Sensor Batching Bug fixes.

i) SensorService dropping events. Increase SOCKET_BUFFER_SIZE in BitTube ctor.
ii) Call flush before every activate.
iii) Emulate flush for older devices. Add a trivial flush complete event when flush is called.

Bug: 10641596
Change-Id: I30d0f3948e830457143f16e157b6ad81908687ce

services/sensorservice/SensorService.cpp

@@ -148,6 +148,21 @@ void SensorService::onFirstRef()
             // debugging sensor list
             mUserSensorListDebug = mSensorList;
 
+            mSocketBufferSize = SOCKET_BUFFER_SIZE_NON_BATCHED;
+            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';
+                sscanf(line, "%u", &mSocketBufferSize);
+                if (mSocketBufferSize > MAX_SOCKET_BUFFER_SIZE_BATCHED) {
+                    mSocketBufferSize = MAX_SOCKET_BUFFER_SIZE_BATCHED;
+                }
+            }
+            ALOGD("Max socket buffer size %u", mSocketBufferSize);
+            if (fp) {
+                fclose(fp);
+            }
+
             run("SensorService", PRIORITY_URGENT_DISPLAY);
             mInitCheck = NO_ERROR;
         }
@@ -255,7 +270,6 @@ status_t SensorService::dump(int fd, const Vector<String16>& args)
         SensorFusion::getInstance().dump(result);
         SensorDevice::getInstance().dump(result);
 
-        result.appendFormat("%d active connections\n", mActiveConnections.size());
         result.append("Active sensors:\n");
         for (size_t i=0 ; i<mActiveSensors.size() ; i++) {
             int handle = mActiveSensors.keyAt(i);
@@ -264,6 +278,17 @@ status_t SensorService::dump(int fd, const Vector<String16>& args)
                     handle,
                     mActiveSensors.valueAt(i)->getNumConnections());
         }
+
+        result.appendFormat("%u Max Socket Buffer size\n", mSocketBufferSize);
+        result.appendFormat("%d 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: %d \n", i);
+                connection->dump(result);
+            }
+        }
     }
     write(fd, result.string(), result.size());
     return NO_ERROR;
@@ -404,7 +429,6 @@ void SensorService::recordLastValue(
         sensors_event_t const * buffer, size_t count)
 {
     Mutex::Autolock _l(mLock);
-
     // record the last event for each sensor
     int32_t prev = buffer[0].sensor;
     for (size_t i=1 ; i<count ; i++) {
@@ -565,6 +589,15 @@ status_t SensorService::enable(const sp<SensorEventConnection>& connection,
 
     status_t err = sensor->batch(connection.get(), handle, reservedFlags, samplingPeriodNs,
                                  maxBatchReportLatencyNs);
+    if (err == NO_ERROR) {
+        connection->setFirstFlushPending(handle, true);
+        status_t err_flush = sensor->flush(connection.get(), handle);
+        // Flush may return error if the sensor is not activated or the underlying h/w sensor does
+        // not support flush.
+        if (err_flush != NO_ERROR) {
+            connection->setFirstFlushPending(handle, false);
+        }
+    }
 
     if (err == NO_ERROR) {
         ALOGD_IF(DEBUG_CONNECTIONS, "Calling activate on %d", handle);
@@ -649,6 +682,21 @@ status_t SensorService::flushSensor(const sp<SensorEventConnection>& connection,
    if (sensor == NULL) {
        return BAD_VALUE;
   }
+  SensorDevice& dev(SensorDevice::getInstance());
+
+  if (dev.getHalDeviceVersion() < SENSORS_DEVICE_API_VERSION_1_1) {
+      // For older devices increment pending flush count, which will send a trivial flush complete
+      // event for all the connections which are registered for updates on this sensor.
+      const SortedVector< wp<SensorEventConnection> > activeConnections(
+                                      getActiveConnections());
+      for (size_t i=0 ; i<activeConnections.size() ; i++) {
+          sp<SensorEventConnection> connection(activeConnections[i].promote());
+          if (connection != 0) {
+              connection->incrementPendingFlushCount(handle);
+          }
+      }
+      return NO_ERROR;
+  }
   return sensor->flush(connection.get(), handle);
 }
 // ---------------------------------------------------------------------------
@@ -683,8 +731,15 @@ bool SensorService::SensorRecord::removeConnection(
 
 SensorService::SensorEventConnection::SensorEventConnection(
         const sp<SensorService>& service, uid_t uid)
-    : mService(service), mChannel(new BitTube()), mUid(uid)
+    : mService(service), mUid(uid)
 {
+    const SensorDevice& device(SensorDevice::getInstance());
+    if (device.getHalDeviceVersion() >= SENSORS_DEVICE_API_VERSION_1_1) {
+        // Increase socket buffer size to 1MB for batching capabilities.
+        mChannel = new BitTube(service->mSocketBufferSize);
+    } else {
+        mChannel = new BitTube(SOCKET_BUFFER_SIZE_NON_BATCHED);
+    }
 }
 
