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# revlog.py - storage back-end for mercurial
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#
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# This provides efficient delta storage with O(1) retrieve and append
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# and O(changes) merge between branches
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#
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# Copyright 2005 Matt Mackall <mpm@selenic.com>
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#
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# This software may be used and distributed according to the terms
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# of the GNU General Public License, incorporated herein by reference.
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import zlib, struct, sha, binascii, heapq
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from mercurial import mdiff
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def hex(node): return binascii.hexlify(node)
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def bin(node): return binascii.unhexlify(node)
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def short(node): return hex(node[:6])
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def compress(text):
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if not text: return text
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if len(text) < 44:
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if text[0] == '\0': return text
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return 'u' + text
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bin = zlib.compress(text)
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if len(bin) > len(text):
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if text[0] == '\0': return text
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return 'u' + text
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return bin
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def decompress(bin):
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if not bin: return bin
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t = bin[0]
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if t == '\0': return bin
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if t == 'x': return zlib.decompress(bin)
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if t == 'u': return bin[1:]
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raise "unknown compression type %s" % t
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def hash(text, p1, p2):
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l = [p1, p2]
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l.sort()
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s = sha.new(l[0])
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s.update(l[1])
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s.update(text)
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return s.digest()
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nullid = "\0" * 20
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indexformat = ">4l20s20s20s"
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class lazyparser:
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def __init__(self, data, revlog):
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self.data = data
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self.s = struct.calcsize(indexformat)
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self.l = len(data)/self.s
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self.index = [None] * self.l
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self.map = {nullid: -1}
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self.all = 0
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self.revlog = revlog
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def load(self, pos=None):
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if self.all: return
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if pos is not None:
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block = pos / 1000
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i = block * 1000
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end = min(self.l, i + 1000)
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else:
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self.all = 1
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i = 0
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end = self.l
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self.revlog.index = self.index
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self.revlog.nodemap = self.map
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while i < end:
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d = self.data[i * self.s: (i + 1) * self.s]
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e = struct.unpack(indexformat, d)
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self.index[i] = e
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self.map[e[6]] = i
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i += 1
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class lazyindex:
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def __init__(self, parser):
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self.p = parser
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def __len__(self):
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return len(self.p.index)
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def load(self, pos):
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self.p.load(pos)
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return self.p.index[pos]
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def __getitem__(self, pos):
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return self.p.index[pos] or self.load(pos)
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def append(self, e):
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self.p.index.append(e)
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class lazymap:
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def __init__(self, parser):
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self.p = parser
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def load(self, key):
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if self.p.all: return
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n = self.p.data.find(key)
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if n < 0: raise KeyError("node " + hex(key))
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pos = n / self.p.s
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self.p.load(pos)
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def __contains__(self, key):
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self.p.load()
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return key in self.p.map
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def __iter__(self):
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yield nullid
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for i in xrange(self.p.l):
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try:
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yield self.p.index[i][6]
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except:
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self.p.load(i)
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yield self.p.index[i][6]
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def __getitem__(self, key):
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try:
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return self.p.map[key]
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except KeyError:
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try:
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self.load(key)
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return self.p.map[key]
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except KeyError:
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raise KeyError("node " + hex(key))
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def __setitem__(self, key, val):
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self.p.map[key] = val
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class revlog:
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def __init__(self, opener, indexfile, datafile):
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self.indexfile = indexfile
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self.datafile = datafile
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self.opener = opener
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self.cache = None
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try:
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i = self.opener(self.indexfile).read()
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except IOError:
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i = ""
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if len(i) > 10000:
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# big index, let's parse it on demand
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parser = lazyparser(i, self)
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self.index = lazyindex(parser)
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self.nodemap = lazymap(parser)
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else:
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s = struct.calcsize(indexformat)
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l = len(i) / s
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self.index = [None] * l
