Track per-window information in ViewFrameInfo

FrameInfo will now be per-window; that is, per-ViewRootImpl.
Some of the information should remain “global” (it remain in Choreographer),
while some information is going to become ViewRootImpl-specific.
Before the information gets passed to the native layer,
 the ViewRootImpl-specific info will be stitched together
with the general Choreographer info.

This change is useful in order to correctly correlate frames with a specific
input event. In the unlikely scenario of a user touching two windows of the
same app simultaneously, this change will allow us to correctly measure the
latency of both frames produced by the windows.

Design doc: https://docs.google.com/document/d/1KMpMBlOxnl7zkWBCbXZZE6ZlaHEA4efYnN6WYK8n3FE/edit?resourcekey=0-eqooVNP0SskupljlTFvtOQ

Test: atest ViewFrameInfoTest
Bug: 169866723
Change-Id: Ib0bf9cd51cbcc0b9b70460c929c480eb490ec322

3 files changed, 107 insertions, 6 deletions

diff --git a/core/java/android/view/ThreadedRenderer.java b/core/java/android/view/ThreadedRenderer.java
index 57ca71ae4b02..d839e3532b64 100644
--- a/core/java/android/view/ThreadedRenderer.java
+++ b/core/java/android/view/ThreadedRenderer.java
@@ -21,6 +21,7 @@ import android.annotation.Nullable;
 import android.app.ActivityManager;
 import android.content.Context;
 import android.content.res.TypedArray;
+import android.graphics.FrameInfo;
 import android.graphics.HardwareRenderer;
 import android.graphics.Picture;
 import android.graphics.Point;
@@ -610,8 +611,7 @@ public final class ThreadedRenderer extends HardwareRenderer {
      * @param attachInfo AttachInfo tied to the specified view.
      */
     void draw(View view, AttachInfo attachInfo, DrawCallbacks callbacks) {
-        final Choreographer choreographer = attachInfo.mViewRootImpl.mChoreographer;
-        choreographer.mFrameInfo.markDrawStart();
+        attachInfo.mViewRootImpl.mViewFrameInfo.markDrawStart();
 
         updateRootDisplayList(view, callbacks);
 
@@ -629,7 +629,9 @@ public final class ThreadedRenderer extends HardwareRenderer {
             attachInfo.mPendingAnimatingRenderNodes = null;
         }
 
