services/sensorservice/SensorService.cpp

/*
 * 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.
 */

#include <cutils/properties.h>

#include <binder/AppOpsManager.h>
#include <binder/BinderService.h>
#include <binder/IServiceManager.h>
#include <binder/PermissionCache.h>

#include <gui/SensorEventQueue.h>

#include <hardware/sensors.h>
#include <hardware_legacy/power.h>

#include "BatteryService.h"
#include "CorrectedGyroSensor.h"
#include "GravitySensor.h"
#include "LinearAccelerationSensor.h"
#include "OrientationSensor.h"
#include "RotationVectorSensor.h"
#include "SensorFusion.h"

#include "SensorService.h"
#include "SensorEventConnection.h"
#include "SensorEventAckReceiver.h"
#include "SensorRecord.h"
#include "SensorRegistrationInfo.h"
#include "MostRecentEventLogger.h"

#include <inttypes.h>
#include <math.h>
#include <stdint.h>
#include <sys/types.h>
#include <sys/socket.h>

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

/*
 * Notes:
 *
 * - what about a gyro-corrected magnetic-field sensor?
 * - run mag sensor from time to time to force calibration
 * - gravity sensor length is wrong (=> drift in linear-acc sensor)
 *
 */

const char* SensorService::WAKE_LOCK_NAME = "SensorService_wakelock";
// Permissions.
static const String16 sDump("android.permission.DUMP");

SensorService::SensorService()
    : mInitCheck(NO_INIT), mSocketBufferSize(SOCKET_BUFFER_SIZE_NON_BATCHED),
      mWakeLockAcquired(false) {
}

void SensorService::onFirstRef() {
    ALOGD("nuSensorService starting...");
    SensorDevice& dev(SensorDevice::getInstance());

    if (dev.initCheck() == NO_ERROR) {
        sensor_t const* list;
        ssize_t count = dev.getSensorList(&list);
        if (count > 0) {
            ssize_t orientationIndex = -1;
            bool hasGyro = false, hasAccel = false, hasMag = false;
            uint32_t virtualSensorsNeeds =
                    (1<<SENSOR_TYPE_GRAVITY) |
                    (1<<SENSOR_TYPE_LINEAR_ACCELERATION) |
                    (1<<SENSOR_TYPE_ROTATION_VECTOR) |
                    (1<<SENSOR_TYPE_GEOMAGNETIC_ROTATION_VECTOR) |
                    (1<<SENSOR_TYPE_GAME_ROTATION_VECTOR);

            mLastEventSeen.setCapacity(count);
            for (ssize_t i=0 ; i<count ; i++) {
                bool useThisSensor=true;

                switch (list[i].type) {
                    case SENSOR_TYPE_ACCELEROMETER:
                        hasAccel = true;
                        break;
                    case SENSOR_TYPE_MAGNETIC_FIELD:
                        hasMag = true;
                        break;
                    case SENSOR_TYPE_ORIENTATION:
                        orientationIndex = i;
                        break;
                    case SENSOR_TYPE_GYROSCOPE:
                    case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
                        hasGyro = true;
                        break;
                    case SENSOR_TYPE_GRAVITY:
                    case SENSOR_TYPE_LINEAR_ACCELERATION:
                    case SENSOR_TYPE_ROTATION_VECTOR:
                    case SENSOR_TYPE_GEOMAGNETIC_ROTATION_VECTOR:
                    case SENSOR_TYPE_GAME_ROTATION_VECTOR:
                        if (IGNORE_HARDWARE_FUSION) {
                            useThisSensor = false;
                        } else {
                            virtualSensorsNeeds &= ~(1<<list[i].type);
                        }
                        break;
                }
                if (useThisSensor) {
                    registerSensor( new HardwareSensor(list[i]) );
                }
            }

            // it's safe to instantiate the SensorFusion object here
            // (it wants to be instantiated after h/w sensors have been
            // registered)
            SensorFusion::getInstance();

            // build the sensor list returned to users
            mUserSensorList = mSensorList;

            if (hasGyro && hasAccel && hasMag) {
                // Add Android virtual sensors if they're not already
                // available in the HAL
                Sensor aSensor;

                aSensor = registerVirtualSensor( new RotationVectorSensor() );
                if (virtualSensorsNeeds & (1<<SENSOR_TYPE_ROTATION_VECTOR)) {
                    mUserSensorList.add(aSensor);
                }

                aSensor = registerVirtualSensor( new OrientationSensor() );
                if (virtualSensorsNeeds & (1<<SENSOR_TYPE_ROTATION_VECTOR)) {
                    // if we are doing our own rotation-vector, also add
                    // the orientation sensor and remove the HAL provided one.
                    mUserSensorList.replaceAt(aSensor, orientationIndex);
                }

                aSensor = registerVirtualSensor(
                                new LinearAccelerationSensor(list, count) );
                if (virtualSensorsNeeds &
                            (1<<SENSOR_TYPE_LINEAR_ACCELERATION)) {
                    mUserSensorList.add(aSensor);
                }

                // virtual debugging sensors are not added to mUserSensorList
                registerVirtualSensor( new CorrectedGyroSensor(list, count) );
                registerVirtualSensor( new GyroDriftSensor() );
            }

            if (hasAccel && hasGyro) {
                Sensor aSensor;

                aSensor = registerVirtualSensor(
                                new GravitySensor(list, count) );
                if (virtualSensorsNeeds & (1<<SENSOR_TYPE_GRAVITY)) {
                    mUserSensorList.add(aSensor);
                }

                aSensor = registerVirtualSensor(
                                new GameRotationVectorSensor() );
                if (virtualSensorsNeeds &
                            (1<<SENSOR_TYPE_GAME_ROTATION_VECTOR)) {
                    mUserSensorList.add(aSensor);
                }
            }

            if (hasAccel && hasMag) {
                Sensor aSensor;

                aSensor = registerVirtualSensor(
                                new GeoMagRotationVectorSensor() );
                if (virtualSensorsNeeds &
                        (1<<SENSOR_TYPE_GEOMAGNETIC_ROTATION_VECTOR)) {
                    mUserSensorList.add(aSensor);
                }
            }

            // debugging sensor list
            mUserSensorListDebug = mSensorList;

