SF: Adding Idle Timer, to detect when devices are idle.
If SF has not received request for the next vsync in 30ms, the device is
considered idle.
The timeout ms can be set via setprop flag: debug.sf.set_idle_timer_ms
see go/surface-flinger-scheduler for more info.
Test: Adding tests for new class.
Bug: 113612090
Change-Id: I5dae075012f3fef9bb8ed48121367c80dff39de0
diff --git a/services/surfaceflinger/Scheduler/IdleTimer.h b/services/surfaceflinger/Scheduler/IdleTimer.h
new file mode 100644
index 0000000..aee3fa3
--- /dev/null
+++ b/services/surfaceflinger/Scheduler/IdleTimer.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2018 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.
+ */
+
+#pragma once
+
+#include <chrono>
+#include <condition_variable>
+#include <thread>
+
+#include <android-base/thread_annotations.h>
+
+namespace android {
+namespace scheduler {
+
+/*
+ * Class that sets off a timer for a given interval, and fires a callback when the
+ * interval expires.
+ */
+class IdleTimer {
+public:
+ using Interval = std::chrono::milliseconds;
+ using TimeoutCallback = std::function<void()>;
+
+ IdleTimer(const Interval& interval, const TimeoutCallback& timeoutCallback);
+ ~IdleTimer();
+
+ void start();
+ void stop();
+ void reset();
+
+private:
+ // Enum to track in what state is the timer.
+ enum class TimerState { STOPPED = 0, RESET = 1, WAITING = 2, IDLE = 3 };
+
+ // Function that loops until the condition for stopping is met.
+ void loop();
+
+ // Thread waiting for timer to expire.
+ std::thread mThread;
+
+ // Condition used to notify mThread.
+ std::condition_variable_any mCondition;
+
+ // Lock used for synchronizing the waiting thread with the application thread.
+ std::mutex mMutex;
+
+ TimerState mState GUARDED_BY(mMutex) = TimerState::RESET;
+
+ // Interval after which timer expires.
+ const Interval mInterval;
+
+ // Callback that happens when timer expires.
+ const TimeoutCallback mTimeoutCallback;
+};
+
+} // namespace scheduler
+} // namespace android