deltas.py
900 lines
| 30.5 KiB
| text/x-python
|
PythonLexer
|
r39366 | # revlogdeltas.py - Logic around delta computation for revlog | ||
# | ||||
# Copyright 2005-2007 Matt Mackall <mpm@selenic.com> | ||||
# Copyright 2018 Octobus <contact@octobus.net> | ||||
# | ||||
# This software may be used and distributed according to the terms of the | ||||
# GNU General Public License version 2 or any later version. | ||||
"""Helper class to compute deltas stored inside revlogs""" | ||||
from __future__ import absolute_import | ||||
|
r39529 | import collections | ||
|
r39366 | import heapq | ||
import struct | ||||
# import stuff from node for others to import from revlog | ||||
from ..node import ( | ||||
nullrev, | ||||
) | ||||
from ..i18n import _ | ||||
from .constants import ( | ||||
REVIDX_ISCENSORED, | ||||
REVIDX_RAWTEXT_CHANGING_FLAGS, | ||||
) | ||||
from ..thirdparty import ( | ||||
attr, | ||||
) | ||||
from .. import ( | ||||
error, | ||||
mdiff, | ||||
) | ||||
RevlogError = error.RevlogError | ||||
CensoredNodeError = error.CensoredNodeError | ||||
# maximum <delta-chain-data>/<revision-text-length> ratio | ||||
LIMIT_DELTA2TEXT = 2 | ||||
class _testrevlog(object): | ||||
"""minimalist fake revlog to use in doctests""" | ||||
def __init__(self, data, density=0.5, mingap=0): | ||||
"""data is an list of revision payload boundaries""" | ||||
self._data = data | ||||
self._srdensitythreshold = density | ||||
self._srmingapsize = mingap | ||||
def start(self, rev): | ||||
if rev == 0: | ||||
return 0 | ||||
return self._data[rev - 1] | ||||
def end(self, rev): | ||||
return self._data[rev] | ||||
def length(self, rev): | ||||
return self.end(rev) - self.start(rev) | ||||
def __len__(self): | ||||
return len(self._data) | ||||
def slicechunk(revlog, revs, deltainfo=None, targetsize=None): | ||||
"""slice revs to reduce the amount of unrelated data to be read from disk. | ||||
``revs`` is sliced into groups that should be read in one time. | ||||
Assume that revs are sorted. | ||||
The initial chunk is sliced until the overall density (payload/chunks-span | ||||
ratio) is above `revlog._srdensitythreshold`. No gap smaller than | ||||
`revlog._srmingapsize` is skipped. | ||||
If `targetsize` is set, no chunk larger than `targetsize` will be yield. | ||||
For consistency with other slicing choice, this limit won't go lower than | ||||
`revlog._srmingapsize`. | ||||
If individual revisions chunk are larger than this limit, they will still | ||||
be raised individually. | ||||
>>> revlog = _testrevlog([ | ||||
... 5, #00 (5) | ||||
... 10, #01 (5) | ||||
... 12, #02 (2) | ||||
... 12, #03 (empty) | ||||
... 27, #04 (15) | ||||
... 31, #05 (4) | ||||
... 31, #06 (empty) | ||||
... 42, #07 (11) | ||||
... 47, #08 (5) | ||||
... 47, #09 (empty) | ||||
... 48, #10 (1) | ||||
... 51, #11 (3) | ||||
... 74, #12 (23) | ||||
... 85, #13 (11) | ||||
... 86, #14 (1) | ||||
... 91, #15 (5) | ||||
... ]) | ||||
>>> list(slicechunk(revlog, list(range(16)))) | ||||
[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]] | ||||
>>> list(slicechunk(revlog, [0, 15])) | ||||
[[0], [15]] | ||||
>>> list(slicechunk(revlog, [0, 11, 15])) | ||||
[[0], [11], [15]] | ||||
>>> list(slicechunk(revlog, [0, 11, 13, 15])) | ||||
[[0], [11, 13, 15]] | ||||
>>> list(slicechunk(revlog, [1, 2, 3, 5, 8, 10, 11, 14])) | ||||
[[1, 2], [5, 8, 10, 11], [14]] | ||||
Slicing with a maximum chunk size | ||||
>>> list(slicechunk(revlog, [0, 11, 13, 15], targetsize=15)) | ||||
[[0], [11], [13], [15]] | ||||
>>> list(slicechunk(revlog, [0, 11, 13, 15], targetsize=20)) | ||||
[[0], [11], [13, 15]] | ||||
""" | ||||
if targetsize is not None: | ||||
targetsize = max(targetsize, revlog._srmingapsize) | ||||
