Choreographer scheduleVsync doFrame

http://aospxref.com/android-13.0.0_r3/xref/frameworks/base/core/java/android/view/Choreographer.java#742

doFrame ->CALLBACK_TRAVERSAL

               AnimationUtils.lockAnimationClock(frameTimeNanos / TimeUtils.NANOS_PER_MS);

            mFrameInfo.markInputHandlingStart();
            doCallbacks(Choreographer.CALLBACK_INPUT, frameData, frameIntervalNanos);

            mFrameInfo.markAnimationsStart();
            doCallbacks(Choreographer.CALLBACK_ANIMATION, frameData, frameIntervalNanos);
            doCallbacks(Choreographer.CALLBACK_INSETS_ANIMATION, frameData,
                    frameIntervalNanos);

            mFrameInfo.markPerformTraversalsStart();
            doCallbacks(Choreographer.CALLBACK_TRAVERSAL, frameData, frameIntervalNanos);

            doCallbacks(Choreographer.CALLBACK_COMMIT, frameData, frameIntervalNanos);
        } finally {
            AnimationUtils.unlockAnimationClock();
            Trace.traceEnd(Trace.TRACE_TAG_VIEW);
        }

scheduleTraversals->mTraversalRunnable

 void scheduleTraversals() {
        if (!mTraversalScheduled) {
            mTraversalScheduled = true;
            mTraversalBarrier = mHandler.getLooper().getQueue().postSyncBarrier();
            mChoreographer.postCallback(
                    Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
            notifyRendererOfFramePending();
            pokeDrawLockIfNeeded();
        }
    }

mTraversalRunnable->doTraversal

    final class TraversalRunnable implements Runnable {
        @Override
        public void run() {
            doTraversal();
        }
    }
final TraversalRunnable mTraversalRunnable = new TraversalRunnable();

scheduleVsyncLocked

    private void scheduleVsyncLocked() {
        try {
            Trace.traceBegin(Trace.TRACE_TAG_VIEW, "Choreographer#scheduleVsyncLocked");
            mDisplayEventReceiver.scheduleVsync();
        } finally {
            Trace.traceEnd(Trace.TRACE_TAG_VIEW);
        }
    }

frameworks/base/core/java/android/view/DisplayEventReceiver.java

    public void scheduleVsync() {
        if (mReceiverPtr == 0) {
            Log.w(TAG, "Attempted to schedule a vertical sync pulse but the display event "
                    + "receiver has already been disposed.");
        } else {
            nativeScheduleVsync(mReceiverPtr);
        }
    }

frameworks/base/core/jni/android_view_DisplayEventReceiver.cpp

nativeScheduleVsync

static void nativeScheduleVsync(JNIEnv* env, jclass clazz, jlong receiverPtr) {
    sp<NativeDisplayEventReceiver> receiver =
            reinterpret_cast<NativeDisplayEventReceiver*>(receiverPtr);
    status_t status = receiver->scheduleVsync();
    if (status) {
        String8 message;
        message.appendFormat("Failed to schedule next vertical sync pulse.  status=%d", status);
        jniThrowRuntimeException(env, message. String());
    }
}

frameworks/native/libs/gui/DisplayEventDispatcher.cpp

scheduleVsync

status_t DisplayEventDispatcher::scheduleVsync() {
    if (!mWaitingForVsync) {
        ALOGV("dispatcher %p ~ Scheduling vsync.", this);

        // Drain all pending events.
        nsecs_t vsyncTimestamp;
        PhysicalDisplayId vsyncDisplayId;
        uint32_t vsyncCount;
        VsyncEventData vsyncEventData;
        if (processPendingEvents(&vsyncTimestamp, &vsyncDisplayId, &vsyncCount, &vsyncEventData)) {
            ALOGE("dispatcher %p ~ last event processed while scheduling was for %" PRId64 "", this,
                  ns2ms(static_cast<nsecs_t>(vsyncTimestamp)));
        }

        status_t status = mReceiver.requestNextVsync();
        if (status) {
            ALOGW("Failed to request next vsync, status=%d", status);
            return status;
        }

        mWaitingForVsync = true;
        mLastScheduleVsyncTime = systemTime(SYSTEM_TIME_MONOTONIC);
    }
    return OK;
}

