phase: extracts heads computation logics from analyzeremotephases

mercurial/phases.py

@@ -1,292 +1,299 b''
 """ Mercurial phases support code
 
     ---
 
     Copyright 2011 Pierre-Yves David <[e-mail]>
                    Logilab SA        <[e-mail]>
                    Augie Fackler     <[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.
 
     ---
 
 This module implements most phase logic in mercurial.
 
 
 Basic Concept
 =============
 
 A 'changeset phases' is an indicator that tells us how a changeset is
 manipulated and communicated. The details of each phase is described below,
 here we describe the properties they have in common.
 
 Like bookmarks, phases are not stored in history and thus are not permanent and
 leave no audit trail.
 
 First, no changeset can be in two phases at once. Phases are ordered, so they
 can be considered from lowest to highest. The default, lowest phase is 'public'
 - this is the normal phase of existing changesets. A child changeset can not be
 in a lower phase than its parents.
 
 These phases share a hierarchy of traits:
 
             immutable shared
     public:     X        X
     draft:               X
     secret:
 
 local commits are draft by default
 
 Phase movement and exchange
 ============================
 
 Phase data are exchanged by pushkey on pull and push. Some server have a
 publish option set, we call them publishing server. Pushing to such server make
 draft changeset publish.
 
 A small list of fact/rules define the exchange of phase:
 
 * old client never changes server states
 * pull never changes server states
 * publish and old server csets are seen as public by client
 
 * Any secret changeset seens in another repository is lowered to at least draft
 
 
 Here is the final table summing up the 49 possible usecase of phase exchange:
 
                            server
                   old     publish      non-publish
                  N   X    N   D   P    N   D   P
     old client
     pull
      N           -   X/X  -   X/D X/P  -   X/D X/P
      X           -   X/X  -   X/D X/P  -   X/D X/P
     push
      X           X/X X/X  X/P X/P X/P  X/D X/D X/P
     new client
     pull
      N           -   P/X  -   P/D P/P  -   D/D P/P
      D           -   P/X  -   P/D P/P  -   D/D P/P
      P           -   P/X  -   P/D P/P  -   P/D P/P
     push
      D           P/X P/X  P/P P/P P/P  D/D D/D P/P
      P           P/X P/X  P/P P/P P/P  P/P P/P P/P
 
 Legend:
 
     A/B = final state on client / state on server
 
     * N = new/not present,
     * P = public,
     * D = draft,
     * X = not tracked (ie: the old client or server has no internal way of
           recording the phase.)
 
     passive = only pushes
 
 
     A cell here can be read like this:
 
     "When a new client pushes a draft changeset (D) to a publishing server
     where it's not present (N), it's marked public on both sides (P/P)."
 
 Note: old client behave as publish server with Draft only content
 - other people see it as public
 - content is pushed as draft
 
 """
 
 import errno
 from node import nullid, bin, hex, short
 from i18n import _
 
 allphases = public, draft, secret = range(3)
 trackedphases = allphases[1:]
 phasenames = ['public', 'draft', 'secret']
 
 def readroots(repo):
     """Read phase roots from disk"""
     roots = [set() for i in allphases]
     try:
         f = repo.sopener('phaseroots')
         try:
             for line in f:
                 phase, nh = line.strip().split()
                 roots[int(phase)].add(bin(nh))
         finally:
             f.close()
     except IOError, inst:
         if inst.errno != errno.ENOENT:
             raise
         for f in repo._phasedefaults:
             roots = f(repo, roots)
     return roots
 
 def writeroots(repo):
     """Write phase roots from disk"""
     f = repo.sopener('phaseroots', 'w', atomictemp=True)
     try:
         for phase, roots in enumerate(repo._phaseroots):
             for h in roots:
                 f.write('%i %s\n' % (phase, hex(h)))
         repo._dirtyphases = False
     finally:
         f.close()
 
 def filterunknown(repo, phaseroots=None):
     """remove unknown nodes from the phase boundary
 
     no data is lost as unknown node only old data for their descentants
     """
     if phaseroots is None:
         phaseroots = repo._phaseroots
     nodemap = repo.changelog.nodemap # to filter unknown nodes
     for phase, nodes in enumerate(phaseroots):
         missing = [node for node in nodes if node not in nodemap]
         if missing:
             for mnode in missing:
                 msg = 'Removing unknown node %(n)s from %(p)i-phase boundary'
                 repo.ui.debug(msg, {'n': short(mnode), 'p': phase})
             nodes.symmetric_difference_update(missing)
             repo._dirtyphases = True
 
 def advanceboundary(repo, targetphase, nodes):
     """Add nodes to a phase changing other nodes phases if necessary.
 
     This function move boundary *forward* this means that all nodes are set
     in the target phase or kept in a *lower* phase.
 