# targetsize should not be specified when evaluating delta candidates: | ||||
# * targetsize is used to ensure we stay within specification when reading, | ||||
# * deltainfo is used to pick are good delta chain when writing. | ||||
if not (deltainfo is None or targetsize is None): | ||||
msg = 'cannot use `targetsize` with a `deltainfo`' | ||||
raise error.ProgrammingError(msg) | ||||
for chunk in _slicechunktodensity(revlog, revs, | ||||
deltainfo, | ||||
revlog._srdensitythreshold, | ||||
revlog._srmingapsize): | ||||
for subchunk in _slicechunktosize(revlog, chunk, targetsize): | ||||
yield subchunk | ||||
def _slicechunktosize(revlog, revs, targetsize=None): | ||||
"""slice revs to match the target size | ||||
This is intended to be used on chunk that density slicing selected by that | ||||
are still too large compared to the read garantee of revlog. This might | ||||
happens when "minimal gap size" interrupted the slicing or when chain are | ||||
built in a way that create large blocks next to each other. | ||||
>>> revlog = _testrevlog([ | ||||
... 3, #0 (3) | ||||
... 5, #1 (2) | ||||
... 6, #2 (1) | ||||
... 8, #3 (2) | ||||
... 8, #4 (empty) | ||||
... 11, #5 (3) | ||||
... 12, #6 (1) | ||||
... 13, #7 (1) | ||||
... 14, #8 (1) | ||||
... ]) | ||||
Cases where chunk is already small enough | ||||
>>> list(_slicechunktosize(revlog, [0], 3)) | ||||
[[0]] | ||||
>>> list(_slicechunktosize(revlog, [6, 7], 3)) | ||||
[[6, 7]] | ||||
>>> list(_slicechunktosize(revlog, [0], None)) | ||||
[[0]] | ||||
>>> list(_slicechunktosize(revlog, [6, 7], None)) | ||||
[[6, 7]] | ||||
cases where we need actual slicing | ||||
>>> list(_slicechunktosize(revlog, [0, 1], 3)) | ||||
[[0], [1]] | ||||
>>> list(_slicechunktosize(revlog, [1, 3], 3)) | ||||
[[1], [3]] | ||||
>>> list(_slicechunktosize(revlog, [1, 2, 3], 3)) | ||||
[[1, 2], [3]] | ||||
>>> list(_slicechunktosize(revlog, [3, 5], 3)) | ||||
[[3], [5]] | ||||
>>> list(_slicechunktosize(revlog, [3, 4, 5], 3)) | ||||
[[3], [5]] | ||||
>>> list(_slicechunktosize(revlog, [5, 6, 7, 8], 3)) | ||||
[[5], [6, 7, 8]] | ||||
>>> list(_slicechunktosize(revlog, [0, 1, 2, 3, 4, 5, 6, 7, 8], 3)) | ||||
[[0], [1, 2], [3], [5], [6, 7, 8]] | ||||
Case with too large individual chunk (must return valid chunk) | ||||
>>> list(_slicechunktosize(revlog, [0, 1], 2)) | ||||
[[0], [1]] | ||||
>>> list(_slicechunktosize(revlog, [1, 3], 1)) | ||||
[[1], [3]] | ||||
>>> list(_slicechunktosize(revlog, [3, 4, 5], 2)) | ||||
[[3], [5]] | ||||
""" | ||||
assert targetsize is None or 0 <= targetsize | ||||
if targetsize is None or segmentspan(revlog, revs) <= targetsize: | ||||
yield revs | ||||
return | ||||
startrevidx = 0 | ||||
startdata = revlog.start(revs[0]) | ||||
endrevidx = 0 | ||||
iterrevs = enumerate(revs) | ||||
next(iterrevs) # skip first rev. | ||||
for idx, r in iterrevs: | ||||
span = revlog.end(r) - startdata | ||||
if span <= targetsize: | ||||
endrevidx = idx | ||||
else: | ||||
chunk = _trimchunk(revlog, revs, startrevidx, endrevidx + 1) | ||||
if chunk: | ||||
yield chunk | ||||
startrevidx = idx | ||||
startdata = revlog.start(r) | ||||
endrevidx = idx | ||||
yield _trimchunk(revlog, revs, startrevidx) | ||||
def _slicechunktodensity(revlog, revs, deltainfo=None, targetdensity=0.5, | ||||
mingapsize=0): | ||||
"""slice revs to reduce the amount of unrelated data to be read from disk. | ||||
``revs`` is sliced into groups that should be read in one time. | ||||
Assume that revs are sorted. | ||||
``deltainfo`` is a _deltainfo instance of a revision that we would append | ||||
to the top of the revlog. | ||||
The initial chunk is sliced until the overall density (payload/chunks-span | ||||
ratio) is above `targetdensity`. No gap smaller than `mingapsize` is | ||||
skipped. | ||||
>>> revlog = _testrevlog([ | ||||
... 5, #00 (5) | ||||
... 10, #01 (5) | ||||
... 12, #02 (2) | ||||
