
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... 27, #04 (15)
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... 31, #05 (4)
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... 31, #06 (empty)
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... 42, #07 (11)
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... 47, #08 (5)
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... 47, #09 (empty)
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... 48, #10 (1)
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... 51, #11 (3)
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... 74, #12 (23)
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... 85, #13 (11)
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... 86, #14 (1)
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... 91, #15 (5)
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... ])
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>>> list(_slicechunktodensity(revlog, list(range(16))))
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[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]]
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>>> list(_slicechunktodensity(revlog, [0, 15]))
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[[0], [15]]
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>>> list(_slicechunktodensity(revlog, [0, 11, 15]))
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[[0], [11], [15]]
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>>> list(_slicechunktodensity(revlog, [0, 11, 13, 15]))
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[[0], [11, 13, 15]]
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>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14]))
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[[1, 2], [5, 8, 10, 11], [14]]
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>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14],
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... mingapsize=20))
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[[1, 2, 3, 5, 8, 10, 11], [14]]
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>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14],
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... targetdensity=0.95))
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[[1, 2], [5], [8, 10, 11], [14]]
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>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14],
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... targetdensity=0.95, mingapsize=12))
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[[1, 2], [5, 8, 10, 11], [14]]
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"""
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start = revlog.start
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length = revlog.length
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if len(revs) <= 1:
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yield revs
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return
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nextrev = len(revlog)
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nextoffset = revlog.end(nextrev - 1)
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if deltainfo is None:
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deltachainspan = segmentspan(revlog, revs)
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chainpayload = sum(length(r) for r in revs)
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else:
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deltachainspan = deltainfo.distance
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chainpayload = deltainfo.compresseddeltalen
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if deltachainspan < mingapsize:
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yield revs
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return
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readdata = deltachainspan
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if deltachainspan:
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density = chainpayload / float(deltachainspan)
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else:
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density = 1.0
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if density >= targetdensity:
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yield revs
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return
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if deltainfo is not None and deltainfo.deltalen:
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revs = list(revs)
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revs.append(nextrev)
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# Store the gaps in a heap to have them sorted by decreasing size
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gapsheap = []
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heapq.heapify(gapsheap)
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prevend = None
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for i, rev in enumerate(revs):
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if rev < nextrev:
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revstart = start(rev)
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revlen = length(rev)
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else:
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revstart = nextoffset
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revlen = deltainfo.deltalen
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# Skip empty revisions to form larger holes
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if revlen == 0:
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continue
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if prevend is not None:
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gapsize = revstart - prevend
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# only consider holes that are large enough
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if gapsize > mingapsize:
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heapq.heappush(gapsheap, (-gapsize, i))
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prevend = revstart + revlen
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# Collect the indices of the largest holes until the density is acceptable
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indicesheap = []
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heapq.heapify(indicesheap)
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while gapsheap and density < targetdensity:
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oppgapsize, gapidx = heapq.heappop(gapsheap)
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heapq.heappush(indicesheap, gapidx)
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# the gap sizes are stored as negatives to be sorted decreasingly
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# by the heap
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readdata -= (-oppgapsize)
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if readdata > 0:
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density = chainpayload / float(readdata)
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else:
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density = 1.0
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# Cut the revs at collected indices
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previdx = 0
