commit 3bae0b027feb873cbb430ee1c3e0408e565b69f2
author Daichi Hirono <hirono@google.com> Fri Oct 27 13:05:13 2017 +0900
committer Daichi Hirono <hirono@google.com> Wed Nov 01 09:07:52 2017 +0900
tree e4366efe727a3c807421b57e47ad84b12601fe26
parent 4f8bd78bfce85bd3d04861f63856c499b5799c37

Sort out various cleanup methods of DragState

DragState has mainly three states.

 * just created
 * after input intercepters is registered
 * after drag start broadcast is sent out
 * after drag end/cancel animation is completed

Previously DragState has multiple cleanup methods for each state and
callers need to choose the correct one.

The CL merges the cleanup methods into one 'closeLocked' method so that
callers can always invoke closeLocked, and DragState can take the
responsibility to relelase its relevant resources depends on its
internal state.

Bug: 65564090
Test: android.server.wm.CrossAppDragAndDropTests, manually check the
      drag and drop behavior on test app.

Change-Id: I257231073b350726bfcebaf1cdf6a02dc0d4ca39

services/core/java/com/android/server/wm/DragDropController.java

diff --git a/services/core/java/com/android/server/wm/DragDropController.java b/services/core/java/com/android/server/wm/DragDropController.java
index 860ff38..b6f0f6a 100644
--- a/services/core/java/com/android/server/wm/DragDropController.java
+++ b/services/core/java/com/android/server/wm/DragDropController.java
@@ -49,6 +49,11 @@
     static final int MSG_TEAR_DOWN_DRAG_AND_DROP_INPUT = 2;
     static final int MSG_ANIMATION_END = 3;
 
+    /**
+     * Drag state per operation.
+     * The variable is cleared by {@code #onDragStateClosedLocked} which is invoked by DragState
+     * itself, thus the variable can be null after calling DragState's methods.
+     */
     DragState mDragState;
 
     private WindowManagerService mService;
@@ -158,9 +163,7 @@
             if (!mService.mInputManager.transferTouchFocus(callingWin.mInputChannel,
                     mDragState.getInputChannel())) {
                 Slog.e(TAG_WM, "Unable to transfer touch focus");
-                mDragState.unregister();
-                mDragState.reset();
-                mDragState = null;
+                mDragState.closeLocked();
                 return false;
             }
 
@@ -282,6 +285,17 @@
         mHandler.sendMessageDelayed(msg, DRAG_TIMEOUT_MS);
     }
 
+    /**
+     * Notifies the current drag state is closed.
+     */
+    void onDragStateClosedLocked(DragState dragState) {
+        if (mDragState != dragState) {
+            Slog.wtf(TAG_WM, "Unknown drag state is closed");
+            return;
+        }
+        mDragState = null;
+    }
+
     private class DragHandler extends Handler {
         /**
          * Lock for window manager.
@@ -304,9 +318,7 @@
                     synchronized (mService.mWindowMap) {
                         // !!! TODO: ANR the app that has failed to start the drag in time
                         if (mDragState != null) {
-                            mDragState.unregister();
-                            mDragState.reset();
-                            mDragState = null;
+                            mDragState.closeLocked();
                         }
                     }
                     break;
@@ -346,7 +358,7 @@
                                     "plyaing animation");
                             return;
                         }
-                        mDragState.onAnimationEndLocked();
+                        mDragState.closeLocked();
                     }
                     break;
                 }