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m = [None] * l
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n = 0
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for f in xrange(0, len(i), s):
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# offset, size, base, linkrev, p1, p2, nodeid
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e = struct.unpack(indexformat, i[f:f + s])
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m[n] = (e[6], n)
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self.index[n] = e
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n += 1
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self.nodemap = dict(m)
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self.nodemap[nullid] = -1
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def tip(self): return self.node(len(self.index) - 1)
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def count(self): return len(self.index)
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def node(self, rev): return (rev < 0) and nullid or self.index[rev][6]
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def rev(self, node): return self.nodemap[node]
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def linkrev(self, node): return self.index[self.nodemap[node]][3]
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def parents(self, node):
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if node == nullid: return (nullid, nullid)
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return self.index[self.nodemap[node]][4:6]
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def start(self, rev): return self.index[rev][0]
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def length(self, rev): return self.index[rev][1]
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def end(self, rev): return self.start(rev) + self.length(rev)
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def base(self, rev): return self.index[rev][2]
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def heads(self):
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p = {}
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h = []
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for r in range(self.count() - 1, -1, -1):
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n = self.node(r)
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if n not in p:
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h.append(n)
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for pn in self.parents(n):
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p[pn] = 1
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return h
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def children(self, node):
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c = []
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p = self.rev(node)
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for r in range(p + 1, self.count()):
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n = self.node(r)
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for pn in self.parents(n):
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if pn == p:
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c.append(p)
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continue
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elif pn == nullid:
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continue
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return c
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def lookup(self, id):
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try:
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rev = int(id)
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if str(rev) != id: raise ValueError
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if rev < 0: rev = self.count() + rev
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if rev < 0 or rev >= self.count(): raise ValueError
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return self.node(rev)
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except (ValueError, OverflowError):
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c = []
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for n in self.nodemap:
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if hex(n).startswith(id):
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c.append(n)
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if len(c) > 1: raise KeyError("Ambiguous identifier")
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if len(c) < 1: raise KeyError("No match found")
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return c[0]
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return None
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def diff(self, a, b):
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return mdiff.textdiff(a, b)
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def patches(self, t, pl):
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return mdiff.patches(t, pl)
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def delta(self, node):
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r = self.rev(node)
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b = self.base(r)
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if r == b:
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return self.diff(self.revision(self.node(r - 1)),
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self.revision(node))
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else:
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f = self.opener(self.datafile)
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f.seek(self.start(r))
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data = f.read(self.length(r))
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return decompress(data)
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def revision(self, node):
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if node == nullid: return ""
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if self.cache and self.cache[0] == node: return self.cache[2]
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text = None
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rev = self.rev(node)
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start, length, base, link, p1, p2, node = self.index[rev]
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end = start + length
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if base != rev: start = self.start(base)
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if self.cache and self.cache[1] >= base and self.cache[1] < rev:
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base = self.cache[1]
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start = self.start(base + 1)
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text = self.cache[2]
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last = 0
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f = self.opener(self.datafile)
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f.seek(start)
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data = f.read(end - start)
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if text is None:
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last = self.length(base)
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text = decompress(data[:last])
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bins = []
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for r in xrange(base + 1, rev + 1):
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s = self.length(r)
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bins.append(decompress(data[last:last + s]))
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last = last + s
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text = mdiff.patches(text, bins)
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if node != hash(text, p1, p2):
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raise IOError("integrity check failed on %s:%d"
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% (self.datafile, rev))
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self.cache = (node, rev, text)
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return text
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def addrevision(self, text, transaction, link, p1=None, p2=None, d=None):
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if text is None: text = ""
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if p1 is None: p1 = self.tip()
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if p2 is None: p2 = nullid
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node = hash(text, p1, p2)
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if node in self.nodemap:
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return node
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n = self.count()
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t = n - 1
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if n:
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base = self.base(t)
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start = self.start(base)
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end = self.end(t)
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if not d:
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prev = self.revision(self.tip())
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d = self.diff(prev, text)
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data = compress(d)
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dist = end - start + len(data)
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# full versions are inserted when the needed deltas
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# become comparable to the uncompressed text
