services/sensorservice/SensorService.h - android_frameworks_native - Gitiles

 /*
  * Copyright (C) 2010 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.
  */

 #ifndef ANDROID_SENSOR_SERVICE_H
 #define ANDROID_SENSOR_SERVICE_H

 #include <stdint.h>
 #include <sys/types.h>

 #include <utils/Vector.h>
 #include <utils/SortedVector.h>
 #include <utils/KeyedVector.h>
 #include <utils/threads.h>
 #include <utils/AndroidThreads.h>
 #include <utils/RefBase.h>
 #include <utils/Looper.h>
 #include <utils/String8.h>

 #include <binder/BinderService.h>

 #include <gui/Sensor.h>
 #include <gui/BitTube.h>
 #include <gui/ISensorServer.h>
 #include <gui/ISensorEventConnection.h>

 #include "SensorInterface.h"

 #if __clang__
 // Clang warns about SensorEventConnection::dump hiding BBinder::dump
 // The cause isn't fixable without changing the API, so let's tell clang
 // this is indeed intentional.
 #pragma clang diagnostic ignored "-Woverloaded-virtual"
 #endif

 // ---------------------------------------------------------------------------

 #define DEBUG_CONNECTIONS   false
 // Max size is 100 KB which is enough to accept a batch of about 1000 events.
 #define MAX_SOCKET_BUFFER_SIZE_BATCHED 100 * 1024
 // For older HALs which don't support batching, use a smaller socket buffer size.
 #define SOCKET_BUFFER_SIZE_NON_BATCHED 4 * 1024

 #define CIRCULAR_BUF_SIZE 10
 #define SENSOR_REGISTRATIONS_BUF_SIZE 20

 struct sensors_poll_device_t;
 struct sensors_module_t;

 namespace android {
 // ---------------------------------------------------------------------------

 class SensorService :
         public BinderService<SensorService>,
         public BnSensorServer,
         protected Thread
 {
     friend class BinderService<SensorService>;

     enum Mode {
        // The regular operating mode where any application can register/unregister/call flush on
        // sensors.
        NORMAL = 0,
        // This mode is only used for testing purposes. Not all HALs support this mode. In this
        // mode, the HAL ignores the sensor data provided by physical sensors and accepts the data
        // that is injected from the SensorService as if it were the real sensor data. This mode
        // is primarily used for testing various algorithms like vendor provided SensorFusion,
        // Step Counter and Step Detector etc. Typically in this mode, there will be a client
        // (a SensorEventConnection) which will be injecting sensor data into the HAL. Normal apps
        // can unregister and register for any sensor that supports injection. Registering to sensors
        // that do not support injection will give an error.
        // TODO(aakella) : Allow exactly one client to inject sensor data at a time.
        DATA_INJECTION = 1,
        // This mode is used only for testing sensors. Each sensor can be tested in isolation with
        // the required sampling_rate and maxReportLatency parameters without having to think about
        // the data rates requested by other applications. End user devices are always expected to be
        // in NORMAL mode. When this mode is first activated, all active sensors from all connections
        // are disabled. Calling flush() will return an error. In this mode, only the requests from
        // selected apps whose package names are whitelisted are allowed (typically CTS apps).  Only
        // these apps can register/unregister/call flush() on sensors. If SensorService switches to
        // NORMAL mode again, all sensors that were previously registered to are activated with the
        // corresponding paramaters if the application hasn't unregistered for sensors in the mean
        // time.
        // NOTE: Non whitelisted app whose sensors were previously deactivated may still receive
        // events if a whitelisted app requests data from the same sensor.
        RESTRICTED = 2

       // State Transitions supported.
       //     RESTRICTED   <---  NORMAL   ---> DATA_INJECTION
       //                  --->           <---

       // Shell commands to switch modes in SensorService.
       // 1) Put SensorService in RESTRICTED mode with packageName .cts. If it is already in
       // restricted mode it is treated as a NO_OP (and packageName is NOT changed).
       // $ adb shell dumpsys sensorservice restrict .cts.
       //
       // 2) Put SensorService in DATA_INJECTION mode with packageName .xts. If it is already in
       // data_injection mode it is treated as a NO_OP (and packageName is NOT changed).
       // $ adb shell dumpsys sensorservice data_injection .xts.
       //
       // 3) Reset sensorservice back to NORMAL mode.
       // $ adb shell dumpsys sensorservice enable
     };

     static const char* WAKE_LOCK_NAME;

     static char const* getServiceName() ANDROID_API { return "sensorservice"; }
     SensorService() ANDROID_API;
     virtual ~SensorService();

     virtual void onFirstRef();

