Merge "Cache WindowManager in StrictMode; add android.util.Singleton"

core/java/android/os/StrictMode.java

@@ -22,6 +22,7 @@ import android.app.ApplicationErrorReport;
 import android.content.Intent;
 import android.util.Log;
 import android.util.Printer;
+import android.util.Singleton;
 import android.view.IWindowManager;
 
 import com.android.internal.os.RuntimeInit;
@@ -922,10 +923,8 @@ public final class StrictMode {
                 return;
             }
 
-            // TODO: cache the window manager stub?
             final IWindowManager windowManager = (info.policy & PENALTY_FLASH) != 0 ?
-                    IWindowManager.Stub.asInterface(ServiceManager.getService("window")) :
-                    null;
+                    sWindowManager.get() : null;
             if (windowManager != null) {
                 try {
                     windowManager.showStrictModeViolation(true);
@@ -1404,6 +1403,12 @@ public final class StrictMode {
         }
     };
 
+    private static Singleton<IWindowManager> sWindowManager = new Singleton<IWindowManager>() {
+        protected IWindowManager create() {
+            return IWindowManager.Stub.asInterface(ServiceManager.getService("window"));
+        }
+    };
+
     /**
      * Enter a named critical span (e.g. an animation)
      *

core/java/android/util/Singleton.java

@@ -0,0 +1,39 @@
+/*
+ * Copyright (C) 2010 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.
+ */
+
+package android.util;
+
+/**
+ * Singleton helper class for lazily initialization.
+ *
+ * Modeled after frameworks/base/include/utils/Singleton.h
+ *
+ * @hide
+ */
+public abstract class Singleton<T> {
+    private T mInstance;
+
+    protected abstract T create();
+
+    public final T get() {
+        synchronized (this) {
+            if (mInstance == null) {
+                mInstance = create();
+            }
+            return mInstance;
+        }
+    }
+}