mercurial/branchmap.py

branchmap: add the tiprev (cache key) on the branchmap object

The actual cache key used on disk is the (tipnode, tiprev) pair. There is no
reason not to use the revision number for the in memory version.

# branchmap.py - logic to computes, maintain and stores branchmap for local repo
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from node import bin, hex, nullid, nullrev
import encoding

def read(repo):
    partial = branchcache()
    try:
        f = repo.opener("cache/branchheads")
        lines = f.read().split('\n')
        f.close()
    except (IOError, OSError):
        return branchcache()

    try:
        last, lrev = lines.pop(0).split(" ", 1)
        last, lrev = bin(last), int(lrev)
        if lrev >= len(repo) or repo[lrev].node() != last:
            # invalidate the cache
            raise ValueError('invalidating branch cache (tip differs)')
        for l in lines:
            if not l:
                continue
            node, label = l.split(" ", 1)
            label = encoding.tolocal(label.strip())
            if not node in repo:
                raise ValueError('invalidating branch cache because node '+
                                 '%s does not exist' % node)
            partial.setdefault(label, []).append(bin(node))
        partial.tipnode = last
        partial.tiprev = lrev
    except KeyboardInterrupt:
        raise
    except Exception, inst:
        if repo.ui.debugflag:
            repo.ui.warn(str(inst), '\n')
        partial = branchcache()
    return partial

def write(repo, branches, tip, tiprev):
    try:
        f = repo.opener("cache/branchheads", "w", atomictemp=True)
        f.write("%s %s\n" % (hex(tip), tiprev))
        for label, nodes in branches.iteritems():
            for node in nodes:
                f.write("%s %s\n" % (hex(node), encoding.fromlocal(label)))
        f.close()
    except (IOError, OSError):
        pass

def update(repo, partial, ctxgen):
    """Given a branchhead cache, partial, that may have extra nodes or be
    missing heads, and a generator of nodes that are at least a superset of
    heads missing, this function updates partial to be correct.
    """
    # collect new branch entries
    newbranches = {}
    for c in ctxgen:
        newbranches.setdefault(c.branch(), []).append(c.node())
    # if older branchheads are reachable from new ones, they aren't
    # really branchheads. Note checking parents is insufficient:
    # 1 (branch a) -> 2 (branch b) -> 3 (branch a)
    for branch, newnodes in newbranches.iteritems():
        bheads = partial.setdefault(branch, [])
        # Remove candidate heads that no longer are in the repo (e.g., as
        # the result of a strip that just happened).  Avoid using 'node in
        # self' here because that dives down into branchcache code somewhat
        # recursively.
        bheadrevs = [repo.changelog.rev(node) for node in bheads
                     if repo.changelog.hasnode(node)]
        newheadrevs = [repo.changelog.rev(node) for node in newnodes
                       if repo.changelog.hasnode(node)]
        ctxisnew = bheadrevs and min(newheadrevs) > max(bheadrevs)
        # Remove duplicates - nodes that are in newheadrevs and are already
        # in bheadrevs.  This can happen if you strip a node whose parent
        # was already a head (because they're on different branches).
        bheadrevs = sorted(set(bheadrevs).union(newheadrevs))

        # Starting from tip means fewer passes over reachable.  If we know
        # the new candidates are not ancestors of existing heads, we don't
        # have to examine ancestors of existing heads
        if ctxisnew:
            iterrevs = sorted(newheadrevs)
        else:
            iterrevs = list(bheadrevs)

        # This loop prunes out two kinds of heads - heads that are
        # superseded by a head in newheadrevs, and newheadrevs that are not
        # heads because an existing head is their descendant.
        while iterrevs:
            latest = iterrevs.pop()
            if latest not in bheadrevs:
                continue
            ancestors = set(repo.changelog.ancestors([latest],
                                                     bheadrevs[0]))
            if ancestors:
                bheadrevs = [b for b in bheadrevs if b not in ancestors]
        partial[branch] = [repo.changelog.node(rev) for rev in bheadrevs]

    # There may be branches that cease to exist when the last commit in the
    # branch was stripped.  This code filters them out.  Note that the
    # branch that ceased to exist may not be in newbranches because
    # newbranches is the set of candidate heads, which when you strip the
    # last commit in a branch will be the parent branch.
    for branch in partial.keys():
        nodes = [head for head in partial[branch]
                 if repo.changelog.hasnode(head)]
        if not nodes:
            del partial[branch]

def updatecache(repo):
    repo = repo.unfiltered()  # Until we get a smarter cache management
    cl = repo.changelog
    tip = cl.tip()
    partial = repo._branchcache
    if partial is not None and partial.tipnode == tip:
        return

    if partial is None or partial.tipnode not in cl.nodemap:
        partial = read(repo)

    catip = repo._cacheabletip()
    # if partial.tiprev == catip: cache is already up to date
    # if partial.tiprev >  catip: we have uncachable element in `partial` can't
    #                             write on disk
    if partial.tiprev < catip:
        ctxgen = (repo[r] for r in cl.revs(partial.tiprev + 1, catip))
        update(repo, partial, ctxgen)
        partial.tipnode = cl.node(catip)
        partial.tiprev = catip
        write(repo, partial, partial.tipnode, partial.tiprev)
    # If cacheable tip were lower than actual tip, we need to update the
    # cache up to tip. This update (from cacheable to actual tip) is not
    # written to disk since it's not cacheable.
    tiprev = len(repo) - 1
    if partial.tiprev < tiprev:
        ctxgen = (repo[r] for r in cl.revs(partial.tiprev + 1, tiprev))
        update(repo, partial, ctxgen)
        partial.tipnode = cl.node(tiprev)
        partial.tiprev = tiprev
    repo._branchcache = partial

class branchcache(dict):
    """A dict like object that hold branches heads cache"""

    def __init__(self, entries=(), tipnode=nullid, tiprev=nullrev):
        super(branchcache, self).__init__(entries)
        self.tipnode = tipnode
        self.tiprev = tiprev