Prevent stale event from being delivered to client
When an on-change sensor is activated, the most recent event is
delivered to the client. A previous change attempted to ensure that
any event that was generated prior to deactivating the sensor would
not be delivered to a client upon activating the sensor. This was to
ensure that an event that was generated in the past, and thus stale,
would not be received by clients. The patch was successful in most
cases, but it did not address the case of a client disabling a sensor
and still maintained a reference to the SensorEventConnection through
the NDK or VNDK.
This patch marks the recent event as stale whenever a sensor
transitions from deactivated to activated. This ensures that the
recent event is always marked as stale, regardless of how the API to
the Sensor Service is utilized.
Bug: 116283108
Test: Verified that stale on-change event is not delivered to a
client.
Change-Id: Iee9a84ec57f5345fb14f0262b492ad100d05c7bb
diff --git a/services/sensorservice/SensorService.cpp b/services/sensorservice/SensorService.cpp
index cbdd473..0269990 100644
--- a/services/sensorservice/SensorService.cpp
+++ b/services/sensorservice/SensorService.cpp
@@ -1381,15 +1381,6 @@
ALOGD_IF(DEBUG_CONNECTIONS, "... and it was the last connection");
mActiveSensors.removeItemsAt(i, 1);
mActiveVirtualSensors.erase(handle);
-
- // If this is the last connection, then mark the RecentEventLogger as stale. This is
- // critical for on-change events since the previous event is sent to a client if the
- // sensor is already active. If two clients request the sensor at the same time, one
- // of the clients would receive a stale event.
- auto logger = mRecentEvent.find(handle);
- if (logger != mRecentEvent.end()) {
- logger->second->setLastEventStale();
- }
delete rec;
size--;
} else {
@@ -1444,6 +1435,20 @@
if (sensor->isVirtual()) {
mActiveVirtualSensors.emplace(handle);
}
+
+ // There was no SensorRecord for this sensor which means it was previously disabled. Mark
+ // the recent event as stale to ensure that the previous event is not sent to a client. This
+ // ensures on-change events that were generated during a previous sensor activation are not
+ // erroneously sent to newly connected clients, especially if a second client registers for
+ // an on-change sensor before the first client receives the updated event. Once an updated
+ // event is received, the recent events will be marked as current, and any new clients will
+ // immediately receive the most recent event.
+ if (sensor->getSensor().getReportingMode() == AREPORTING_MODE_ON_CHANGE) {
+ auto logger = mRecentEvent.find(handle);
+ if (logger != mRecentEvent.end()) {
+ logger->second->setLastEventStale();
+ }
+ }
} else {
if (rec->addConnection(connection)) {
// this sensor is already activated, but we are adding a connection that uses it.