 SensorService::SensorEventConnection::~SensorEventConnection()
@@ -697,10 +752,22 @@ void SensorService::SensorEventConnection::onFirstRef()
 {
 }
 
+void SensorService::SensorEventConnection::dump(String8& result) {
+    Mutex::Autolock _l(mConnectionLock);
+    for (size_t i = 0; i < mSensorInfo.size(); ++i) {
+        const FlushInfo& flushInfo = mSensorInfo.valueAt(i);
+        result.appendFormat("\t %s | status: %s | pending flush events %d\n",
+                            mService->getSensorName(mSensorInfo.keyAt(i)).string(),
+                            flushInfo.mFirstFlushPending ? "First flush pending" :
+                                                           "active",
+                            flushInfo.mPendingFlushEventsToSend);
+    }
+}
+
 bool SensorService::SensorEventConnection::addSensor(int32_t handle) {
     Mutex::Autolock _l(mConnectionLock);
-    if (mSensorInfo.indexOf(handle) < 0) {
+    if (mSensorInfo.indexOfKey(handle) < 0) {
-        mSensorInfo.add(handle);
+        mSensorInfo.add(handle, FlushInfo());
         return true;
     }
     return false;
@@ -708,7 +775,7 @@ bool SensorService::SensorEventConnection::addSensor(int32_t handle) {
 
 bool SensorService::SensorEventConnection::removeSensor(int32_t handle) {
     Mutex::Autolock _l(mConnectionLock);
-    if (mSensorInfo.remove(handle) >= 0) {
+    if (mSensorInfo.removeItem(handle) >= 0) {
         return true;
     }
     return false;
@@ -716,7 +783,7 @@ bool SensorService::SensorEventConnection::removeSensor(int32_t handle) {
 
 bool SensorService::SensorEventConnection::hasSensor(int32_t handle) const {
     Mutex::Autolock _l(mConnectionLock);
-    return mSensorInfo.indexOf(handle) >= 0;
+    return mSensorInfo.indexOfKey(handle) >= 0;
 }
 
 bool SensorService::SensorEventConnection::hasAnySensor() const {
@@ -724,12 +791,32 @@ bool SensorService::SensorEventConnection::hasAnySensor() const {
     return mSensorInfo.size() ? true : false;
 }
 
+void SensorService::SensorEventConnection::setFirstFlushPending(int32_t handle,
+                                bool value) {
+    Mutex::Autolock _l(mConnectionLock);
+    ssize_t index = mSensorInfo.indexOfKey(handle);
+    if (index >= 0) {
+        FlushInfo& flushInfo = mSensorInfo.editValueAt(index);
+        flushInfo.mFirstFlushPending = value;
+    }
+}
+
+void SensorService::SensorEventConnection::incrementPendingFlushCount(int32_t handle) {
+    Mutex::Autolock _l(mConnectionLock);
+    ssize_t index = mSensorInfo.indexOfKey(handle);
+    if (index >= 0) {
+        FlushInfo& flushInfo = mSensorInfo.editValueAt(index);
+        flushInfo.mPendingFlushEventsToSend++;
+    }
+}
+
 status_t SensorService::SensorEventConnection::sendEvents(
         sensors_event_t const* buffer, size_t numEvents,
         sensors_event_t* scratch)
 {
     // filter out events not for this connection
     size_t count = 0;
+
     if (scratch) {
         Mutex::Autolock _l(mConnectionLock);
         size_t i=0;
@@ -742,10 +829,18 @@ status_t SensorService::SensorEventConnection::sendEvents(
                 // filtered correctly. buffer[i].sensor is zero for meta_data events.
                 curr = buffer[i].meta_data.sensor;
             }
-            if (mSensorInfo.indexOf(curr) >= 0)  {
+            ssize_t index = mSensorInfo.indexOfKey(curr);
+            if (index >= 0 && mSensorInfo[index].mFirstFlushPending == true &&
+                buffer[i].type == SENSOR_TYPE_META_DATA) {
+                // This is the first flush before activate is called. Events can now be sent for
+                // this sensor on this connection.
+                ALOGD_IF(DEBUG_CONNECTIONS, "First flush event for sensor==%d ",
+                         buffer[i].meta_data.sensor);
+                mSensorInfo.editValueAt(index).mFirstFlushPending = false;
+            }
+            if (index >= 0 && mSensorInfo[index].mFirstFlushPending == false)  {
                 do {
-                    scratch[count] = buffer[i];
+                    scratch[count++] = buffer[i++];
-                    ++count; ++i;
                 } while ((i<numEvents) && ((buffer[i].sensor == curr) ||
                          (buffer[i].type == SENSOR_TYPE_META_DATA  &&
                           buffer[i].meta_data.sensor == curr)));
@@ -758,19 +853,62 @@ status_t SensorService::SensorEventConnection::sendEvents(
         count = numEvents;
     }
 