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while indicesheap:
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idx = heapq.heappop(indicesheap)
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chunk = _trimchunk(revlog, revs, previdx, idx)
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if chunk:
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yield chunk
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previdx = idx
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chunk = _trimchunk(revlog, revs, previdx)
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if chunk:
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yield chunk
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def _trimchunk(revlog, revs, startidx, endidx=None):
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"""returns revs[startidx:endidx] without empty trailing revs
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Doctest Setup
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>>> revlog = _testrevlog([
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... 5, #0
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... 10, #1
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... 12, #2
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... 12, #3 (empty)
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... 17, #4
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... 21, #5
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... 21, #6 (empty)
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... ])
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Contiguous cases:
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>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 0)
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[0, 1, 2, 3, 4, 5]
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>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 0, 5)
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[0, 1, 2, 3, 4]
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>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 0, 4)
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[0, 1, 2]
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>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 2, 4)
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[2]
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>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 3)
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[3, 4, 5]
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>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 3, 5)
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[3, 4]
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Discontiguous cases:
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>>> _trimchunk(revlog, [1, 3, 5, 6], 0)
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[1, 3, 5]
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>>> _trimchunk(revlog, [1, 3, 5, 6], 0, 2)
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[1]
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>>> _trimchunk(revlog, [1, 3, 5, 6], 1, 3)
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[3, 5]
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>>> _trimchunk(revlog, [1, 3, 5, 6], 1)
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[3, 5]
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"""
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length = revlog.length
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if endidx is None:
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endidx = len(revs)
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# If we have a non-emtpy delta candidate, there are nothing to trim
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if revs[endidx - 1] < len(revlog):
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# Trim empty revs at the end, except the very first revision of a chain
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while (endidx > 1
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and endidx > startidx
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and length(revs[endidx - 1]) == 0):
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endidx -= 1
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return revs[startidx:endidx]
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def segmentspan(revlog, revs, deltainfo=None):
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"""Get the byte span of a segment of revisions
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revs is a sorted array of revision numbers
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>>> revlog = _testrevlog([
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... 5, #0
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... 10, #1
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... 12, #2
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... 12, #3 (empty)
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... 17, #4
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... ])
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>>> segmentspan(revlog, [0, 1, 2, 3, 4])
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17
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>>> segmentspan(revlog, [0, 4])
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17
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|
>>> segmentspan(revlog, [3, 4])
|
|
|
5
|
|
|
>>> segmentspan(revlog, [1, 2, 3,])
|
|
|
7
|
|
|
>>> segmentspan(revlog, [1, 3])
|
|
|
7
|
|
|
"""
|
|
|
if not revs:
|
|
|
return 0
|
|
|
if deltainfo is not None and len(revlog) <= revs[-1]:
|
|
|
if len(revs) == 1:
|
|
|
return deltainfo.deltalen
|
|
|
offset = revlog.end(len(revlog) - 1)
|
|
|
end = deltainfo.deltalen + offset
|
|
|
else:
|
|
|
end = revlog.end(revs[-1])
|
|
|
return end - revlog.start(revs[0])
|
|
|
|
|
|
def _textfromdelta(fh, revlog, baserev, delta, p1, p2, flags, expectednode):
|
|
|
"""build full text from a (base, delta) pair and other metadata"""
|
|
|
# special case deltas which replace entire base; no need to decode
|
|
|
# base revision. this neatly avoids censored bases, which throw when
|
|
|
# they're decoded.
|
|
|
hlen = struct.calcsize(">lll")
|
|
|
if delta[:hlen] == mdiff.replacediffheader(revlog.rawsize(baserev),
|
|
|
len(delta) - hlen):
|
|
|
fulltext = delta[hlen:]
|
|
|
else:
|
|
|
# deltabase is rawtext before changed by flag processors, which is
|
|
|
# equivalent to non-raw text
|
|
|
basetext = revlog.revision(baserev, _df=fh, raw=False)
|
|
|
fulltext = mdiff.patch(basetext, delta)
|
|
|
|
|
|
try:
|
|
|
res = revlog._processflags(fulltext, flags, 'read', raw=True)
|
|
|
fulltext, validatehash = res
|
|
|
if validatehash:
|
|
|
revlog.checkhash(fulltext, expectednode, p1=p1, p2=p2)
|
|
|
if flags & REVIDX_ISCENSORED:
|
|
|
raise RevlogError(_('node %s is not censored') % expectednode)
|
|
|
except CensoredNodeError:
|
|
|
# must pass the censored index flag to add censored revisions
|
|
|
if not flags & REVIDX_ISCENSORED:
|
|
|
raise
|
|
|
return fulltext
|
|
|
|
|
|
@attr.s(slots=True, frozen=True)
|
|
|
class _deltainfo(object):
|
|
|
distance = attr.ib()
|
|
|
deltalen = attr.ib()
|
|
|
data = attr.ib()
|
|
|
base = attr.ib()
|
|
|
chainbase = attr.ib()
|
|
|
chainlen = attr.ib()
|
|
|
compresseddeltalen = attr.ib()
|
|
|
snapshotdepth = attr.ib()
|
|
|
|
|
|
def isgooddeltainfo(revlog, deltainfo, revinfo):
|
|
|
"""Returns True if the given delta is good. Good means that it is within
|
|
|
the disk span, disk size, and chain length bounds that we know to be
|
|
|
performant."""
