Merge "Implement fake STHAL" into udc-dev

media/aidl/android/media/soundtrigger_middleware/ISoundTriggerMiddlewareService.aidl

@@ -13,11 +13,13 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
+
 package android.media.soundtrigger_middleware;
 
 import android.media.permission.Identity;
-import android.media.soundtrigger_middleware.ISoundTriggerModule;
 import android.media.soundtrigger_middleware.ISoundTriggerCallback;
+import android.media.soundtrigger_middleware.ISoundTriggerInjection;
+import android.media.soundtrigger_middleware.ISoundTriggerModule;
 import android.media.soundtrigger_middleware.SoundTriggerModuleDescriptor;
 
 /**
@@ -86,4 +88,12 @@ interface ISoundTriggerMiddlewareService {
                                           in Identity middlemanIdentity,
                                           in Identity originatorIdentity,
                                           ISoundTriggerCallback callback);
+
+    /**
+     * Attach an injection interface interface to the ST mock HAL.
+     * See {@link ISoundTriggerInjection} for injection details.
+     * If another client attaches, this session will be pre-empted.
+     */
+    void attachFakeHalInjection(ISoundTriggerInjection injection);
+
 }

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/FakeHalFactory.java

@@ -0,0 +1,96 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.soundtrigger_middleware;
+
+import android.media.soundtrigger_middleware.IInjectGlobalEvent;
+import android.media.soundtrigger_middleware.ISoundTriggerInjection;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.util.Slog;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.server.soundtrigger_middleware.FakeSoundTriggerHal.ExecutorHolder;
+
+
+/**
+ * Alternate HAL factory which constructs {@link FakeSoundTriggerHal} with addition hooks to
+ * observe framework events.
+ */
+class FakeHalFactory implements HalFactory {
+
+    private static final String TAG = "FakeHalFactory";
+    private final ISoundTriggerInjection mInjection;
+
+    FakeHalFactory(ISoundTriggerInjection injection) {
+        mInjection = injection;
+    }
+
+    /**
+     * We override the methods below at the {@link ISoundTriggerHal} level, because
+     * they do not represent real HAL events, rather, they are framework exclusive.
+     * So, we intercept them here and report them to the injection interface.
+     */
+    @Override
+    public ISoundTriggerHal create() {
+        final FakeSoundTriggerHal hal = new FakeSoundTriggerHal(mInjection);
+        final IInjectGlobalEvent session = hal.getGlobalEventInjection();
+        // The fake hal is a ST3 HAL implementation.
+        final ISoundTriggerHal wrapper = new SoundTriggerHw3Compat(hal,
+                /* reboot runnable */ () -> {
+                    try {
+                        session.triggerRestart();
+                    }
+                    catch (RemoteException e) {
+                        Slog.wtf(TAG, "Unexpected RemoteException from same process");
+                    }
+                }) {
+            @Override
+            public void detach() {
+                ExecutorHolder.INJECTION_EXECUTOR.execute(() -> {
+                    try {
+                        mInjection.onFrameworkDetached(session);
+                    } catch (RemoteException e) {
+                        Slog.wtf(TAG, "Unexpected RemoteException from same process");
+                    }
+                });
+            }
+
+            @Override
+            public void clientAttached(IBinder token) {
+                ExecutorHolder.INJECTION_EXECUTOR.execute(() -> {
+                    try {
+                        mInjection.onClientAttached(token, session);
+                    } catch (RemoteException e) {
+                        Slog.wtf(TAG, "Unexpected RemoteException from same process");
+                    }
+                });
+            }
+
+            @Override
+            public void clientDetached(IBinder token) {
+                ExecutorHolder.INJECTION_EXECUTOR.execute(() -> {
