Add modification threshold for BlockerCache.flush(), to avoid wasteful IO.

svn path=/main/trunk/; revision=10549

diff --git a/pym/_emerge/__init__.py b/pym/_emerge/__init__.py
index f346093ed67ec2117442185dbbca5e16fea9053f..ae471a9759f7916ea700f75ce659344775d93dd5 100644 (file)
--- a/pym/_emerge/__init__.py
+++ b/pym/_emerge/__init__.py
@@ -1449,6 +1449,11 @@ class BlockerCache(DictMixin):
                1) the set of installed packages (including COUNTER) has changed
                2) the old-style virtuals have changed
        """
+
+       # Number of uncached packages to trigger cache update, since
+       # it's wasteful to update it for every vdb change.
+       _cache_threshold = 5
+
        class BlockerData(object):
 
                __slots__ = ("__weakref__", "atoms", "counter")
@@ -1464,7 +1469,7 @@ class BlockerCache(DictMixin):
                        portage.CACHE_PATH.lstrip(os.path.sep), "vdb_blockers.pickle")
                self._cache_version = "1"
                self._cache_data = None
-               self._modified = False
+               self._modified = 0
                self._load()
 
        def _load(self):
@@ -1534,7 +1539,7 @@ class BlockerCache(DictMixin):
                        self._cache_data = {"version":self._cache_version}
                        self._cache_data["blockers"] = {}
                        self._cache_data["virtuals"] = self._virtuals
-               self._modified = False
+               self._modified = 0
 
        def flush(self):
                """If the current user has permission and the internal blocker cache
@@ -1552,7 +1557,7 @@ class BlockerCache(DictMixin):
                        "virtuals" : vardb.settings.getvirtuals()
                }
                """
-               if self._modified and \
+               if self._modified >= self._cache_threshold and \
                        secpass >= 2:
                        try:
                                f = portage.util.atomic_ofstream(self._cache_filename)
@@ -1562,7 +1567,7 @@ class BlockerCache(DictMixin):
                                        self._cache_filename, gid=portage.portage_gid, mode=0644)
                        except (IOError, OSError), e:
                                pass
-                       self._modified = False
+                       self._modified = 0
 
        def __setitem__(self, cpv, blocker_data):
                """
@@ -1576,14 +1581,13 @@ class BlockerCache(DictMixin):
                """
                self._cache_data["blockers"][cpv] = \
                        (blocker_data.counter, tuple(str(x) for x in blocker_data.atoms))
-               self._modified = True
+               self._modified += 1
 
        def __iter__(self):
                return iter(self._cache_data["blockers"])
 
        def __delitem__(self, cpv):
                del self._cache_data["blockers"][cpv]
-               self._modified = True
 
        def __getitem__(self, cpv):
                """