            // Check if the device really supports batching by looking at the FIFO event
            // counts for each sensor.
            bool batchingSupported = false;
            for (size_t i = 0; i < mSensorList.size(); ++i) {
                if (mSensorList[i].getFifoMaxEventCount() > 0) {
                    batchingSupported = true;
                    break;
                }
            }

            if (batchingSupported) {
                // Increase socket buffer size to a max of 100 KB for batching capabilities.
                mSocketBufferSize = MAX_SOCKET_BUFFER_SIZE_BATCHED;
            } else {
                mSocketBufferSize = SOCKET_BUFFER_SIZE_NON_BATCHED;
            }

            // Compare the socketBufferSize value against the system limits and limit
            // it to maxSystemSocketBufferSize if necessary.
            FILE *fp = fopen("/proc/sys/net/core/wmem_max", "r");
            char line[128];
            if (fp != NULL && fgets(line, sizeof(line), fp) != NULL) {
                line[sizeof(line) - 1] = '\0';
                size_t maxSystemSocketBufferSize;
                sscanf(line, "%zu", &maxSystemSocketBufferSize);
                if (mSocketBufferSize > maxSystemSocketBufferSize) {
                    mSocketBufferSize = maxSystemSocketBufferSize;
                }
            }
            if (fp) {
                fclose(fp);
            }

            mWakeLockAcquired = false;
            mLooper = new Looper(false);
            const size_t minBufferSize = SensorEventQueue::MAX_RECEIVE_BUFFER_EVENT_COUNT;
            mSensorEventBuffer = new sensors_event_t[minBufferSize];
            mSensorEventScratch = new sensors_event_t[minBufferSize];
            mMapFlushEventsToConnections = new SensorEventConnection const * [minBufferSize];
            mCurrentOperatingMode = NORMAL;

            mNextSensorRegIndex = 0;
            for (int i = 0; i < SENSOR_REGISTRATIONS_BUF_SIZE; ++i) {
                mLastNSensorRegistrations.push();
            }

            mInitCheck = NO_ERROR;
            mAckReceiver = new SensorEventAckReceiver(this);
            mAckReceiver->run("SensorEventAckReceiver", PRIORITY_URGENT_DISPLAY);
            run("SensorService", PRIORITY_URGENT_DISPLAY);
        }
    }
}

Sensor SensorService::registerSensor(SensorInterface* s) {
    const Sensor sensor(s->getSensor());

    // add handle to used handle list
    mUsedHandleList.add(sensor.getHandle());
    // add to the sensor list (returned to clients)
    mSensorList.add(sensor);
    // add to our handle->SensorInterface mapping
    mSensorMap.add(sensor.getHandle(), s);
    // create an entry in the mLastEventSeen array
    mLastEventSeen.add(sensor.getHandle(), NULL);

    return sensor;
}

Sensor SensorService::registerDynamicSensor(SensorInterface* s) {
    Sensor sensor = registerSensor(s);
    mDynamicSensorList.add(sensor);

    auto compareSensorHandle = [] (const Sensor* lhs, const Sensor* rhs) {
        return lhs->getHandle() - rhs->getHandle();
    };
    mDynamicSensorList.sort(compareSensorHandle);
    return sensor;
}

bool SensorService::unregisterDynamicSensor(int handle) {
    bool found = false;

    for (size_t i = 0 ; i < mSensorList.size() ; i++) {
        if (mSensorList[i].getHandle() == handle) {
            mSensorList.removeAt(i);
            found = true;
            break;
        }
    }

    if (found) {
        for (size_t i = 0 ; i < mDynamicSensorList.size() ; i++) {
            if (mDynamicSensorList[i].getHandle() == handle) {
                mDynamicSensorList.removeAt(i);
            }
        }

        mSensorMap.removeItem(handle);
        mLastEventSeen.removeItem(handle);
    }
    return found;
}

Sensor SensorService::registerVirtualSensor(SensorInterface* s) {
    Sensor sensor = registerSensor(s);
    mVirtualSensorList.add( s );
    return sensor;
}

bool SensorService::isNewHandle(int handle) {
    for (int h : mUsedHandleList) {
        if (h == handle) {
            return false;
        }
    }
    return true;
}

SensorService::~SensorService() {
    for (size_t i=0 ; i<mSensorMap.size() ; i++) {
        delete mSensorMap.valueAt(i);
    }
}

status_t SensorService::dump(int fd, const Vector<String16>& args) {
    String8 result;
    if (!PermissionCache::checkCallingPermission(sDump)) {
        result.appendFormat("Permission Denial: can't dump SensorService from pid=%d, uid=%d\n",
                IPCThreadState::self()->getCallingPid(),
                IPCThreadState::self()->getCallingUid());
    } else {
        if (args.size() > 2) {
           return INVALID_OPERATION;
        }
        Mutex::Autolock _l(mLock);
        SensorDevice& dev(SensorDevice::getInstance());
        if (args.size() == 2 && args[0] == String16("restrict")) {
            // If already in restricted mode. Ignore.
            if (mCurrentOperatingMode == RESTRICTED) {
                return status_t(NO_ERROR);
            }
            // If in any mode other than normal, ignore.
            if (mCurrentOperatingMode != NORMAL) {
                return INVALID_OPERATION;
            }
            mCurrentOperatingMode = RESTRICTED;
            dev.disableAllSensors();
            // Clear all pending flush connections for all active sensors. If one of the active
            // connections has called flush() and the underlying sensor has been disabled before a
            // flush complete event is returned, we need to remove the connection from this queue.
            for (size_t i=0 ; i< mActiveSensors.size(); ++i) {
                mActiveSensors.valueAt(i)->clearAllPendingFlushConnections();
            }
            mWhiteListedPackage.setTo(String8(args[1]));
            return status_t(NO_ERROR);
        } else if (args.size() == 1 && args[0] == String16("enable")) {
            // If currently in restricted mode, reset back to NORMAL mode else ignore.
            if (mCurrentOperatingMode == RESTRICTED) {
                mCurrentOperatingMode = NORMAL;
                dev.enableAllSensors();
            }
            if (mCurrentOperatingMode == DATA_INJECTION) {
               resetToNormalModeLocked();
            }
            mWhiteListedPackage.clear();
            return status_t(NO_ERROR);
        } else if (args.size() == 2 && args[0] == String16("data_injection")) {
            if (mCurrentOperatingMode == NORMAL) {
                dev.disableAllSensors();
                status_t err = dev.setMode(DATA_INJECTION);
                if (err == NO_ERROR) {
                    mCurrentOperatingMode = DATA_INJECTION;
                } else {
                    // Re-enable sensors.
                    dev.enableAllSensors();
                }
                mWhiteListedPackage.setTo(String8(args[1]));
                return NO_ERROR;
            } else if (mCurrentOperatingMode == DATA_INJECTION) {
                // Already in DATA_INJECTION mode. Treat this as a no_op.
                return NO_ERROR;
            } else {
                // Transition to data injection mode supported only from NORMAL mode.
                return INVALID_OPERATION;
            }
        } else if (mSensorList.size() == 0) {
            result.append("No Sensors on the device\n");
        } else {
            // Default dump the sensor list and debugging information.
            result.append("Sensor List:\n");
            for (size_t i=0 ; i<mSensorList.size() ; i++) {
                const Sensor& s(mSensorList[i]);
                result.appendFormat(
                        "%-15s| %-10s| version=%d |%-20s| 0x%08x | \"%s\" | type=%d |",
                        s.getName().string(),
                        s.getVendor().string(),
                        s.getVersion(),
                        s.getStringType().string(),
                        s.getHandle(),
                        s.getRequiredPermission().string(),
                        s.getType());