+                    try {
+                        mInjection.onClientDetached(token);
+                    } catch (RemoteException e) {
+                        Slog.wtf(TAG, "Unexpected RemoteException from same process");
+                    }
+                });
+            }
+        };
+        return wrapper;
+    }
+}

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/FakeSoundTriggerHal.java

@@ -0,0 +1,712 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.soundtrigger_middleware;
+
+import android.annotation.Nullable;
+import android.hardware.soundtrigger3.ISoundTriggerHw;
+import android.hardware.soundtrigger3.ISoundTriggerHwCallback;
+import android.hardware.soundtrigger3.ISoundTriggerHwGlobalCallback;
+import android.media.soundtrigger.ModelParameter;
+import android.media.soundtrigger.ModelParameterRange;
+import android.media.soundtrigger.PhraseRecognitionEvent;
+import android.media.soundtrigger.PhraseRecognitionExtra;
+import android.media.soundtrigger.PhraseSoundModel;
+import android.media.soundtrigger.Properties;
+import android.media.soundtrigger.RecognitionConfig;
+import android.media.soundtrigger.RecognitionEvent;
+import android.media.soundtrigger.RecognitionMode;
+import android.media.soundtrigger.RecognitionStatus;
+import android.media.soundtrigger.SoundModel;
+import android.media.soundtrigger.SoundModelType;
+import android.media.soundtrigger.Status;
+import android.media.soundtrigger_middleware.IAcknowledgeEvent;
+import android.media.soundtrigger_middleware.IInjectGlobalEvent;
+import android.media.soundtrigger_middleware.IInjectModelEvent;
+import android.media.soundtrigger_middleware.IInjectRecognitionEvent;
+import android.media.soundtrigger_middleware.ISoundTriggerInjection;
+import android.os.DeadObjectException;
+import android.os.IBinder;
+import android.os.Parcel;
+import android.os.RemoteException;
+import android.os.ServiceSpecificException;
+import android.util.Slog;
+
+import com.android.internal.annotations.GuardedBy;
+import com.android.internal.util.FunctionalUtils;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.NoSuchElementException;
+import java.util.concurrent.Executor;
+import java.util.concurrent.Executors;
+
+
+/**
+ * Fake HAL implementation, which offers injection via
+ * {@link ISoundTriggerInjection}.
+ * Since this is a test interface, upon unexpected operations from the framework,
+ * we will abort.
+ */
+public class FakeSoundTriggerHal extends ISoundTriggerHw.Stub {
+    private static final String TAG = "FakeSoundTriggerHal";
+
+    // Fake values for valid model param range
+    private static final int THRESHOLD_MIN = -10;
+    private static final int THRESHOLD_MAX = 10;
+
+    // Logically const
+    private final Object mLock = new Object();
+    private final Properties mProperties;
+
+    // These cannot be injected, since we rely on:
+    // 1) Serialization
+    // 2) Running in a different thread
+    // And there is no Executor interface with these requirements
+    // These factories clean up the pools on finalizer.
+    // Package private so the FakeHalFactory can dispatch
+    static class ExecutorHolder {
+        static final Executor CALLBACK_EXECUTOR =
+                Executors.newSingleThreadExecutor();
+        static final Executor INJECTION_EXECUTOR =
+                Executors.newSingleThreadExecutor();
+    }
+
+    // Dispatcher interface for callbacks, using the executors above
+    private final InjectionDispatcher mInjectionDispatcher;
+
+    // Created on construction, passed back to clients.
+    private final IInjectGlobalEvent.Stub mGlobalEventSession;
+
+    @GuardedBy("mLock")
+    private IBinder.DeathRecipient mDeathRecipient;
+
+    @GuardedBy("mLock")
+    private GlobalCallbackDispatcher mGlobalCallbackDispatcher = null;
+
+    @GuardedBy("mLock")
+    private boolean mIsResourceContended = false;
+    @GuardedBy("mLock")
+    private final Map<Integer, ModelSession> mModelSessionMap = new HashMap<>();
+
+    // Current version of the STHAL relies on integer model session ids.
