Add choreographer API to the NDK.

Change-Id: Icb8cffd3cd3bd06814466be72db3e26f6a62cbc6
diff --git a/native/android/choreographer.cpp b/native/android/choreographer.cpp
new file mode 100644
index 0000000..cc2fd77
--- /dev/null
+++ b/native/android/choreographer.cpp
@@ -0,0 +1,205 @@
+/*
+ * Copyright (C) 2015 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.
+ */
+
+#define LOG_TAG "Choreographer"
+//#define LOG_NDEBUG 0
+
+#include <cinttypes>
+#include <queue>
+#include <thread>
+
+#include <android/choreographer.h>
+#include <androidfw/DisplayEventDispatcher.h>
+#include <gui/ISurfaceComposer.h>
+#include <utils/Looper.h>
+#include <utils/Mutex.h>
+#include <utils/Timers.h>
+
+namespace android {
+
+static inline const char* toString(bool value) {
+    return value ? "true" : "false";
+}
+
+struct FrameCallback {
+    AChoreographer_frameCallback callback;
+    void* data;
+    nsecs_t dueTime;
+
+    inline bool operator<(const FrameCallback& rhs) const {
+        // Note that this is intentionally flipped because we want callbacks due sooner to be at
+        // the head of the queue
+        return dueTime > rhs.dueTime;
+    }
+};
+
+
+class Choreographer : public DisplayEventDispatcher, public MessageHandler {
+public:
+    void postFrameCallback(AChoreographer_frameCallback cb, void* data);
+    void postFrameCallbackDelayed(AChoreographer_frameCallback cb, void* data, nsecs_t delay);
+
+    enum {
+        MSG_SCHEDULE_CALLBACKS = 0,
+        MSG_SCHEDULE_VSYNC = 1
+    };
+    virtual void handleMessage(const Message& message) override;
+
+    static Choreographer* getForThread();
+
+protected:
+    virtual ~Choreographer() = default;
+
+private:
+    Choreographer(const sp<Looper>& looper);
+    Choreographer(const Choreographer&) = delete;
+
+    virtual void dispatchVsync(nsecs_t timestamp, int32_t id, uint32_t count);
+    virtual void dispatchHotplug(nsecs_t timestamp, int32_t id, bool connected);
+
+    void scheduleCallbacks();
+
+    // Protected by mLock
+    std::priority_queue<FrameCallback> mCallbacks;
+
+    mutable Mutex mLock;
+
+    const sp<Looper> mLooper;
+    const std::thread::id mThreadId;
+};
+
+
+thread_local Choreographer* gChoreographer;
+Choreographer* Choreographer::getForThread() {
+    if (gChoreographer == nullptr) {
+        sp<Looper> looper = Looper::getForThread();
+        if (!looper.get()) {
+            ALOGW("No looper prepared for thread");
+            return nullptr;
+        }
+        gChoreographer = new Choreographer(looper);
+        status_t result = gChoreographer->initialize();
+        if (result != OK) {
+            ALOGW("Failed to initialize");
+            return nullptr;
+        }
+    }
+    return gChoreographer;
+}
+
+Choreographer::Choreographer(const sp<Looper>& looper) :
+    DisplayEventDispatcher(looper), mLooper(looper), mThreadId(std::this_thread::get_id()) {
+}
+
+void Choreographer::postFrameCallback(AChoreographer_frameCallback cb, void* data) {
+    postFrameCallbackDelayed(cb, data, 0);
+}
+
+void Choreographer::postFrameCallbackDelayed(
+        AChoreographer_frameCallback cb, void* data, nsecs_t delay) {
+    nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
+    FrameCallback callback{cb, data, now + delay};
+    {
+        AutoMutex _l{mLock};
+        mCallbacks.push(callback);
+    }
+    if (callback.dueTime <= now) {
+        if (std::this_thread::get_id() != mThreadId) {
+            Message m{MSG_SCHEDULE_VSYNC};
+            mLooper->sendMessage(this, m);
+        } else {
+            scheduleVsync();
+        }
+    } else {
+        Message m{MSG_SCHEDULE_CALLBACKS};
+        mLooper->sendMessageDelayed(delay, this, m);
+    }
+}
+
+void Choreographer::scheduleCallbacks() {
+    AutoMutex _{mLock};
+    nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
+    if (mCallbacks.top().dueTime <= now) {
+        ALOGV("choreographer %p ~ scheduling vsync", this);
+        scheduleVsync();
+        return;
+    }
+}
+
+
+void Choreographer::dispatchVsync(nsecs_t timestamp, int32_t id, uint32_t) {
+    if (id != ISurfaceComposer::eDisplayIdMain) {
+        ALOGV("choreographer %p ~ ignoring vsync signal for non-main display (id=%d)", this, id);
+        scheduleVsync();
+        return;
+    }
+    std::vector<FrameCallback> callbacks{};
+    {
+        AutoMutex _l{mLock};
+        nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
+        while (!mCallbacks.empty() && mCallbacks.top().dueTime < now) {
+            callbacks.push_back(mCallbacks.top());
+            mCallbacks.pop();
+        }
+    }
+    for (const auto& cb : callbacks) {
+        cb.callback(timestamp, cb.data);
+    }
+}
+
+void Choreographer::dispatchHotplug(nsecs_t, int32_t id, bool connected) {
+    ALOGV("choreographer %p ~ received hotplug event (id=%" PRId32 ", connected=%s), ignoring.",
+            this, id, toString(connected));
+}
+
+void Choreographer::handleMessage(const Message& message) {
+    switch (message.what) {
+    case MSG_SCHEDULE_CALLBACKS:
+        scheduleCallbacks();
+        break;
+    case MSG_SCHEDULE_VSYNC:
+        scheduleVsync();
+        break;
+    }
+}
+
+}
+
+/* Glue for the NDK interface */
+
+using android::Choreographer;
+
+static inline Choreographer* AChoreographer_to_Choreographer(AChoreographer* choreographer) {
+    return reinterpret_cast<Choreographer*>(choreographer);
+}
+
+static inline AChoreographer* Choreographer_to_AChoreographer(Choreographer* choreographer) {
+    return reinterpret_cast<AChoreographer*>(choreographer);
+}
+
+AChoreographer* AChoreographer_getInstance() {
+    return Choreographer_to_AChoreographer(Choreographer::getForThread());
+}
+
+void AChoreographer_postFrameCallback(AChoreographer* choreographer,
+        AChoreographer_frameCallback callback, void* data) {
+    AChoreographer_to_Choreographer(choreographer)->postFrameCallback(callback, data);
+}
+void AChoreographer_postFrameCallbackDelayed(AChoreographer* choreographer,
+        AChoreographer_frameCallback callback, void* data, long delayMillis) {
+    AChoreographer_to_Choreographer(choreographer)->postFrameCallbackDelayed(
+            callback, data, ms2ns(delayMillis));
+}