Mercurial > hg
view mercurial/pure/mpatch.py @ 20906:7a634b34fc91
wireproto: add decorator for wire protocol command
Move move in the same direction we took for command line commands. each wire
protocol function will be decorated with its name and arguments.
Beside beside easier to read, this open the road to easily adding more metadata
(like security level or return type)
author | Pierre-Yves David <pierre-yves.david@fb.com> |
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date | Fri, 28 Mar 2014 14:30:11 -0700 |
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