SensorService.cpp revision 4342fdf14ffb792a36c1de25ad14b745df628da2 
1/*
2 * Copyright (C) 2010 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdint.h>
18#include <math.h>
19#include <sys/types.h>
20
21#include <cutils/properties.h>
22
23#include <utils/SortedVector.h>
24#include <utils/KeyedVector.h>
25#include <utils/threads.h>
26#include <utils/Atomic.h>
27#include <utils/Errors.h>
28#include <utils/RefBase.h>
29#include <utils/Singleton.h>
30#include <utils/String16.h>
31
32#include <binder/BinderService.h>
33#include <binder/IServiceManager.h>
34#include <binder/PermissionCache.h>
35
36#include <gui/ISensorServer.h>
37#include <gui/ISensorEventConnection.h>
38#include <gui/SensorEventQueue.h>
39
40#include <hardware/sensors.h>
41#include <hardware_legacy/power.h>
42
43#include "BatteryService.h"
44#include "CorrectedGyroSensor.h"
45#include "GravitySensor.h"
46#include "LinearAccelerationSensor.h"
47#include "OrientationSensor.h"
48#include "RotationVectorSensor.h"
49#include "SensorFusion.h"
50#include "SensorService.h"
51
52namespace android {
53// ---------------------------------------------------------------------------
54
55/*
56 * Notes:
57 *
58 * - what about a gyro-corrected magnetic-field sensor?
59 * - run mag sensor from time to time to force calibration
60 * - gravity sensor length is wrong (=> drift in linear-acc sensor)
61 *
62 */
63
64const char* SensorService::WAKE_LOCK_NAME = "SensorService";
65
66SensorService::SensorService()
67    : mInitCheck(NO_INIT)
68{
69}
70
71void SensorService::onFirstRef()
72{
73    ALOGD("nuSensorService starting...");
74
75    SensorDevice& dev(SensorDevice::getInstance());
76
77    if (dev.initCheck() == NO_ERROR) {
78        sensor_t const* list;
79        ssize_t count = dev.getSensorList(&list);
80        if (count > 0) {
81            ssize_t orientationIndex = -1;
82            bool hasGyro = false;
83            uint32_t virtualSensorsNeeds =
84                    (1<<SENSOR_TYPE_GRAVITY) |
85                    (1<<SENSOR_TYPE_LINEAR_ACCELERATION) |
86                    (1<<SENSOR_TYPE_ROTATION_VECTOR);
87
88            mLastEventSeen.setCapacity(count);
89            for (ssize_t i=0 ; i<count ; i++) {
90                registerSensor( new HardwareSensor(list[i]) );
91                switch (list[i].type) {
92                    case SENSOR_TYPE_ORIENTATION:
93                        orientationIndex = i;
94                        break;
95                    case SENSOR_TYPE_GYROSCOPE:
96                        hasGyro = true;
97                        break;
98                    case SENSOR_TYPE_GRAVITY:
99                    case SENSOR_TYPE_LINEAR_ACCELERATION:
100                    case SENSOR_TYPE_ROTATION_VECTOR:
101                        virtualSensorsNeeds &= ~(1<<list[i].type);
102                        break;
103                }
104            }
105
106            // it's safe to instantiate the SensorFusion object here
107            // (it wants to be instantiated after h/w sensors have been
108            // registered)
109            const SensorFusion& fusion(SensorFusion::getInstance());
110
111            if (hasGyro) {
112                // Always instantiate Android's virtual sensors. Since they are
113                // instantiated behind sensors from the HAL, they won't
114                // interfere with applications, unless they looks specifically
115                // for them (by name).
116
117                registerVirtualSensor( new RotationVectorSensor() );
118                registerVirtualSensor( new GravitySensor(list, count) );
119                registerVirtualSensor( new LinearAccelerationSensor(list, count) );
120
121                // these are optional
122                registerVirtualSensor( new OrientationSensor() );
123                registerVirtualSensor( new CorrectedGyroSensor(list, count) );
124            }
125
126            // build the sensor list returned to users
127            mUserSensorList = mSensorList;
128
129            if (hasGyro) {
130                // virtual debugging sensors are not added to mUserSensorList
131                registerVirtualSensor( new GyroDriftSensor() );
132            }
133
134            if (hasGyro &&
135                    (virtualSensorsNeeds & (1<<SENSOR_TYPE_ROTATION_VECTOR))) {
136                // if we have the fancy sensor fusion, and it's not provided by the
137                // HAL, use our own (fused) orientation sensor by removing the
138                // HAL supplied one form the user list.
