Mercurial > hg
view mercurial/pure/mpatch.py @ 26894:41957e50e109
hgweb: compute changeset parents and children for log pages lazily
Log pages, i.e. changelog, filelog and search results page computed children
and parents for each changeset shown, because spartan hgweb style shows this
info. Turns out, computing all this is heavy and also unnecessary for log pages
in all other hgweb styles.
Luckily, templates allow an easy way to do computations on demand: just pass
the heavy part of code as a callable and it will be only called when needed.
Here are some benchmarks on the mercurial repository (best of 3):
time wget http://127.0.0.1:8021/
before: 0m0.050s
after: 0m0.040s
time wget http://127.0.0.1:8021/?revcount=960
before: 0m1.164s
after: 0m0.389s
time wget http://127.0.0.1:8021/log/tip/mercurial/commands.py
before: 0m0.047s
after: 0m0.042s
time wget http://127.0.0.1:8021/log/tip/mercurial/commands.py?revcount=960
before: 0m0.830s
after: 0m0.434s
author | Anton Shestakov <av6@dwimlabs.net> |
---|---|
date | Tue, 10 Nov 2015 23:02:59 +0800 |
parents | 525fdb738975 |
children | 9a17576103a4 |
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# mpatch.py - Python implementation of mpatch.c # # Copyright 2009 Matt Mackall <mpm@selenic.com> and others # # This software may be used and distributed according to the terms of the # GNU General Public License version 2 or any later version. import struct try: from cStringIO import StringIO except ImportError: from StringIO import StringIO # This attempts to apply a series of patches in time proportional to # the total size of the patches, rather than patches * len(text). This # means rather than shuffling strings around, we shuffle around # pointers to fragments with fragment lists. # # When the fragment lists get too long, we collapse them. To do this # efficiently, we do all our operations inside a buffer created by # mmap and simply use memmove. This avoids creating a bunch of large # temporary string buffers. def patches(a, bins): if not bins: return a plens = [len(x) for x in bins] pl = sum(plens) bl = len(a) + pl tl = bl + bl + pl # enough for the patches and two working texts b1, b2 = 0, bl if not tl: return a m = StringIO() def move(dest, src, count): """move count bytes from src to dest The file pointer is left at the end of dest. """ m.seek(src) buf = m.read(count) m.seek(dest) m.write(buf) # load our original text m.write(a) frags = [(len(a), b1)] # copy all the patches into our segment so we can memmove from them pos = b2 + bl m.seek(pos) for p in bins: m.write(p) def pull(dst, src, l): # pull l bytes from src while l: f = src.pop() if f[0] > l: # do we need to split? src.append((f[0] - l, f[1] + l)) dst.append((l, f[1])) return dst.append(f) l -= f[0] def collect(buf, list): start = buf for l, p in reversed(list): move(buf, p, l) buf += l return (buf - start, start) for plen in plens: # if our list gets too long, execute it if len(frags) > 128: b2, b1 = b1, b2 frags = [collect(b1, frags)] new = [] end = pos + plen last = 0 while pos < end: m.seek(pos) p1, p2, l = struct.unpack(">lll", m.read(12)) pull(new, frags, p1 - last) # what didn't change pull([], frags, p2 - p1) # what got deleted new.append((l, pos + 12)) # what got added pos += l + 12 last = p2 frags.extend(reversed(new)) # what was left at the end t = collect(b2, frags) m.seek(t[1]) return m.read(t[0]) def patchedsize(orig, delta): outlen, last, bin = 0, 0, 0 binend = len(delta) data = 12 while data <= binend: decode = delta[bin:bin + 12] start, end, length = struct.unpack(">lll", decode) if start > end: break bin = data + length data = bin + 12 outlen += start - last last = end outlen += length if bin != binend: raise ValueError("patch cannot be decoded") outlen += orig - last return outlen