diff mercurial/obsolete.py @ 17469:fb72eec7efd8

obsolete: introduce caches for all meaningful sets

This changeset introduces caches on the `obsstore` that keeps track of sets of
revisions meaningful for obsolescence related logics. For now they are:

- obsolete: changesets used as precursors (and not public),
- extinct:  obsolete changesets with osbolete descendants only,
- unstable: non obsolete changesets with obsolete ancestors.

The cache is accessed using the `getobscache(repo, '<set-name>')` function which
builds the cache on demand. The `clearobscaches(repo)` function takes care of
clearing the caches if any.

Caches are cleared when one of these events happens:

- a new marker is added,
- a new changeset is added,
- some changesets are made public,
- some public changesets are demoted to draft or secret.

Declaration of more sets is made easy because we will have to handle at least
two other "troubles" (latecomer and conflicting).

Caches are now used by revset and changectx. It is usually not much more
expensive to compute the whole set than to check the property of a few elements.
The performance boost is welcome in case we apply obsolescence logic on a lot of
revisions. This makes the feature usable!

--- a/mercurial/obsolete.py	Mon Aug 27 09:37:49 2012 -0700
+++ b/mercurial/obsolete.py	Tue Aug 28 20:52:04 2012 +0200
@@ -161,6 +161,8 @@
     """
 
     def __init__(self, sopener):
+        # caches for various obsolescence related cache
+        self.caches = {}
         self._all = []
         # new markers to serialize
         self.precursors = {}
@@ -220,6 +222,8 @@
                 # call 'filecacheentry.refresh()'  here
                 f.close()
             self._load(new)
+            # new marker *may* have changed several set. invalidate the cache.
+            self.caches.clear()
         return len(new)
 
     def mergemarkers(self, transation, data):
@@ -327,3 +331,67 @@
                 if suc not in seen:
                     seen.add(suc)
                     remaining.add(suc)
+
+# mapping of 'set-name' -> <function to computer this set>
+cachefuncs = {}
+def cachefor(name):
+    """Decorator to register a function as computing the cache for a set"""
+    def decorator(func):
+        assert name not in cachefuncs
+        cachefuncs[name] = func
+        return func
+    return decorator
+
+def getobscache(repo, name):
+    """Return the set of revision that belong to the <name> set
+
+    Such access may compute the set and cache it for future use"""
+    if not repo.obsstore:
+        return ()
+    if name not in repo.obsstore.caches:
+        repo.obsstore.caches[name] = cachefuncs[name](repo)
+    return repo.obsstore.caches[name]
+
+# To be simple we need to invalidate obsolescence cache when:
+#
+# - new changeset is added:
+# - public phase is changed
+# - obsolescence marker are added
+# - strip is used a repo
+def clearobscaches(repo):
+    """Remove all obsolescence related cache from a repo
+
+    This remove all cache in obsstore is the obsstore already exist on the
+    repo.
+
+    (We could be smarter here given the exact event that trigger the cache
+    clearing)"""
+    # only clear cache is there is obsstore data in this repo
+    if 'obsstore' in repo._filecache:
+        repo.obsstore.caches.clear()
+
+@cachefor('obsolete')
+def _computeobsoleteset(repo):
+    """the set of obsolete revisions"""
+    obs = set()
+    nm = repo.changelog.nodemap
+    for prec in repo.obsstore.precursors:
+        rev = nm.get(prec)
+        if rev is not None:
+            obs.add(rev)
+    return set(repo.revs('%ld - public()', obs))
+
+@cachefor('unstable')
+def _computeunstableset(repo):
+    """the set of non obsolete revisions with obsolete parents"""
+    return set(repo.revs('(obsolete()::) - obsolete()'))
+
+@cachefor('suspended')
+def _computesuspendedset(repo):
+    """the set of obsolete parents with non obsolete descendants"""
+    return set(repo.revs('obsolete() and obsolete()::unstable()'))
+
+@cachefor('extinct')
+def _computeextinctset(repo):
+    """the set of obsolete parents without non obsolete descendants"""
+    return set(repo.revs('obsolete() - obsolete()::unstable()'))