Mercurial > hg
view mercurial/revlog.py @ 1721:801756d0ca84
add pretxncommit hook.
hook allows check of changeset after create, but before transaction
is committed. hook failure rolls transaction back.
makes place for local policies like commit message must contain bug id
or reviewer signoff.
change also adds parent changeset ids to commit hook environment,
because is cheap and useful.
| author | Vadim Gelfer <vadim.gelfer@gmail.com> |
|---|---|
| date | Tue, 14 Feb 2006 17:13:18 -0800 |
| parents | 8959700c2b19 |
| children | d457fec76ab0 |
line wrap: on
line source
""" 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. """ from node import * from i18n import gettext as _ from demandload import demandload demandload(globals(), "binascii errno heapq mdiff sha struct zlib") def hash(text, p1, p2): """generate a hash from the given text and its parent hashes This hash combines both the current file contents and its history in a manner that makes it easy to distinguish nodes with the same content in the revision graph. """ l = [p1, p2] l.sort() s = sha.new(l[0]) s.update(l[1]) s.update(text) return s.digest() def compress(text): """ generate a possibly-compressed representation of text """ 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) def decompress(bin): """ decompress the given input """ 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 RevlogError(_("unknown compression type %s") % t) indexformat = ">4l20s20s20s" class lazyparser(object): """ this class avoids the need to parse the entirety of large indices By default we parse and load 1000 entries at a time. If no position is specified, we load the whole index, and replace the lazy objects in revlog with the underlying objects for efficiency in cases where we look at most of the nodes. """ def __init__(self, data, revlog): self.data = data self.s = struct.calcsize(indexformat) self.l = len(data)/self.s self.index = [None] * self.l self.map = {nullid: -1} self.all = 0 self.revlog = revlog def trunc(self, pos): self.l = pos/self.s def load(self, pos=None): if self.all: return if pos is not None: block = pos / 1000 i = block * 1000 end = min(self.l, i + 1000) else: self.all = 1 i = 0 end = self.l self.revlog.index = self.index self.revlog.nodemap = self.map 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(object): """a lazy version of the index array""" def __init__(self, parser): self.p = parser def __len__(self): return len(self.p.index) def load(self, pos): if pos < 0: pos += len(self.p.index) self.p.load(pos) return self.p.index[pos] def __getitem__(self, pos): return self.p.index[pos] or self.load(pos) def __delitem__(self, pos): del self.p.index[pos] def append(self, e): self.p.index.append(e) def trunc(self, pos): self.p.trunc(pos) class lazymap(object): """a lazy version of the node map""" def __init__(self, parser): self.p = parser def load(self, key): if self.p.all: return n = self.p.data.find(key) if n < 0: raise KeyError(key) pos = n / self.p.s self.p.load(pos) def __contains__(self, key): self.p.load() return key in self.p.map def __iter__(self): yield nullid 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] def __getitem__(self, key): try: return self.p.map[key] except KeyError: try: self.load(key) return self.p.map[key] except KeyError: raise KeyError("node " + hex(key)) def __setitem__(self, key, val): self.p.map[key] = val def __delitem__(self, key): del self.p.map[key] class RevlogError(Exception): pass class revlog(object): """ the underlying revision storage object A revlog consists of two parts, an index and the revision data. The index is a file with a fixed record size containing information on each revision, includings its nodeid (hash), the nodeids of its parents, the position and offset of its data within the data file, and the revision it's based on. Finally, each entry contains a linkrev entry that can serve as a pointer to external data. The revision data itself is a linear collection of data chunks. Each chunk represents a revision and is usually represented as a delta against the previous chunk. To bound lookup time, runs of deltas are limited to about 2 times the length of the original version data. This makes retrieval of a version proportional to its size, or O(1) relative to the number of revisions. Both pieces of the revlog are written to in an append-only fashion, which means we never need to rewrite a file to insert or remove data, and can use some simple techniques to avoid the need for locking while reading. """ def __init__(self, opener, indexfile, datafile): """ create a revlog object opener is a function that abstracts the file opening operation and can be used to implement COW semantics or the like. """ self.indexfile = indexfile self.datafile = datafile self.opener = opener self.cache = None self.chunkcache = None try: i = self.opener(self.indexfile).read() except IOError, inst: if inst.errno != errno.ENOENT: raise i = "" if i and