1 files changed, 105 insertions, 0 deletions
diff --git a/pym/portage/cache/metadata_overlay.py b/pym/portage/cache/metadata_overlay.py
new file mode 100644
index 000000000..d82ba96f8
--- /dev/null
+++ b/pym/portage/cache/metadata_overlay.py
@@ -0,0 +1,105 @@
+# Copyright 1999-2006 Gentoo Foundation
+# Distributed under the terms of the GNU General Public License v2
+# $Header: $
+
+import time
+if not hasattr(__builtins__, "set"):
+	from sets import Set as set
+from cache import template
+from cache.cache_errors import CacheCorruption
+from cache.flat_hash import database as db_rw
+from cache.metadata import database as db_ro
+
+class database(template.database):
+
+	serialize_eclasses = False
+
+	def __init__(self, location, label, auxdbkeys, db_rw=db_rw, db_ro=db_ro,
+		*args, **config):
+		super_config = config.copy()
+		super_config.pop("gid", None)
+		super(database, self).__init__(location, label, auxdbkeys,
+			*args, **super_config)
+		self.db_rw = db_rw(location, label, auxdbkeys, **config)
+		self.commit = self.db_rw.commit
+		self.autocommits = self.db_rw.autocommits
+		if isinstance(db_ro, type):
+			ro_config = config.copy()
+			ro_config["readonly"] = True
+			self.db_ro = db_ro(label, "metadata/cache", auxdbkeys, **ro_config)
+		else:
+			self.db_ro = db_ro
+
+	def __getitem__(self, cpv):
+		"""funnel whiteout validation through here, since value needs to be fetched"""
+		try:
+			value = self.db_rw[cpv]
+		except KeyError:
+			return self.db_ro[cpv] # raises a KeyError when necessary
+		except CacheCorruption:
+			del self.db_rw[cpv]
+			return self.db_ro[cpv] # raises a KeyError when necessary
+		if self._is_whiteout(value):
+			if self._is_whiteout_valid(cpv, value):
+				raise KeyError(cpv)
+			else:
+				del self.db_rw[cpv]
+				return self.db_ro[cpv] # raises a KeyError when necessary
+		else:
+			return value
+
+	def _setitem(self, name, values):
+		value_ro = self.db_ro.get(name, None)
+		if value_ro is not None and \
+			self._are_values_identical(value_ro, values):
+			# we have matching values in the underlying db_ro
+			# so it is unnecessary to store data in db_rw
+			try:
+				del self.db_rw[name] # delete unwanted whiteout when necessary
+			except KeyError:
+				pass
+			return
+		self.db_rw[name] = values
+
+	def _delitem(self, cpv):
+		value = self[cpv] # validates whiteout and/or raises a KeyError when necessary
+		if self.db_ro.has_key(cpv):
+			self.db_rw[cpv] = self._create_whiteout(value)
+		else:
+			del self.db_rw[cpv]
+
+	def __contains__(self, cpv):
+		try:
+			self[cpv] # validates whiteout when necessary
+		except KeyError:
+			return False
+		return True
+
+	def iterkeys(self):
+		s = set()
+		for cpv in self.db_rw.iterkeys():
+			if self.has_key(cpv): # validates whiteout when necessary
+				yield cpv
+			# set includes whiteouts so they won't be yielded later
+			s.add(cpv)
+		for cpv in self.db_ro.iterkeys():
+			if cpv not in s:
+				yield cpv
+
+	def _is_whiteout(self, value):
+		return value["EAPI"] == "whiteout"
+
+	def _create_whiteout(self, value):
+		return {"EAPI":"whiteout","_eclasses_":value["_eclasses_"],"_mtime_":value["_mtime_"]}
+
+	def _is_whiteout_valid(self, name, value_rw):
+		try:
+			value_ro = self.db_ro[name]
+			return self._are_values_identical(value_rw,value_ro)
+		except KeyError:
+			return False
+
+	def _are_values_identical(self, value1, value2):
+		if long(value1["_mtime_"]) != long(value2["_mtime_"]):
+			return False
+		return value1["_eclasses_"] == value2["_eclasses_"]