revlog.py
473 lines
| 14.7 KiB
| text/x-python
|
PythonLexer
/ mercurial / revlog.py
|
r0 | # revlog.py - storage back-end for mercurial | ||
# | ||||
# This provides efficient delta storage with O(1) retrieve and append | ||||
# and O(changes) merge between branches | ||||
# | ||||
# Copyright 2005 Matt Mackall <mpm@selenic.com> | ||||
# | ||||
# This software may be used and distributed according to the terms | ||||
# of the GNU General Public License, incorporated herein by reference. | ||||
|
r36 | import zlib, struct, sha, os, tempfile, binascii | ||
|
r0 | from mercurial import mdiff | ||
|
r36 | def hex(node): return binascii.hexlify(node) | ||
def bin(node): return binascii.unhexlify(node) | ||||
|
r83 | def short(node): return hex(node[:4]) | ||
|
r36 | |||
|
r0 | def compress(text): | ||
|
r112 | if not text: return text | ||
if len(text) < 44: | ||||
if text[0] == '\0': return text | ||||
return 'u' + text | ||||
bin = zlib.compress(text) | ||||
if len(bin) > len(text): | ||||
if text[0] == '\0': return text | ||||
return 'u' + text | ||||
return bin | ||||
|
r0 | |||
def decompress(bin): | ||||
|
r112 | if not bin: return bin | ||
t = bin[0] | ||||
if t == '\0': return bin | ||||
if t == 'x': return zlib.decompress(bin) | ||||
if t == 'u': return bin[1:] | ||||
raise "unknown compression type %s" % t | ||||
|
r0 | |||
def hash(text, p1, p2): | ||||
l = [p1, p2] | ||||
l.sort() | ||||
return sha.sha(l[0] + l[1] + text).digest() | ||||
nullid = "\0" * 20 | ||||
indexformat = ">4l20s20s20s" | ||||
|
r76 | class lazyparser: | ||
def __init__(self, data): | ||||
self.data = data | ||||
self.s = struct.calcsize(indexformat) | ||||
self.l = len(data)/self.s | ||||
self.index = [None] * self.l | ||||
self.map = {nullid: -1} | ||||
if 0: | ||||
n = 0 | ||||
i = self.data | ||||
s = struct.calcsize(indexformat) | ||||
for f in xrange(0, len(i), s): | ||||
# offset, size, base, linkrev, p1, p2, nodeid | ||||
e = struct.unpack(indexformat, i[f:f + s]) | ||||
self.map[e[6]] = n | ||||
self.index.append(e) | ||||
n += 1 | ||||
def load(self, pos): | ||||
block = pos / 1000 | ||||
i = block * 1000 | ||||
end = min(self.l, i + 1000) | ||||
while i < end: | ||||
d = self.data[i * self.s: (i + 1) * self.s] | ||||
e = struct.unpack(indexformat, d) | ||||
self.index[i] = e | ||||
self.map[e[6]] = i | ||||
i += 1 | ||||
class lazyindex: | ||||
def __init__(self, parser): | ||||
self.p = parser | ||||
def __len__(self): | ||||
return len(self.p.index) | ||||
|
r115 | def load(self, pos): | ||
self.p.load(pos) | ||||
return self.p.index[pos] | ||||
|
r76 | def __getitem__(self, pos): | ||
|
r115 | return self.p.index[pos] or self.load(pos) | ||
|
r76 | def append(self, e): | ||
self.p.index.append(e) | ||||
class lazymap: | ||||
def __init__(self, parser): | ||||
self.p = parser | ||||
def load(self, key): | ||||
n = self.p.data.find(key) | ||||
|
r86 | if n < 0: raise KeyError("node " + hex(key)) | ||
|
r76 | pos = n / self.p.s | ||
self.p.load(pos) | ||||
def __contains__(self, key): | ||||
try: | ||||
|
r77 | self[key] | ||
|
r76 | return True | ||
except KeyError: | ||||
return False | ||||
|
r97 | def __iter__(self): | ||
for i in xrange(self.p.l): | ||||
try: | ||||
yield self.p.index[i][6] | ||||