     // Thread interface
     virtual bool threadLoop();

     // ISensorServer interface
     virtual Vector<Sensor> getSensorList(const String16& opPackageName);
     virtual sp<ISensorEventConnection> createSensorEventConnection(const String8& packageName,
              int requestedMode, const String16& opPackageName);
     virtual int isDataInjectionEnabled();
     virtual status_t dump(int fd, const Vector<String16>& args);

     class SensorEventConnection : public BnSensorEventConnection, public LooperCallback {
         friend class SensorService;
         virtual ~SensorEventConnection();
         virtual void onFirstRef();
         virtual sp<BitTube> getSensorChannel() const;
         virtual status_t enableDisable(int handle, bool enabled, nsecs_t samplingPeriodNs,
                                        nsecs_t maxBatchReportLatencyNs, int reservedFlags);
         virtual status_t setEventRate(int handle, nsecs_t samplingPeriodNs);
         virtual status_t flush();
         // Count the number of flush complete events which are about to be dropped in the buffer.
         // Increment mPendingFlushEventsToSend in mSensorInfo. These flush complete events will be
         // sent separately before the next batch of events.
         void countFlushCompleteEventsLocked(sensors_event_t const* scratch, int numEventsDropped);

         // Check if there are any wake up events in the buffer. If yes, return the index of the
         // first wake_up sensor event in the buffer else return -1. This wake_up sensor event will
         // have the flag WAKE_UP_SENSOR_EVENT_NEEDS_ACK set. Exactly one event per packet will have
         // the wake_up flag set. SOCK_SEQPACKET ensures that either the entire packet is read or
         // dropped.
         int findWakeUpSensorEventLocked(sensors_event_t const* scratch, int count);

         // Send pending flush_complete events. There may have been flush_complete_events that are
         // dropped which need to be sent separately before other events. On older HALs (1_0) this
         // method emulates the behavior of flush().
         void sendPendingFlushEventsLocked();

         // Writes events from mEventCache to the socket.
         void writeToSocketFromCache();

         // Compute the approximate cache size from the FIFO sizes of various sensors registered for
         // this connection. Wake up and non-wake up sensors have separate FIFOs but FIFO may be
         // shared amongst wake-up sensors and non-wake up sensors.
         int computeMaxCacheSizeLocked() const;

         // When more sensors register, the maximum cache size desired may change. Compute max cache
         // size, reallocate memory and copy over events from the older cache.
         void reAllocateCacheLocked(sensors_event_t const* scratch, int count);

         // LooperCallback method. If there is data to read on this fd, it is an ack from the
         // app that it has read events from a wake up sensor, decrement mWakeLockRefCount.
         // If this fd is available for writing send the data from the cache.
         virtual int handleEvent(int fd, int events, void* data);

         // Increment mPendingFlushEventsToSend for the given sensor handle.
         void incrementPendingFlushCount(int32_t handle);

         // Add or remove the file descriptor associated with the BitTube to the looper. If mDead is
         // set to true or there are no more sensors for this connection, the file descriptor is
         // removed if it has been previously added to the Looper. Depending on the state of the
         // connection FD may be added to the Looper. The flags to set are determined by the internal
         // state of the connection. FDs are added to the looper when wake-up sensors are registered
         // (to poll for acknowledgements) and when write fails on the socket when there are too many
         // error and the other end hangs up or when this client unregisters for this connection.
         void updateLooperRegistration(const sp<Looper>& looper);
         void updateLooperRegistrationLocked(const sp<Looper>& looper);

         sp<SensorService> const mService;
         sp<BitTube> mChannel;
         uid_t mUid;
         mutable Mutex mConnectionLock;
         // Number of events from wake up sensors which are still pending and haven't been delivered
         // to the corresponding application. It is incremented by one unit for each write to the
         // socket.
         uint32_t mWakeLockRefCount;

         // If this flag is set to true, it means that the file descriptor associated with the
         // BitTube has been added to the Looper in SensorService. This flag is typically set when
         // this connection has wake-up sensors associated with it or when write has failed on this
         // connection and we're storing some events in the cache.
         bool mHasLooperCallbacks;
         // If there are any errors associated with the Looper this flag is set to true and
         // mWakeLockRefCount is reset to zero. needsWakeLock method will always return false, if
         // this flag is set.
         bool mDead;