+    // Send pending flush events (if any) before sending events from the cache.
+    {
+        ASensorEvent flushCompleteEvent;
+        flushCompleteEvent.type = SENSOR_TYPE_META_DATA;
+        flushCompleteEvent.sensor = 0;
+        Mutex::Autolock _l(mConnectionLock);
+        // Loop through all the sensors for this connection and check if there are any pending
+        // flush complete events to be sent.
+        for (size_t i = 0; i < mSensorInfo.size(); ++i) {
+            FlushInfo& flushInfo = mSensorInfo.editValueAt(i);
+            while (flushInfo.mPendingFlushEventsToSend > 0) {
+                flushCompleteEvent.meta_data.sensor = mSensorInfo.keyAt(i);
+                ssize_t size = SensorEventQueue::write(mChannel, &flushCompleteEvent, 1);
+                if (size < 0) {
+                    // ALOGW("dropping %d events on the floor", count);
+                    countFlushCompleteEvents(scratch, count);
+                    return size;
+                }
+                ALOGD_IF(DEBUG_CONNECTIONS, "sent dropped flush complete event==%d ",
+                         flushCompleteEvent.meta_data.sensor);
+                flushInfo.mPendingFlushEventsToSend--;
+            }
+        }
+    }
+
     // NOTE: ASensorEvent and sensors_event_t are the same type
     ssize_t size = SensorEventQueue::write(mChannel,
             reinterpret_cast<ASensorEvent const*>(scratch), count);
     if (size == -EAGAIN) {
         // the destination doesn't accept events anymore, it's probably
         // full. For now, we just drop the events on the floor.
-        //ALOGW("dropping %d events on the floor", count);
+        // ALOGW("dropping %d events on the floor", count);
+        countFlushCompleteEvents(scratch, count);
         return size;
     }
 
     return size < 0 ? status_t(size) : status_t(NO_ERROR);
 }
 
+void SensorService::SensorEventConnection::countFlushCompleteEvents(
+                sensors_event_t* scratch, const int numEventsDropped) {
+    ALOGD_IF(DEBUG_CONNECTIONS, "dropping %d events ", numEventsDropped);
+    Mutex::Autolock _l(mConnectionLock);
+    // Count flushComplete events in the events that are about to the dropped. These will be sent
+    // separately before the next batch of events.
+    for (int j = 0; j < numEventsDropped; ++j) {
+        if (scratch[j].type == SENSOR_TYPE_META_DATA) {
+            FlushInfo& flushInfo = mSensorInfo.editValueFor(scratch[j].meta_data.sensor);
+            flushInfo.mPendingFlushEventsToSend++;
+            ALOGD_IF(DEBUG_CONNECTIONS, "increment pendingFlushCount %d",
+                     flushInfo.mPendingFlushEventsToSend);
+        }
+    }
+    return;
+}
+
 sp<BitTube> SensorService::SensorEventConnection::getSensorChannel() const
 {
     return mChannel;
@@ -799,6 +937,7 @@ status_t SensorService::SensorEventConnection::setEventRate(
 status_t  SensorService::SensorEventConnection::flushSensor(int handle) {
     return mService->flushSensor(this, handle);
 }
+
 // ---------------------------------------------------------------------------
 }; // namespace android
 

services/sensorservice/SensorService.h

@@ -38,6 +38,9 @@
 // ---------------------------------------------------------------------------
 
 #define DEBUG_CONNECTIONS   false
+// Max size is 1 MB which is enough to accept a batch of about 10k events.
+#define MAX_SOCKET_BUFFER_SIZE_BATCHED 1024 * 1024
+#define SOCKET_BUFFER_SIZE_NON_BATCHED 4 * 1024
 
 struct sensors_poll_device_t;
 struct sensors_module_t;
@@ -77,14 +80,27 @@ class SensorService :
                                        nsecs_t maxBatchReportLatencyNs, int reservedFlags);
         virtual status_t setEventRate(int handle, nsecs_t samplingPeriodNs);
         virtual status_t flushSensor(int handle);
+        // 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 countFlushCompleteEvents(sensors_event_t* scratch, int numEventsDropped);
 
         sp<SensorService> const mService;
-        sp<BitTube> const mChannel;
+        sp<BitTube> mChannel;
         uid_t mUid;
         mutable Mutex mConnectionLock;
 
-        // protected by SensorService::mLock
+        struct FlushInfo {
-        SortedVector<int> mSensorInfo;
+            // 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;
 
     public:
         SensorEventConnection(const sp<SensorService>& service, uid_t uid);
@@ -95,6 +111,9 @@ class SensorService :
         bool hasAnySensor() const;
         bool addSensor(int32_t handle);
         bool removeSensor(int32_t handle);
+        void setFirstFlushPending(int32_t handle, bool value);
+        void incrementPendingFlushCount(int32_t handle);
+        void dump(String8& result);
 
         uid_t getUid() const { return mUid; }
     };
@@ -130,6 +149,7 @@ class SensorService :
     DefaultKeyedVector<int, SensorInterface*> mSensorMap;
     Vector<SensorInterface *> mVirtualSensorList;
     status_t mInitCheck;
+    size_t mSocketBufferSize;
 
     // protected by mLock
     mutable Mutex mLock;