except: | ||||
self.p.load(i) | ||||
yield self.p.index[i][6] | ||||
|
r76 | def __getitem__(self, key): | ||
try: | ||||
return self.p.map[key] | ||||
except KeyError: | ||||
|
r86 | try: | ||
self.load(key) | ||||
return self.p.map[key] | ||||
except KeyError: | ||||
raise KeyError("node " + hex(key)) | ||||
|
r76 | def __setitem__(self, key, val): | ||
self.p.map[key] = val | ||||
|
r0 | class revlog: | ||
def __init__(self, opener, indexfile, datafile): | ||||
self.indexfile = indexfile | ||||
self.datafile = datafile | ||||
self.opener = opener | ||||
self.cache = None | ||||
# read the whole index for now, handle on-demand later | ||||
try: | ||||
i = self.opener(self.indexfile).read() | ||||
|
r73 | except IOError: | ||
|
r76 | i = "" | ||
parser = lazyparser(i) | ||||
self.index = lazyindex(parser) | ||||
self.nodemap = lazymap(parser) | ||||
|
r0 | |||
def tip(self): return self.node(len(self.index) - 1) | ||||
def count(self): return len(self.index) | ||||
|
r26 | def node(self, rev): return (rev < 0) and nullid or self.index[rev][6] | ||
|
r0 | def rev(self, node): return self.nodemap[node] | ||
def linkrev(self, node): return self.index[self.nodemap[node]][3] | ||||
|
r2 | def parents(self, node): | ||
if node == nullid: return (nullid, nullid) | ||||
return self.index[self.nodemap[node]][4:6] | ||||
|
r0 | |||
def start(self, rev): return self.index[rev][0] | ||||
def length(self, rev): return self.index[rev][1] | ||||
def end(self, rev): return self.start(rev) + self.length(rev) | ||||
def base(self, rev): return self.index[rev][2] | ||||
|
r36 | def lookup(self, id): | ||
try: | ||||
rev = int(id) | ||||
return self.node(rev) | ||||
except ValueError: | ||||
c = [] | ||||
for n in self.nodemap: | ||||
if id in hex(n): | ||||
c.append(n) | ||||
if len(c) > 1: raise KeyError("Ambiguous identifier") | ||||
|
r67 | if len(c) < 1: raise KeyError("No match found") | ||
|
r36 | return c[0] | ||
return None | ||||
|
r0 | def diff(self, a, b): | ||
return mdiff.textdiff(a, b) | ||||
|
r73 | def patches(self, t, pl): | ||
return mdiff.patches(t, pl) | ||||
|
r0 | def revision(self, node): | ||
|
r36 | if node == nullid: return "" | ||
|
r0 | if self.cache and self.cache[0] == node: return self.cache[2] | ||
text = None | ||||
rev = self.rev(node) | ||||
base = self.base(rev) | ||||
start = self.start(base) | ||||
end = self.end(rev) | ||||
if self.cache and self.cache[1] >= base and self.cache[1] < rev: | ||||
base = self.cache[1] | ||||
start = self.start(base + 1) | ||||
text = self.cache[2] | ||||
last = 0 | ||||
f = self.opener(self.datafile) | ||||
f.seek(start) | ||||
data = f.read(end - start) | ||||
if not text: | ||||
last = self.length(base) | ||||
text = decompress(data[:last]) | ||||
|
r71 | bins = [] | ||
|
r64 | for r in xrange(base + 1, rev + 1): | ||
|
r0 | s = self.length(r) | ||
|
r71 | bins.append(decompress(data[last:last + s])) | ||
|
r0 | last = last + s | ||
|
r71 | text = mdiff.patches(text, bins) | ||
|
r0 | (p1, p2) = self.parents(node) | ||
|
r26 | if node != hash(text, p1, p2): | ||
|
r98 | raise IOError("integrity check failed on %s:%d" | ||
% (self.datafile, rev)) | ||||
|
r0 | |||
self.cache = (node, rev, text) | ||||
return text | ||||