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if not n or dist > len(text) * 2:
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data = compress(text)
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base = n
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else:
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base = self.base(t)
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offset = 0
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if t >= 0:
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offset = self.end(t)
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e = (offset, len(data), base, link, p1, p2, node)
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self.index.append(e)
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self.nodemap[node] = n
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entry = struct.pack(indexformat, *e)
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transaction.add(self.datafile, e[0])
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self.opener(self.datafile, "a").write(data)
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transaction.add(self.indexfile, n * len(entry))
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self.opener(self.indexfile, "a").write(entry)
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self.cache = (node, n, text)
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return node
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def ancestor(self, a, b):
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# calculate the distance of every node from root
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dist = {nullid: 0}
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for i in xrange(self.count()):
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n = self.node(i)
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p1, p2 = self.parents(n)
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dist[n] = max(dist[p1], dist[p2]) + 1
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# traverse ancestors in order of decreasing distance from root
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def ancestors(node):
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# we store negative distances because heap returns smallest member
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h = [(-dist[node], node)]
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seen = {}
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earliest = self.count()
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while h:
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d, n = heapq.heappop(h)
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if n not in seen:
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seen[n] = 1
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r = self.rev(n)
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yield (-d, r, n)
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for p in self.parents(n):
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heapq.heappush(h, (-dist[p], p))
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x = ancestors(a)
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y = ancestors(b)
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lx = x.next()
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ly = y.next()
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# increment each ancestor list until it is closer to root than
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# the other, or they match
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while 1:
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if lx == ly:
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return lx[2]
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elif lx < ly:
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ly = y.next()
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elif lx > ly:
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lx = x.next()
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def group(self, linkmap):
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# given a list of changeset revs, return a set of deltas and
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# metadata corresponding to nodes. the first delta is
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# parent(nodes[0]) -> nodes[0] the receiver is guaranteed to
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# have this parent as it has all history before these
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# changesets. parent is parent[0]
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revs = []
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needed = {}
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# find file nodes/revs that match changeset revs
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for i in xrange(0, self.count()):
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if self.index[i][3] in linkmap:
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revs.append(i)
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needed[i] = 1
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# if we don't have any revisions touched by these changesets, bail
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if not revs:
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yield struct.pack(">l", 0)
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return
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# add the parent of the first rev
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p = self.parents(self.node(revs[0]))[0]
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revs.insert(0, self.rev(p))
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# for each delta that isn't contiguous in the log, we need to
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# reconstruct the base, reconstruct the result, and then
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# calculate the delta. We also need to do this where we've
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# stored a full version and not a delta
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for i in xrange(0, len(revs) - 1):
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a, b = revs[i], revs[i + 1]
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if a + 1 != b or self.base(b) == b:
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for j in xrange(self.base(a), a + 1):
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needed[j] = 1
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for j in xrange(self.base(b), b + 1):
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needed[j] = 1
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# calculate spans to retrieve from datafile
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needed = needed.keys()
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needed.sort()
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spans = []
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oo = -1
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ol = 0
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for n in needed:
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if n < 0: continue
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o = self.start(n)
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l = self.length(n)
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if oo + ol == o: # can we merge with the previous?
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nl = spans[-1][2]
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nl.append((n, l))
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ol += l
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spans[-1] = (oo, ol, nl)
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else:
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oo = o
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ol = l
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spans.append((oo, ol, [(n, l)]))
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# read spans in, divide up chunks
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chunks = {}
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for span in spans:
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# we reopen the file for each span to make http happy for now
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f = self.opener(self.datafile)
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f.seek(span[0])
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data = f.read(span[1])
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# divide up the span
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pos = 0
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for r, l in span[2]:
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chunks[r] = decompress(data[pos: pos + l])
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pos += l
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# helper to reconstruct intermediate versions
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def construct(text, base, rev):
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bins = [chunks[r] for r in xrange(base + 1, rev + 1)]
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return mdiff.patches(text, bins)
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# build deltas
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deltas = []
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for d in xrange(0, len(revs) - 1):
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a, b = revs[d], revs[d + 1]
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n = self.node(b)
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# do we need to construct a new delta?