139                if (orientationIndex >= 0) {
140                    mUserSensorList.removeItemsAt(orientationIndex);
141                }
142            }
143
144            // debugging sensor list
145            for (size_t i=0 ; i<mSensorList.size() ; i++) {
146                switch (mSensorList[i].getType()) {
147                    case SENSOR_TYPE_GRAVITY:
148                    case SENSOR_TYPE_LINEAR_ACCELERATION:
149                    case SENSOR_TYPE_ROTATION_VECTOR:
150                        if (strstr(mSensorList[i].getVendor().string(), "Google")) {
151                            mUserSensorListDebug.add(mSensorList[i]);
152                        }
153                        break;
154                    default:
155                        mUserSensorListDebug.add(mSensorList[i]);
156                        break;
157                }
158            }
159
160            run("SensorService", PRIORITY_URGENT_DISPLAY);
161            mInitCheck = NO_ERROR;
162        }
163    }
164}
165
166void SensorService::registerSensor(SensorInterface* s)
167{
168    sensors_event_t event;
169    memset(&event, 0, sizeof(event));
170
171    const Sensor sensor(s->getSensor());
172    // add to the sensor list (returned to clients)
173    mSensorList.add(sensor);
174    // add to our handle->SensorInterface mapping
175    mSensorMap.add(sensor.getHandle(), s);
176    // create an entry in the mLastEventSeen array
177    mLastEventSeen.add(sensor.getHandle(), event);
178}
179
180void SensorService::registerVirtualSensor(SensorInterface* s)
181{
182    registerSensor(s);
183    mVirtualSensorList.add( s );
184}
185
186SensorService::~SensorService()
187{
188    for (size_t i=0 ; i<mSensorMap.size() ; i++)
189        delete mSensorMap.valueAt(i);
190}
191
192static const String16 sDump("android.permission.DUMP");
193
194status_t SensorService::dump(int fd, const Vector<String16>& args)
195{
196    const size_t SIZE = 1024;
197    char buffer[SIZE];
198    String8 result;
199    if (!PermissionCache::checkCallingPermission(sDump)) {
200        snprintf(buffer, SIZE, "Permission Denial: "
201                "can't dump SurfaceFlinger from pid=%d, uid=%d\n",
202                IPCThreadState::self()->getCallingPid(),
203                IPCThreadState::self()->getCallingUid());
204        result.append(buffer);
205    } else {
206        Mutex::Autolock _l(mLock);
207        snprintf(buffer, SIZE, "Sensor List:\n");
208        result.append(buffer);
209        for (size_t i=0 ; i<mSensorList.size() ; i++) {
210            const Sensor& s(mSensorList[i]);
211            const sensors_event_t& e(mLastEventSeen.valueFor(s.getHandle()));
212            snprintf(buffer, SIZE,
213                    "%-48s| %-32s | 0x%08x | maxRate=%7.2fHz | "
214                    "last=<%5.1f,%5.1f,%5.1f>\n",
215                    s.getName().string(),
216                    s.getVendor().string(),
217                    s.getHandle(),
218                    s.getMinDelay() ? (1000000.0f / s.getMinDelay()) : 0.0f,
219                    e.data[0], e.data[1], e.data[2]);
220            result.append(buffer);
221        }
222        SensorFusion::getInstance().dump(result, buffer, SIZE);
223        SensorDevice::getInstance().dump(result, buffer, SIZE);
224
225        snprintf(buffer, SIZE, "%d active connections\n",
226                mActiveConnections.size());
227        result.append(buffer);
228        snprintf(buffer, SIZE, "Active sensors:\n");
229        result.append(buffer);
230        for (size_t i=0 ; i<mActiveSensors.size() ; i++) {
231            int handle = mActiveSensors.keyAt(i);
232            snprintf(buffer, SIZE, "%s (handle=0x%08x, connections=%d)\n",
233                    getSensorName(handle).string(),
234                    handle,
235                    mActiveSensors.valueAt(i)->getNumConnections());
236            result.append(buffer);
237        }
238    }
239    write(fd, result.string(), result.size());
240    return NO_ERROR;
241}
242
243void SensorService::cleanupAutoDisabledSensor(const sp<SensorEventConnection>& connection,
244        sensors_event_t const* buffer, const int count) {
245    for (int i=0 ; i<count ; i++) {
246        int handle = buffer[i].sensor;
247        if (getSensorType(handle) == SENSOR_TYPE_SIGNIFICANT_MOTION) {
248            if (connection->hasSensor(handle)) {
249                cleanupWithoutDisable(connection, handle);
250            }
251        }
252    }
253}
254
255bool SensorService::threadLoop()
256{
257    ALOGD("nuSensorService thread starting...");
258
259    const size_t numEventMax = 16;
260    const size_t minBufferSize = numEventMax + numEventMax * mVirtualSensorList.size();
261    sensors_event_t buffer[minBufferSize];
262    sensors_event_t scratch[minBufferSize];
263    SensorDevice& device(SensorDevice::getInstance());
264    const size_t vcount = mVirtualSensorList.size();
265
266    ssize_t count;
267    bool wakeLockAcquired = false;
268    const int halVersion = device.getHalDeviceVersion();
269    do {
270        count = device.poll(buffer, numEventMax);
271        if (count<0) {
272            ALOGE("sensor poll failed (%s)", strerror(-count));
273            break;
274        }
275
276        // Poll has returned. Hold a wakelock.