|
|
|
if deltainfo is None:
|
|
|
return False
|
|
|
|
|
|
# - 'deltainfo.distance' is the distance from the base revision --
|
|
|
# bounding it limits the amount of I/O we need to do.
|
|
|
# - 'deltainfo.compresseddeltalen' is the sum of the total size of
|
|
|
# deltas we need to apply -- bounding it limits the amount of CPU
|
|
|
# we consume.
|
|
|
|
|
|
if revlog._sparserevlog:
|
|
|
# As sparse-read will be used, we can consider that the distance,
|
|
|
# instead of being the span of the whole chunk,
|
|
|
# is the span of the largest read chunk
|
|
|
base = deltainfo.base
|
|
|
|
|
|
if base != nullrev:
|
|
|
deltachain = revlog._deltachain(base)[0]
|
|
|
else:
|
|
|
deltachain = []
|
|
|
|
|
|
# search for the first non-snapshot revision
|
|
|
for idx, r in enumerate(deltachain):
|
|
|
if not revlog.issnapshot(r):
|
|
|
break
|
|
|
deltachain = deltachain[idx:]
|
|
|
chunks = slicechunk(revlog, deltachain, deltainfo)
|
|
|
all_span = [segmentspan(revlog, revs, deltainfo)
|
|
|
for revs in chunks]
|
|
|
distance = max(all_span)
|
|
|
else:
|
|
|
distance = deltainfo.distance
|
|
|
|
|
|
textlen = revinfo.textlen
|
|
|
defaultmax = textlen * 4
|
|
|
maxdist = revlog._maxdeltachainspan
|
|
|
if not maxdist:
|
|
|
maxdist = distance # ensure the conditional pass
|
|
|
maxdist = max(maxdist, defaultmax)
|
|
|
if revlog._sparserevlog and maxdist < revlog._srmingapsize:
|
|
|
# In multiple place, we are ignoring irrelevant data range below a
|
|
|
# certain size. Be also apply this tradeoff here and relax span
|
|
|
# constraint for small enought content.
|
|
|
maxdist = revlog._srmingapsize
|
|
|
|
|
|
# Bad delta from read span:
|
|
|
#
|
|
|
# If the span of data read is larger than the maximum allowed.
|
|
|
if maxdist < distance:
|
|
|
return False
|
|
|
|
|
|
# Bad delta from new delta size:
|
|
|
#
|
|
|
# If the delta size is larger than the target text, storing the
|
|
|
# delta will be inefficient.
|
|
|
if textlen < deltainfo.deltalen:
|
|
|
return False
|
|
|
|
|
|
# Bad delta from cumulated payload size:
|
|
|
#
|
|
|
# If the sum of delta get larger than K * target text length.
|
|
|
if textlen * LIMIT_DELTA2TEXT < deltainfo.compresseddeltalen:
|
|
|
return False
|
|
|
|
|
|
# Bad delta from chain length:
|
|
|
#
|
|
|
# If the number of delta in the chain gets too high.
|
|
|
if (revlog._maxchainlen
|
|
|
and revlog._maxchainlen < deltainfo.chainlen):
|
|
|
return False
|
|
|
|
|
|
# bad delta from intermediate snapshot size limit
|
|
|
#
|
|
|
# If an intermediate snapshot size is higher than the limit. The
|
|
|
# limit exist to prevent endless chain of intermediate delta to be
|
|
|
# created.
|
|
|
if (deltainfo.snapshotdepth is not None and
|
|
|
(textlen >> deltainfo.snapshotdepth) < deltainfo.deltalen):
|
|
|
return False
|
|
|
|
|
|
# bad delta if new intermediate snapshot is larger than the previous
|
|
|
# snapshot
|
|
|
if (deltainfo.snapshotdepth
|
|
|
and revlog.length(deltainfo.base) < deltainfo.deltalen):
|
|
|
return False
|
|
|
|
|
|
return True
|
|
|
|
|
|
def _candidategroups(revlog, textlen, p1, p2, cachedelta):
|
|
|
"""Provides group of revision to be tested as delta base
|
|
|
|
|
|
This top level function focus on emitting groups with unique and worthwhile
|
|
|
content. See _raw_candidate_groups for details about the group order.