+    // Generate them monotonically starting at 101
+    @GuardedBy("mLock")
+    private int mModelKeyCounter = 101;
+
+    @GuardedBy("mLock")
+    private boolean mIsDead = false;
+
+    private class ModelSession extends IInjectModelEvent.Stub {
+        // Logically const
+        private final boolean mIsKeyphrase;
+        private final CallbackDispatcher mCallbackDispatcher;
+        private final int mModelHandle;
+
+        // Model parameter
+        @GuardedBy("FakeSoundTriggerHal.this.mLock")
+        private int mThreshold = 0;
+
+        // Mutable
+        @GuardedBy("FakeSoundTriggerHal.this.mLock")
+        private boolean mIsUnloaded = false; // Latch
+
+        // Only a single recognition session is able to be active for a model
+        // session at any given time. Null if no recognition is active.
+        @GuardedBy("FakeSoundTriggerHal.this.mLock")
+        @Nullable private RecognitionSession mRecognitionSession;
+
+        private ModelSession(int modelHandle, CallbackDispatcher callbackDispatcher,
+                boolean isKeyphrase) {
+            mModelHandle = modelHandle;
+            mCallbackDispatcher = callbackDispatcher;
+            mIsKeyphrase = isKeyphrase;
+        }
+
+        private RecognitionSession startRecognitionForModel() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                mRecognitionSession = new RecognitionSession();
+                return mRecognitionSession;
+            }
+        }
+
+        private RecognitionSession stopRecognitionForModel() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                RecognitionSession session = mRecognitionSession;
+                mRecognitionSession = null;
+                return session;
+            }
+        }
+
+        private void forceRecognitionForModel() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                if (mIsKeyphrase) {
+                    PhraseRecognitionEvent phraseEvent =
+                            createDefaultKeyphraseEvent(RecognitionStatus.FORCED);
+                    mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                            cb.phraseRecognitionCallback(mModelHandle, phraseEvent));
+                } else {
+                    RecognitionEvent event = createDefaultEvent(RecognitionStatus.FORCED);
+                    mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                            cb.recognitionCallback(mModelHandle, event));
+                }
+            }
+        }
+
+        private void setThresholdFactor(int value) {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                mThreshold = value;
+            }
+        }
+
+        private int getThresholdFactor() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                return mThreshold;
+            }
+        }
+
+        private boolean getIsUnloaded() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                return mIsUnloaded;
+            }
+        }
+
+        private RecognitionSession getRecogSession() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                return mRecognitionSession;
+            }
+        }
+
+
+        /** oneway **/
+        @Override
+        public void triggerUnloadModel() {
+            synchronized (FakeSoundTriggerHal.this.mLock) {
+                if (mIsDead || mIsUnloaded) return;
+                if (mRecognitionSession != null) {
+                    // Must abort model before triggering unload
+                    mRecognitionSession.triggerAbortRecognition();
+                }
+                // Invalidate the model session
+                mIsUnloaded = true;
+                mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                        cb.modelUnloaded(mModelHandle));
+                // Don't notify the injection that an unload has occurred, since it is what
+                // triggered the unload
+
+                // Notify if we could have denied a previous model due to contention
+                if (getNumLoadedModelsLocked() == (mProperties.maxSoundModels - 1)
+                        && !mIsResourceContended) {
+                    mGlobalCallbackDispatcher.wrap((ISoundTriggerHwGlobalCallback cb) ->
+                            cb.onResourcesAvailable());
+                }
+            }
+        }
+
+        private class RecognitionSession extends IInjectRecognitionEvent.Stub {
+
+            @Override
+            /** oneway **/
+            public void triggerRecognitionEvent(byte[] data,
+                    @Nullable PhraseRecognitionExtra[] phraseExtras) {
+                synchronized (FakeSoundTriggerHal.this.mLock) {
+                    // Check if our session has already been invalidated
+                    if (mIsDead || mRecognitionSession != this) return;
+                    // Invalidate the recognition session
+                    mRecognitionSession = null;
+                    // Trigger the callback.
