diff --git a/include/binder/Permission.h b/include/binder/Permission.h
deleted file mode 100644
index 9542d50..0000000
--- a/include/binder/Permission.h
+++ /dev/null
@@ -1,68 +0,0 @@
-/*
- * Copyright (C) 2009 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef BINDER_PERMISSION_H
-#define BINDER_PERMISSION_H
-
-#include <stdint.h>
-#include <unistd.h>
-
-#include <utils/SortedVector.h>
-#include <utils/String16.h>
-#include <utils/threads.h>
-
-namespace android {
-// ---------------------------------------------------------------------------
-
-/*
- * Permission caches the result of the permission check for the given
- * permission name and the provided uid/pid. It also handles a few
- * known cases efficiently (caller is in the same process or is root).
- * The package manager does something similar but lives in dalvik world
- * and is therefore extremely slow to access.
- */
-
-class Permission
-{
-public:
-            Permission(char const* name);
-            Permission(const String16& name);
-            Permission(const Permission& rhs);
-    virtual ~Permission();
-
-    bool operator < (const Permission& rhs) const;
-
-    // checks the current binder call's caller has access to this permission
-    bool checkCalling() const;
-    
-    // checks the specified pid/uid has access to this permission
-    bool check(pid_t pid, uid_t uid) const;
-    
-protected:
-    virtual bool doCheckPermission(pid_t pid, uid_t uid) const;
-
-private:
-    Permission& operator = (const Permission& rhs) const;
-    const String16 mPermissionName;
-    mutable SortedVector<uid_t> mGranted;
-    const pid_t mPid;
-    mutable Mutex mLock;
-};
-
-// ---------------------------------------------------------------------------
-}; // namespace android
-
-#endif /* BINDER_PERMISSION_H */
diff --git a/include/binder/PermissionCache.h b/include/binder/PermissionCache.h
new file mode 100644
index 0000000..1171d48
--- /dev/null
+++ b/include/binder/PermissionCache.h
@@ -0,0 +1,79 @@
+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef BINDER_PERMISSION_H
+#define BINDER_PERMISSION_H
+
+#include <stdint.h>
+#include <unistd.h>
+
+#include <utils/String16.h>
+#include <utils/Singleton.h>
+
+namespace android {
+// ---------------------------------------------------------------------------
+
+/*
+ * PermissionCache caches permission checks for a given uid.
+ *
+ * Currently the cache is not updated when there is a permission change,
+ * for instance when an application is uninstalled.
+ *
+ * IMPORTANT: for the reason stated above, only system permissions are safe
+ * to cache. This restriction may be lifted at a later time.
+ *
+ */
+
+class PermissionCache : Singleton<PermissionCache> {
+    struct Entry {
+        String16    name;
+        uid_t       uid;
+        bool        granted;
+        inline bool operator < (const Entry& e) const {
+            return (uid == e.uid) ? (name < e.name) : (uid < e.uid);
+        }
+    };
+    mutable Mutex mLock;
+    // we pool all the permission names we see, as many permissions checks
+    // will have identical names
+    SortedVector< String16 > mPermissionNamesPool;
+    // this is our cache per say. it stores pooled names.
+    SortedVector< Entry > mCache;
+
+    // free the whole cache, but keep the permission name pool
+    void purge();
+
+    status_t check(bool* granted,
+            const String16& permission, uid_t uid) const;
+
+    void cache(const String16& permission, uid_t uid, bool granted);
+
+public:
+    PermissionCache();
+
+    static bool checkCallingPermission(const String16& permission);
+
+    static bool checkCallingPermission(const String16& permission,
+                                int32_t* outPid, int32_t* outUid);
+
+    static bool checkPermission(const String16& permission,
+            pid_t pid, uid_t uid);
+};
+
+// ---------------------------------------------------------------------------
+}; // namespace android
+
+#endif /* BINDER_PERMISSION_H */