... 12, #03 (empty) | ||||
... 27, #04 (15) | ||||
... 31, #05 (4) | ||||
... 31, #06 (empty) | ||||
... 42, #07 (11) | ||||
... 47, #08 (5) | ||||
... 47, #09 (empty) | ||||
... 48, #10 (1) | ||||
... 51, #11 (3) | ||||
... 74, #12 (23) | ||||
... 85, #13 (11) | ||||
... 86, #14 (1) | ||||
... 91, #15 (5) | ||||
... ]) | ||||
>>> list(_slicechunktodensity(revlog, list(range(16)))) | ||||
[[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15]] | ||||
>>> list(_slicechunktodensity(revlog, [0, 15])) | ||||
[[0], [15]] | ||||
>>> list(_slicechunktodensity(revlog, [0, 11, 15])) | ||||
[[0], [11], [15]] | ||||
>>> list(_slicechunktodensity(revlog, [0, 11, 13, 15])) | ||||
[[0], [11, 13, 15]] | ||||
>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14])) | ||||
[[1, 2], [5, 8, 10, 11], [14]] | ||||
>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14], | ||||
... mingapsize=20)) | ||||
[[1, 2, 3, 5, 8, 10, 11], [14]] | ||||
>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14], | ||||
... targetdensity=0.95)) | ||||
[[1, 2], [5], [8, 10, 11], [14]] | ||||
>>> list(_slicechunktodensity(revlog, [1, 2, 3, 5, 8, 10, 11, 14], | ||||
... targetdensity=0.95, mingapsize=12)) | ||||
[[1, 2], [5, 8, 10, 11], [14]] | ||||
""" | ||||
start = revlog.start | ||||
length = revlog.length | ||||
if len(revs) <= 1: | ||||
yield revs | ||||
return | ||||
nextrev = len(revlog) | ||||
nextoffset = revlog.end(nextrev - 1) | ||||
if deltainfo is None: | ||||
deltachainspan = segmentspan(revlog, revs) | ||||
chainpayload = sum(length(r) for r in revs) | ||||
else: | ||||
deltachainspan = deltainfo.distance | ||||
chainpayload = deltainfo.compresseddeltalen | ||||
if deltachainspan < mingapsize: | ||||
yield revs | ||||
return | ||||
readdata = deltachainspan | ||||
if deltachainspan: | ||||
density = chainpayload / float(deltachainspan) | ||||
else: | ||||
density = 1.0 | ||||
if density >= targetdensity: | ||||
yield revs | ||||
return | ||||
if deltainfo is not None and deltainfo.deltalen: | ||||
revs = list(revs) | ||||
revs.append(nextrev) | ||||
# Store the gaps in a heap to have them sorted by decreasing size | ||||
gapsheap = [] | ||||
heapq.heapify(gapsheap) | ||||
prevend = None | ||||
for i, rev in enumerate(revs): | ||||
if rev < nextrev: | ||||
revstart = start(rev) | ||||
revlen = length(rev) | ||||
else: | ||||
revstart = nextoffset | ||||
revlen = deltainfo.deltalen | ||||
# Skip empty revisions to form larger holes | ||||
if revlen == 0: | ||||
continue | ||||
if prevend is not None: | ||||
gapsize = revstart - prevend | ||||
# only consider holes that are large enough | ||||
if gapsize > mingapsize: | ||||
heapq.heappush(gapsheap, (-gapsize, i)) | ||||
prevend = revstart + revlen | ||||
# Collect the indices of the largest holes until the density is acceptable | ||||
indicesheap = [] | ||||
heapq.heapify(indicesheap) | ||||
while gapsheap and density < targetdensity: | ||||
oppgapsize, gapidx = heapq.heappop(gapsheap) | ||||
heapq.heappush(indicesheap, gapidx) | ||||
# the gap sizes are stored as negatives to be sorted decreasingly | ||||
# by the heap | ||||
readdata -= (-oppgapsize) | ||||
if readdata > 0: | ||||
density = chainpayload / float(readdata) | ||||
else: | ||||
density = 1.0 | ||||
# Cut the revs at collected indices | ||||
previdx = 0 | ||||
while indicesheap: | ||||
idx = heapq.heappop(indicesheap) | ||||
chunk = _trimchunk(revlog, revs, previdx, idx) | ||||
if chunk: | ||||
yield chunk | ||||
previdx = idx | ||||
chunk = _trimchunk(revlog, revs, previdx) | ||||
if chunk: | ||||
yield chunk | ||||
def _trimchunk(revlog, revs, startidx, endidx=None): | ||||
"""returns revs[startidx:endidx] without empty trailing revs | ||||
Doctest Setup | ||||
>>> revlog = _testrevlog([ | ||||
... 5, #0 | ||||
... 10, #1 | ||||