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if a + 1 != b or self.base(b) == b:
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if a >= 0:
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base = self.base(a)
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ta = chunks[self.base(a)]
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ta = construct(ta, base, a)
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else:
|
|
|
ta = ""
|
|
|
|
|
|
base = self.base(b)
|
|
|
if a > base:
|
|
|
base = a
|
|
|
tb = ta
|
|
|
else:
|
|
|
tb = chunks[self.base(b)]
|
|
|
tb = construct(tb, base, b)
|
|
|
d = self.diff(ta, tb)
|
|
|
else:
|
|
|
d = chunks[b]
|
|
|
|
|
|
p = self.parents(n)
|
|
|
meta = n + p[0] + p[1] + linkmap[self.linkrev(n)]
|
|
|
l = struct.pack(">l", len(meta) + len(d) + 4)
|
|
|
yield l
|
|
|
yield meta
|
|
|
yield d
|
|
|
|
|
|
yield struct.pack(">l", 0)
|
|
|
|
|
|
def addgroup(self, revs, linkmapper, transaction, unique = 0):
|
|
|
# given a set of deltas, add them to the revision log. the
|
|
|
# first delta is against its parent, which should be in our
|
|
|
# log, the rest are against the previous delta.
|
|
|
|
|
|
# track the base of the current delta log
|
|
|
r = self.count()
|
|
|
t = r - 1
|
|
|
node = nullid
|
|
|
|
|
|
base = prev = -1
|
|
|
start = end = 0
|
|
|
if r:
|
|
|
start = self.start(self.base(t))
|
|
|
end = self.end(t)
|
|
|
measure = self.length(self.base(t))
|
|
|
base = self.base(t)
|
|
|
prev = self.tip()
|
|
|
|
|
|
transaction.add(self.datafile, end)
|
|
|
transaction.add(self.indexfile, r * struct.calcsize(indexformat))
|
|
|
dfh = self.opener(self.datafile, "a")
|
|
|
ifh = self.opener(self.indexfile, "a")
|
|
|
|
|
|
# loop through our set of deltas
|
|
|
chain = None
|
|
|
for chunk in revs:
|
|
|
node, p1, p2, cs = struct.unpack("20s20s20s20s", chunk[:80])
|
|
|
link = linkmapper(cs)
|
|
|
if node in self.nodemap:
|
|
|
# this can happen if two branches make the same change
|
|
|
if unique:
|
|
|
raise "already have %s" % hex(node[:4])
|
|
|
continue
|
|
|
delta = chunk[80:]
|
|
|
|
|
|
if not chain:
|
|
|
# retrieve the parent revision of the delta chain
|
|
|
chain = p1
|
|
|
if not chain in self.nodemap:
|
|
|
raise "unknown base %s" % short(chain[:4])
|
|
|
|
|
|
# full versions are inserted when the needed deltas become
|
|
|
# comparable to the uncompressed text or when the previous
|
|
|
# version is not the one we have a delta against. We use
|
|
|
# the size of the previous full rev as a proxy for the
|
|
|
# current size.
|
|
|
|
|
|
if chain == prev:
|
|
|
cdelta = compress(delta)
|
|
|
|
|
|
if chain != prev or (end - start + len(cdelta)) > measure * 2:
|
|
|
# flush our writes here so we can read it in revision
|
|
|
dfh.flush()
|
|
|
ifh.flush()
|
|
|
text = self.revision(chain)
|
|
|
text = self.patches(text, [delta])
|
|
|
chk = self.addrevision(text, transaction, link, p1, p2)
|
|
|
if chk != node:
|
|
|
raise "consistency error adding group"
|
|
|
measure = len(text)
|
|
|
else:
|
|
|
e = (end, len(cdelta), self.base(t), link, p1, p2, node)
|
|
|
self.index.append(e)
|
|
|
self.nodemap[node] = r
|
|
|
dfh.write(cdelta)
|
|
|
ifh.write(struct.pack(indexformat, *e))
|
|
|
|
|
|
t, r, chain, prev = r, r + 1, node, node
|
|
|
start = self.start(self.base(t))
|
|
|
end = self.end(t)
|
|
|
|
|
|
dfh.close()
|
|
|
ifh.close()
|
|
|
return node
|
|
|
|