int DisplayEventDispatcher::handleEvent(int, int events, void*) {
...
 if (processPendingEvents(&vsyncTimestamp, &vsyncDisplayId, &vsyncCount, &vsyncEventData)) {
        ALOGV("dispatcher %p ~ Vsync pulse: timestamp=%" PRId64
              ", displayId=%s, count=%d, vsyncId=%" PRId64,
              this, ns2ms(vsyncTimestamp), to_string(vsyncDisplayId).c_str(), vsyncCount,
              vsyncEventData.preferredVsyncId());
        mWaitingForVsync = false;
        mLastVsyncCount = vsyncCount;
        dispatchVsync(vsyncTimestamp, vsyncDisplayId, vsyncCount, vsyncEventData);
    }

frameworks/base/core/jni/android_view_DisplayEventReceiver.cpp#137

dispatchVsync

void NativeDisplayEventReceiver::dispatchVsync(nsecs_t timestamp, PhysicalDisplayId displayId,
                                               uint32_t count, VsyncEventData vsyncEventData) {
    JNIEnv* env = AndroidRuntime::getJNIEnv();

    ScopedLocalRef<jobject> receiverObj(env, jniGetReferent(env, mReceiverWeakGlobal));
    if (receiverObj.get()) {
        ALOGV("receiver %p ~ Invoking vsync handler.", this);

        jobject javaVsyncEventData = createJavaVsyncEventData(env, vsyncEventData);
        env->CallVoidMethod(receiverObj.get(), gDisplayEventReceiverClassInfo.dispatchVsync,
                            timestamp, displayId.value, count, javaVsyncEventData);
        ALOGV("receiver %p ~ Returned from vsync handler.", this);
    }

    mMessageQueue->raiseAndClearException(env, "dispatchVsync");
}

frameworks/base/core/java/android/view/DisplayEventReceiver.java#292

dispatchVsync ->onVsync

  private void dispatchVsync(long timestampNanos, long physicalDisplayId, int frame,
            VsyncEventData vsyncEventData) {
        onVsync(timestampNanos, physicalDisplayId, frame, vsyncEventData);
    }

frameworks/base/core/java/android/view/Choreographer.java

FrameDisplayEventReceiver ->onVsync ->run() ->doFrame

      private final class FrameDisplayEventReceiver extends DisplayEventReceiver
            implements Runnable {
        private boolean mHavePendingVsync;
        private long mTimestampNanos;
        private int mFrame;
        private VsyncEventData mLastVsyncEventData = new VsyncEventData();

        public FrameDisplayEventReceiver(Looper looper, int vsyncSource) {
            super(looper, vsyncSource, 0);
        }

        // TODO(b/116025192): physicalDisplayId is ignored because SF only emits VSYNC events for
        // the internal display and DisplayEventReceiver#scheduleVsync only allows requesting VSYNC
        // for the internal display implicitly.
        @Override
        public void onVsync(long timestampNanos, long physicalDisplayId, int frame,
                VsyncEventData vsyncEventData) {
            try {
                if (Trace.isTagEnabled(Trace.TRACE_TAG_VIEW)) {
                    Trace.traceBegin(Trace.TRACE_TAG_VIEW,
                            "Choreographer#onVsync "
                                    + vsyncEventData.preferredFrameTimeline().vsyncId);
                }
                // Post the vsync event to the Handler.
                // The idea is to prevent incoming vsync events from completely starving
                // the message queue.  If there are no messages in the queue with timestamps
                // earlier than the frame time, then the vsync event will be processed immediately.
                // Otherwise, messages that predate the vsync event will be handled first.
                long now = System.nanoTime();
                if (timestampNanos > now) {
                    Log.w(TAG, "Frame time is " + ((timestampNanos - now) * 0.000001f)
                            + " ms in the future!  Check that graphics HAL is generating vsync "
                            + "timestamps using the correct timebase.");
                    timestampNanos = now;
                }

                if (mHavePendingVsync) {
                    Log.w(TAG, "Already have a pending vsync event.  There should only be "
                            + "one at a time.");
                } else {
                    mHavePendingVsync = true;
                }

                mTimestampNanos = timestampNanos;
                mFrame = frame;
                mLastVsyncEventData = vsyncEventData;
                Message msg = Message.obtain(mHandler, this);
                msg.setAsynchronous(true);
                mHandler.sendMessageAtTime(msg, timestampNanos / TimeUtils.NANOS_PER_MS);
            } finally {
                Trace.traceEnd(Trace.TRACE_TAG_VIEW);
            }
        }

        @Override
        public void run() {
            mHavePendingVsync = false;
            doFrame(mTimestampNanos, mFrame, mLastVsyncEventData);
        }
    }