                const int reportingMode = s.getReportingMode();
                if (reportingMode == AREPORTING_MODE_CONTINUOUS) {
                    result.append(" continuous | ");
                } else if (reportingMode == AREPORTING_MODE_ON_CHANGE) {
                    result.append(" on-change | ");
                } else if (reportingMode == AREPORTING_MODE_ONE_SHOT) {
                    result.append(" one-shot | ");
                } else {
                    result.append(" special-trigger | ");
                }

                if (s.getMaxDelay() > 0) {
                    result.appendFormat("minRate=%.2fHz | ", 1e6f / s.getMaxDelay());
                } else {
                    result.appendFormat("maxDelay=%dus |", s.getMaxDelay());
                }

                if (s.getMinDelay() > 0) {
                    result.appendFormat("maxRate=%.2fHz | ", 1e6f / s.getMinDelay());
                } else {
                    result.appendFormat("minDelay=%dus |", s.getMinDelay());
                }

                if (s.getFifoMaxEventCount() > 0) {
                    result.appendFormat("FifoMax=%d events | ",
                            s.getFifoMaxEventCount());
                } else {
                    result.append("no batching | ");
                }

                if (s.isWakeUpSensor()) {
                    result.appendFormat("wakeUp | ");
                } else {
                    result.appendFormat("non-wakeUp | ");
                }

                int bufIndex = mLastEventSeen.indexOfKey(s.getHandle());
                if (bufIndex >= 0) {
                    const MostRecentEventLogger* buf = mLastEventSeen.valueAt(bufIndex);
                    if (buf != NULL && s.getRequiredPermission().isEmpty()) {
                        buf->printBuffer(result);
                    } else {
                        result.append("last=<> \n");
                    }
                }
                result.append("\n");
            }
            SensorFusion::getInstance().dump(result);
            SensorDevice::getInstance().dump(result);

            result.append("Active sensors:\n");
            for (size_t i=0 ; i<mActiveSensors.size() ; i++) {
                int handle = mActiveSensors.keyAt(i);
                result.appendFormat("%s (handle=0x%08x, connections=%zu)\n",
                        getSensorName(handle).string(),
                        handle,
                        mActiveSensors.valueAt(i)->getNumConnections());
            }

            result.appendFormat("Socket Buffer size = %zd events\n",
                                mSocketBufferSize/sizeof(sensors_event_t));
            result.appendFormat("WakeLock Status: %s \n", mWakeLockAcquired ? "acquired" :
                    "not held");
            result.appendFormat("Mode :");
            switch(mCurrentOperatingMode) {
               case NORMAL:
                   result.appendFormat(" NORMAL\n");
                   break;
               case RESTRICTED:
                   result.appendFormat(" RESTRICTED : %s\n", mWhiteListedPackage.string());
                   break;
               case DATA_INJECTION:
                   result.appendFormat(" DATA_INJECTION : %s\n", mWhiteListedPackage.string());
            }
            result.appendFormat("%zd active connections\n", mActiveConnections.size());

            for (size_t i=0 ; i < mActiveConnections.size() ; i++) {
                sp<SensorEventConnection> connection(mActiveConnections[i].promote());
                if (connection != 0) {
                    result.appendFormat("Connection Number: %zu \n", i);
                    connection->dump(result);
                }
            }

            result.appendFormat("Previous Registrations:\n");
            // Log in the reverse chronological order.
            int currentIndex = (mNextSensorRegIndex - 1 + SENSOR_REGISTRATIONS_BUF_SIZE) %
                SENSOR_REGISTRATIONS_BUF_SIZE;
            const int startIndex = currentIndex;
            do {
                const SensorRegistrationInfo& reg_info = mLastNSensorRegistrations[currentIndex];
                if (SensorRegistrationInfo::isSentinel(reg_info)) {
                    // Ignore sentinel, proceed to next item.
                    currentIndex = (currentIndex - 1 + SENSOR_REGISTRATIONS_BUF_SIZE) %
                        SENSOR_REGISTRATIONS_BUF_SIZE;
                    continue;
                }
                if (reg_info.mActivated) {
                   result.appendFormat("%02d:%02d:%02d activated package=%s handle=0x%08x "
                           "samplingRate=%dus maxReportLatency=%dus\n",
                           reg_info.mHour, reg_info.mMin, reg_info.mSec,
                           reg_info.mPackageName.string(), reg_info.mSensorHandle,
                           reg_info.mSamplingRateUs, reg_info.mMaxReportLatencyUs);
                } else {
                   result.appendFormat("%02d:%02d:%02d de-activated package=%s handle=0x%08x\n",
                           reg_info.mHour, reg_info.mMin, reg_info.mSec,
                           reg_info.mPackageName.string(), reg_info.mSensorHandle);
                }
                currentIndex = (currentIndex - 1 + SENSOR_REGISTRATIONS_BUF_SIZE) %
                        SENSOR_REGISTRATIONS_BUF_SIZE;
            } while(startIndex != currentIndex);
        }
    }
    write(fd, result.string(), result.size());
    return NO_ERROR;
}

void SensorService::cleanupAutoDisabledSensorLocked(const sp<SensorEventConnection>& connection,
        sensors_event_t const* buffer, const int count) {
    for (int i=0 ; i<count ; i++) {
        int handle = buffer[i].sensor;
        if (buffer[i].type == SENSOR_TYPE_META_DATA) {
            handle = buffer[i].meta_data.sensor;
        }
        if (connection->hasSensor(handle)) {
            SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
            // If this buffer has an event from a one_shot sensor and this connection is registered
            // for this particular one_shot sensor, try cleaning up the connection.
            if (sensor != NULL &&
                sensor->getSensor().getReportingMode() == AREPORTING_MODE_ONE_SHOT) {
                sensor->autoDisable(connection.get(), handle);
                cleanupWithoutDisableLocked(connection, handle);
            }

