Mercurial > hg
view mercurial/pure/mpatch.py @ 24071:184a2f6f40da
bundle2.unbundle20: add compressed() method
Bundlerepo uses the compressed() method to determine whether it should write
an uncompressed temporary file. Since we don't support compressed bundle2 files
at the moment, make this method return true.
author | Eric Sumner <ericsumner@fb.com> |
---|---|
date | Thu, 05 Feb 2015 15:56:50 -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