revlog.py
201 lines
| 6.2 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. | ||||
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r2 | import zlib, struct, sha, os, tempfile | ||
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r0 | from mercurial import mdiff | ||
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 | ||||
self.nodemap = { -1: nullid, nullid: -1 } | ||||
# 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): | ||||
# offset, size, base, linkrev, p1, p2, nodeid, changeset | ||||
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) | ||||
def node(self, rev): return rev < 0 and nullid or self.index[rev][6] | ||||
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] | ||||
def revisions(self, list): | ||||
# this can be optimized to do spans, etc | ||||
# be stupid for now | ||||
for r in list: | ||||
yield self.revision(r) | ||||
def diff(self, a, b): | ||||
return mdiff.textdiff(a, b) | ||||
def patch(self, text, patch): | ||||
return mdiff.patch(text, patch) | ||||
def revision(self, node): | ||||
if node is nullid: return "" | ||||
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) | ||||
if self.node(rev) != hash(text, p1, p2): | ||||
raise "Consistency check failed on %s:%d" % (self.datafile, rev) | ||||
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()) | ||||
if 0: | ||||
dd = self.diff(prev, text) | ||||
tt = self.patch(prev, dd) | ||||
if tt != text: | ||||
print prev | ||||
print text | ||||
print tt | ||||
raise "diff+patch failed" | ||||
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) | ||||
transaction.add(self.datafile, e[0]) | ||||
self.opener(self.datafile, "a").write(data) | ||||
transaction.add(self.indexfile, n * len(entry)) | ||||
self.opener(self.indexfile, "a").write(entry) | ||||
self.cache = (node, n, text) | ||||
return node | ||||
def ancestor(self, a, b): | ||||
def expand(e1, e2, a1, a2): | ||||
ne = [] | ||||
for n in e1: | ||||
(p1, p2) = self.parents(n) | ||||
if p1 in a2: return p1 | ||||
if p2 in a2: return p2 | ||||
if p1 != nullid and p1 not in a1: | ||||
a1[p1] = 1 | ||||
ne.append(p1) | ||||
if p2 != nullid and p2 not in a1: | ||||
a1[p2] = 1 | ||||
ne.append(p2) | ||||
return expand(e2, ne, a2, a1) | ||||
return expand([a], [b], {a:1}, {b:1}) | ||||
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()) | ||||