        }
   }
}

bool SensorService::threadLoop() {
    ALOGD("nuSensorService thread starting...");

    // each virtual sensor could generate an event per "real" event, that's why we need to size
    // numEventMax much smaller than MAX_RECEIVE_BUFFER_EVENT_COUNT.  in practice, this is too
    // aggressive, but guaranteed to be enough.
    const size_t minBufferSize = SensorEventQueue::MAX_RECEIVE_BUFFER_EVENT_COUNT;
    const size_t numEventMax = minBufferSize / (1 + mVirtualSensorList.size());

    SensorDevice& device(SensorDevice::getInstance());
    const size_t vcount = mVirtualSensorList.size();

    const int halVersion = device.getHalDeviceVersion();
    do {
        ssize_t count = device.poll(mSensorEventBuffer, numEventMax);
        if (count < 0) {
            ALOGE("sensor poll failed (%s)", strerror(-count));
            break;
        }

        // Reset sensors_event_t.flags to zero for all events in the buffer.
        for (int i = 0; i < count; i++) {
             mSensorEventBuffer[i].flags = 0;
        }

        // Make a copy of the connection vector as some connections may be removed during the course
        // of this loop (especially when one-shot sensor events are present in the sensor_event
        // buffer). Promote all connections to StrongPointers before the lock is acquired. If the
        // destructor of the sp gets called when the lock is acquired, it may result in a deadlock
        // as ~SensorEventConnection() needs to acquire mLock again for cleanup. So copy all the
        // strongPointers to a vector before the lock is acquired.
        SortedVector< sp<SensorEventConnection> > activeConnections;
        populateActiveConnections(&activeConnections);

        Mutex::Autolock _l(mLock);
        // Poll has returned. Hold a wakelock if one of the events is from a wake up sensor. The
        // rest of this loop is under a critical section protected by mLock. Acquiring a wakeLock,
        // sending events to clients (incrementing SensorEventConnection::mWakeLockRefCount) should
        // not be interleaved with decrementing SensorEventConnection::mWakeLockRefCount and
        // releasing the wakelock.
        bool bufferHasWakeUpEvent = false;
        for (int i = 0; i < count; i++) {
            if (isWakeUpSensorEvent(mSensorEventBuffer[i])) {
                bufferHasWakeUpEvent = true;
                break;
            }
        }

        if (bufferHasWakeUpEvent && !mWakeLockAcquired) {
            setWakeLockAcquiredLocked(true);
        }
        recordLastValueLocked(mSensorEventBuffer, count);

        // handle virtual sensors
        if (count && vcount) {
            sensors_event_t const * const event = mSensorEventBuffer;
            const size_t activeVirtualSensorCount = mActiveVirtualSensors.size();
            if (activeVirtualSensorCount) {
                size_t k = 0;
                SensorFusion& fusion(SensorFusion::getInstance());
                if (fusion.isEnabled()) {
                    for (size_t i=0 ; i<size_t(count) ; i++) {
                        fusion.process(event[i]);
                    }
                }
                for (size_t i=0 ; i<size_t(count) && k<minBufferSize ; i++) {
                    for (size_t j=0 ; j<activeVirtualSensorCount ; j++) {
                        if (count + k >= minBufferSize) {
                            ALOGE("buffer too small to hold all events: "
                                    "count=%zd, k=%zu, size=%zu",
                                    count, k, minBufferSize);
                            break;
                        }
                        sensors_event_t out;
                        SensorInterface* si = mActiveVirtualSensors.valueAt(j);
                        if (si->process(&out, event[i])) {
                            mSensorEventBuffer[count + k] = out;
                            k++;
                        }
                    }
                }
                if (k) {
                    // record the last synthesized values
                    recordLastValueLocked(&mSensorEventBuffer[count], k);
                    count += k;
                    // sort the buffer by time-stamps
                    sortEventBuffer(mSensorEventBuffer, count);
                }
            }
        }

        // handle backward compatibility for RotationVector sensor
        if (halVersion < SENSORS_DEVICE_API_VERSION_1_0) {
            for (int i = 0; i < count; i++) {
                if (mSensorEventBuffer[i].type == SENSOR_TYPE_ROTATION_VECTOR) {
                    // All the 4 components of the quaternion should be available
                    // No heading accuracy. Set it to -1
                    mSensorEventBuffer[i].data[4] = -1;
                }
            }
        }

        for (int i = 0; i < count; ++i) {
            // Map flush_complete_events in the buffer to SensorEventConnections which called flush on
            // the hardware sensor. mapFlushEventsToConnections[i] will be the SensorEventConnection
            // mapped to the corresponding flush_complete_event in mSensorEventBuffer[i] if such a
            // mapping exists (NULL otherwise).
            mMapFlushEventsToConnections[i] = NULL;
            if (mSensorEventBuffer[i].type == SENSOR_TYPE_META_DATA) {
                const int sensor_handle = mSensorEventBuffer[i].meta_data.sensor;
                SensorRecord* rec = mActiveSensors.valueFor(sensor_handle);
                if (rec != NULL) {
                    mMapFlushEventsToConnections[i] = rec->getFirstPendingFlushConnection();
                    rec->removeFirstPendingFlushConnection();
                }
            }

