view hgext3rd/serverminitopic.py @ 3248:07c9b6f445bf

stablerange: rework the debug command to allow for multiple method

Similar to what we did for the other debug command related to sorting, we
prepare for the arrival of multiple method to produce the result (including
simple implementation that are easy to read but do not scale).

"""enable a minimal verison of topic for server

Non publishing repository will see topic as "branch:topic" in the branch field.

In addition to adding the extensions, the feature must be manually enabled in the config:

    [experimental]
    server-mini-topic = yes
"""
import hashlib
import contextlib

from mercurial import (
    branchmap,
    context,
    encoding,
    extensions,
    node,
    registrar,
    util,
    wireproto,
)

if util.safehasattr(registrar, 'configitem'):

    configtable = {}
    configitem = registrar.configitem(configtable)
    configitem('experimental', 'server-mini-topic',
               default=False,
    )

def hasminitopic(repo):
    """true if minitopic is enabled on the repository

    (The value is cached on the repository)
    """
    enabled = getattr(repo, '_hasminitopic', None)
    if enabled is None:
        enabled = (repo.ui.configbool('experimental', 'server-mini-topic')
                   and not repo.publishing())
        repo._hasminitopic = enabled
    return enabled

### make topic visible though "ctx.branch()"

class topicchangectx(context.changectx):
    """a sunclass of changectx that add topic to the branch name"""

    def branch(self):
        branch = super(topicchangectx, self).branch()
        if hasminitopic(self._repo) and self.phase():
            topic = self._changeset.extra.get('topic')
            if topic is not None:
                topic = encoding.tolocal(topic)
                branch = '%s:%s' % (branch, topic)
        return branch

### avoid caching topic data in rev-branch-cache

class revbranchcacheoverlay(object):
    """revbranch mixin that don't use the cache for non public changeset"""

    def _init__(self, *args, **kwargs):
        super(revbranchcacheoverlay, self).__init__(*args, **kwargs)
        if 'branchinfo' in vars(self):
            del self.branchinfo

    def branchinfo(self, rev):
        """return branch name and close flag for rev, using and updating
        persistent cache."""
        phase = self._repo._phasecache.phase(self, rev)
        if phase:
            ctx = self._repo[rev]
            return ctx.branch(), ctx.closesbranch()
        return super(revbranchcacheoverlay, self).branchinfo(rev)

def reposetup(ui, repo):
    """install a repo class with a special revbranchcache"""

    if hasminitopic(repo):
        repo = repo.unfiltered()

        class minitopicrepo(repo.__class__):
            """repository subclass that install the modified cache"""

            def revbranchcache(self):
                if self._revbranchcache is None:
                    cache = super(minitopicrepo, self).revbranchcache()

                    class topicawarerbc(revbranchcacheoverlay, cache.__class__):
                        pass
                    cache.__class__ = topicawarerbc
                    if 'branchinfo' in vars(cache):
                        del cache.branchinfo
                    self._revbranchcache = cache
                return self._revbranchcache

        repo.__class__ = minitopicrepo

### topic aware branch head cache

def _phaseshash(repo, maxrev):
    """uniq ID for a phase matching a set of rev"""
    revs = set()
    cl = repo.changelog
    fr = cl.filteredrevs
    nm = cl.nodemap
    for roots in repo._phasecache.phaseroots[1:]:
        for n in roots:
            r = nm.get(n)
            if r not in fr and r < maxrev:
                revs.add(r)
    key = node.nullid
    revs = sorted(revs)
    if revs:
        s = hashlib.sha1()
        for rev in revs:
            s.update('%s;' % rev)
        key = s.digest()
    return key

# needed to prevent reference used for 'super()' call using in branchmap.py to
# no go into cycle. (yes, URG)
_oldbranchmap = branchmap.branchcache

@contextlib.contextmanager
def oldbranchmap():
    previous = branchmap.branchcache
    try:
        branchmap.branchcache = _oldbranchmap
        yield
    finally:
        branchmap.branchcache = previous

_publiconly = set([
    'base',
    'immutable',
])

def mighttopic(repo):
    return hasminitopic(repo) and repo.filtername not in _publiconly

class _topiccache(branchmap.branchcache): # combine me with branchmap.branchcache

    def __init__(self, *args, **kwargs):
        # super() call may fail otherwise
        with oldbranchmap():
            super(_topiccache, self).__init__(*args, **kwargs)
        self.phaseshash = None

    def copy(self):
        """return an deep copy of the branchcache object"""
        new = self.__class__(self, self.tipnode, self.tiprev, self.filteredhash,
                             self._closednodes)
        new.phaseshash = self.phaseshash
        return new

    def validfor(self, repo):
        """Is the cache content valid regarding a repo

        - False when cached tipnode is unknown or if we detect a strip.
        - True when cache is up to date or a subset of current repo."""
        valid = super(_topiccache, self).validfor(repo)
        if not valid:
            return False
        elif not mighttopic(repo) and self.phaseshash is None:
            # phasehash at None means this is a branchmap
            # coming from a public only set
            return True
        else:
            try:
                valid = self.phaseshash == _phaseshash(repo, self.tiprev)
                return valid
            except IndexError:
                return False

    def write(self, repo):
        # we expect (hope) mutable set to be small enough to be that computing
        # it all the time will be fast enough
        if not mighttopic(repo):
            super(_topiccache, self).write(repo)

    def update(self, repo, revgen):
        """Given a branchhead cache, self, that may have extra nodes or be
        missing heads, and a generator of nodes that are strictly a superset of
        heads missing, this function updates self to be correct.
        """
        super(_topiccache, self).update(repo, revgen)
        if mighttopic(repo):
            self.phaseshash = _phaseshash(repo, self.tiprev)

def wrapread(orig, repo):
    # Avoiding to write cache for filter where topic applies is a good step,
    # but we need to also avoid reading it. Existing branchmap cache might
    # exists before the turned the feature on.
    if mighttopic(repo):
        return None
    return orig(repo)

# advertise topic capabilities

def wireprotocaps(orig, repo, proto):
    caps = orig(repo, proto)
    if hasminitopic(repo):
        caps.append('topics')
    return caps

# wrap the necessary bit

def wrapclass(container, oldname, new):
    old = getattr(container, oldname)
    if not issubclass(old, new):
        targetclass = new
        # check if someone else already wrapped the class and handle that
        if not issubclass(new, old):
            class targetclass(new, old):
                pass
        setattr(container, oldname, targetclass)
    current = getattr(container, oldname)
    assert issubclass(current, new), (current, new, targetclass)

def uisetup(ui):
    wrapclass(context, 'changectx', topicchangectx)
    wrapclass(branchmap, 'branchcache', _topiccache)
    extensions.wrapfunction(branchmap, 'read', wrapread)
    extensions.wrapfunction(wireproto, '_capabilities', wireprotocaps)