Make states atomic and update comments
Bug: 166800618
Test: atest VtsHalBiometricsFingerprintTargetTest
Change-Id: I52ee6e8b6ddefdc972e803bcd81819f04061a570
diff --git a/biometrics/fingerprint/aidl/default/Session.cpp b/biometrics/fingerprint/aidl/default/Session.cpp
index f6a0314..8db3205 100644
--- a/biometrics/fingerprint/aidl/default/Session.cpp
+++ b/biometrics/fingerprint/aidl/default/Session.cpp
@@ -46,7 +46,7 @@
void Session::enterStateOrCrash(int cookie, SessionState state) {
CHECK(mScheduledState == state);
- mCurrentState = mScheduledState;
+ mCurrentState = state;
mScheduledState = SessionState::IDLING;
mCb->onStateChanged(cookie, mCurrentState);
}
diff --git a/biometrics/fingerprint/aidl/default/include/Session.h b/biometrics/fingerprint/aidl/default/include/Session.h
index adda831..b5e55b3 100644
--- a/biometrics/fingerprint/aidl/default/include/Session.h
+++ b/biometrics/fingerprint/aidl/default/include/Session.h
@@ -82,13 +82,28 @@
// by calling ISessionCallback#onStateChanged.
void enterIdling(int cookie);
+ // The sensor and user IDs for which this session was created.
int32_t mSensorId;
int32_t mUserId;
+
+ // Callback for talking to the framework. This callback must only be called from non-binder
+ // threads to prevent nested binder calls and consequently a binder thread exhaustion.
+ // Practically, it means that this callback should always be called from the worker thread.
std::shared_ptr<ISessionCallback> mCb;
+
+ // Module that communicates to the actual fingerprint hardware, keystore, TEE, etc. In real
+ // life such modules typically consume a lot of memory and are slow to initialize. This is here
+ // to showcase how such a module can be used within a Session without incurring the high
+ // initialization costs every time a Session is constructed.
FakeFingerprintEngine* mEngine;
+
+ // Worker thread that allows to schedule tasks for asynchronous execution.
WorkerThread* mWorker;
- SessionState mScheduledState;
- SessionState mCurrentState;
+
+ // Simple representation of the session's state machine. These are atomic because they can be
+ // modified from both the main and the worker threads.
+ std::atomic<SessionState> mScheduledState;
+ std::atomic<SessionState> mCurrentState;
};
} // namespace aidl::android::hardware::biometrics::fingerprint