277        // Todo(): add a flag to the sensors definitions to indicate
278        // the sensors which can wake up the AP
279        for (int i = 0; i < count; i++) {
280            if (getSensorType(buffer[i].sensor) == SENSOR_TYPE_SIGNIFICANT_MOTION) {
281                 acquire_wake_lock(PARTIAL_WAKE_LOCK, WAKE_LOCK_NAME);
282                 wakeLockAcquired = true;
283                 break;
284            }
285        }
286
287        recordLastValue(buffer, count);
288
289        // handle virtual sensors
290        if (count && vcount) {
291            sensors_event_t const * const event = buffer;
292            const DefaultKeyedVector<int, SensorInterface*> virtualSensors(
293                    getActiveVirtualSensors());
294            const size_t activeVirtualSensorCount = virtualSensors.size();
295            if (activeVirtualSensorCount) {
296                size_t k = 0;
297                SensorFusion& fusion(SensorFusion::getInstance());
298                if (fusion.isEnabled()) {
299                    for (size_t i=0 ; i<size_t(count) ; i++) {
300                        fusion.process(event[i]);
301                    }
302                }
303                for (size_t i=0 ; i<size_t(count) && k<minBufferSize ; i++) {
304                    for (size_t j=0 ; j<activeVirtualSensorCount ; j++) {
305                        if (count + k >= minBufferSize) {
306                            ALOGE("buffer too small to hold all events: "
307                                    "count=%u, k=%u, size=%u",
308                                    count, k, minBufferSize);
309                            break;
310                        }
311                        sensors_event_t out;
312                        SensorInterface* si = virtualSensors.valueAt(j);
313                        if (si->process(&out, event[i])) {
314                            buffer[count + k] = out;
315                            k++;
316                        }
317                    }
318                }
319                if (k) {
320                    // record the last synthesized values
321                    recordLastValue(&buffer[count], k);
322                    count += k;
323                    // sort the buffer by time-stamps
324                    sortEventBuffer(buffer, count);
325                }
326            }
327        }
328
329        // handle backward compatibility for RotationVector sensor
330        if (halVersion < SENSORS_DEVICE_API_VERSION_1_0) {
331            for (int i = 0; i < count; i++) {
332                if (getSensorType(buffer[i].sensor) == SENSOR_TYPE_ROTATION_VECTOR) {
333                    // All the 4 components of the quaternion should be available
334                    // No heading accuracy. Set it to -1
335                    buffer[i].data[4] = -1;
336                }
337            }
338        }
339
340        // send our events to clients...
341        const SortedVector< wp<SensorEventConnection> > activeConnections(
342                getActiveConnections());
343        size_t numConnections = activeConnections.size();
344        for (size_t i=0 ; i<numConnections ; i++) {
345            sp<SensorEventConnection> connection(
346                    activeConnections[i].promote());
347            if (connection != 0) {
348                connection->sendEvents(buffer, count, scratch);
349                // Some sensors need to be auto disabled after the trigger
350                cleanupAutoDisabledSensor(connection, buffer, count);
351            }
352        }
353
354        // We have read the data, upper layers should hold the wakelock.
