revlog.py
412 lines
| 13.0 KiB
| text/x-python
|
PythonLexer
/ mercurial / revlog.py
mpm@selenic.com
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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. | ||||
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r36 | import zlib, struct, sha, os, tempfile, binascii | ||
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r0 | from mercurial import mdiff | ||
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r36 | def hex(node): return binascii.hexlify(node) | ||
def bin(node): return binascii.unhexlify(node) | ||||
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r0 | def compress(text): | ||
return zlib.compress(text) | ||||
def decompress(bin): | ||||
return zlib.decompress(bin) | ||||
def hash(text, p1, p2): | ||||
l = [p1, p2] | ||||
l.sort() | ||||
return sha.sha(l[0] + l[1] + text).digest() | ||||
nullid = "\0" * 20 | ||||
indexformat = ">4l20s20s20s" | ||||
class revlog: | ||||
def __init__(self, opener, indexfile, datafile): | ||||
self.indexfile = indexfile | ||||
self.datafile = datafile | ||||
self.index = [] | ||||
self.opener = opener | ||||
self.cache = None | ||||
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r36 | self.nodemap = {nullid: -1} | ||
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r0 | # read the whole index for now, handle on-demand later | ||
try: | ||||
n = 0 | ||||
i = self.opener(self.indexfile).read() | ||||
s = struct.calcsize(indexformat) | ||||
for f in range(0, len(i), s): | ||||
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r26 | # offset, size, base, linkrev, p1, p2, nodeid | ||
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r0 | e = struct.unpack(indexformat, i[f:f + s]) | ||
self.nodemap[e[6]] = n | ||||
self.index.append(e) | ||||
n += 1 | ||||
except IOError: pass | ||||
def tip(self): return self.node(len(self.index) - 1) | ||||
def count(self): return len(self.index) | ||||
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r26 | def node(self, rev): return (rev < 0) and nullid or self.index[rev][6] | ||
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r0 | def rev(self, node): return self.nodemap[node] | ||
def linkrev(self, node): return self.index[self.nodemap[node]][3] | ||||
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r2 | def parents(self, node): | ||
if node == nullid: return (nullid, nullid) | ||||
return self.index[self.nodemap[node]][4:6] | ||||
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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] | ||||
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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") | ||||
if len(c) < 1: raise KeyError | ||||
return c[0] | ||||
return None | ||||
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r0 | def revisions(self, list): | ||
# this can be optimized to do spans, etc | ||||
# be stupid for now | ||||
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r14 | for node in list: | ||
yield self.revision(node) | ||||
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r0 | |||
def diff(self, a, b): | ||||
return mdiff.textdiff(a, b) | ||||
def patch(self, text, patch): | ||||
return mdiff.patch(text, patch) | ||||
def revision(self, node): | ||||
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r36 | if node == nullid: return "" | ||
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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]) | ||||
for r in range(base + 1, rev + 1): | ||||
s = self.length(r) | ||||
b = decompress(data[last:last + s]) | ||||
text = self.patch(text, b) | ||||
last = last + s | ||||
(p1, p2) = self.parents(node) | ||||
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r26 | if node != hash(text, p1, p2): | ||
raise "integrity check failed on %s:%d" % (self.datafile, rev) | ||||
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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: | ||||
start = self.start(self.base(t)) | ||||
end = self.end(t) | ||||
prev = self.revision(self.tip()) | ||||
data = compress(self.diff(prev, text)) | ||||
# full versions are inserted when the needed deltas | ||||
# become comparable to the uncompressed text | ||||
if not n or (end + len(data) - start) > len(text) * 2: | ||||
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) | ||||
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r26 | transaction.add(self.datafile, e[0]) | ||
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r0 | self.opener(self.datafile, "a").write(data) | ||
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r41 | transaction.add(self.indexfile, n * len(entry)) | ||
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r0 | self.opener(self.indexfile, "a").write(entry) | ||
self.cache = (node, n, text) | ||||
return node | ||||
def ancestor(self, a, b): | ||||
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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 | ||||
mpm@selenic.com
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r0 | |||
def mergedag(self, other, transaction, linkseq, accumulate = None): | ||||
"""combine the nodes from other's DAG into ours""" | ||||
old = self.tip() | ||||
i = self.count() | ||||
l = [] | ||||
# merge the other revision log into our DAG | ||||
for r in range(other.count()): | ||||
id = other.node(r) | ||||
if id not in self.nodemap: | ||||
(xn, yn) = other.parents(id) | ||||
l.append((id, xn, yn)) | ||||
self.nodemap[id] = i | ||||
i += 1 | ||||
# merge node date for new nodes | ||||
r = other.revisions([e[0] for e in l]) | ||||
for e in l: | ||||
t = r.next() | ||||
if accumulate: accumulate(t) | ||||
self.addrevision(t, transaction, linkseq.next(), e[1], e[2]) | ||||
# return the unmerged heads for later resolving | ||||
return (old, self.tip()) | ||||
mpm@selenic.com
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r46 | |||
def group(self, linkmap): | ||||
# given a list of changeset revs, return a set of deltas and | ||||
# metadata corresponding to nodes the first delta is | ||||
# 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): | ||||
for r in range(base + 1, rev + 1): | ||||
b = decompress(chunks[r]) | ||||
text = self.patch(text, b) | ||||
return text | ||||
# build deltas | ||||
deltas = [] | ||||
for d in range(0, len(revs) - 1): | ||||
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. | ||||
if len(data) <= 4: return | ||||
# retrieve the parent revision of the delta chain | ||||
chain = data[28:48] | ||||
text = self.revision(chain) | ||||
# 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 | ||||
pos = 4 | ||||
while pos < len(data): | ||||
l, node, p1, p2, cs = struct.unpack(">l20s20s20s20s", | ||||
data[pos:pos+84]) | ||||
link = linkmapper(cs) | ||||
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() | ||||
text = self.revision(self.node(t)) | ||||
text = self.patch(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 = r, r + 1 | ||||
chain = prev | ||||
start = self.start(self.base(t)) | ||||
end = self.end(t) | ||||
dfh.close() | ||||
ifh.close() | ||||
return node | ||||