            // handle dynamic sensor meta events, process registration and unregistration of dynamic
            // sensor based on content of event.
            if (mSensorEventBuffer[i].type == SENSOR_TYPE_DYNAMIC_SENSOR_META) {
                if (mSensorEventBuffer[i].dynamic_sensor_meta.connected) {
                    int handle = mSensorEventBuffer[i].dynamic_sensor_meta.handle;
                    const sensor_t& dynamicSensor =
                            *(mSensorEventBuffer[i].dynamic_sensor_meta.sensor);
                    ALOGI("Dynamic sensor handle 0x%x connected, type %d, name %s",
                          handle, dynamicSensor.type, dynamicSensor.name);

                    if (isNewHandle(handle)) {
                        sensor_t s = dynamicSensor;
                        // make sure the dynamic sensor flag is set
                        s.flags |= DYNAMIC_SENSOR_MASK;
                        // force the handle to be consistent
                        s.handle = handle;
                        SensorInterface *si = new HardwareSensor(s);

                        // This will release hold on dynamic sensor meta, so it should be called after
                        // Sensor object is created.
                        device.handleDynamicSensorConnection(handle, true /*connected*/);
                        registerDynamicSensor(si);
                    } else {
                        ALOGE("Handle %d has been used, cannot use again before reboot.", handle);
                    }
                } else {
                    int handle = mSensorEventBuffer[i].dynamic_sensor_meta.handle;
                    ALOGI("Dynamic sensor handle 0x%x disconnected", handle);

                    device.handleDynamicSensorConnection(handle, false /*connected*/);
                    if (!unregisterDynamicSensor(handle)) {
                        ALOGE("Dynamic sensor release error.");
                    }

                    size_t numConnections = activeConnections.size();
                    for (size_t i=0 ; i < numConnections; ++i) {
                        if (activeConnections[i] != NULL) {
                            activeConnections[i]->removeSensor(handle);
                        }
                    }
                }
            }
        }


        // Send our events to clients. Check the state of wake lock for each client and release the
        // lock if none of the clients need it.
        bool needsWakeLock = false;
        size_t numConnections = activeConnections.size();
        for (size_t i=0 ; i < numConnections; ++i) {
            if (activeConnections[i] != 0) {
                activeConnections[i]->sendEvents(mSensorEventBuffer, count, mSensorEventScratch,
                        mMapFlushEventsToConnections);
                needsWakeLock |= activeConnections[i]->needsWakeLock();
                // If the connection has one-shot sensors, it may be cleaned up after first trigger.
                // Early check for one-shot sensors.
                if (activeConnections[i]->hasOneShotSensors()) {
                    cleanupAutoDisabledSensorLocked(activeConnections[i], mSensorEventBuffer,
                            count);
                }
            }
        }

        if (mWakeLockAcquired && !needsWakeLock) {
            setWakeLockAcquiredLocked(false);
        }
    } while (!Thread::exitPending());

    ALOGW("Exiting SensorService::threadLoop => aborting...");
    abort();
    return false;
}

sp<Looper> SensorService::getLooper() const {
    return mLooper;
}

void SensorService::resetAllWakeLockRefCounts() {
    SortedVector< sp<SensorEventConnection> > activeConnections;
    populateActiveConnections(&activeConnections);
    {
        Mutex::Autolock _l(mLock);
        for (size_t i=0 ; i < activeConnections.size(); ++i) {
            if (activeConnections[i] != 0) {
                activeConnections[i]->resetWakeLockRefCount();
            }
        }
        setWakeLockAcquiredLocked(false);
    }
}

void SensorService::setWakeLockAcquiredLocked(bool acquire) {
    if (acquire) {
        if (!mWakeLockAcquired) {
            acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_NAME);
            mWakeLockAcquired = true;
        }
        mLooper->wake();
    } else {
        if (mWakeLockAcquired) {
            release_wake_lock(WAKE_LOCK_NAME);
            mWakeLockAcquired = false;
        }
    }
}

bool SensorService::isWakeLockAcquired() {
    Mutex::Autolock _l(mLock);
    return mWakeLockAcquired;
}

bool SensorService::SensorEventAckReceiver::threadLoop() {
    ALOGD("new thread SensorEventAckReceiver");
    sp<Looper> looper = mService->getLooper();
    do {
        bool wakeLockAcquired = mService->isWakeLockAcquired();
        int timeout = -1;
        if (wakeLockAcquired) timeout = 5000;
        int ret = looper->pollOnce(timeout);
        if (ret == ALOOPER_POLL_TIMEOUT) {
           mService->resetAllWakeLockRefCounts();
        }
    } while(!Thread::exitPending());
    return false;
}

void SensorService::recordLastValueLocked(
        const sensors_event_t* buffer, size_t count) {
    for (size_t i = 0; i < count; i++) {
        if (buffer[i].type == SENSOR_TYPE_META_DATA ||
            buffer[i].type == SENSOR_TYPE_DYNAMIC_SENSOR_META ||
            buffer[i].type == SENSOR_TYPE_ADDITIONAL_INFO ||
            mLastEventSeen.indexOfKey(buffer[i].sensor) <0 ) {
            continue;
        }

        MostRecentEventLogger* &circular_buf = mLastEventSeen.editValueFor(buffer[i].sensor);
        if (circular_buf == NULL) {
            circular_buf = new MostRecentEventLogger(buffer[i].type);
        }
        circular_buf->addEvent(buffer[i]);
    }
}

void SensorService::sortEventBuffer(sensors_event_t* buffer, size_t count) {
    struct compar {
        static int cmp(void const* lhs, void const* rhs) {
            sensors_event_t const* l = static_cast<sensors_event_t const*>(lhs);
            sensors_event_t const* r = static_cast<sensors_event_t const*>(rhs);
            return l->timestamp - r->timestamp;
        }
    };
    qsort(buffer, count, sizeof(sensors_event_t), compar::cmp);
}

String8 SensorService::getSensorName(int handle) const {
    size_t count = mUserSensorList.size();
    for (size_t i=0 ; i<count ; i++) {
        const Sensor& sensor(mUserSensorList[i]);
        if (sensor.getHandle() == handle) {
            return sensor.getName();
        }
    }
    return String8("unknown");
}

bool SensorService::isVirtualSensor(int handle) const {
    SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
    return sensor != NULL && sensor->isVirtual();
}

bool SensorService::isWakeUpSensorEvent(const sensors_event_t& event) const {
    int handle = event.sensor;
    if (event.type == SENSOR_TYPE_META_DATA) {
        handle = event.meta_data.sensor;
    }
    SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
    return sensor != NULL && sensor->getSensor().isWakeUpSensor();
}