         bool mDataInjectionMode;
         struct FlushInfo {
             // The number of flush complete events dropped for this sensor is stored here.
             // They are sent separately before the next batch of events.
             int mPendingFlushEventsToSend;
             // Every activate is preceded by a flush. Only after the first flush complete is
             // received, the events for the sensor are sent on that *connection*.
             bool mFirstFlushPending;
             FlushInfo() : mPendingFlushEventsToSend(0), mFirstFlushPending(false) {}
         };
         // protected by SensorService::mLock. Key for this vector is the sensor handle.
         KeyedVector<int, FlushInfo> mSensorInfo;
         sensors_event_t *mEventCache;
         int mCacheSize, mMaxCacheSize;
         String8 mPackageName;
         const String16 mOpPackageName;
 #if DEBUG_CONNECTIONS
         int mEventsReceived, mEventsSent, mEventsSentFromCache;
         int mTotalAcksNeeded, mTotalAcksReceived;
 #endif

     public:
         SensorEventConnection(const sp<SensorService>& service, uid_t uid, String8 packageName,
                  bool isDataInjectionMode, const String16& opPackageName);

         status_t sendEvents(sensors_event_t const* buffer, size_t count,
                 sensors_event_t* scratch,
                 SensorEventConnection const * const * mapFlushEventsToConnections = NULL);
         bool hasSensor(int32_t handle) const;
         bool hasAnySensor() const;
         bool hasOneShotSensors() const;
         bool addSensor(int32_t handle);
         bool removeSensor(int32_t handle);
         void setFirstFlushPending(int32_t handle, bool value);
         void dump(String8& result);
         bool needsWakeLock();
         void resetWakeLockRefCount();
         String8 getPackageName() const;

         uid_t getUid() const { return mUid; }
     };

     class SensorRecord {
         SortedVector< wp<SensorEventConnection> > mConnections;
         // A queue of all flush() calls made on this sensor. Flush complete events will be
         // sent in this order.
         Vector< wp<SensorEventConnection> > mPendingFlushConnections;
     public:
         SensorRecord(const sp<SensorEventConnection>& connection);
         bool addConnection(const sp<SensorEventConnection>& connection);
         bool removeConnection(const wp<SensorEventConnection>& connection);
         size_t getNumConnections() const { return mConnections.size(); }

         void addPendingFlushConnection(const sp<SensorEventConnection>& connection);
         void removeFirstPendingFlushConnection();
         SensorEventConnection * getFirstPendingFlushConnection();
         void clearAllPendingFlushConnections();
     };

     class SensorEventAckReceiver : public Thread {
         sp<SensorService> const mService;
     public:
         virtual bool threadLoop();
         SensorEventAckReceiver(const sp<SensorService>& service): mService(service) {}
     };

     // sensor_event_t with only the data and the timestamp.
     struct TrimmedSensorEvent {
         union {
             float *mData;
             uint64_t mStepCounter;
         };
         // Timestamp from the sensor_event.
         int64_t mTimestamp;
         // HH:MM:SS local time at which this sensor event is read at SensorService. Useful
         // for debugging.
         int32_t mHour, mMin, mSec;

         TrimmedSensorEvent(int sensorType);
         static bool isSentinel(const TrimmedSensorEvent& event);

         ~TrimmedSensorEvent() {
             delete [] mData;
         }
     };

     // A circular buffer of TrimmedSensorEvents. The size of this buffer is typically 10. The
     // last N events generated from the sensor are stored in this buffer. The buffer is NOT
     // cleared when the sensor unregisters and as a result one may see very old data in the
     // dumpsys output but this is WAI.
     class CircularBuffer {
         int mNextInd;
         int mSensorType;
         int mBufSize;
         TrimmedSensorEvent ** mTrimmedSensorEventArr;
     public:
         CircularBuffer(int sensor_event_type);
         void addEvent(const sensors_event_t& sensor_event);
         void printBuffer(String8& buffer) const;
         bool populateLastEvent(sensors_event_t *event);
         ~CircularBuffer();
     };

     struct SensorRegistrationInfo {
         int32_t mSensorHandle;
         String8 mPackageName;
         bool mActivated;
         int32_t mSamplingRateUs;
         int32_t mMaxReportLatencyUs;
         int32_t mHour, mMin, mSec;

