Merge "Improve performance of WindowState.toString()"

Author: Dianne Hackborn

services/java/com/android/server/WindowManagerService.java

@@ -6005,6 +6005,11 @@ private final class WindowState implements WindowManagerPolicy.WindowState {
         // Input channel
         InputChannel mInputChannel;
 
+        // Used to improve performance of toString()
+        String mStringNameCache;
+        CharSequence mLastTitle;
+        boolean mWasPaused;
+
         WindowState(Session s, IWindow c, WindowToken token,
                WindowState attachedWindow, WindowManager.LayoutParams a,
                int viewVisibility) {
@@ -7262,9 +7267,14 @@ String makeInputChannelName() {
 
         @Override
         public String toString() {
-            return "Window{"
-                + Integer.toHexString(System.identityHashCode(this))
-                + " " + mAttrs.getTitle() + " paused=" + mToken.paused + "}";
+            if (mStringNameCache == null || mLastTitle != mAttrs.getTitle()
+                    || mWasPaused != mToken.paused) {
+                mLastTitle = mAttrs.getTitle();
+                mWasPaused = mToken.paused;
+                mStringNameCache = "Window{" + Integer.toHexString(System.identityHashCode(this))
+                        + " " + mLastTitle + " paused=" + mWasPaused + "}";
+            }
+            return mStringNameCache;
         }
     }