Vector<Sensor> SensorService::getSensorList(const String16& opPackageName) {
    char value[PROPERTY_VALUE_MAX];
    property_get("debug.sensors", value, "0");
    const Vector<Sensor>& initialSensorList = (atoi(value)) ?
            mUserSensorListDebug : mUserSensorList;
    Vector<Sensor> accessibleSensorList;
    for (size_t i = 0; i < initialSensorList.size(); i++) {
        Sensor sensor = initialSensorList[i];
        if (canAccessSensor(sensor, "getSensorList", opPackageName)) {
            accessibleSensorList.add(sensor);
        } else {
            ALOGI("Skipped sensor %s because it requires permission %s and app op %d",
                  sensor.getName().string(),
                  sensor.getRequiredPermission().string(),
                  sensor.getRequiredAppOp());
        }
    }
    return accessibleSensorList;
}

Vector<Sensor> SensorService::getDynamicSensorList(const String16& opPackageName) {
    Vector<Sensor> accessibleSensorList;
    for (size_t i = 0; i < mDynamicSensorList.size(); i++) {
        Sensor sensor = mDynamicSensorList[i];
        if (canAccessSensor(sensor, "getDynamicSensorList", opPackageName)) {
            accessibleSensorList.add(sensor);
        } else {
            ALOGI("Skipped sensor %s because it requires permission %s and app op %d",
                  sensor.getName().string(),
                  sensor.getRequiredPermission().string(),
                  sensor.getRequiredAppOp());
        }
    }
    return accessibleSensorList;
}

sp<ISensorEventConnection> SensorService::createSensorEventConnection(const String8& packageName,
        int requestedMode, const String16& opPackageName) {
    // Only 2 modes supported for a SensorEventConnection ... NORMAL and DATA_INJECTION.
    if (requestedMode != NORMAL && requestedMode != DATA_INJECTION) {
        return NULL;
    }

    Mutex::Autolock _l(mLock);
    // To create a client in DATA_INJECTION mode to inject data, SensorService should already be
    // operating in DI mode.
    if (requestedMode == DATA_INJECTION) {
        if (mCurrentOperatingMode != DATA_INJECTION) return NULL;
        if (!isWhiteListedPackage(packageName)) return NULL;
    }

    uid_t uid = IPCThreadState::self()->getCallingUid();
    sp<SensorEventConnection> result(new SensorEventConnection(this, uid, packageName,
            requestedMode == DATA_INJECTION, opPackageName));
    if (requestedMode == DATA_INJECTION) {
        if (mActiveConnections.indexOf(result) < 0) {
            mActiveConnections.add(result);
        }
        // Add the associated file descriptor to the Looper for polling whenever there is data to
        // be injected.
        result->updateLooperRegistration(mLooper);
    }
    return result;
}

int SensorService::isDataInjectionEnabled() {
    Mutex::Autolock _l(mLock);
    return (mCurrentOperatingMode == DATA_INJECTION);
}

status_t SensorService::resetToNormalMode() {
    Mutex::Autolock _l(mLock);
    return resetToNormalModeLocked();
}

status_t SensorService::resetToNormalModeLocked() {
    SensorDevice& dev(SensorDevice::getInstance());
    dev.enableAllSensors();
    status_t err = dev.setMode(NORMAL);
    mCurrentOperatingMode = NORMAL;
    return err;
}

void SensorService::cleanupConnection(SensorEventConnection* c) {
    Mutex::Autolock _l(mLock);
    const wp<SensorEventConnection> connection(c);
    size_t size = mActiveSensors.size();
    ALOGD_IF(DEBUG_CONNECTIONS, "%zu active sensors", size);
    for (size_t i=0 ; i<size ; ) {
        int handle = mActiveSensors.keyAt(i);
        if (c->hasSensor(handle)) {
            ALOGD_IF(DEBUG_CONNECTIONS, "%zu: disabling handle=0x%08x", i, handle);
            SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
            ALOGE_IF(!sensor, "mSensorMap[handle=0x%08x] is null!", handle);
            if (sensor) {
                sensor->activate(c, false);
            }
            c->removeSensor(handle);
        }
        SensorRecord* rec = mActiveSensors.valueAt(i);
        ALOGE_IF(!rec, "mActiveSensors[%zu] is null (handle=0x%08x)!", i, handle);
        ALOGD_IF(DEBUG_CONNECTIONS,
                "removing connection %p for sensor[%zu].handle=0x%08x",
                c, i, handle);

        if (rec && rec->removeConnection(connection)) {
            ALOGD_IF(DEBUG_CONNECTIONS, "... and it was the last connection");
            mActiveSensors.removeItemsAt(i, 1);
            mActiveVirtualSensors.removeItem(handle);
            delete rec;
            size--;
        } else {
            i++;
        }
    }
    c->updateLooperRegistration(mLooper);
    mActiveConnections.remove(connection);
    BatteryService::cleanup(c->getUid());
    if (c->needsWakeLock()) {
        checkWakeLockStateLocked();
    }
}

SensorInterface* SensorService::getSensorInterfaceFromHandle(int handle) const {
    ssize_t index = mSensorMap.indexOfKey(handle);
    return index < 0 ? nullptr : mSensorMap.valueAt(index);
}

Sensor SensorService::getSensorFromHandle(int handle) const {
    SensorInterface* si = getSensorInterfaceFromHandle(handle);
    return si ? si->getSensor() : Sensor();
}

status_t SensorService::enable(const sp<SensorEventConnection>& connection,
        int handle, nsecs_t samplingPeriodNs, nsecs_t maxBatchReportLatencyNs, int reservedFlags,
        const String16& opPackageName) {
    if (mInitCheck != NO_ERROR)
        return mInitCheck;

    SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
    if (sensor == NULL) {
        return BAD_VALUE;
    }

    if (!canAccessSensor(sensor->getSensor(), "Tried enabling", opPackageName)) {
        return BAD_VALUE;
    }

    Mutex::Autolock _l(mLock);
    if ((mCurrentOperatingMode == RESTRICTED || mCurrentOperatingMode == DATA_INJECTION)
           && !isWhiteListedPackage(connection->getPackageName())) {
        return INVALID_OPERATION;
    }