         SensorRegistrationInfo() : mPackageName() {
             mSensorHandle = mSamplingRateUs = mMaxReportLatencyUs = INT32_MIN;
             mHour = mMin = mSec = INT32_MIN;
             mActivated = false;
         }

         static bool isSentinel(const SensorRegistrationInfo& info) {
            return (info.mHour == INT32_MIN && info.mMin == INT32_MIN && info.mSec == INT32_MIN);
         }
     };

     static int getNumEventsForSensorType(int sensor_event_type);
     String8 getSensorName(int handle) const;
     bool isVirtualSensor(int handle) const;
     Sensor getSensorFromHandle(int handle) const;
     bool isWakeUpSensor(int type) const;
     void recordLastValueLocked(sensors_event_t const* buffer, size_t count);
     static void sortEventBuffer(sensors_event_t* buffer, size_t count);
     Sensor registerSensor(SensorInterface* sensor);
     Sensor registerVirtualSensor(SensorInterface* sensor);
     status_t cleanupWithoutDisable(
             const sp<SensorEventConnection>& connection, int handle);
     status_t cleanupWithoutDisableLocked(
             const sp<SensorEventConnection>& connection, int handle);
     void cleanupAutoDisabledSensorLocked(const sp<SensorEventConnection>& connection,
             sensors_event_t const* buffer, const int count);
     static bool canAccessSensor(const Sensor& sensor, const char* operation,
             const String16& opPackageName);
     // SensorService acquires a partial wakelock for delivering events from wake up sensors. This
     // method checks whether all the events from these wake up sensors have been delivered to the
     // corresponding applications, if yes the wakelock is released.
     void checkWakeLockState();
     void checkWakeLockStateLocked();
     bool isWakeLockAcquired();
     bool isWakeUpSensorEvent(const sensors_event_t& event) const;

     SensorRecord * getSensorRecord(int handle);

     sp<Looper> getLooper() const;

     // Reset mWakeLockRefCounts for all SensorEventConnections to zero. This may happen if
     // SensorService did not receive any acknowledgements from apps which have registered for
     // wake_up sensors.
     void resetAllWakeLockRefCounts();

     // Acquire or release wake_lock. If wake_lock is acquired, set the timeout in the looper to
     // 5 seconds and wake the looper.
     void setWakeLockAcquiredLocked(bool acquire);

     // Send events from the event cache for this particular connection.
     void sendEventsFromCache(const sp<SensorEventConnection>& connection);

     // Promote all weak referecences in mActiveConnections vector to strong references and add them
     // to the output vector.
     void populateActiveConnections(SortedVector< sp<SensorEventConnection> >* activeConnections);

     // If SensorService is operating in RESTRICTED mode, only select whitelisted packages are
     // allowed to register for or call flush on sensors. Typically only cts test packages are
     // allowed.
     bool isWhiteListedPackage(const String8& packageName);

     // Reset the state of SensorService to NORMAL mode.
     status_t resetToNormalMode();
     status_t resetToNormalModeLocked();

     // constants
     Vector<Sensor> mSensorList;
     Vector<Sensor> mUserSensorListDebug;
     Vector<Sensor> mUserSensorList;
     DefaultKeyedVector<int, SensorInterface*> mSensorMap;
     Vector<SensorInterface *> mVirtualSensorList;
     status_t mInitCheck;
     // Socket buffersize used to initialize BitTube. This size depends on whether batching is
     // supported or not.
     uint32_t mSocketBufferSize;
     sp<Looper> mLooper;
     sp<SensorEventAckReceiver> mAckReceiver;

     // protected by mLock
     mutable Mutex mLock;
     DefaultKeyedVector<int, SensorRecord*> mActiveSensors;
     DefaultKeyedVector<int, SensorInterface*> mActiveVirtualSensors;
     SortedVector< wp<SensorEventConnection> > mActiveConnections;
     bool mWakeLockAcquired;
     sensors_event_t *mSensorEventBuffer, *mSensorEventScratch;
     SensorEventConnection const **mMapFlushEventsToConnections;
     Mode mCurrentOperatingMode;
     // This packagaName is set when SensorService is in RESTRICTED or DATA_INJECTION mode. Only
     // applications with this packageName are allowed to activate/deactivate or call flush on
     // sensors. To run CTS this is can be set to ".cts." and only CTS tests will get access to
     // sensors.
     String8 mWhiteListedPackage;

     // The size of this vector is constant, only the items are mutable
     KeyedVector<int32_t, CircularBuffer *> mLastEventSeen;

     int mNextSensorRegIndex;
     Vector<SensorRegistrationInfo> mLastNSensorRegistrations;
 public:
     void cleanupConnection(SensorEventConnection* connection);
     status_t enable(const sp<SensorEventConnection>& connection, int handle,
                     nsecs_t samplingPeriodNs,  nsecs_t maxBatchReportLatencyNs, int reservedFlags,
                     const String16& opPackageName);
     status_t disable(const sp<SensorEventConnection>& connection, int handle);
     status_t setEventRate(const sp<SensorEventConnection>& connection, int handle, nsecs_t ns,
                           const String16& opPackageName);
     status_t flushSensor(const sp<SensorEventConnection>& connection,
                          const String16& opPackageName);
 };

 // ---------------------------------------------------------------------------
 }; // namespace android

