Mercurial > hg
view mercurial/simplemerge.py @ 30212:260af19891f2
changegroup: increase write buffer size to 128k
By default, Python defers to the operating system for choosing the
default buffer size on opened files. On my Linux machine, the default
is 4k, which is really small for 2016.
This patch bumps the write buffer size when writing
changegroups/bundles to 128k. This matches the 128k read buffer
we already use on revlogs.
It's worth noting that this only impacts when writing to an explicit
file (such as during `hg bundle`). Buffers when writing to bundle
files via the repo vfs or to a temporary file are not impacted.
When producing a none-v2 bundle file of the mozilla-unified repository,
this change caused the number of write() system calls to drop from
952,449 to 29,788. After this change, the most frequent system
calls are fstat(), read(), lseek(), and open(). There were
2,523,672 system calls after this patch (so a net decrease of
~950k is statistically significant).
This change shows no performance change on my system. But I have a
high-end system with a fast SSD. It is quite possible this change
will have a significant impact on network file systems, where
extra network round trips due to excessive I/O system calls could
introduce significant latency.
author | Gregory Szorc <gregory.szorc@gmail.com> |
---|---|
date | Sun, 16 Oct 2016 13:35:23 -0700 |
parents | c3e9269d9602 |
children | 5f7d13d3bd4d |
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# Copyright (C) 2004, 2005 Canonical Ltd # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation; either version 2 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program; if not, see <http://www.gnu.org/licenses/>. # mbp: "you know that thing where cvs gives you conflict markers?" # s: "i hate that." from __future__ import absolute_import import os import sys from .i18n import _ from . import ( error, mdiff, scmutil, util, ) class CantReprocessAndShowBase(Exception): pass def intersect(ra, rb): """Given two ranges return the range where they intersect or None. >>> intersect((0, 10), (0, 6)) (0, 6) >>> intersect((0, 10), (5, 15)) (5, 10) >>> intersect((0, 10), (10, 15)) >>> intersect((0, 9), (10, 15)) >>> intersect((0, 9), (7, 15)) (7, 9) """ assert ra[0] <= ra[1] assert rb[0] <= rb[1] sa = max(ra[0], rb[0]) sb = min(ra[1], rb[1]) if sa < sb: return sa, sb else: return None def compare_range(a, astart, aend, b, bstart, bend): """Compare a[astart:aend] == b[bstart:bend], without slicing. """ if (aend - astart) != (bend - bstart): return False for ia, ib in zip(xrange(astart, aend), xrange(bstart, bend)): if a[ia] != b[ib]: return False else: return True class Merge3Text(object): """3-way merge of texts. Given strings BASE, OTHER, THIS, tries to produce a combined text incorporating the changes from both BASE->OTHER and BASE->THIS.""" def __init__(self, basetext, atext, btext, base=None, a=None, b=None): self.basetext = basetext self.atext = atext self.btext = btext if base is None: base = mdiff.splitnewlines(basetext) if a is None: a = mdiff.splitnewlines(atext) if b is None: b = mdiff.splitnewlines(btext) self.base = base self.a = a self.b = b def merge_lines(self, name_a=None, name_b=None, name_base=None, start_marker='<<<<<<<', mid_marker='=======', end_marker='>>>>>>>', base_marker=None, localorother=None, minimize=False): """Return merge in cvs-like form. """ self.conflicts = False newline = '\n' if len(self.a) > 0: if self.a[0].endswith('\r\n'): newline = '\r\n' elif self.a[0].endswith('\r'): newline = '\r' if name_a and start_marker: start_marker = start_marker + ' ' + name_a if name_b and end_marker: end_marker = end_marker + ' ' + name_b if name_base and base_marker: base_marker = base_marker + ' ' + name_base merge_regions = self.merge_regions() if minimize: merge_regions = self.minimize(merge_regions) for t in merge_regions: what = t[0] if what == 'unchanged': for i in range(t[1], t[2]): yield self.base[i] elif what == 'a' or what == 'same': for