    SensorRecord* rec = mActiveSensors.valueFor(handle);
    if (rec == 0) {
        rec = new SensorRecord(connection);
        mActiveSensors.add(handle, rec);
        if (sensor->isVirtual()) {
            mActiveVirtualSensors.add(handle, sensor);
        }
    } else {
        if (rec->addConnection(connection)) {
            // this sensor is already activated, but we are adding a connection that uses it.
            // Immediately send down the last known value of the requested sensor if it's not a
            // "continuous" sensor.
            if (sensor->getSensor().getReportingMode() == AREPORTING_MODE_ON_CHANGE) {
                // NOTE: The wake_up flag of this event may get set to
                // WAKE_UP_SENSOR_EVENT_NEEDS_ACK if this is a wake_up event.
                MostRecentEventLogger *circular_buf = mLastEventSeen.valueFor(handle);
                if (circular_buf) {
                    sensors_event_t event;
                    memset(&event, 0, sizeof(event));
                    // It is unlikely that this buffer is empty as the sensor is already active.
                    // One possible corner case may be two applications activating an on-change
                    // sensor at the same time.
                    if(circular_buf->populateLastEvent(&event)) {
                        event.sensor = handle;
                        if (event.version == sizeof(sensors_event_t)) {
                            if (isWakeUpSensorEvent(event) && !mWakeLockAcquired) {
                                setWakeLockAcquiredLocked(true);
                            }
                            connection->sendEvents(&event, 1, NULL);
                            if (!connection->needsWakeLock() && mWakeLockAcquired) {
                                checkWakeLockStateLocked();
                            }
                        }
                    }
                }
            }
        }
    }

    if (connection->addSensor(handle)) {
        BatteryService::enableSensor(connection->getUid(), handle);
        // the sensor was added (which means it wasn't already there)
        // so, see if this connection becomes active
        if (mActiveConnections.indexOf(connection) < 0) {
            mActiveConnections.add(connection);
        }
    } else {
        ALOGW("sensor %08x already enabled in connection %p (ignoring)",
            handle, connection.get());
    }

    nsecs_t minDelayNs = sensor->getSensor().getMinDelayNs();
    if (samplingPeriodNs < minDelayNs) {
        samplingPeriodNs = minDelayNs;
    }

    ALOGD_IF(DEBUG_CONNECTIONS, "Calling batch handle==%d flags=%d"
                                "rate=%" PRId64 " timeout== %" PRId64"",
             handle, reservedFlags, samplingPeriodNs, maxBatchReportLatencyNs);

    status_t err = sensor->batch(connection.get(), handle, 0, samplingPeriodNs,
                                 maxBatchReportLatencyNs);

    // Call flush() before calling activate() on the sensor. Wait for a first
    // flush complete event before sending events on this connection. Ignore
    // one-shot sensors which don't support flush(). Ignore on-change sensors
    // to maintain the on-change logic (any on-change events except the initial
    // one should be trigger by a change in value). Also if this sensor isn't
    // already active, don't call flush().
    if (err == NO_ERROR &&
            sensor->getSensor().getReportingMode() == AREPORTING_MODE_CONTINUOUS &&
            rec->getNumConnections() > 1) {
        connection->setFirstFlushPending(handle, true);
        status_t err_flush = sensor->flush(connection.get(), handle);
        // Flush may return error if the underlying h/w sensor uses an older HAL.
        if (err_flush == NO_ERROR) {
            rec->addPendingFlushConnection(connection.get());
        } else {
            connection->setFirstFlushPending(handle, false);
        }
    }

    if (err == NO_ERROR) {
        ALOGD_IF(DEBUG_CONNECTIONS, "Calling activate on %d", handle);
        err = sensor->activate(connection.get(), true);
    }

    if (err == NO_ERROR) {
        connection->updateLooperRegistration(mLooper);
        SensorRegistrationInfo &reg_info =
            mLastNSensorRegistrations.editItemAt(mNextSensorRegIndex);
        reg_info.mSensorHandle = handle;
        reg_info.mSamplingRateUs = samplingPeriodNs/1000;
        reg_info.mMaxReportLatencyUs = maxBatchReportLatencyNs/1000;
        reg_info.mActivated = true;
        reg_info.mPackageName = connection->getPackageName();
        time_t rawtime = time(NULL);
        struct tm * timeinfo = localtime(&rawtime);
        reg_info.mHour = timeinfo->tm_hour;
        reg_info.mMin = timeinfo->tm_min;
        reg_info.mSec = timeinfo->tm_sec;
        mNextSensorRegIndex = (mNextSensorRegIndex + 1) % SENSOR_REGISTRATIONS_BUF_SIZE;
    }

    if (err != NO_ERROR) {
        // batch/activate has failed, reset our state.
        cleanupWithoutDisableLocked(connection, handle);
    }
    return err;
}

status_t SensorService::disable(const sp<SensorEventConnection>& connection, int handle) {
    if (mInitCheck != NO_ERROR)
        return mInitCheck;

    Mutex::Autolock _l(mLock);
    status_t err = cleanupWithoutDisableLocked(connection, handle);
    if (err == NO_ERROR) {
        SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
        err = sensor ? sensor->activate(connection.get(), false) : status_t(BAD_VALUE);

    }
    if (err == NO_ERROR) {
        SensorRegistrationInfo &reg_info =
            mLastNSensorRegistrations.editItemAt(mNextSensorRegIndex);
        reg_info.mActivated = false;
        reg_info.mPackageName= connection->getPackageName();
        reg_info.mSensorHandle = handle;
        time_t rawtime = time(NULL);
        struct tm * timeinfo = localtime(&rawtime);
        reg_info.mHour = timeinfo->tm_hour;
        reg_info.mMin = timeinfo->tm_min;
        reg_info.mSec = timeinfo->tm_sec;
        mNextSensorRegIndex = (mNextSensorRegIndex + 1) % SENSOR_REGISTRATIONS_BUF_SIZE;
    }
    return err;
}

status_t SensorService::cleanupWithoutDisable(
        const sp<SensorEventConnection>& connection, int handle) {
    Mutex::Autolock _l(mLock);
    return cleanupWithoutDisableLocked(connection, handle);
}

status_t SensorService::cleanupWithoutDisableLocked(
        const sp<SensorEventConnection>& connection, int handle) {
    SensorRecord* rec = mActiveSensors.valueFor(handle);
    if (rec) {
        // see if this connection becomes inactive
        if (connection->removeSensor(handle)) {
            BatteryService::disableSensor(connection->getUid(), handle);
        }
        if (connection->hasAnySensor() == false) {
            connection->updateLooperRegistration(mLooper);
            mActiveConnections.remove(connection);
        }
        // see if this sensor becomes inactive
        if (rec->removeConnection(connection)) {
            mActiveSensors.removeItem(handle);
            mActiveVirtualSensors.removeItem(handle);
            delete rec;
        }
        return NO_ERROR;
    }
    return BAD_VALUE;
}

status_t SensorService::setEventRate(const sp<SensorEventConnection>& connection,
        int handle, nsecs_t ns, const String16& opPackageName) {
    if (mInitCheck != NO_ERROR)
        return mInitCheck;

    SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
    if (!sensor)
        return BAD_VALUE;

    if (!canAccessSensor(sensor->getSensor(), "Tried configuring", opPackageName)) {
        return BAD_VALUE;
    }

    if (ns < 0)
        return BAD_VALUE;

    nsecs_t minDelayNs = sensor->getSensor().getMinDelayNs();
    if (ns < minDelayNs) {
        ns = minDelayNs;
    }

    return sensor->setDelay(connection.get(), handle, ns);
}

status_t SensorService::flushSensor(const sp<SensorEventConnection>& connection,
        const String16& opPackageName) {
    if (mInitCheck != NO_ERROR) return mInitCheck;
    SensorDevice& dev(SensorDevice::getInstance());
    const int halVersion = dev.getHalDeviceVersion();
    status_t err(NO_ERROR);
    Mutex::Autolock _l(mLock);
    // Loop through all sensors for this connection and call flush on each of them.
    for (size_t i = 0; i < connection->mSensorInfo.size(); ++i) {
        const int handle = connection->mSensorInfo.keyAt(i);
        SensorInterface* sensor = getSensorInterfaceFromHandle(handle);
        if (sensor->getSensor().getReportingMode() == AREPORTING_MODE_ONE_SHOT) {
            ALOGE("flush called on a one-shot sensor");
            err = INVALID_OPERATION;
            continue;
        }
        if (halVersion <= SENSORS_DEVICE_API_VERSION_1_0 || isVirtualSensor(handle)) {
            // For older devices just increment pending flush count which will send a trivial
            // flush complete event.
            connection->incrementPendingFlushCount(handle);
        } else {
            if (!canAccessSensor(sensor->getSensor(), "Tried flushing", opPackageName)) {
                err = INVALID_OPERATION;
                continue;
            }
            status_t err_flush = sensor->flush(connection.get(), handle);
            if (err_flush == NO_ERROR) {
                SensorRecord* rec = mActiveSensors.valueFor(handle);
                if (rec != NULL) rec->addPendingFlushConnection(connection);
            }
            err = (err_flush != NO_ERROR) ? err_flush : err;
        }
    }
    return err;
}

bool SensorService::canAccessSensor(const Sensor& sensor, const char* operation,
        const String16& opPackageName) {
    const String8& requiredPermission = sensor.getRequiredPermission();

    if (requiredPermission.length() <= 0) {
        return true;
    }

    bool hasPermission = false;

    // Runtime permissions can't use the cache as they may change.
    if (sensor.isRequiredPermissionRuntime()) {
        hasPermission = checkPermission(String16(requiredPermission),
                IPCThreadState::self()->getCallingPid(), IPCThreadState::self()->getCallingUid());
    } else {
        hasPermission = PermissionCache::checkCallingPermission(String16(requiredPermission));
    }

    if (!hasPermission) {
        ALOGE("%s a sensor (%s) without holding its required permission: %s",
                operation, sensor.getName().string(), sensor.getRequiredPermission().string());
        return false;
    }

    const int32_t opCode = sensor.getRequiredAppOp();
    if (opCode >= 0) {
        AppOpsManager appOps;
        if (appOps.noteOp(opCode, IPCThreadState::self()->getCallingUid(), opPackageName)
                        != AppOpsManager::MODE_ALLOWED) {
            ALOGE("%s a sensor (%s) without enabled required app op: %d",
                    operation, sensor.getName().string(), opCode);
            return false;
        }
    }

    return true;
}

void SensorService::checkWakeLockState() {
    Mutex::Autolock _l(mLock);
    checkWakeLockStateLocked();
}

void SensorService::checkWakeLockStateLocked() {
    if (!mWakeLockAcquired) {
        return;
    }
    bool releaseLock = true;
    for (size_t i=0 ; i<mActiveConnections.size() ; i++) {
        sp<SensorEventConnection> connection(mActiveConnections[i].promote());
        if (connection != 0) {
            if (connection->needsWakeLock()) {
                releaseLock = false;
                break;
            }
        }
    }
    if (releaseLock) {
        setWakeLockAcquiredLocked(false);
    }
}

void SensorService::sendEventsFromCache(const sp<SensorEventConnection>& connection) {
    Mutex::Autolock _l(mLock);
    connection->writeToSocketFromCache();
    if (connection->needsWakeLock()) {
        setWakeLockAcquiredLocked(true);
    }
}

void SensorService::populateActiveConnections(
        SortedVector< sp<SensorEventConnection> >* activeConnections) {
    Mutex::Autolock _l(mLock);
    for (size_t i=0 ; i < mActiveConnections.size(); ++i) {
        sp<SensorEventConnection> connection(mActiveConnections[i].promote());
        if (connection != 0) {
            activeConnections->add(connection);
        }
    }
}

bool SensorService::isWhiteListedPackage(const String8& packageName) {
    return (packageName.contains(mWhiteListedPackage.string()));
}

int SensorService::getNumEventsForSensorType(int sensor_event_type) {
    if (sensor_event_type >= SENSOR_TYPE_DEVICE_PRIVATE_BASE) {
        return 16;
    }
    switch (sensor_event_type) {
        case SENSOR_TYPE_ROTATION_VECTOR:
        case SENSOR_TYPE_GEOMAGNETIC_ROTATION_VECTOR:
            return 5;

        case SENSOR_TYPE_MAGNETIC_FIELD_UNCALIBRATED:
        case SENSOR_TYPE_GYROSCOPE_UNCALIBRATED:
            return 6;

        case SENSOR_TYPE_GAME_ROTATION_VECTOR:
            return 4;

        case SENSOR_TYPE_SIGNIFICANT_MOTION:
        case SENSOR_TYPE_STEP_DETECTOR:
        case SENSOR_TYPE_STEP_COUNTER:
            return 1;

         default:
            return 3;
    }
}

}; // namespace android