 #endif // ANDROID_SENSOR_SERVICE_H
	/*
	* Copyright (C) 2010 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.
	*/

	#ifndef ANDROID_SENSOR_SERVICE_H
	#define ANDROID_SENSOR_SERVICE_H

	#include <stdint.h>
	#include <sys/types.h>

	#include <utils/Vector.h>
	#include <utils/SortedVector.h>
	#include <utils/KeyedVector.h>
	#include <utils/threads.h>
	#include <utils/AndroidThreads.h>
	#include <utils/RefBase.h>
	#include <utils/Looper.h>
	#include <utils/String8.h>

	#include <binder/BinderService.h>

	#include <gui/Sensor.h>
	#include <gui/BitTube.h>
	#include <gui/ISensorServer.h>
	#include <gui/ISensorEventConnection.h>

	#include "SensorInterface.h"

	#if __clang__
	// Clang warns about SensorEventConnection::dump hiding BBinder::dump
	// The cause isn't fixable without changing the API, so let's tell clang
	// this is indeed intentional.
	#pragma clang diagnostic ignored "-Woverloaded-virtual"
	#endif

	// ---------------------------------------------------------------------------

	#define DEBUG_CONNECTIONS false
	// Max size is 100 KB which is enough to accept a batch of about 1000 events.
	#define MAX_SOCKET_BUFFER_SIZE_BATCHED 100 * 1024
	// For older HALs which don't support batching, use a smaller socket buffer size.
	#define SOCKET_BUFFER_SIZE_NON_BATCHED 4 * 1024

	#define CIRCULAR_BUF_SIZE 10
	#define SENSOR_REGISTRATIONS_BUF_SIZE 20

	struct sensors_poll_device_t;
	struct sensors_module_t;

	namespace android {
	// ---------------------------------------------------------------------------

	class SensorService :
	public BinderService<SensorService>,
	public BnSensorServer,
	protected Thread
	{
	friend class BinderService<SensorService>;

	enum Mode {
	// The regular operating mode where any application can register/unregister/call flush on
	// sensors.
	NORMAL = 0,
	// This mode is only used for testing purposes. Not all HALs support this mode. In this
	// mode, the HAL ignores the sensor data provided by physical sensors and accepts the data
	// that is injected from the SensorService as if it were the real sensor data. This mode
	// is primarily used for testing various algorithms like vendor provided SensorFusion,
	// Step Counter and Step Detector etc. Typically in this mode, there will be a client
	// (a SensorEventConnection) which will be injecting sensor data into the HAL. Normal apps
	// can unregister and register for any sensor that supports injection. Registering to sensors
	// that do not support injection will give an error.
	// TODO(aakella) : Allow exactly one client to inject sensor data at a time.
	DATA_INJECTION = 1,
	// This mode is used only for testing sensors. Each sensor can be tested in isolation with
	// the required sampling_rate and maxReportLatency parameters without having to think about
	// the data rates requested by other applications. End user devices are always expected to be
	// in NORMAL mode. When this mode is first activated, all active sensors from all connections
	// are disabled. Calling flush() will return an error. In this mode, only the requests from
	// selected apps whose package names are whitelisted are allowed (typically CTS apps). Only
	// these apps can register/unregister/call flush() on sensors. If SensorService switches to
	// NORMAL mode again, all sensors that were previously registered to are activated with the
	// corresponding paramaters if the application hasn't unregistered for sensors in the mean
	// time.
	// NOTE: Non whitelisted app whose sensors were previously deactivated may still receive
	// events if a whitelisted app requests data from the same sensor.
	RESTRICTED = 2

	// State Transitions supported.
	// RESTRICTED <--- NORMAL ---> DATA_INJECTION
	// ---> <---

	// Shell commands to switch modes in SensorService.
	// 1) Put SensorService in RESTRICTED mode with packageName .cts. If it is already in
	// restricted mode it is treated as a NO_OP (and packageName is NOT changed).
	// $ adb shell dumpsys sensorservice restrict .cts.
	//
	// 2) Put SensorService in DATA_INJECTION mode with packageName .xts. If it is already in
	// data_injection mode it is treated as a NO_OP (and packageName is NOT changed).
	// $ adb shell dumpsys sensorservice data_injection .xts.
	//
	// 3) Reset sensorservice back to NORMAL mode.
	// $ adb shell dumpsys sensorservice enable
	};

	static const char* WAKE_LOCK_NAME;

	static char const* getServiceName() ANDROID_API { return "sensorservice"; }
	SensorService() ANDROID_API;
	virtual ~SensorService();

	virtual void onFirstRef();

	// Thread interface
	virtual bool threadLoop();