     Simplify boundary to contains phase roots only."""
     delroots = [] # set of root deleted by this path
     for phase in xrange(targetphase + 1, len(allphases)):
         # filter nodes that are not in a compatible phase already
         # XXX rev phase cache might have been invalidated by a previous loop
         # XXX we need to be smarter here
         nodes = [n for n in nodes if repo[n].phase() >= phase]
         if not nodes:
             break # no roots to move anymore
         roots = repo._phaseroots[phase]
         olds = roots.copy()
         ctxs = list(repo.set('roots((%ln::) - (%ln::%ln))', olds, olds, nodes))
         roots.clear()
         roots.update(ctx.node() for ctx in ctxs)
         if olds != roots:
             # invalidate cache (we probably could be smarter here
             if '_phaserev' in vars(repo):
                 del repo._phaserev
             repo._dirtyphases = True
             # some roots may need to be declared for lower phases
             delroots.extend(olds - roots)
         # declare deleted root in the target phase
         if targetphase != 0:
             retractboundary(repo, targetphase, delroots)
 
 
 def retractboundary(repo, targetphase, nodes):
     """Set nodes back to a phase changing other nodes phases if necessary.
 
     This function move boundary *backward* this means that all nodes are set
     in the target phase or kept in a *higher* phase.
 
     Simplify boundary to contains phase roots only."""
     currentroots = repo._phaseroots[targetphase]
     newroots = [n for n in nodes if repo[n].phase() < targetphase]
     if newroots:
         currentroots.update(newroots)
         ctxs = repo.set('roots(%ln::)', currentroots)
         currentroots.intersection_update(ctx.node() for ctx in ctxs)
         if '_phaserev' in vars(repo):
             del repo._phaserev
         repo._dirtyphases = True
 
 
 def listphases(repo):
     """List phases root for serialisation over pushkey"""
     keys = {}
     value = '%i' % draft
     for root in repo._phaseroots[draft]:
         keys[hex(root)] = value
 
     if repo.ui.configbool('phases', 'publish', True):
         # Add an extra data to let remote know we are a publishing repo.
         # Publishing repo can't just pretend they are old repo. When pushing to
         # a publishing repo, the client still need to push phase boundary
         #
         # Push do not only push changeset. It also push phase data. New
         # phase data may apply to common changeset which won't be push (as they
         # are common).  Here is a very simple example:
         #
         # 1) repo A push changeset X as draft to repo B
         # 2) repo B make changeset X public
         # 3) repo B push to repo A. X is not pushed but the data that X as now
         #    public should
         #
         # The server can't handle it on it's own as it has no idea of client
         # phase data.
         keys['publishing'] = 'True'
     return keys
 
 def pushphase(repo, nhex, oldphasestr, newphasestr):
     """List phases root for serialisation over pushkey"""
     lock = repo.lock()
     try:
         currentphase = repo[nhex].phase()
         newphase = abs(int(newphasestr)) # let's avoid negative index surprise
         oldphase = abs(int(oldphasestr)) # let's avoid negative index surprise
         if currentphase == oldphase and newphase < oldphase:
             advanceboundary(repo, newphase, [bin(nhex)])
             return 1
         else:
             return 0
     finally:
         lock.release()
 
 def visibleheads(repo):
     """return the set of visible head of this repo"""
     # XXX we want a cache on this
     sroots = repo._phaseroots[secret]
     if sroots:
         # XXX very slow revset. storing heads or secret "boundary" would help.
         revset = repo.set('heads(not (%ln::))', sroots)
 
         vheads = [ctx.node() for ctx in revset]
         if not vheads:
             vheads.append(nullid)
     else:
         vheads = repo.heads()
     return vheads
 
 def analyzeremotephases(repo, subset, roots):
     """Compute phases heads and root in a subset of node from root dict
 
     * subset is heads of the subset
     * roots is {<nodeid> => phase} mapping. key and value are string.
 
     Accept unknown element input
     """
     # build list from dictionary
     draftroots = []
     nodemap = repo.changelog.nodemap # to filter unknown nodes
     for nhex, phase in roots.iteritems():
         if nhex == 'publishing': # ignore data related to publish option
             continue
         node = bin(nhex)
         phase = int(phase)
         if phase == 0:
             if node != nullid:
                 repo.ui.warn(_('ignoring inconsistent public root'
                                ' from remote: %s\n') % nhex)
         elif phase == 1:
             if node in nodemap:
                 draftroots.append(node)
         else:
             repo.ui.warn(_('ignoring unexpected root from remote: %i %s\n')
                          % (phase, nhex))
     # compute heads
-    revset = repo.set('heads((%ln + parents(%ln)) - (%ln::%ln))',
-                      subset, draftroots, draftroots, subset)
-    publicheads = [c.node() for c in revset]
+    publicheads = newheads(repo, subset, draftroots)
     return publicheads, draftroots
 
+def newheads(repo, heads, roots):
+    """compute new head of a subset minus another
+
+    * `heads`: define the first subset
+    * `rroots`: define the second we substract to the first"""
+    revset = repo.set('heads((%ln + parents(%ln)) - (%ln::%ln))',
+                      heads, roots, roots, heads)
+    return [c.node() for c in revset]
+