def addrevision(self, text, transaction, link, p1=None, p2=None): | ||||
if text is None: text = "" | ||||
if p1 is None: p1 = self.tip() | ||||
if p2 is None: p2 = nullid | ||||
node = hash(text, p1, p2) | ||||
n = self.count() | ||||
t = n - 1 | ||||
if n: | ||||
|
r64 | base = self.base(t) | ||
start = self.start(base) | ||||
|
r0 | end = self.end(t) | ||
prev = self.revision(self.tip()) | ||||
|
r98 | d = self.diff(prev, text) | ||
if self.patches(prev, [d]) != text: | ||||
raise AssertionError("diff failed") | ||||
data = compress(d) | ||||
|
r64 | dist = end - start + len(data) | ||
|
r0 | |||
# full versions are inserted when the needed deltas | ||||
# become comparable to the uncompressed text | ||||
|
r64 | if not n or dist > len(text) * 2: | ||
|
r0 | data = compress(text) | ||
base = n | ||||
else: | ||||
base = self.base(t) | ||||
offset = 0 | ||||
if t >= 0: | ||||
offset = self.end(t) | ||||
e = (offset, len(data), base, link, p1, p2, node) | ||||
self.index.append(e) | ||||
self.nodemap[node] = n | ||||
entry = struct.pack(indexformat, *e) | ||||
|
r26 | transaction.add(self.datafile, e[0]) | ||
|
r0 | self.opener(self.datafile, "a").write(data) | ||
|
r41 | transaction.add(self.indexfile, n * len(entry)) | ||
|
r0 | self.opener(self.indexfile, "a").write(entry) | ||
self.cache = (node, n, text) | ||||
return node | ||||
def ancestor(self, a, b): | ||||
|
r45 | def expand(list, map): | ||
a = [] | ||||
while list: | ||||
n = list.pop(0) | ||||
map[n] = 1 | ||||
yield n | ||||
for p in self.parents(n): | ||||
if p != nullid and p not in map: | ||||
list.append(p) | ||||
yield nullid | ||||
amap = {} | ||||
bmap = {} | ||||
ag = expand([a], amap) | ||||
bg = expand([b], bmap) | ||||
adone = bdone = 0 | ||||
while not adone or not bdone: | ||||
if not adone: | ||||
an = ag.next() | ||||
if an == nullid: | ||||
adone = 1 | ||||
elif an in bmap: | ||||
return an | ||||
if not bdone: | ||||
bn = bg.next() | ||||
if bn == nullid: | ||||
bdone = 1 | ||||
elif bn in amap: | ||||
return bn | ||||
return nullid | ||||
|
r0 | |||
|
r46 | def group(self, linkmap): | ||
# given a list of changeset revs, return a set of deltas and | ||||
|
r94 | # metadata corresponding to nodes. the first delta is | ||
|
r46 | # parent(nodes[0]) -> nodes[0] the receiver is guaranteed to | ||
# have this parent as it has all history before these | ||||
# changesets. parent is parent[0] | ||||
revs = [] | ||||
needed = {} | ||||
# find file nodes/revs that match changeset revs | ||||
for i in xrange(0, self.count()): | ||||
if self.index[i][3] in linkmap: | ||||
revs.append(i) | ||||
needed[i] = 1 | ||||
# if we don't have any revisions touched by these changesets, bail | ||||
if not revs: return struct.pack(">l", 0) | ||||
# add the parent of the first rev | ||||
p = self.parents(self.node(revs[0]))[0] | ||||
revs.insert(0, self.rev(p)) | ||||
# for each delta that isn't contiguous in the log, we need to | ||||
# reconstruct the base, reconstruct the result, and then | ||||
# calculate the delta. We also need to do this where we've | ||||
# stored a full version and not a delta | ||||
for i in xrange(0, len(revs) - 1): | ||||
a, b = revs[i], revs[i + 1] | ||||
if a + 1 != b or self.base(b) == b: | ||||