i[:4] != "\0\0\0\0": raise RevlogError(_("incompatible revlog signature on %s") % self.indexfile) if len(i) > 10000: # big index, let's parse it on demand parser = lazyparser(i, self) self.index = lazyindex(parser) self.nodemap = lazymap(parser) else: s = struct.calcsize(indexformat) l = len(i) / s self.index = [None] * l m = [None] * l n = 0 for f in xrange(0, l * s, s): # offset, size, base, linkrev, p1, p2, nodeid e = struct.unpack(indexformat, i[f:f + s]) m[n] = (e[6], n) self.index[n] = e n += 1 self.nodemap = dict(m) self.nodemap[nullid] = -1 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): try: return self.nodemap[node] except KeyError: raise RevlogError(_('%s: no node %s') % (self.indexfile, hex(node))) def linkrev(self, node): return self.index[self.rev(node)][3] def parents(self, node): if node == nullid: return (nullid, nullid) return self.index[self.rev(node)][4:6] 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 reachable(self, rev, stop=None): reachable = {} visit = [rev] reachable[rev] = 1 if stop: stopn = self.rev(stop) else: stopn = 0 while visit: n = visit.pop(0) if n == stop: continue if n == nullid: continue for p in self.parents(n): if self.rev(p) < stopn: continue if p not in reachable: reachable[p] = 1 visit.append(p) return reachable def nodesbetween(self, roots=None, heads=None): """Return a tuple containing three elements. Elements 1 and 2 contain a final list bases and heads after all the unreachable ones have been pruned. Element 0 contains a topologically sorted list of all nodes that satisfy these constraints: 1. All nodes must be descended from a node in roots (the nodes on roots are considered descended from themselves). 2. All nodes must also be ancestors of a node in heads (the nodes in heads are considered to be their own ancestors). If roots is unspecified, nullid is assumed as the only root. If heads is unspecified, it is taken to be the output of the heads method (i.e. a list of all nodes in the repository that have no children).""" nonodes = ([], [], []) if roots is not None: roots = list(roots) if not roots: return nonodes lowestrev = min([self.rev(n) for n in roots]) else: roots = [nullid] # Everybody's a descendent of nullid lowestrev = -1 if (lowestrev == -1) and (heads is None): # We want _all_ the nodes! return ([self.node(r) for r in xrange(0, self.count())], [nullid], list(self.heads())) if heads is None: # All nodes are ancestors, so the latest ancestor is the last # node. highestrev = self.count() - 1 # Set ancestors to None to signal that every node is an ancestor. ancestors = None # Set heads to an empty dictionary for later discovery of heads heads = {} else: heads = list(heads) if not heads: return nonodes ancestors = {} # Start at the top and keep marking parents until we're done. nodestotag = heads[:] # Turn heads into a dictionary so we can remove 'fake' heads. # Also, later we will be using it to filter out the heads we can't # find from roots. heads = dict.fromkeys(heads, 0) # Remember where the top was so we can use it as a limit later. highestrev = max([self.rev(n) for n in nodestotag]) while nodestotag: # grab a node to tag n = nodestotag.pop() # Never tag nullid if n == nullid: continue # A node's revision number represents its place in a # topologically sorted list of nodes. r = self.rev(n) if r >= lowestrev: if n not in ancestors: # If we are possibly a descendent of one of the roots # and we haven't already been marked as an ancestor ancestors[n] = 1 # Mark as ancestor # Add non-nullid parents to list of nodes to tag. nodestotag.extend([p for p in self.parents(n) if p != nullid]) elif n in heads: # We've seen it before, is it a fake head? # So it is, real heads should not be the ancestors of # any other heads. heads.pop(n) if not ancestors: return nonodes # Now that we have our set of ancestors, we want to remove any # roots that are not ancestors. # If one of the roots was nullid, everything is included anyway. if lowestrev > -1: # But, since we weren't, let's recompute the lowest rev to not # include roots that aren't ancestors. # Filter out roots that aren't ancestors of heads roots = [n for n in roots if n in ancestors] # Recompute the lowest revision if roots: lowestrev = min([self.rev(n) for n in roots]) else: # No more roots? Return empty list return nonodes else: # We are descending from nullid, and don't need to care about # any other roots. lowestrev = -1 roots = [nullid] # Transform our roots list into a 'set' (i.e. a dictionary where the # values don't matter. descendents = dict.fromkeys(roots, 1) # Also, keep the original roots so we can filter out roots that aren't # 'real' roots (i.e. are descended from other roots). roots = descendents.copy() # Our topologically sorted list of output nodes. orderedout = [] # Don't start at nullid since we don't want nullid in our output list, # and if nullid shows up in descedents, empty parents will look like # they're descendents. for