i in range(t[1], t[2]): yield self.a[i] elif what == 'b': for i in range(t[1], t[2]): yield self.b[i] elif what == 'conflict': if localorother == 'local': for i in range(t[3], t[4]): yield self.a[i] elif localorother == 'other': for i in range(t[5], t[6]): yield self.b[i] else: self.conflicts = True if start_marker is not None: yield start_marker + newline for i in range(t[3], t[4]): yield self.a[i] if base_marker is not None: yield base_marker + newline for i in range(t[1], t[2]): yield self.base[i] if mid_marker is not None: yield mid_marker + newline for i in range(t[5], t[6]): yield self.b[i] if end_marker is not None: yield end_marker + newline else: raise ValueError(what) def merge_groups(self): """Yield sequence of line groups. Each one is a tuple: 'unchanged', lines Lines unchanged from base 'a', lines Lines taken from a 'same', lines Lines taken from a (and equal to b) 'b', lines Lines taken from b 'conflict', base_lines, a_lines, b_lines Lines from base were changed to either a or b and conflict. """ for t in self.merge_regions(): what = t[0] if what == 'unchanged': yield what, self.base[t[1]:t[2]] elif what == 'a' or what == 'same': yield what, self.a[t[1]:t[2]] elif what == 'b': yield what, self.b[t[1]:t[2]] elif what == 'conflict': yield (what, self.base[t[1]:t[2]], self.a[t[3]:t[4]], self.b[t[5]:t[6]]) else: raise ValueError(what) def merge_regions(self): """Return sequences of matching and conflicting regions. This returns tuples, where the first value says what kind we have: 'unchanged', start, end Take a region of base[start:end] 'same', astart, aend b and a are different from base but give the same result 'a', start, end Non-clashing insertion from a[start:end] 'conflict', zstart, zend, astart, aend, bstart, bend Conflict between a and b, with z as common ancestor Method is as follows: The two sequences align only on regions which match the base and both descendants. These are found by doing a two-way diff of each one against the base, and then finding the intersections between those regions. These "sync regions" are by definition unchanged in both and easily dealt with. The regions in between can be in any of three cases: conflicted, or changed on only one side. """ # section a[0:ia] has been disposed of, etc iz = ia = ib = 0 for region in self.find_sync_regions(): zmatch, zend, amatch, aend, bmatch, bend = region #print 'match base [%d:%d]' % (zmatch, zend) matchlen = zend - zmatch assert matchlen >= 0 assert matchlen == (aend - amatch) assert matchlen == (bend - bmatch) len_a = amatch - ia len_b = bmatch - ib len_base = zmatch - iz assert len_a >= 0 assert len_b >= 0 assert len_base >= 0 #print 'unmatched a=%d, b=%d' % (len_a, len_b) if len_a or len_b: # try to avoid actually slicing the lists equal_a = compare_range(self.a, ia, amatch, self.base, iz, zmatch) equal_b = compare_range(self.b, ib, bmatch, self.base, iz, zmatch) same = compare_range(self.a, ia, amatch, self.b, ib, bmatch) if same: yield 'same', ia, amatch elif equal_a and not equal_b: yield 'b', ib, bmatch elif equal_b and not equal_a: yield 'a', ia, amatch elif not equal_a and not equal_b: yield 'conflict', iz, zmatch, ia, amatch, ib, bmatch else: raise AssertionError("can't handle a=b=base but unmatched") ia = amatch ib = bmatch iz = zmatch # if the same part of the base was deleted on both sides # that's OK, we can just skip it. if matchlen > 0: assert ia == amatch assert ib == bmatch assert iz == zmatch yield 'unchanged', zmatch, zend iz = zend ia = aend ib = bend def minimize(self, merge_regions): """Trim conflict regions of lines where A and B sides match. Lines where both A and B have made the same changes at the begining or the end of each merge region are eliminated from the conflict region and are instead considered the same. """ for region in merge_regions: if region[0] != "conflict": yield region continue issue, z1, z2, a1, a2, b1, b2 = region alen = a2 - a1 blen = b2 - b1 # find matches at the front ii = 0 while ii < alen