|
|
|
"""
|
|
|
# should we try to build a delta?
|
|
|
if not (len(revlog) and revlog._storedeltachains):
|
|
|
yield None
|
|
|
return
|
|
|
|
|
|
deltalength = revlog.length
|
|
|
deltaparent = revlog.deltaparent
|
|
|
good = None
|
|
|
|
|
|
deltas_limit = textlen * LIMIT_DELTA2TEXT
|
|
|
|
|
|
tested = set([nullrev])
|
|
|
candidates = _refinedgroups(revlog, p1, p2, cachedelta)
|
|
|
while True:
|
|
|
temptative = candidates.send(good)
|
|
|
if temptative is None:
|
|
|
break
|
|
|
group = []
|
|
|
for rev in temptative:
|
|
|
# skip over empty delta (no need to include them in a chain)
|
|
|
while not (rev == nullrev or rev in tested or deltalength(rev)):
|
|
|
rev = deltaparent(rev)
|
|
|
tested.add(rev)
|
|
|
# filter out revision we tested already
|
|
|
if rev in tested:
|
|
|
continue
|
|
|
tested.add(rev)
|
|
|
# filter out delta base that will never produce good delta
|
|
|
if deltas_limit < revlog.length(rev):
|
|
|
continue
|
|
|
# no need to try a delta against nullrev, this will be done as a
|
|
|
# last resort.
|
|
|
if rev == nullrev:
|
|
|
continue
|
|
|
# no delta for rawtext-changing revs (see "candelta" for why)
|
|
|
if revlog.flags(rev) & REVIDX_RAWTEXT_CHANGING_FLAGS:
|
|
|
continue
|
|
|
group.append(rev)
|
|
|
if group:
|
|
|
# XXX: in the sparse revlog case, group can become large,
|
|
|
# impacting performances. Some bounding or slicing mecanism
|
|
|
# would help to reduce this impact.
|
|
|
good = yield tuple(group)
|
|
|
yield None
|
|
|
|
|
|
def _findsnapshots(revlog, cache, start_rev):
|
|
|
"""find snapshot from start_rev to tip"""
|
|
|
deltaparent = revlog.deltaparent
|
|
|
issnapshot = revlog.issnapshot
|
|
|
for rev in revlog.revs(start_rev):
|
|
|
if issnapshot(rev):
|
|
|
cache[deltaparent(rev)].append(rev)
|
|
|
|
|
|
def _refinedgroups(revlog, p1, p2, cachedelta):
|
|
|
good = None
|
|
|
# First we try to reuse a the delta contained in the bundle.
|
|
|
# (or from the source revlog)
|
|
|
#
|
|
|
# This logic only applies to general delta repositories and can be disabled
|
|
|
# through configuration. Disabling reuse source delta is useful when
|
|
|
# we want to make sure we recomputed "optimal" deltas.
|
|
|
if cachedelta and revlog._generaldelta and revlog._lazydeltabase:
|
|
|
# Assume what we received from the server is a good choice
|
|
|
# build delta will reuse the cache
|
|
|
good = yield (cachedelta[0],)
|
|
|
if good is not None:
|
|
|
yield None
|
|
|
return
|
|
|
for candidates in _rawgroups(revlog, p1, p2, cachedelta):
|
|
|
good = yield candidates
|
|
|
if good is not None:
|
|
|
break
|
|
|
|
|
|
# if we have a refinable value, try to refine it
|
|
|
if good is not None and good not in (p1, p2) and revlog.issnapshot(good):
|
|
|
# refine snapshot down
|
|
|
previous = None
|
|
|
while previous != good:
|
|
|
previous = good
|
|
|
base = revlog.deltaparent(good)
|
|
|
if base == nullrev:
|
|
|
break
|
|
|
good = yield (base,)
|
|
|
# refine snapshot up
|
|
|
#
|
|
|
# XXX the _findsnapshots call can be expensive and is "duplicated" with
|
|
|
# the one done in `_rawgroups`. Once we start working on performance,
|
|
|
# we should make the two logics share this computation.
|
|
|
snapshots = collections.defaultdict(list)
|
|
|
_findsnapshots(revlog, snapshots, good + 1)
|
|
|
previous = None
|
|
|
while good != previous:
|
|
|
previous = good
|
|
|
children = tuple(sorted(c for c in snapshots[good]))
|
|
|
good = yield children
|
|
|
|
|
|
# we have found nothing
|
|
|
yield None
|
|
|
|
|
|
def _rawgroups(revlog, p1, p2, cachedelta):
|
|
|
"""Provides group of revision to be tested as delta base
|
|
|
|
|
|
This lower level function focus on emitting delta theorically interresting
|
|
|
without looking it any practical details.