	// ISensorServer interface
	virtual Vector<Sensor> getSensorList(const String16& opPackageName);
	virtual sp<ISensorEventConnection> createSensorEventConnection(const String8& packageName,
	int requestedMode, const String16& opPackageName);
	virtual int isDataInjectionEnabled();
	virtual status_t dump(int fd, const Vector<String16>& args);

	class SensorEventConnection : public BnSensorEventConnection, public LooperCallback {
	friend class SensorService;
	virtual ~SensorEventConnection();
	virtual void onFirstRef();
	virtual sp<BitTube> getSensorChannel() const;
	virtual status_t enableDisable(int handle, bool enabled, nsecs_t samplingPeriodNs,
	nsecs_t maxBatchReportLatencyNs, int reservedFlags);
	virtual status_t setEventRate(int handle, nsecs_t samplingPeriodNs);
	virtual status_t flush();
	// Count the number of flush complete events which are about to be dropped in the buffer.
	// Increment mPendingFlushEventsToSend in mSensorInfo. These flush complete events will be
	// sent separately before the next batch of events.
	void countFlushCompleteEventsLocked(sensors_event_t const* scratch, int numEventsDropped);

	// Check if there are any wake up events in the buffer. If yes, return the index of the
	// first wake_up sensor event in the buffer else return -1. This wake_up sensor event will
	// have the flag WAKE_UP_SENSOR_EVENT_NEEDS_ACK set. Exactly one event per packet will have
	// the wake_up flag set. SOCK_SEQPACKET ensures that either the entire packet is read or
	// dropped.
	int findWakeUpSensorEventLocked(sensors_event_t const* scratch, int count);

	// Send pending flush_complete events. There may have been flush_complete_events that are
	// dropped which need to be sent separately before other events. On older HALs (1_0) this
	// method emulates the behavior of flush().
	void sendPendingFlushEventsLocked();

	// Writes events from mEventCache to the socket.
	void writeToSocketFromCache();

	// Compute the approximate cache size from the FIFO sizes of various sensors registered for
	// this connection. Wake up and non-wake up sensors have separate FIFOs but FIFO may be
	// shared amongst wake-up sensors and non-wake up sensors.
	int computeMaxCacheSizeLocked() const;

	// When more sensors register, the maximum cache size desired may change. Compute max cache
	// size, reallocate memory and copy over events from the older cache.
	void reAllocateCacheLocked(sensors_event_t const* scratch, int count);

	// LooperCallback method. If there is data to read on this fd, it is an ack from the
	// app that it has read events from a wake up sensor, decrement mWakeLockRefCount.
	// If this fd is available for writing send the data from the cache.
	virtual int handleEvent(int fd, int events, void* data);

	// Increment mPendingFlushEventsToSend for the given sensor handle.
	void incrementPendingFlushCount(int32_t handle);

	// Add or remove the file descriptor associated with the BitTube to the looper. If mDead is
	// set to true or there are no more sensors for this connection, the file descriptor is
	// removed if it has been previously added to the Looper. Depending on the state of the
	// connection FD may be added to the Looper. The flags to set are determined by the internal
	// state of the connection. FDs are added to the looper when wake-up sensors are registered
	// (to poll for acknowledgements) and when write fails on the socket when there are too many
	// error and the other end hangs up or when this client unregisters for this connection.
	void updateLooperRegistration(const sp<Looper>& looper);
	void updateLooperRegistrationLocked(const sp<Looper>& looper);

	sp<SensorService> const mService;
	sp<BitTube> mChannel;
	uid_t mUid;
	mutable Mutex mConnectionLock;
	// Number of events from wake up sensors which are still pending and haven't been delivered
	// to the corresponding application. It is incremented by one unit for each write to the
	// socket.
	uint32_t mWakeLockRefCount;

	// If this flag is set to true, it means that the file descriptor associated with the
	// BitTube has been added to the Looper in SensorService. This flag is typically set when
	// this connection has wake-up sensors associated with it or when write has failed on this
	// connection and we're storing some events in the cache.
	bool mHasLooperCallbacks;
	// If there are any errors associated with the Looper this flag is set to true and
	// mWakeLockRefCount is reset to zero. needsWakeLock method will always return false, if
	// this flag is set.
	bool mDead;