... 12, #2 | ||||
... 12, #3 (empty) | ||||
... 17, #4 | ||||
... 21, #5 | ||||
... 21, #6 (empty) | ||||
... ]) | ||||
Contiguous cases: | ||||
>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 0) | ||||
[0, 1, 2, 3, 4, 5] | ||||
>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 0, 5) | ||||
[0, 1, 2, 3, 4] | ||||
>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 0, 4) | ||||
[0, 1, 2] | ||||
>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 2, 4) | ||||
[2] | ||||
>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 3) | ||||
[3, 4, 5] | ||||
>>> _trimchunk(revlog, [0, 1, 2, 3, 4, 5, 6], 3, 5) | ||||
[3, 4] | ||||
Discontiguous cases: | ||||
>>> _trimchunk(revlog, [1, 3, 5, 6], 0) | ||||
[1, 3, 5] | ||||
>>> _trimchunk(revlog, [1, 3, 5, 6], 0, 2) | ||||
[1] | ||||
>>> _trimchunk(revlog, [1, 3, 5, 6], 1, 3) | ||||
[3, 5] | ||||
>>> _trimchunk(revlog, [1, 3, 5, 6], 1) | ||||
[3, 5] | ||||
""" | ||||
length = revlog.length | ||||
if endidx is None: | ||||
endidx = len(revs) | ||||
# If we have a non-emtpy delta candidate, there are nothing to trim | ||||
if revs[endidx - 1] < len(revlog): | ||||
# Trim empty revs at the end, except the very first revision of a chain | ||||
while (endidx > 1 | ||||
and endidx > startidx | ||||
and length(revs[endidx - 1]) == 0): | ||||
endidx -= 1 | ||||
return revs[startidx:endidx] | ||||
def segmentspan(revlog, revs, deltainfo=None): | ||||
"""Get the byte span of a segment of revisions | ||||
revs is a sorted array of revision numbers | ||||
>>> revlog = _testrevlog([ | ||||
... 5, #0 | ||||
... 10, #1 | ||||
... 12, #2 | ||||
... 12, #3 (empty) | ||||
... 17, #4 | ||||
... ]) | ||||
>>> segmentspan(revlog, [0, 1, 2, 3, 4]) | ||||
17 | ||||
>>> segmentspan(revlog, [0, 4]) | ||||
17 | ||||
>>> 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]) | ||||
|
r39367 | 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 | ||||
|
r39366 | @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 | ||||
|
r39373 | def _candidategroups(revlog, textlen, p1, p2, cachedelta): | ||
|
r39372 | """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. | ||||
|
r39370 | """ | ||
|
r39372 | # should we try to build a delta? | ||
if not (len(revlog) and revlog._storedeltachains): | ||||
|
r39533 | yield None | ||
|
r39372 | return | ||
|
r39373 | deltalength = revlog.length | ||
deltaparent = revlog.deltaparent | ||||
|
r39534 | good = None | ||
|
r39373 | |||
deltas_limit = textlen * LIMIT_DELTA2TEXT | ||||
|
r39372 | tested = set([nullrev]) | ||
|
r39535 | candidates = _refinedgroups(revlog, p1, p2, cachedelta) | ||
while True: | ||||
|
r39536 | temptative = candidates.send(good) | ||
|
r39535 | if temptative is None: | ||
break | ||||
|
r39373 | 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) | ||||
|
r39372 | if group: | ||
|
r39529 | # XXX: in the sparse revlog case, group can become large, | ||
# impacting performances. Some bounding or slicing mecanism | ||||
# would help to reduce this impact. | ||||
|
r39534 | good = yield tuple(group) | ||
|
r39533 | yield None | ||
|
r39372 | |||
|
r39529 | def _findsnapshots(revlog, cache, start_rev): | ||
"""find snapshot from start_rev to tip""" | ||||
deltaparent = revlog.deltaparent | ||||
|
r39531 | issnapshot = revlog.issnapshot | ||
|
r39529 | for rev in revlog.revs(start_rev): | ||
|
r39531 | if issnapshot(rev): | ||
cache[deltaparent(rev)].append(rev) | ||||
|
r39529 | |||
|
r39532 | def _refinedgroups(revlog, p1, p2, cachedelta): | ||
good = None | ||||
|
r39537 | # 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 | ||||
|
r39532 | for candidates in _rawgroups(revlog, p1, p2, cachedelta): | ||
good = yield candidates | ||||
if good is not None: | ||||
break | ||||
|
r39538 | |||
# 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,) | ||||
|