+                    if (mIsKeyphrase) {
+                        PhraseRecognitionEvent phraseEvent =
+                                createDefaultKeyphraseEvent(RecognitionStatus.SUCCESS);
+                        phraseEvent.common.data = data;
+                        if (phraseExtras != null) phraseEvent.phraseExtras = phraseExtras;
+                        mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                                cb.phraseRecognitionCallback(mModelHandle, phraseEvent));
+                    } else {
+                        RecognitionEvent event = createDefaultEvent(RecognitionStatus.SUCCESS);
+                        event.data = data;
+                        mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                                cb.recognitionCallback(mModelHandle, event));
+                    }
+                }
+            }
+
+            @Override
+            /** oneway **/
+            public void triggerAbortRecognition() {
+                synchronized (FakeSoundTriggerHal.this.mLock) {
+                    if (mIsDead || mRecognitionSession != this) return;
+                    // Clear the session state
+                    mRecognitionSession = null;
+                    // Trigger the callback.
+                    if (mIsKeyphrase) {
+                        mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                                cb.phraseRecognitionCallback(mModelHandle,
+                                    createDefaultKeyphraseEvent(RecognitionStatus.ABORTED)));
+                    } else {
+                        mCallbackDispatcher.wrap((ISoundTriggerHwCallback cb) ->
+                                cb.recognitionCallback(mModelHandle,
+                                    createDefaultEvent(RecognitionStatus.ABORTED)));
+                    }
+                }
+            }
+        }
+    }
+
+    // Since this is always constructed, it needs to be cheap to create.
+    public FakeSoundTriggerHal(ISoundTriggerInjection injection) {
+        mProperties = createDefaultProperties();
+        mInjectionDispatcher = new InjectionDispatcher(injection);
+        mGlobalCallbackDispatcher = null; // If this NPEs before registration, we want to abort.
+        // Implement the IInjectGlobalEvent IInterface.
+        // Since we can't extend multiple IInterface from the same object, instantiate an instance
+        // for our clients.
+        mGlobalEventSession = new IInjectGlobalEvent.Stub() {
+            /**
+             * Overrides IInjectGlobalEvent method.
+             * Simulate a HAL process restart. This method is not included in regular HAL interface,
+             * since the entire process is restarted by sending a signal.
+             * Since we run in-proc, we must offer an explicit restart method.
+             * oneway
+             */
+            @Override
+            public void triggerRestart() throws RemoteException {
+                synchronized (FakeSoundTriggerHal.this.mLock) {
+                    if (mIsDead) throw new DeadObjectException();
+                    mIsDead = true;
+                    mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                            cb.onRestarted(this));
+                    mModelSessionMap.clear();
+                    if (mDeathRecipient != null) {
+                        final DeathRecipient deathRecipient = mDeathRecipient;
+                        ExecutorHolder.CALLBACK_EXECUTOR.execute(() -> {
+                            try {
+                                deathRecipient.binderDied(FakeSoundTriggerHal.this.asBinder());
+                            } catch (Throwable e) {
+                                // We don't expect RemoteException at the moment since we run
+                                // in the same process
+                                Slog.wtf(TAG, "Callback dispatch threw", e);
+                            }
+                        });
+                    }
+                }
+            }
+
+            /**
+             * Overrides IInjectGlobalEvent method.
+             * oneway
+             */
+            @Override
+            public void setResourceContention(boolean isResourcesContended,
+                        IAcknowledgeEvent callback) throws RemoteException {
+                synchronized (FakeSoundTriggerHal.this.mLock) {
+                    if (mIsDead) throw new DeadObjectException();
+                    mIsResourceContended = isResourcesContended;
+                    // Introducing contention is the only injection which can't be
+                    // observed by the ST client.