|
|
|
|
|
|
The group order aims at providing fast or small candidates first.
|
|
|
"""
|
|
|
gdelta = revlog._generaldelta
|
|
|
sparse = revlog._sparserevlog
|
|
|
curr = len(revlog)
|
|
|
prev = curr - 1
|
|
|
deltachain = lambda rev: revlog._deltachain(rev)[0]
|
|
|
|
|
|
if gdelta:
|
|
|
# exclude already lazy tested base if any
|
|
|
parents = [p for p in (p1, p2) if p != nullrev]
|
|
|
|
|
|
if not revlog._deltabothparents and len(parents) == 2:
|
|
|
parents.sort()
|
|
|
# To minimize the chance of having to build a fulltext,
|
|
|
# pick first whichever parent is closest to us (max rev)
|
|
|
yield (parents[1],)
|
|
|
# then the other one (min rev) if the first did not fit
|
|
|
yield (parents[0],)
|
|
|
elif len(parents) > 0:
|
|
|
# Test all parents (1 or 2), and keep the best candidate
|
|
|
yield parents
|
|
|
|
|
|
if sparse and parents:
|
|
|
snapshots = collections.defaultdict(list) # map: base-rev: snapshot-rev
|
|
|
# See if we can use an existing snapshot in the parent chains to use as
|
|
|
# a base for a new intermediate-snapshot
|
|
|
#
|
|
|
# search for snapshot in parents delta chain
|
|
|
# map: snapshot-level: snapshot-rev
|
|
|
parents_snaps = collections.defaultdict(set)
|
|
|
candidate_chains = [deltachain(p) for p in parents]
|
|
|
for chain in candidate_chains:
|
|
|
for idx, s in enumerate(chain):
|
|
|
if not revlog.issnapshot(s):
|
|
|
break
|
|
|
parents_snaps[idx].add(s)
|
|
|
snapfloor = min(parents_snaps[0]) + 1
|
|
|
_findsnapshots(revlog, snapshots, snapfloor)
|
|
|
# search for the highest "unrelated" revision
|
|
|
#
|
|
|
# Adding snapshots used by "unrelated" revision increase the odd we
|
|
|
# reuse an independant, yet better snapshot chain.
|
|
|
#
|
|
|
# XXX instead of building a set of revisions, we could lazily enumerate
|
|
|
# over the chains. That would be more efficient, however we stick to
|
|
|
# simple code for now.
|
|
|
all_revs = set()
|
|
|
for chain in candidate_chains:
|
|
|
all_revs.update(chain)
|
|
|
other = None
|
|
|
for r in revlog.revs(prev, snapfloor):
|
|
|
if r not in all_revs:
|
|
|
other = r
|
|
|
break
|
|
|
if other is not None:
|
|
|
# To avoid unfair competition, we won't use unrelated intermediate
|
|
|
# snapshot that are deeper than the ones from the parent delta
|
|
|
# chain.
|
|
|
max_depth = max(parents_snaps.keys())
|
|
|
chain = deltachain(other)
|
|
|
for idx, s in enumerate(chain):
|
|
|
if s < snapfloor:
|
|
|
continue
|
|
|
if max_depth < idx:
|
|
|
break
|
|
|
if not revlog.issnapshot(s):
|
|
|
break
|
|
|
parents_snaps[idx].add(s)
|
|
|
# Test them as possible intermediate snapshot base
|
|
|
# We test them from highest to lowest level. High level one are more
|
|
|
# likely to result in small delta
|
|
|
floor = None
|
|
|
for idx, snaps in sorted(parents_snaps.items(), reverse=True):
|
|
|
siblings = set()
|
|
|
for s in snaps:
|
|
|
siblings.update(snapshots[s])