r39539 | # 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 | ||||
|
r39535 | # we have found nothing | ||
yield None | ||||
|
r39532 | |||
|
r39372 | 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. | ||||
|
r39370 | """ | ||
gdelta = revlog._generaldelta | ||||
|
r39528 | sparse = revlog._sparserevlog | ||
|
r39370 | curr = len(revlog) | ||
prev = curr - 1 | ||||
|
r39528 | deltachain = lambda rev: revlog._deltachain(rev)[0] | ||
|
r39370 | |||
|
r39372 | if gdelta: | ||
# exclude already lazy tested base if any | ||||
parents = [p for p in (p1, p2) if p != nullrev] | ||||
|
r39370 | |||
|
r39372 | 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 | ||||
|
r39370 | |||
|
r39528 | if sparse and parents: | ||
|
r39530 | snapshots = collections.defaultdict(list) # map: base-rev: snapshot-rev | ||
|
r39528 | # See if we can use an existing snapshot in the parent chains to use as | ||
# a base for a new intermediate-snapshot | ||||
|
r39530 | # | ||
# search for snapshot in parents delta chain | ||||
# map: snapshot-level: snapshot-rev | ||||
parents_snaps = collections.defaultdict(set) | ||||
|
r39528 | for p in parents: | ||
|
r39530 | for idx, s in enumerate(deltachain(p)): | ||
if not revlog.issnapshot(s): | ||||
break | ||||
parents_snaps[idx].add(s) | ||||
|
r39531 | snapfloor = min(parents_snaps[0]) + 1 | ||
_findsnapshots(revlog, snapshots, snapfloor) | ||||
|
r39530 | # 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 | ||||
|
r39531 | floor = None | ||
|
r39530 | for idx, snaps in sorted(parents_snaps.items(), reverse=True): | ||
|
r39531 | 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. | ||||
|
r39530 | yield tuple(sorted(snaps)) | ||
|
r39531 | floor = min(snaps) | ||
|
r39529 | # 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]) | ||||
|
r39528 | |||
|
r39372 | # other approach failed try against prev to hopefully save us a | ||
# fulltext. | ||||
yield (prev,) | ||||
|
r39370 | |||
|
r39366 | 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] | ||||
|
r39367 | fulltext = btext[0] = _textfromdelta(fh, revlog, baserev, delta, | ||
revinfo.p1, revinfo.p2, | ||||
revinfo.flags, revinfo.node) | ||||
return fulltext | ||||
|
r39366 | |||
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) | ||||
|
r39369 | 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) | ||||
|
r39366 | 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 | ||||
|
r39370 | _candidategroups | ||
|
r39369 | |||
If no suitable deltabase is found, we return delta info for a full | ||||
snapshot. | ||||
|
r39366 | """ | ||
if not revinfo.textlen: | ||||
|
r39369 | return self._fullsnapshotinfo(fh, revinfo) | ||
|
r39366 | |||
|
r39368 | # 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: | ||||
|
r39369 | return self._fullsnapshotinfo(fh, revinfo) | ||
|
r39368 | |||
|
r39366 | cachedelta = revinfo.cachedelta | ||
p1 = revinfo.p1 | ||||
p2 = revinfo.p2 | ||||
revlog = self.revlog | ||||
deltainfo = None | ||||
|
r39371 | p1r, p2r = revlog.rev(p1), revlog.rev(p2) | ||
|
r39373 | groups = _candidategroups(self.revlog, revinfo.textlen, | ||
p1r, p2r, cachedelta) | ||||
|
r39533 | candidaterevs = next(groups) | ||
while candidaterevs is not None: | ||||
|
r39366 | nominateddeltas = [] | ||
|
r39534 | if deltainfo is not None: | ||
# if we already found a good delta, | ||||
# challenge it against refined candidates | ||||
nominateddeltas.append(deltainfo) | ||||
|
r39366 | 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) | ||||
|
r39534 | if deltainfo is not None: | ||
candidaterevs = groups.send(deltainfo.base) | ||||
else: | ||||
candidaterevs = next(groups) | ||||
|
r39366 | |||
|
r39369 | if deltainfo is None: | ||
deltainfo = self._fullsnapshotinfo(fh, revinfo) | ||||
|
r39366 | return deltainfo | ||