and ii < blen and \ self.a[a1 + ii] == self.b[b1 + ii]: ii += 1 startmatches = ii # find matches at the end ii = 0 while ii < alen and ii < blen and \ self.a[a2 - ii - 1] == self.b[b2 - ii - 1]: ii += 1 endmatches = ii if startmatches > 0: yield 'same', a1, a1 + startmatches yield ('conflict', z1, z2, a1 + startmatches, a2 - endmatches, b1 + startmatches, b2 - endmatches) if endmatches > 0: yield 'same', a2 - endmatches, a2 def find_sync_regions(self): """Return a list of sync regions, where both descendants match the base. Generates a list of (base1, base2, a1, a2, b1, b2). There is always a zero-length sync region at the end of all the files. """ ia = ib = 0 amatches = mdiff.get_matching_blocks(self.basetext, self.atext) bmatches = mdiff.get_matching_blocks(self.basetext, self.btext) len_a = len(amatches) len_b = len(bmatches) sl = [] while ia < len_a and ib < len_b: abase, amatch, alen = amatches[ia] bbase, bmatch, blen = bmatches[ib] # there is an unconflicted block at i; how long does it # extend? until whichever one ends earlier. i = intersect((abase, abase + alen), (bbase, bbase + blen)) if i: intbase = i[0] intend = i[1] intlen = intend - intbase # found a match of base[i[0], i[1]]; this may be less than # the region that matches in either one assert intlen <= alen assert intlen <= blen assert abase <= intbase assert bbase <= intbase asub = amatch + (intbase - abase) bsub = bmatch + (intbase - bbase) aend = asub + intlen bend = bsub + intlen assert self.base[intbase:intend] == self.a[asub:aend], \ (self.base[intbase:intend], self.a[asub:aend]) assert self.base[intbase:intend] == self.b[bsub:bend] sl.append((intbase, intend, asub, aend, bsub, bend)) # advance whichever one ends first in the base text if (abase + alen) < (bbase + blen): ia += 1 else: ib += 1 intbase = len(self.base) abase = len(self.a) bbase = len(self.b) sl.append((intbase, intbase, abase, abase, bbase, bbase)) return sl def find_unconflicted(self): """Return a list of ranges in base that are not conflicted.""" am = mdiff.get_matching_blocks(self.basetext, self.atext) bm = mdiff.get_matching_blocks(self.basetext, self.btext) unc = [] while am and bm: # there is an unconflicted block at i; how long does it # extend? until whichever one ends earlier. a1 = am[0][0] a2 = a1 + am[0][2] b1 = bm[0][0] b2 = b1 + bm[0][2] i = intersect((a1, a2), (b1, b2)) if i: unc.append(i) if a2 < b2: del am[0] else: del bm[0] return unc def simplemerge(ui, local, base, other, **opts): def readfile(filename): f = open(filename, "rb") text = f.read() f.close() if util.binary(text): msg = _("%s looks like a binary file.") % filename if not opts.get('quiet'): ui.warn(_('warning: %s\n') % msg) if not opts.get('text'): raise error.Abort(msg) return text mode = opts.get('mode','merge') if mode == 'union': name_a = None name_b = None name_base = None else: name_a = local name_b = other name_base = None labels = opts.get('label', []) if len(labels) > 0: name_a = labels[0] if len(labels) > 1: name_b = labels[1] if len(labels) > 2: name_base = labels[2] if len(labels) > 3: raise error.Abort(_("can only specify three labels.")) try: localtext = readfile(local) basetext = readfile(base) othertext = readfile(other) except error.Abort: return 1 local = os.path.realpath(local) if not opts.get('print'): opener = scmutil.opener(os.path.dirname(local)) out = opener(os.path.basename(local), "w", atomictemp=True) else: out = sys.stdout m3 = Merge3Text(basetext, localtext, othertext) extrakwargs = { "localorother": opts.get("localorother", None), 'minimize': True, } if mode == 'union': extrakwargs['start_marker'] = None extrakwargs['mid_marker'] = None extrakwargs['end_marker'] = None elif name_base is not None: extrakwargs['base_marker'] = '|||||||' extrakwargs['name_base'] = name_base extrakwargs['minimize'] = False for line in m3.merge_lines(name_a=name_a, name_b=name_b, **extrakwargs): out.write(line) if not opts.get('print'): out.close() if m3.conflicts and not mode == 'union': return 1