355        if (wakeLockAcquired) release_wake_lock(WAKE_LOCK_NAME);
356
357    } while (count >= 0 || Thread::exitPending());
358
359    ALOGW("Exiting SensorService::threadLoop => aborting...");
360    abort();
361    return false;
362}
363
364void SensorService::recordLastValue(
365        sensors_event_t const * buffer, size_t count)
366{
367    Mutex::Autolock _l(mLock);
368
369    // record the last event for each sensor
370    int32_t prev = buffer[0].sensor;
371    for (size_t i=1 ; i<count ; i++) {
372        // record the last event of each sensor type in this buffer
373        int32_t curr = buffer[i].sensor;
374        if (curr != prev) {
375            mLastEventSeen.editValueFor(prev) = buffer[i-1];
376            prev = curr;
377        }
378    }
379    mLastEventSeen.editValueFor(prev) = buffer[count-1];
380}
381
382void SensorService::sortEventBuffer(sensors_event_t* buffer, size_t count)
383{
384    struct compar {
385        static int cmp(void const* lhs, void const* rhs) {
386            sensors_event_t const* l = static_cast<sensors_event_t const*>(lhs);
387            sensors_event_t const* r = static_cast<sensors_event_t const*>(rhs);
388            return l->timestamp - r->timestamp;
389        }
390    };
391    qsort(buffer, count, sizeof(sensors_event_t), compar::cmp);
392}
393
394SortedVector< wp<SensorService::SensorEventConnection> >
395SensorService::getActiveConnections() const
396{
397    Mutex::Autolock _l(mLock);
398    return mActiveConnections;
399}
400
401DefaultKeyedVector<int, SensorInterface*>
402SensorService::getActiveVirtualSensors() const
403{
404    Mutex::Autolock _l(mLock);
405    return mActiveVirtualSensors;
406}
407
408String8 SensorService::getSensorName(int handle) const {
409    size_t count = mUserSensorList.size();
410    for (size_t i=0 ; i<count ; i++) {
411        const Sensor& sensor(mUserSensorList[i]);
412        if (sensor.getHandle() == handle) {
413            return sensor.getName();
414        }
415    }
416    String8 result("unknown");
417    return result;
418}
419
420int SensorService::getSensorType(int handle) const {
421    size_t count = mUserSensorList.size();
422    for (size_t i=0 ; i<count ; i++) {
423        const Sensor& sensor(mUserSensorList[i]);
424        if (sensor.getHandle() == handle) {
425            return sensor.getType();
426        }
427    }
428    return -1;
429}
430
431
432Vector<Sensor> SensorService::getSensorList()
433{
434    char value[PROPERTY_VALUE_MAX];
435    property_get("debug.sensors", value, "0");
436    if (atoi(value)) {
437        return mUserSensorListDebug;
438    }
439    return mUserSensorList;
440}
441
442sp<ISensorEventConnection> SensorService::createSensorEventConnection()
443{
444    uid_t uid = IPCThreadState::self()->getCallingUid();
445    sp<SensorEventConnection> result(new SensorEventConnection(this, uid));
446    return result;
447}
448
449void SensorService::cleanupConnection(SensorEventConnection* c)
450{
451    Mutex::Autolock _l(mLock);
452    const wp<SensorEventConnection> connection(c);
453    size_t size = mActiveSensors.size();
454    ALOGD_IF(DEBUG_CONNECTIONS, "%d active sensors", size);
455    for (size_t i=0 ; i<size ; ) {
456        int handle = mActiveSensors.keyAt(i);
457        if (c->hasSensor(handle)) {
458            ALOGD_IF(DEBUG_CONNECTIONS, "%i: disabling handle=0x%08x", i, handle);
459            SensorInterface* sensor = mSensorMap.valueFor( handle );
460            ALOGE_IF(!sensor, "mSensorMap[handle=0x%08x] is null!", handle);
461            if (sensor) {
462                sensor->activate(c, false);
463            }
464        }
465        SensorRecord* rec = mActiveSensors.valueAt(i);
466        ALOGE_IF(!rec, "mActiveSensors[%d] is null (handle=0x%08x)!", i, handle);
467        ALOGD_IF(DEBUG_CONNECTIONS,
468                "removing connection %p for sensor[%d].handle=0x%08x",
469                c, i, handle);
470
471        if (rec && rec->removeConnection(connection)) {
472            ALOGD_IF(DEBUG_CONNECTIONS, "... and it was the last connection");
473            mActiveSensors.removeItemsAt(i, 1);
474            mActiveVirtualSensors.removeItem(handle);
475            delete rec;
476            size--;
477        } else {
478            i++;
479        }
480    }
481    mActiveConnections.remove(connection);
482    BatteryService::cleanup(c->getUid());
483}
484
485status_t SensorService::enable(const sp<SensorEventConnection>& connection,
486        int handle)
487{
488    if (mInitCheck != NO_ERROR)
489        return mInitCheck;
490
491    Mutex::Autolock _l(mLock);
492    SensorInterface* sensor = mSensorMap.valueFor(handle);
493    SensorRecord* rec = mActiveSensors.valueFor(handle);
494    if (rec == 0) {
495        rec = new SensorRecord(connection);
496        mActiveSensors.add(handle, rec);
497        if (sensor->isVirtual()) {
498            mActiveVirtualSensors.add(handle, sensor);
499        }
500    } else {
501        if (rec->addConnection(connection)) {
502            // this sensor is already activated, but we are adding a
503            // connection that uses it. Immediately send down the last
504            // known value of the requested sensor if it's not a
505            // "continuous" sensor.