	bool mDataInjectionMode;
	struct FlushInfo {
	// The number of flush complete events dropped for this sensor is stored here.
	// They are sent separately before the next batch of events.
	int mPendingFlushEventsToSend;
	// Every activate is preceded by a flush. Only after the first flush complete is
	// received, the events for the sensor are sent on that connection.
	bool mFirstFlushPending;
	FlushInfo() : mPendingFlushEventsToSend(0), mFirstFlushPending(false) {}
	};
	// protected by SensorService::mLock. Key for this vector is the sensor handle.
	KeyedVector<int, FlushInfo> mSensorInfo;
	sensors_event_t *mEventCache;
	int mCacheSize, mMaxCacheSize;
	String8 mPackageName;
	const String16 mOpPackageName;
	#if DEBUG_CONNECTIONS
	int mEventsReceived, mEventsSent, mEventsSentFromCache;
	int mTotalAcksNeeded, mTotalAcksReceived;
	#endif

	public:
	SensorEventConnection(const sp<SensorService>& service, uid_t uid, String8 packageName,
	bool isDataInjectionMode, const String16& opPackageName);

	status_t sendEvents(sensors_event_t const* buffer, size_t count,
	sensors_event_t* scratch,
	SensorEventConnection const * const * mapFlushEventsToConnections = NULL);
	bool hasSensor(int32_t handle) const;
	bool hasAnySensor() const;
	bool hasOneShotSensors() const;
	bool addSensor(int32_t handle);
	bool removeSensor(int32_t handle);
	void setFirstFlushPending(int32_t handle, bool value);
	void dump(String8& result);
	bool needsWakeLock();
	void resetWakeLockRefCount();
	String8 getPackageName() const;

	uid_t getUid() const { return mUid; }
	};

	class SensorRecord {
	SortedVector< wp<SensorEventConnection> > mConnections;
	// A queue of all flush() calls made on this sensor. Flush complete events will be
	// sent in this order.
	Vector< wp<SensorEventConnection> > mPendingFlushConnections;
	public:
	SensorRecord(const sp<SensorEventConnection>& connection);
	bool addConnection(const sp<SensorEventConnection>& connection);
	bool removeConnection(const wp<SensorEventConnection>& connection);
	size_t getNumConnections() const { return mConnections.size(); }

	void addPendingFlushConnection(const sp<SensorEventConnection>& connection);
	void removeFirstPendingFlushConnection();
	SensorEventConnection * getFirstPendingFlushConnection();
	void clearAllPendingFlushConnections();
	};

	class SensorEventAckReceiver : public Thread {
	sp<SensorService> const mService;
	public:
	virtual bool threadLoop();
	SensorEventAckReceiver(const sp<SensorService>& service): mService(service) {}
	};

	// sensor_event_t with only the data and the timestamp.
	struct TrimmedSensorEvent {
	union {
	float *mData;
	uint64_t mStepCounter;
	};
	// Timestamp from the sensor_event.
	int64_t mTimestamp;
	// HH:MM:SS local time at which this sensor event is read at SensorService. Useful
	// for debugging.
	int32_t mHour, mMin, mSec;

	TrimmedSensorEvent(int sensorType);
	static bool isSentinel(const TrimmedSensorEvent& event);

	~TrimmedSensorEvent() {
	delete [] mData;
	}
	};

	// A circular buffer of TrimmedSensorEvents. The size of this buffer is typically 10. The
	// last N events generated from the sensor are stored in this buffer. The buffer is NOT
	// cleared when the sensor unregisters and as a result one may see very old data in the
	// dumpsys output but this is WAI.
	class CircularBuffer {
	int mNextInd;
	int mSensorType;
	int mBufSize;
	TrimmedSensorEvent ** mTrimmedSensorEventArr;
	public:
	CircularBuffer(int sensor_event_type);
	void addEvent(const sensors_event_t& sensor_event);
	void printBuffer(String8& buffer) const;
	bool populateLastEvent(sensors_event_t *event);
	~CircularBuffer();
	};

	struct SensorRegistrationInfo {
	int32_t mSensorHandle;
	String8 mPackageName;
	bool mActivated;
	int32_t mSamplingRateUs;
	int32_t mMaxReportLatencyUs;
	int32_t mHour, mMin, mSec;

	SensorRegistrationInfo() : mPackageName() {
	mSensorHandle = mSamplingRateUs = mMaxReportLatencyUs = INT32_MIN;
	mHour = mMin = mSec = INT32_MIN;
	mActivated = false;
	}

	static bool isSentinel(const SensorRegistrationInfo& info) {
	return (info.mHour == INT32_MIN && info.mMin == INT32_MIN && info.mSec == INT32_MIN);
	}
	};

