Acquire and Release Wake Lock

Acquire a wake lock in the Sensors 2.0 Default implementation whenever
there are outstanding WAKE_UP events. Release the wake lock whenever
the number of oustanding WAKE_UP events is zero or at least
SensorTimeout::WAKE_LOCK_SECONDS seconds have elapsed since the
previous WAKE_UP event was written to the Event FMQ.

Bug: 111070257
Test: Builds, wake lock is acquired and released as expected.
Change-Id: I7c57724430144fd4022646d1fef1b1fa8bc4235d
diff --git a/sensors/2.0/default/Sensors.h b/sensors/2.0/default/Sensors.h
index f543935..eba3f97 100644
--- a/sensors/2.0/default/Sensors.h
+++ b/sensors/2.0/default/Sensors.h
@@ -21,10 +21,13 @@
 
 #include <android/hardware/sensors/2.0/ISensors.h>
 #include <fmq/MessageQueue.h>
+#include <hardware_legacy/power.h>
 #include <hidl/MQDescriptor.h>
 #include <hidl/Status.h>
 
+#include <atomic>
 #include <memory>
+#include <thread>
 
 namespace android {
 namespace hardware {
@@ -80,7 +83,7 @@
     Return<void> configDirectReport(int32_t sensorHandle, int32_t channelHandle, RateLevel rate,
                                     configDirectReport_cb _hidl_cb) override;
 
-    void postEvents(const std::vector<Event>& events) override;
+    void postEvents(const std::vector<Event>& events, bool wakeup) override;
 
    private:
     /**
@@ -88,6 +91,18 @@
      */
     void deleteEventFlag();
 
+    /**
+     * Function to read the Wake Lock FMQ and release the wake lock when appropriate
+     */
+    void readWakeLockFMQ();
+
+    static void startReadWakeLockThread(Sensors* sensors);
+
+    /**
+     * Responsible for acquiring and releasing a wake lock when there are unhandled WAKE_UP events
+     */
+    void updateWakeLock(int32_t eventsWritten, int32_t eventsHandled);
+
     using EventMessageQueue = MessageQueue<Event, kSynchronizedReadWrite>;
     using WakeLockMessageQueue = MessageQueue<uint32_t, kSynchronizedReadWrite>;
 
@@ -117,9 +132,39 @@
     std::map<int32_t, std::shared_ptr<Sensor>> mSensors;
 
     /**
-     * Lock to protect writes and reads to the FMQs
+     * Lock to protect writes to the FMQs
      */
-    std::mutex mLock;
+    std::mutex mWriteLock;
+
+    /**
+     * Lock to protect acquiring and releasing the wake lock
+     */
+    std::mutex mWakeLockLock;
+
+    /**
+     * Track the number of WAKE_UP events that have not been handled by the framework
+     */
+    uint32_t mOutstandingWakeUpEvents;
+
+    /**
+     * A thread to read the Wake Lock FMQ
+     */
+    std::thread mWakeLockThread;
+
+    /**
+     * Flag to indicate that the Wake Lock Thread should continue to run
+     */
+    std::atomic_bool mReadWakeLockQueueRun;
+
+    /**
+     * Track the time when the wake lock should automatically be released
+     */
+    int64_t mAutoReleaseWakeLockTime;
+
+    /**
+     * Flag to indicate if a wake lock has been acquired
+     */
+    bool mHasWakeLock;
 };
 
 }  // namespace implementation