-        int syncResult = syncAndDrawFrame(choreographer.mFrameInfo);
+        final FrameInfo frameInfo = attachInfo.mViewRootImpl.getUpdatedFrameInfo();
+
+        int syncResult = syncAndDrawFrame(frameInfo);
         if ((syncResult & SYNC_LOST_SURFACE_REWARD_IF_FOUND) != 0) {
             Log.w("OpenGLRenderer", "Surface lost, forcing relayout");
             // We lost our surface. For a relayout next frame which should give us a new
diff --git a/core/java/android/view/ViewFrameInfo.java b/core/java/android/view/ViewFrameInfo.java
new file mode 100644
index 000000000000..890d071f8090
--- /dev/null
+++ b/core/java/android/view/ViewFrameInfo.java
@@ -0,0 +1,81 @@
+/*
+ * Copyright (C) 2020 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.view;
+
+import android.graphics.FrameInfo;
+
+/**
+ * The timing information of events taking place in ViewRootImpl
+ * @hide
+ */
+public class ViewFrameInfo {
+    public long drawStart;
+    public long oldestInputEventTime; // the time of the oldest input event consumed for this frame
+    public long newestInputEventTime; // the time of the newest input event consumed for this frame
+    // Various flags set to provide extra metadata about the current frame. See flag definitions
+    // inside FrameInfo.
+    // @see android.graphics.FrameInfo.FLAG_WINDOW_LAYOUT_CHANGED
+    public long flags;
+
+    /**
+     * Update the oldest event time.
+     * @param eventTime the time of the input event
+     */
+    public void updateOldestInputEvent(long eventTime) {
+        if (oldestInputEventTime == 0 || eventTime < oldestInputEventTime) {
+            oldestInputEventTime = eventTime;
+        }
+    }
+
+    /**
+     * Update the newest event time.
+     * @param eventTime the time of the input event
+     */
+    public void updateNewestInputEvent(long eventTime) {
+        if (newestInputEventTime == 0 || eventTime > newestInputEventTime) {
+            newestInputEventTime = eventTime;
+        }
+    }
+
+    /**
+     * Populate the missing fields using the data from ViewFrameInfo
+     * @param frameInfo : the structure FrameInfo object to populate
+     */
+    public void populateFrameInfo(FrameInfo frameInfo) {
+        frameInfo.frameInfo[FrameInfo.FLAGS] |= flags;
+        frameInfo.frameInfo[FrameInfo.DRAW_START] = drawStart;
+        frameInfo.frameInfo[FrameInfo.OLDEST_INPUT_EVENT] = oldestInputEventTime;
+        frameInfo.frameInfo[FrameInfo.NEWEST_INPUT_EVENT] = newestInputEventTime;
+    }
+
+    /**
+     * Reset this data. Should typically be invoked after calling "populateFrameInfo".
+     */
+    public void reset() {
+        drawStart = 0;
+        oldestInputEventTime = 0;
+        newestInputEventTime = 0;
+        flags = 0;
+    }
+
+    /**
+     * Record the current time, and store it in 'drawStart'
+     */
+    public void markDrawStart() {
+        drawStart = System.nanoTime();
+    }
+}
diff --git a/core/java/android/view/ViewRootImpl.java b/core/java/android/view/ViewRootImpl.java
index 2bea0d6b4b04..ae162ede2c70 100644
--- a/core/java/android/view/ViewRootImpl.java
+++ b/core/java/android/view/ViewRootImpl.java
@@ -423,7 +423,7 @@ public final class ViewRootImpl implements ViewParent,
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
     int mHeight;
     @UnsupportedAppUsage(maxTargetSdk = Build.VERSION_CODES.R, trackingBug = 170729553)
-    Rect mDirty;
+    private Rect mDirty;
     public boolean mIsAnimating;
 
     private boolean mUseMTRenderer;
@@ -446,6 +446,23 @@ public final class ViewRootImpl implements ViewParent,
     @UnsupportedAppUsage
     FallbackEventHandler mFallbackEventHandler;
     final Choreographer mChoreographer;
+    protected final ViewFrameInfo mViewFrameInfo = new ViewFrameInfo();
+
+    /**
+     * Update the Choreographer's FrameInfo object with the timing information for the current
+     * ViewRootImpl instance. Erase the data in the current ViewFrameInfo to prepare for the next
+     * frame.
+     * @return the updated FrameInfo object
+     */
+    protected @NonNull FrameInfo getUpdatedFrameInfo() {
+        // Since Choreographer is a thread-local singleton while we can have multiple
+        // ViewRootImpl's, populate the frame information from the current viewRootImpl before
+        // starting the draw
+        FrameInfo frameInfo = mChoreographer.mFrameInfo;
+        mViewFrameInfo.populateFrameInfo(frameInfo);
+        mViewFrameInfo.reset();
+        return frameInfo;
+    }
 
     // used in relayout to get SurfaceControl size
     // for BLAST adapter surface setup
@@ -2675,7 +2692,7 @@ public final class ViewRootImpl implements ViewParent,
                         // to resume them
                         mDirty.set(0, 0, mWidth, mHeight);
                     }
-                    mChoreographer.mFrameInfo.addFlags(FrameInfo.FLAG_WINDOW_LAYOUT_CHANGED);
+                    mViewFrameInfo.flags |= FrameInfo.FLAG_WINDOW_LAYOUT_CHANGED;
                 }
                 relayoutResult = relayoutWindow(params, viewVisibility, insetsPending);
 
@@ -8138,7 +8155,8 @@ public final class ViewRootImpl implements ViewParent,
                     oldestEventTime = me.getHistoricalEventTimeNano(0);
                 }
             }
-            mChoreographer.mFrameInfo.updateInputEventTime(eventTime, oldestEventTime);
+            mViewFrameInfo.updateOldestInputEvent(oldestEventTime);
+            mViewFrameInfo.updateNewestInputEvent(eventTime);
 
             deliverInputEvent(q);
         }