view mercurial/manifest.py @ 1803:06e7447c7302

speed up hg log --patch

Changing dodiff to read the manifest/changelog for node1 before calling
repo.update allows us to take advantage of the revlog revision cache.

Before this patch and my previous "speed up hg log --debug" patch, when
using hg log -p to display three revisions (A, B and C), dodiff and
repo.changes would end up reading the manifests in this order:

 B A B A C B C B

With both patches, this order becomes:

 A A B B B B C C

(This considers only dodiff and repo.changes.  I'm not sure how other
parts of hg log enter the picture.)

The speed up will depend on the revisions being displayed.  (All
"before" times already have my previous "speed up hg log --debug" patch
applied.)

hg repo (tip = 414e81ae971f).  hg log -p
         before           after
real    0m50.981s       0m45.279s
user    0m47.930s       0m42.560s
sys     0m2.526s        0m2.523s
output size: 6917897 bytes

kernel repo (tip = 9d4e135960ed).  hg log -p -l64
         before           after
real    2m14.995s       1m45.025s
user    2m9.509s        1m33.900s
sys     0m3.663s        0m2.942s
output size: 31497621 bytes

same kernel repo.  hg log -p -l64 -r c84c2069592f:0
         before           after
real    1m48.045s       1m0.076s
user    1m44.094s       0m58.492s
sys     0m2.603s        0m1.103s
output size: 197983 bytes

c84c2069592f was the tip of a 10 day old kernel repo that I had lying
around and was where I first tested this patch.  For some weird
coincidence it's also a place where the patch makes a huge difference.

# manifest.py - manifest revision class for mercurial
#
# Copyright 2005 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import struct
from revlog import *
from i18n import gettext as _
from demandload import *
demandload(globals(), "bisect array")

class manifest(revlog):
    def __init__(self, opener):
        self.mapcache = None
        self.listcache = None
        revlog.__init__(self, opener, "00manifest.i", "00manifest.d")

    def read(self, node):
        if node == nullid: return {} # don't upset local cache
        if self.mapcache and self.mapcache[0] == node:
            return self.mapcache[1]
        text = self.revision(node)
        map = {}
        flag = {}
        self.listcache = array.array('c', text)
        lines = text.splitlines(1)
        for l in lines:
            (f, n) = l.split('\0')
            map[f] = bin(n[:40])
            flag[f] = (n[40:-1] == "x")
        self.mapcache = (node, map, flag)
        return map

    def readflags(self, node):
        if node == nullid: return {} # don't upset local cache
        if not self.mapcache or self.mapcache[0] != node:
            self.read(node)
        return self.mapcache[2]

    def diff(self, a, b):
        return mdiff.textdiff(str(a), str(b))

    def add(self, map, flags, transaction, link, p1=None, p2=None,
            changed=None):

        # returns a tuple (start, end).  If the string is found
        # m[start:end] are the line containing that string.  If start == end
        # the string was not found and they indicate the proper sorted 
        # insertion point.  This was taken from bisect_left, and modified
        # to find line start/end as it goes along.
        #
        # m should be a buffer or a string
        # s is a string
        #
        def manifestsearch(m, s, lo=0, hi=None):
            def advance(i, c):
                while i < lenm and m[i] != c:
                    i += 1
                return i
            lenm = len(m)
            if not hi:
                hi = lenm
            while lo < hi:
                mid = (lo + hi) // 2
                start = mid
                while start > 0 and m[start-1] != '\n':
                    start -= 1
                end = advance(start, '\0')
                if m[start:end] < s:
                    # we know that after the null there are 40 bytes of sha1
                    # this translates to the bisect lo = mid + 1
                    lo = advance(end + 40, '\n') + 1
                else:
                    # this translates to the bisect hi = mid
                    hi = start
            end = advance(lo, '\0')
            found = m[lo:end]
            if cmp(s, found) == 0: 
                # we know that after the null there are 40 bytes of sha1
                end = advance(end + 40, '\n')
                return (lo, end+1)
            else:
                return (lo, lo)

        # apply the changes collected during the bisect loop to our addlist
        # return a delta suitable for addrevision
        def addlistdelta(addlist, x):
            # start from the bottom up
            # so changes to the offsets don't mess things up.
            i = len(x)
            while i > 0:
                i -= 1
                start = x[i][0]
                end = x[i][1]
                if x[i][2]:
                    addlist[start:end] = array.array('c', x[i][2])
                else:
                    del addlist[start:end]
            return "".join([struct.pack(">lll", d[0], d[1], len(d[2])) + d[2] \
                            for d in x ])

        # if we're using the listcache, make sure it is valid and
        # parented by the same node we're diffing against
        if not changed or not self.listcache or not p1 or \
               self.mapcache[0] != p1:
            files = map.keys()
            files.sort()

            # if this is changed to support newlines in filenames,
            # be sure to check the templates/ dir again (especially *-raw.tmpl)
            text = ["%s\000%s%s\n" %
                            (f, hex(map[f]), flags[f] and "x" or '')
                            for f in files]
            self.listcache = array.array('c', "".join(text))
            cachedelta = None
        else:
            addlist = self.listcache

            # combine the changed lists into one list for sorting
            work = [[x, 0] for x in changed[0]]
            work[len(work):] = [[x, 1] for x in changed[1]]
            work.sort()

            delta = []
            dstart = None
            dend = None
            dline = [""]
            start = 0
            # zero copy representation of addlist as a buffer
            addbuf = buffer(addlist)

            # start with a readonly loop that finds the offset of
            # each line and creates the deltas
            for w in work:
                f = w[0]
                # bs will either be the index of the item or the insert point
                start, end = manifestsearch(addbuf, f, start)
                if w[1] == 0:
                    l = "%s\000%s%s\n" % (f, hex(map[f]),
                                          flags[f] and "x" or '')
                else:
                    l = ""
                if start == end and w[1] == 1:
                    # item we want to delete was not found, error out
                    raise AssertionError(
                            _("failed to remove %s from manifest\n") % f)
                if dstart != None and dstart <= start and dend >= start:
                    if dend < end:
                        dend = end
                    if l:
                        dline.append(l)
                else:
                    if dstart != None:
                        delta.append([dstart, dend, "".join(dline)])
                    dstart = start
                    dend = end
                    dline = [l]

            if dstart != None:
                delta.append([dstart, dend, "".join(dline)])
            # apply the delta to the addlist, and get a delta for addrevision
            cachedelta = addlistdelta(addlist, delta)

            # the delta is only valid if we've been processing the tip revision
            if self.mapcache[0] != self.tip():
                cachedelta = None
            self.listcache = addlist

        n = self.addrevision(buffer(self.listcache), transaction, link, p1,  \
                             p2, cachedelta)
        self.mapcache = (n, map, flags)

        return n