|
|
|
# Before considering making a new intermediate snapshot, we check
|
|
|
# if an existing snapshot, children of base we consider, would be
|
|
|
# suitable.
|
|
|
#
|
|
|
# It give a change to reuse a delta chain "unrelated" to the
|
|
|
# current revision instead of starting our own. Without such
|
|
|
# re-use, topological branches would keep reopening new chains.
|
|
|
# Creating more and more snapshot as the repository grow.
|
|
|
|
|
|
if floor is not None:
|
|
|
# We only do this for siblings created after the one in our
|
|
|
# parent's delta chain. Those created before has less chances
|
|
|
# to be valid base since our ancestors had to create a new
|
|
|
# snapshot.
|
|
|
siblings = [r for r in siblings if floor < r]
|
|
|
yield tuple(sorted(siblings))
|
|
|
# then test the base from our parent's delta chain.
|
|
|
yield tuple(sorted(snaps))
|
|
|
floor = min(snaps)
|
|
|
# No suitable base found in the parent chain, search if any full
|
|
|
# snapshots emitted since parent's base would be a suitable base for an
|
|
|
# intermediate snapshot.
|
|
|
#
|
|
|
# It give a chance to reuse a delta chain unrelated to the current
|
|
|
# revisions instead of starting our own. Without such re-use,
|
|
|
# topological branches would keep reopening new full chains. Creating
|
|
|
# more and more snapshot as the repository grow.
|
|
|
yield tuple(snapshots[nullrev])
|
|
|
|
|
|
if not sparse:
|
|
|
# other approach failed try against prev to hopefully save us a
|
|
|
# fulltext.
|
|
|
yield (prev,)
|
|
|
|
|
|
class deltacomputer(object):
|
|
|
def __init__(self, revlog):
|
|
|
self.revlog = revlog
|
|
|
|
|
|
def buildtext(self, revinfo, fh):
|
|
|
"""Builds a fulltext version of a revision
|
|
|
|
|
|
revinfo: _revisioninfo instance that contains all needed info
|
|
|
fh: file handle to either the .i or the .d revlog file,
|
|
|
depending on whether it is inlined or not
|
|
|
"""
|
|
|
btext = revinfo.btext
|
|
|
if btext[0] is not None:
|
|
|
return btext[0]
|
|
|
|
|
|
revlog = self.revlog
|
|
|
cachedelta = revinfo.cachedelta
|
|
|
baserev = cachedelta[0]
|
|
|
delta = cachedelta[1]
|
|
|
|
|
|
fulltext = btext[0] = _textfromdelta(fh, revlog, baserev, delta,
|
|
|
revinfo.p1, revinfo.p2,
|
|
|
revinfo.flags, revinfo.node)
|
|
|
return fulltext
|
|
|
|
|
|
def _builddeltadiff(self, base, revinfo, fh):
|
|
|
revlog = self.revlog
|
|
|
t = self.buildtext(revinfo, fh)
|
|
|
if revlog.iscensored(base):
|
|
|
# deltas based on a censored revision must replace the
|
|
|
# full content in one patch, so delta works everywhere
|
|
|
header = mdiff.replacediffheader(revlog.rawsize(base), len(t))
|
|
|
delta = header + t
|
|
|
else:
|
|
|
ptext = revlog.revision(base, _df=fh, raw=True)
|
|
|
delta = mdiff.textdiff(ptext, t)
|
|
|
|
|
|
return delta
|
|
|
|
|
|
def _builddeltainfo(self, revinfo, base, fh):
