Resample sensor events for non-direct connections.
The resampler is to guarantee that apps cannot obtain more than 200 Hz
when their sampling rates are being throttled.
Test: atest CtsSensorTestCases CtsSensorRatePermissionTestCases
Bug: 136069189
Change-Id: I2e7d522f71382a517c7e6708136ac55917486fa5
diff --git a/services/sensorservice/SensorEventConnection.cpp b/services/sensorservice/SensorEventConnection.cpp
index 46fc34b..a2e7f23 100644
--- a/services/sensorservice/SensorEventConnection.cpp
+++ b/services/sensorservice/SensorEventConnection.cpp
@@ -287,6 +287,29 @@
}
}
+// TODO(b/179649922): A better algorithm to guarantee that capped connections will get a sampling
+// rate close to 200 Hz. With the current algorithm, apps might be punished unfairly: E.g.,two apps
+// make requests to the sensor service at the same time, one is not capped and uses 250 Hz, and one
+//is capped, the capped connection will only get 125 Hz.
+void SensorService::SensorEventConnection::addSensorEventsToBuffer(bool shouldResample,
+ const sensors_event_t& sensorEvent, sensors_event_t* buffer, int* index) {
+ if (!shouldResample || !mService->isSensorInCappedSet(sensorEvent.type)) {
+ buffer[(*index)++] = sensorEvent;
+ } else {
+ int64_t lastTimestamp = -1;
+ auto entry = mSensorLastTimestamp.find(sensorEvent.sensor);
+ if (entry != mSensorLastTimestamp.end()) {
+ lastTimestamp = entry->second;
+ }
+ // Allow 10% headroom here because the clocks are not perfect.
+ if (lastTimestamp == -1 || sensorEvent.timestamp - lastTimestamp
+ >= 0.9 * SENSOR_SERVICE_CAPPED_SAMPLING_PERIOD_NS) {
+ mSensorLastTimestamp[sensorEvent.sensor] = sensorEvent.timestamp;
+ buffer[(*index)++] = sensorEvent;
+ }
+ }
+}
+
status_t SensorService::SensorEventConnection::sendEvents(
sensors_event_t const* buffer, size_t numEvents,
sensors_event_t* scratch,
@@ -295,6 +318,8 @@
std::unique_ptr<sensors_event_t[]> sanitizedBuffer;
+ bool shouldResample = mService->isMicSensorPrivacyEnabledForUid(mUid) ||
+ mIsRateCappedBasedOnPermission;
int count = 0;
Mutex::Autolock _l(mConnectionLock);
if (scratch) {
@@ -348,7 +373,7 @@
// Regular sensor event, just copy it to the scratch buffer after checking
// the AppOp.
if (hasSensorAccess() && noteOpIfRequired(buffer[i])) {
- scratch[count++] = buffer[i];
+ addSensorEventsToBuffer(shouldResample, buffer[i], scratch, &count);
}
}
i++;
@@ -358,12 +383,13 @@
buffer[i].meta_data.sensor == sensor_handle)));
}
} else {
+ sanitizedBuffer.reset(new sensors_event_t[numEvents]);
+ scratch = sanitizedBuffer.get();
if (hasSensorAccess()) {
- scratch = const_cast<sensors_event_t *>(buffer);
- count = numEvents;
+ for (size_t i = 0; i < numEvents; i++) {
+ addSensorEventsToBuffer(shouldResample, buffer[i], scratch, &count);
+ }
} else {
- sanitizedBuffer.reset(new sensors_event_t[numEvents]);
- scratch = sanitizedBuffer.get();
for (size_t i = 0; i < numEvents; i++) {
if (buffer[i].type == SENSOR_TYPE_META_DATA) {
scratch[count++] = buffer[i++];