	static int getNumEventsForSensorType(int sensor_event_type);
	String8 getSensorName(int handle) const;
	bool isVirtualSensor(int handle) const;
	Sensor getSensorFromHandle(int handle) const;
	bool isWakeUpSensor(int type) const;
	void recordLastValueLocked(sensors_event_t const* buffer, size_t count);
	static void sortEventBuffer(sensors_event_t* buffer, size_t count);
	Sensor registerSensor(SensorInterface* sensor);
	Sensor registerVirtualSensor(SensorInterface* sensor);
	status_t cleanupWithoutDisable(
	const sp<SensorEventConnection>& connection, int handle);
	status_t cleanupWithoutDisableLocked(
	const sp<SensorEventConnection>& connection, int handle);
	void cleanupAutoDisabledSensorLocked(const sp<SensorEventConnection>& connection,
	sensors_event_t const* buffer, const int count);
	static bool canAccessSensor(const Sensor& sensor, const char* operation,
	const String16& opPackageName);
	// SensorService acquires a partial wakelock for delivering events from wake up sensors. This
	// method checks whether all the events from these wake up sensors have been delivered to the
	// corresponding applications, if yes the wakelock is released.
	void checkWakeLockState();
	void checkWakeLockStateLocked();
	bool isWakeLockAcquired();
	bool isWakeUpSensorEvent(const sensors_event_t& event) const;

	SensorRecord * getSensorRecord(int handle);

	sp<Looper> getLooper() const;

	// Reset mWakeLockRefCounts for all SensorEventConnections to zero. This may happen if
	// SensorService did not receive any acknowledgements from apps which have registered for
	// wake_up sensors.
	void resetAllWakeLockRefCounts();

	// Acquire or release wake_lock. If wake_lock is acquired, set the timeout in the looper to
	// 5 seconds and wake the looper.
	void setWakeLockAcquiredLocked(bool acquire);

	// Send events from the event cache for this particular connection.
	void sendEventsFromCache(const sp<SensorEventConnection>& connection);

	// Promote all weak referecences in mActiveConnections vector to strong references and add them
	// to the output vector.
	void populateActiveConnections(SortedVector< sp<SensorEventConnection> >* activeConnections);

	// If SensorService is operating in RESTRICTED mode, only select whitelisted packages are
	// allowed to register for or call flush on sensors. Typically only cts test packages are
	// allowed.
	bool isWhiteListedPackage(const String8& packageName);

	// Reset the state of SensorService to NORMAL mode.
	status_t resetToNormalMode();
	status_t resetToNormalModeLocked();

	// constants
	Vector<Sensor> mSensorList;
	Vector<Sensor> mUserSensorListDebug;
	Vector<Sensor> mUserSensorList;
	DefaultKeyedVector<int, SensorInterface*> mSensorMap;
	Vector<SensorInterface *> mVirtualSensorList;
	status_t mInitCheck;
	// Socket buffersize used to initialize BitTube. This size depends on whether batching is
	// supported or not.
	uint32_t mSocketBufferSize;
	sp<Looper> mLooper;
	sp<SensorEventAckReceiver> mAckReceiver;

	// protected by mLock
	mutable Mutex mLock;
	DefaultKeyedVector<int, SensorRecord*> mActiveSensors;
	DefaultKeyedVector<int, SensorInterface*> mActiveVirtualSensors;
	SortedVector< wp<SensorEventConnection> > mActiveConnections;
	bool mWakeLockAcquired;
	sensors_event_t mSensorEventBuffer, mSensorEventScratch;
	SensorEventConnection const **mMapFlushEventsToConnections;
	Mode mCurrentOperatingMode;
	// This packagaName is set when SensorService is in RESTRICTED or DATA_INJECTION mode. Only
	// applications with this packageName are allowed to activate/deactivate or call flush on
	// sensors. To run CTS this is can be set to ".cts." and only CTS tests will get access to
	// sensors.
	String8 mWhiteListedPackage;

	// The size of this vector is constant, only the items are mutable
	KeyedVector<int32_t, CircularBuffer *> mLastEventSeen;

	int mNextSensorRegIndex;
	Vector<SensorRegistrationInfo> mLastNSensorRegistrations;
	public:
	void cleanupConnection(SensorEventConnection* connection);
	status_t enable(const sp<SensorEventConnection>& connection, int handle,
	nsecs_t samplingPeriodNs, nsecs_t maxBatchReportLatencyNs, int reservedFlags,
	const String16& opPackageName);
	status_t disable(const sp<SensorEventConnection>& connection, int handle);
	status_t setEventRate(const sp<SensorEventConnection>& connection, int handle, nsecs_t ns,
	const String16& opPackageName);
	status_t flushSensor(const sp<SensorEventConnection>& connection,
	const String16& opPackageName);
	};

	// ---------------------------------------------------------------------------
	}; // namespace android

	#endif // ANDROID_SENSOR_SERVICE_H