|
|
|
# can we use the cached delta?
|
|
|
if revinfo.cachedelta and revinfo.cachedelta[0] == base:
|
|
|
delta = revinfo.cachedelta[1]
|
|
|
else:
|
|
|
delta = self._builddeltadiff(base, revinfo, fh)
|
|
|
revlog = self.revlog
|
|
|
header, data = revlog.compress(delta)
|
|
|
deltalen = len(header) + len(data)
|
|
|
chainbase = revlog.chainbase(base)
|
|
|
offset = revlog.end(len(revlog) - 1)
|
|
|
dist = deltalen + offset - revlog.start(chainbase)
|
|
|
if revlog._generaldelta:
|
|
|
deltabase = base
|
|
|
else:
|
|
|
deltabase = chainbase
|
|
|
chainlen, compresseddeltalen = revlog._chaininfo(base)
|
|
|
chainlen += 1
|
|
|
compresseddeltalen += deltalen
|
|
|
|
|
|
revlog = self.revlog
|
|
|
snapshotdepth = None
|
|
|
if deltabase == nullrev:
|
|
|
snapshotdepth = 0
|
|
|
elif revlog._sparserevlog and revlog.issnapshot(deltabase):
|
|
|
# A delta chain should always be one full snapshot,
|
|
|
# zero or more semi-snapshots, and zero or more deltas
|
|
|
p1, p2 = revlog.rev(revinfo.p1), revlog.rev(revinfo.p2)
|
|
|
if deltabase not in (p1, p2) and revlog.issnapshot(deltabase):
|
|
|
snapshotdepth = len(revlog._deltachain(deltabase)[0])
|
|
|
|
|
|
return _deltainfo(dist, deltalen, (header, data), deltabase,
|
|
|
chainbase, chainlen, compresseddeltalen,
|
|
|
snapshotdepth)
|
|
|
|
|
|
def _fullsnapshotinfo(self, fh, revinfo):
|
|
|
curr = len(self.revlog)
|
|
|
rawtext = self.buildtext(revinfo, fh)
|
|
|
data = self.revlog.compress(rawtext)
|
|
|
compresseddeltalen = deltalen = dist = len(data[1]) + len(data[0])
|
|
|
deltabase = chainbase = curr
|
|
|
snapshotdepth = 0
|
|
|
chainlen = 1
|
|
|
|
|
|
return _deltainfo(dist, deltalen, data, deltabase,
|
|
|
chainbase, chainlen, compresseddeltalen,
|
|
|
snapshotdepth)
|
|
|
|
|
|
def finddeltainfo(self, revinfo, fh):
|
|
|
"""Find an acceptable delta against a candidate revision
|
|
|
|
|
|
revinfo: information about the revision (instance of _revisioninfo)
|
|
|
fh: file handle to either the .i or the .d revlog file,
|
|
|
depending on whether it is inlined or not
|
|
|
|
|
|
Returns the first acceptable candidate revision, as ordered by
|
|
|
_candidategroups
|
|
|
|
|
|
If no suitable deltabase is found, we return delta info for a full
|
|
|
snapshot.
|
|
|
"""
|
|
|
if not revinfo.textlen:
|
|
|
return self._fullsnapshotinfo(fh, revinfo)
|
|
|
|
|
|
# no delta for flag processor revision (see "candelta" for why)
|
|
|
# not calling candelta since only one revision needs test, also to
|
|
|
# avoid overhead fetching flags again.
|
|
|
if revinfo.flags & REVIDX_RAWTEXT_CHANGING_FLAGS:
|
|
|
return self._fullsnapshotinfo(fh, revinfo)
|
|
|
|
|
|
cachedelta = revinfo.cachedelta
|
|
|
p1 = revinfo.p1
|
|
|
p2 = revinfo.p2
|
|
|
revlog = self.revlog
|
|
|
|
|
|
deltainfo = None
|
|
|
p1r, p2r = revlog.rev(p1), revlog.rev(p2)
|
|
|
groups = _candidategroups(self.revlog, revinfo.textlen,
|
|
|
p1r, p2r, cachedelta)
|
|
|
candidaterevs = next(groups)
|
|
|
while candidaterevs is not None:
|
|
|
nominateddeltas = []
|
|
|
if deltainfo is not None:
|
|
|
# if we already found a good delta,
|
|
|
# challenge it against refined candidates
|
|
|
nominateddeltas.append(deltainfo)
|
|
|
for candidaterev in candidaterevs:
|
|
|
candidatedelta = self._builddeltainfo(revinfo, candidaterev, fh)
|
|
|
if isgooddeltainfo(self.revlog, candidatedelta, revinfo):
|
|
|
nominateddeltas.append(candidatedelta)
|
|
|
if nominateddeltas:
|
|
|
deltainfo = min(nominateddeltas, key=lambda x: x.deltalen)
|
|
|
if deltainfo is not None:
|
|
|
candidaterevs = groups.send(deltainfo.base)
|
|
|
else:
|
|
|
candidaterevs = next(groups)
|
|
|
|
|
|
if deltainfo is None:
|
|
|
deltainfo = self._fullsnapshotinfo(fh, revinfo)
|
|
|
return deltainfo
|
|
|
|