for j in xrange(self.base(a), a + 1): | ||||
needed[j] = 1 | ||||
for j in xrange(self.base(b), b + 1): | ||||
needed[j] = 1 | ||||
# calculate spans to retrieve from datafile | ||||
needed = needed.keys() | ||||
needed.sort() | ||||
spans = [] | ||||
for n in needed: | ||||
if n < 0: continue | ||||
o = self.start(n) | ||||
l = self.length(n) | ||||
spans.append((o, l, [(n, l)])) | ||||
# merge spans | ||||
merge = [spans.pop(0)] | ||||
while spans: | ||||
e = spans.pop(0) | ||||
f = merge[-1] | ||||
if e[0] == f[0] + f[1]: | ||||
merge[-1] = (f[0], f[1] + e[1], f[2] + e[2]) | ||||
else: | ||||
merge.append(e) | ||||
# read spans in, divide up chunks | ||||
chunks = {} | ||||
for span in merge: | ||||
# we reopen the file for each span to make http happy for now | ||||
f = self.opener(self.datafile) | ||||
f.seek(span[0]) | ||||
data = f.read(span[1]) | ||||
# divide up the span | ||||
pos = 0 | ||||
for r, l in span[2]: | ||||
chunks[r] = data[pos: pos + l] | ||||
pos += l | ||||
# helper to reconstruct intermediate versions | ||||
def construct(text, base, rev): | ||||
|
r71 | bins = [decompress(chunks[r]) for r in xrange(base + 1, rev + 1)] | ||
return mdiff.patches(text, bins) | ||||
|
r46 | |||
# build deltas | ||||
deltas = [] | ||||
|
r71 | for d in xrange(0, len(revs) - 1): | ||
|
r46 | a, b = revs[d], revs[d + 1] | ||
n = self.node(b) | ||||
if a + 1 != b or self.base(b) == b: | ||||
if a >= 0: | ||||
base = self.base(a) | ||||
ta = decompress(chunks[self.base(a)]) | ||||
ta = construct(ta, base, a) | ||||
else: | ||||
ta = "" | ||||
base = self.base(b) | ||||
if a > base: | ||||
base = a | ||||
tb = ta | ||||
else: | ||||
tb = decompress(chunks[self.base(b)]) | ||||
tb = construct(tb, base, b) | ||||
d = self.diff(ta, tb) | ||||
else: | ||||
d = decompress(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) | ||||
deltas.append(l + meta + d) | ||||
l = struct.pack(">l", sum(map(len, deltas)) + 4) | ||||
deltas.insert(0, l) | ||||
return "".join(deltas) | ||||
def addgroup(self, data, linkmapper, transaction): | ||||
# 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. | ||||
|
r65 | if not data: return self.tip() | ||
|
r46 | |||
# retrieve the parent revision of the delta chain | ||||
|
r65 | chain = data[24:44] | ||
|
r84 | if not chain in self.nodemap: | ||
raise "unknown base %s" % short(chain[:4]) | ||||
|
r46 | |||
# track the base of the current delta log | ||||
r = self.count() | ||||
t = r - 1 | ||||
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 | ||||
|
r65 | pos = 0 | ||
|
r46 | while pos < len(data): | ||
l, node, p1, p2, cs = struct.unpack(">l20s20s20s20s", | ||||
data[pos:pos+84]) | ||||
|
r94 | link = linkmapper(cs) | ||
|
r77 | if node in self.nodemap: | ||
raise "already have %s" % hex(node[:4]) | ||||
|
r46 | delta = data[pos + 84:pos + l] | ||
pos += l | ||||
# 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() | ||||
|
r65 | text = self.revision(chain) | ||
|
r73 | text = self.patches(text, [delta]) | ||
|
r46 | 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)) | ||||
|
r65 | t, r, chain, prev = r, r + 1, node, node | ||
|
r46 | start = self.start(self.base(t)) | ||
end = self.end(t) | ||||
dfh.close() | ||||
ifh.close() | ||||
return node | ||||