r in xrange(max(lowestrev, 0), highestrev + 1): n = self.node(r) isdescendent = False if lowestrev == -1: # Everybody is a descendent of nullid isdescendent = True elif n in descendents: # n is already a descendent isdescendent = True # This check only needs to be done here because all the roots # will start being marked is descendents before the loop. if n in roots: # If n was a root, check if it's a 'real' root. p = tuple(self.parents(n)) # If any of its parents are descendents, it's not a root. if (p[0] in descendents) or (p[1] in descendents): roots.pop(n) else: p = tuple(self.parents(n)) # A node is a descendent if either of its parents are # descendents. (We seeded the dependents list with the roots # up there, remember?) if (p[0] in descendents) or (p[1] in descendents): descendents[n] = 1 isdescendent = True if isdescendent and ((ancestors is None) or (n in ancestors)): # Only include nodes that are both descendents and ancestors. orderedout.append(n) if (ancestors is not None) and (n in heads): # We're trying to figure out which heads are reachable # from roots. # Mark this head as having been reached heads[n] = 1 elif ancestors is None: # Otherwise, we're trying to discover the heads. # Assume this is a head because if it isn't, the next step # will eventually remove it. heads[n] = 1 # But, obviously its parents aren't. for p in self.parents(n): heads.pop(p, None) heads = [n for n in heads.iterkeys() if heads[n] != 0] roots = roots.keys() assert orderedout assert roots assert heads return (orderedout, roots, heads) def heads(self, start=None): """return the list of all nodes that have no children if start is specified, only heads that are descendants of start will be returned """ if start is None: start = nullid reachable = {start: 1} heads = {start: 1} startrev = self.rev(start) for r in xrange(startrev + 1, self.count()): n = self.node(r) for pn in self.parents(n): if pn in reachable: reachable[n] = 1 heads[n] = 1 if pn in heads: del heads[pn] return heads.keys() def children(self, node): """find the children of a given node""" c = [] p = self.rev(node) for r in range(p + 1, self.count()): n = self.node(r) for pn in self.parents(n): if pn == node: c.append(n) continue elif pn == nullid: continue return c def lookup(self, id): """locate a node based on revision number or subset of hex nodeid""" try: rev = int(id) if str(rev) != id: raise ValueError if rev < 0: rev = self.count() + rev if rev < 0 or rev >= self.count(): raise ValueError return self.node(rev) except (ValueError, OverflowError): c = [] for n in self.nodemap: if hex(n).startswith(id): c.append(n) if len(c) > 1: raise RevlogError(_("Ambiguous identifier")) if len(c) < 1: raise RevlogError(_("No match found")) return c[0] return None def diff(self, a, b): """return a delta between two revisions""" return mdiff.textdiff(a, b) def patches(self, t, pl): """apply a list of patches to a string""" return mdiff.patches(t, pl) def chunk(self, rev): start, length = self.start(rev), self.length(rev) end = start + length def loadcache(): cache_length = max(4096 * 1024, length) # 4Mo df = self.opener(self.datafile) df.seek(start) self.chunkcache = (start, df.read(cache_length)) if not self.chunkcache: loadcache() cache_start = self.chunkcache[0] cache_end = cache_start + len(self.chunkcache[1]) if start >= cache_start and end <= cache_end: # it is cached offset = start - cache_start else: loadcache() offset = 0 #def checkchunk(): # df = self.opener(self.datafile) # df.seek(start) # return df.read(length) #assert s == checkchunk() return decompress(self.chunkcache[1][offset:offset + length]) def delta(self, node): """return or calculate a delta between a node and its predecessor""" r = self.rev(node) b = self.base(r) if r == b: return self.diff(self.revision(self.node(r - 1)), self.revision(node)) else: return self.chunk(r) def revision(self, node): """return an uncompressed revision of a given""" if node == nullid: return "" if self.cache and self.cache[0] == node: return self.cache[2] # look up what we need to read text = None rev = self.rev(node) base = self.base(rev) # do we have useful data cached? if self.cache and self.cache[1] >= base and self.cache[1] < rev: base = self.cache[1] text = self.cache[2] else: text = self.chunk(base) bins = [] for r in xrange(base + 1, rev + 1): bins.append(self.chunk(r)) text = mdiff.patches(text, bins) p1, p2 = self.parents(node) if node != hash(text, p1, p2): raise RevlogError(_("integrity 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, d=None): """add a revision to the log text - the revision data to add transaction - the transaction object used for rollback link - the linkrev data to add p1, p2 - the parent nodeids of the revision d - an optional precomputed delta """ if text is None: text = "" if p1 is None: p1 = self.tip() if p2 is None: p2 = nullid node = hash(text, p1, p2) if node in self.nodemap: return node n = self.count() t = n - 