Index: portage-2.1_pre3/pym/cache/util.py
===================================================================
--- portage-2.1_pre3.orig/pym/cache/util.py
+++ portage-2.1_pre3/pym/cache/util.py
@@ -101,3 +101,13 @@ class non_quiet_mirroring(quiet_mirrorin
 	def corruption(self,key,*arg):	print "corrupt %s:" % key,arg
 	def eclass_stale(self,key,*arg):print "stale %s:"%key,arg
 
+def is_cache_valid(emtime, eclasses, mydata):
+	if emtime != long(mydata.get("_mtime_", 0)):
+		return False
+	ec_dict = mydata.get("_eclasses_", [])
+	if len(ec_dict) == 0:
+		return True
+	for eclass, tup in ec_dict.iteritems():
+		if eclass not in eclasses or tuple(tup) != eclasses[eclass]:
+			return False
+	return True
Index: portage-2.1_pre3/pym/portage.py
===================================================================
--- portage-2.1_pre3.orig/pym/portage.py
+++ portage-2.1_pre3/pym/portage.py
@@ -29,6 +29,7 @@ try:
 	from time import sleep
 	from random import shuffle
 	from cache.cache_errors import CacheError
+	from cache.util import is_cache_valid
 except SystemExit, e:
 	raise
 except Exception, e:
@@ -4721,7 +4722,12 @@ class portdbapi(dbapi):
 		for x in self.porttrees:
 			# location, label, auxdbkeys
 			self.auxdb[x] = self.auxdbmodule(portage_const.DEPCACHE_PATH, x, filtered_auxdbkeys, gid=portage_gid)
-			
+
+		if "metadb" in self.mysettings.features:
+			for x in self.porttrees:
+				if os.path.exists(x+"/metadata/cache"):
+					self.metadb[x]=self.metadbmodule(x, "metadata/cache", auxdbkeys)
+
 	def close_caches(self):
 		for x in self.auxdb.keys():
 			self.auxdb[x].sync()
@@ -4825,14 +4831,16 @@ class portdbapi(dbapi):
 			raise KeyError
 
 		try:
-			mydata = self.auxdb[mylocation][mycpv]
-			if emtime != long(mydata.get("_mtime_", 0)):
-				doregen = True
-			elif len(mydata.get("_eclasses_", [])) > 0:
-				doregen = not self.eclassdb.is_eclass_data_valid(mydata["_eclasses_"])
-			else:
-				doregen = False
-				
+			mydata=None
+			doregen=False
+			if self.metadb.has_key(mylocation):
+				try:
+					mydata = self.metadb[mylocation][mycpv]
+				except (KeyError, CacheError):
+					pass
+			if not mydata or not is_cache_valid(emtime, self.eclassdb.eclasses, mydata):
+				mydata = self.auxdb[mylocation][mycpv]
+				doregen = not is_cache_valid(emtime, self.eclassdb.eclasses, mydata)
 		except KeyError:
 			doregen = True
 		except CacheError:
Index: portage-2.1_pre3/bin/emerge
===================================================================
--- portage-2.1_pre3.orig/bin/emerge
+++ portage-2.1_pre3/bin/emerge
@@ -2768,6 +2768,10 @@ if myaction in ["sync","rsync","metadata
 	except:
 		pass
 
+	if updatecache_flg and "metadb" in portage.features:
+		updatecache_flg=False
+		print "!!! Skipping metadata transfer because metadb is in FEATURES."
+
 	if os.path.exists(myportdir+"/metadata/cache") and updatecache_flg:
 		if "--quiet" not in myopts:
 			print "\n>>> Updating Portage cache:      ",