506            if (sensor->getSensor().getMinDelay() == 0) {
507                sensors_event_t scratch;
508                sensors_event_t& event(mLastEventSeen.editValueFor(handle));
509                if (event.version == sizeof(sensors_event_t)) {
510                    connection->sendEvents(&event, 1);
511                }
512            }
513        }
514    }
515
516    if (connection->addSensor(handle)) {
517        BatteryService::enableSensor(connection->getUid(), handle);
518        // the sensor was added (which means it wasn't already there)
519        // so, see if this connection becomes active
520        if (mActiveConnections.indexOf(connection) < 0) {
521            mActiveConnections.add(connection);
522        }
523    } else {
524        ALOGW("sensor %08x already enabled in connection %p (ignoring)",
525            handle, connection.get());
526    }
527
528
529    // we are setup, now enable the sensor.
530    status_t err = sensor ? sensor->activate(connection.get(), true) : status_t(BAD_VALUE);
531
532    if (err != NO_ERROR) {
533        // enable has failed, reset our state.
534        cleanupWithoutDisable(connection, handle);
535    }
536    return err;
537}
538
539status_t SensorService::disable(const sp<SensorEventConnection>& connection,
540        int handle)
541{
542    if (mInitCheck != NO_ERROR)
543        return mInitCheck;
544
545    status_t err = cleanupWithoutDisable(connection, handle);
546    if (err == NO_ERROR) {
547        SensorInterface* sensor = mSensorMap.valueFor(handle);
548        err = sensor ? sensor->activate(connection.get(), false) : status_t(BAD_VALUE);
549    }
550    return err;
551}
552
553status_t SensorService::cleanupWithoutDisable(const sp<SensorEventConnection>& connection,
554        int handle) {
555    Mutex::Autolock _l(mLock);
556    SensorRecord* rec = mActiveSensors.valueFor(handle);
557    if (rec) {
558        // see if this connection becomes inactive
559        if (connection->removeSensor(handle)) {
560            BatteryService::disableSensor(connection->getUid(), handle);
561        }
562        if (connection->hasAnySensor() == false) {
563            mActiveConnections.remove(connection);
564        }
565        // see if this sensor becomes inactive
566        if (rec->removeConnection(connection)) {
567            mActiveSensors.removeItem(handle);
568            mActiveVirtualSensors.removeItem(handle);
569            delete rec;
570        }
571        return NO_ERROR;
572    }
573    return BAD_VALUE;
574}
575
576status_t SensorService::setEventRate(const sp<SensorEventConnection>& connection,
577        int handle, nsecs_t ns)
578{
579    if (mInitCheck != NO_ERROR)
580        return mInitCheck;
581
582    SensorInterface* sensor = mSensorMap.valueFor(handle);
583    if (!sensor)
584        return BAD_VALUE;
585
586    if (ns < 0)
587        return BAD_VALUE;
588
589    nsecs_t minDelayNs = sensor->getSensor().getMinDelayNs();
590    if (ns < minDelayNs) {
591        ns = minDelayNs;
592    }
593
594    if (ns < MINIMUM_EVENTS_PERIOD)
595        ns = MINIMUM_EVENTS_PERIOD;
596
597    return sensor->setDelay(connection.get(), handle, ns);
598}
599
600// ---------------------------------------------------------------------------
601
602SensorService::SensorRecord::SensorRecord(
603        const sp<SensorEventConnection>& connection)
604{
605    mConnections.add(connection);
606}
607
608bool SensorService::SensorRecord::addConnection(
609        const sp<SensorEventConnection>& connection)
610{
611    if (mConnections.indexOf(connection) < 0) {
612        mConnections.add(connection);
613        return true;
614    }
615    return false;
616}
617
618bool SensorService::SensorRecord::removeConnection(