1 if n: base = self.base(t) start = self.start(base) end = self.end(t) if not d: prev = self.revision(self.tip()) d = self.diff(prev, str(text)) data = compress(d) l = len(data[1]) + len(data[0]) dist = end - start + l # full versions are inserted when the needed deltas # become comparable to the uncompressed text if not n or dist > len(text) * 2: data = compress(text) l = len(data[1]) + len(data[0]) base = n else: base = self.base(t) offset = 0 if t >= 0: offset = self.end(t) e = (offset, l, base, link, p1, p2, node) self.index.append(e) self.nodemap[node] = n entry = struct.pack(indexformat, *e) transaction.add(self.datafile, e[0]) f = self.opener(self.datafile, "a") if data[0]: f.write(data[0]) f.write(data[1]) 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): """calculate the least common ancestor of nodes a and b""" # calculate the distance of every node from root dist = {nullid: 0} for i in xrange(self.count()): n = self.node(i) p1, p2 = self.parents(n) dist[n] = max(dist[p1], dist[p2]) + 1 # traverse ancestors in order of decreasing distance from root def ancestors(node): # we store negative distances because heap returns smallest member h = [(-dist[node], node)] seen = {} earliest = self.count() while h: d, n = heapq.heappop(h) if n not in seen: seen[n] = 1 r = self.rev(n) yield (-d, n) for p in self.parents(n): heapq.heappush(h, (-dist[p], p)) def generations(node): sg, s = None, {} for g,n in ancestors(node): if g != sg: if sg: yield sg, s sg, s = g, {n:1} else: s[n] = 1 yield sg, s x = generations(a) y = generations(b) gx = x.next() gy = y.next() # increment each ancestor list until it is closer to root than # the other, or they match while 1: #print "ancestor gen %s %s" % (gx[0], gy[0]) if gx[0] == gy[0]: # find the intersection i = [ n for n in gx[1] if n in gy[1] ] if i: return i[0] else: #print "next" gy = y.next() gx = x.next() elif gx[0] < gy[0]: #print "next y" gy = y.next() else: #print "next x" gx = x.next() def group(self, nodelist, lookup, infocollect=None): """calculate a delta group 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 = [self.rev(n) for n in nodelist] # if we don't have any revisions touched by these changesets, bail if not revs: yield struct.pack(">l", 0) return # add the parent of the first rev p = self.parents(self.node(revs[0]))[0] revs.insert(0, self.rev(p)) # helper to reconstruct intermediate versions def construct(text, base, rev): bins = [self.chunk(r) for r in xrange(base + 1, rev + 1)] return mdiff.patches(text, bins) # build deltas for d in xrange(0, len(revs) - 1): a, b = revs[d], revs[d + 1] na = self.node(a) nb = self.node(b) if infocollect is not None: infocollect(nb) # do we need to construct a new delta? if a + 1 != b or self.base(b) == b: ta = self.revision(na) tb = self.revision(nb) d = self.diff(ta, tb) else: d = self.chunk(b) p = self.parents(nb) meta = nb + p[0] + p[1] + lookup(nb) 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): """ add a delta group 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 = measure = 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 RevlogError(_("already have %s") % hex(node[:4])) chain = node continue delta = chunk[80:] for p in (p1, p2): if not p in self.nodemap: raise RevlogError(_("unknown parent %s") % short(p1)) if not chain: # retrieve the parent revision of the delta chain chain = p1 if not chain in self.nodemap: raise RevlogError(_("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: tempd = compress(delta) cdelta = tempd[0] + tempd[1] 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 RevlogError(_("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 def strip(self, rev, minlink): if self.count() == 0 or rev >= self.count(): return # When stripping away a revision, we need to make sure it # does not actually belong to an older changeset. # The minlink parameter defines the oldest revision # we're allowed to strip away. while minlink > self.index[rev][3]: rev += 1 if rev >= self.count(): return # first truncate the files on disk end = self.start(rev) self.opener(self.datafile, "a").truncate(end) end = rev * struct.calcsize(indexformat) self.opener(self.indexfile, "a").truncate(end) # then reset internal state in memory to forget those revisions self.cache = None self.chunkcache = None for p in self.index[rev:]: del self.nodemap[p[6]] del self.index[rev:] # truncating the lazyindex also truncates the lazymap. if isinstance(self.index, lazyindex): self.index.trunc(end) def checksize(self): expected = 0 if self.count(): expected = self.end(self.count() - 1) try: f = self.opener(self.datafile) f.seek(0, 2) actual = f.tell() dd = actual - expected except IOError, inst: if inst.errno != errno.ENOENT: raise dd = 0 try: f = self.opener(self.indexfile) f.seek(0, 2) actual = f.tell() s = struct.calcsize(indexformat) i = actual / s di = actual - (i * s) except IOError, inst: if inst.errno != errno.ENOENT: raise di = 0 return (dd, di)