619        const wp<SensorEventConnection>& connection)
620{
621    ssize_t index = mConnections.indexOf(connection);
622    if (index >= 0) {
623        mConnections.removeItemsAt(index, 1);
624    }
625    return mConnections.size() ? false : true;
626}
627
628// ---------------------------------------------------------------------------
629
630SensorService::SensorEventConnection::SensorEventConnection(
631        const sp<SensorService>& service, uid_t uid)
632    : mService(service), mChannel(new BitTube()), mUid(uid)
633{
634}
635
636SensorService::SensorEventConnection::~SensorEventConnection()
637{
638    ALOGD_IF(DEBUG_CONNECTIONS, "~SensorEventConnection(%p)", this);
639    mService->cleanupConnection(this);
640}
641
642void SensorService::SensorEventConnection::onFirstRef()
643{
644}
645
646bool SensorService::SensorEventConnection::addSensor(int32_t handle) {
647    Mutex::Autolock _l(mConnectionLock);
648    if (mSensorInfo.indexOf(handle) < 0) {
649        mSensorInfo.add(handle);
650        return true;
651    }
652    return false;
653}
654
655bool SensorService::SensorEventConnection::removeSensor(int32_t handle) {
656    Mutex::Autolock _l(mConnectionLock);
657    if (mSensorInfo.remove(handle) >= 0) {
658        return true;
659    }
660    return false;
661}
662
663bool SensorService::SensorEventConnection::hasSensor(int32_t handle) const {
664    Mutex::Autolock _l(mConnectionLock);
665    return mSensorInfo.indexOf(handle) >= 0;
666}
667
668bool SensorService::SensorEventConnection::hasAnySensor() const {
669    Mutex::Autolock _l(mConnectionLock);
670    return mSensorInfo.size() ? true : false;
671}
672
673status_t SensorService::SensorEventConnection::sendEvents(
674        sensors_event_t const* buffer, size_t numEvents,
675        sensors_event_t* scratch)
676{
677    // filter out events not for this connection
678    size_t count = 0;
679    if (scratch) {
680        Mutex::Autolock _l(mConnectionLock);
681        size_t i=0;
682        while (i<numEvents) {
683            const int32_t curr = buffer[i].sensor;
684            if (mSensorInfo.indexOf(curr) >= 0) {
685                do {
686                    scratch[count++] = buffer[i++];
687                } while ((i<numEvents) && (buffer[i].sensor == curr));
688            } else {
689                i++;
690            }
691        }
692    } else {
693        scratch = const_cast<sensors_event_t *>(buffer);
694        count = numEvents;
695    }
696
697    // NOTE: ASensorEvent and sensors_event_t are the same type
698    ssize_t size = SensorEventQueue::write(mChannel,
699            reinterpret_cast<ASensorEvent const*>(scratch), count);
700    if (size == -EAGAIN) {
701        // the destination doesn't accept events anymore, it's probably
702        // full. For now, we just drop the events on the floor.
703        //ALOGW("dropping %d events on the floor", count);
704        return size;
705    }
706
707    return size < 0 ? status_t(size) : status_t(NO_ERROR);
708}
709
710sp<BitTube> SensorService::SensorEventConnection::getSensorChannel() const
711{
712    return mChannel;
713}
714
715status_t SensorService::SensorEventConnection::enableDisable(
716        int handle, bool enabled)
717{
718    status_t err;
719    if (enabled) {
720        err = mService->enable(this, handle);
721    } else {
722        err = mService->disable(this, handle);
723    }
724    return err;
725}
726
727status_t SensorService::SensorEventConnection::setEventRate(
728        int handle, nsecs_t ns)
729{
730    return mService->setEventRate(this, handle, ns);
731}
732
733// ---------------------------------------------------------------------------
734}; // namespace android
735
736