+                    mInjectionDispatcher.wrap((ISoundTriggerInjection unused) ->
+                            callback.eventReceived());
+                    if (!mIsResourceContended) {
+                        mGlobalCallbackDispatcher.wrap((ISoundTriggerHwGlobalCallback cb) ->
+                                    cb.onResourcesAvailable());
+                    }
+                }
+            }
+        };
+        // Register the global event injection interface
+        mInjectionDispatcher.wrap((ISoundTriggerInjection cb)
+                -> cb.registerGlobalEventInjection(mGlobalEventSession));
+    }
+
+    /**
+     * Get the {@link IInjectGlobalEvent} associated with this instance of the STHAL.
+     * Used as a session token, valid until restarted.
+     */
+    public IInjectGlobalEvent getGlobalEventInjection() {
+        return mGlobalEventSession;
+    }
+
+    // TODO(b/274467228) we can remove the next three methods when this HAL is moved out-of-proc,
+    // so process restart at death notification is appropriately handled by the binder.
+    @Override
+    public void linkToDeath(IBinder.DeathRecipient recipient, int flags) {
+        synchronized (mLock) {
+            if (mDeathRecipient != null) {
+                Slog.wtf(TAG, "Received two death recipients concurrently");
+            }
+            mDeathRecipient = recipient;
+        }
+    }
+
+    @Override
+    public boolean unlinkToDeath(IBinder.DeathRecipient recipient, int flags) {
+        synchronized (mLock) {
+            if (mIsDead) return false;
+            if (mDeathRecipient != recipient) {
+                throw new NoSuchElementException();
+            }
+            mDeathRecipient = null;
+            return true;
+        }
+    }
+
+    // STHAL method overrides to follow
+    @Override
+    public Properties getProperties() throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            Parcel parcel = Parcel.obtain();
+            try {
+                mProperties.writeToParcel(parcel, 0 /* flags */);
+                parcel.setDataPosition(0);
+                return Properties.CREATOR.createFromParcel(parcel);
+            } finally {
+                parcel.recycle();
+            }
+        }
+    }
+
+    @Override
+    public void registerGlobalCallback(
+            ISoundTriggerHwGlobalCallback callback) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            mGlobalCallbackDispatcher = new GlobalCallbackDispatcher(callback);
+        }
+    }
+
+    @Override
+    public int loadSoundModel(SoundModel soundModel,
+            ISoundTriggerHwCallback callback) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            if (mIsResourceContended || getNumLoadedModelsLocked() == mProperties.maxSoundModels) {
+                throw new ServiceSpecificException(Status.RESOURCE_CONTENTION);
+            }
+            int key = mModelKeyCounter++;
+            ModelSession session = new ModelSession(key, new CallbackDispatcher(callback), false);
+
+            mModelSessionMap.put(key, session);
+
+            mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                    cb.onSoundModelLoaded(soundModel, null, session, mGlobalEventSession));
+            return key;
+        }
+    }
+
+    @Override
+    public int loadPhraseSoundModel(PhraseSoundModel soundModel,
+            ISoundTriggerHwCallback callback) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            if (mIsResourceContended || getNumLoadedModelsLocked() == mProperties.maxSoundModels) {
+                throw new ServiceSpecificException(Status.RESOURCE_CONTENTION);
+            }
+
+            int key = mModelKeyCounter++;
+            ModelSession session = new ModelSession(key, new CallbackDispatcher(callback), true);
+
+            mModelSessionMap.put(key, session);
+
+            mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                    cb.onSoundModelLoaded(soundModel.common, soundModel.phrases, session,
+                        mGlobalEventSession));
+            return key;
+        }
+    }
+
+    @Override
+    public void unloadSoundModel(int modelHandle) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to unload model which was never loaded");
+            }
+
+            if (session.getRecogSession() != null) {
+                Slog.wtf(TAG, "Session unloaded before recog stopped!");
+            }
+
+            // Session is stale
+            if (session.getIsUnloaded()) return;
+            mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                    cb.onSoundModelUnloaded(session));
+
+            // Notify if we could have denied a previous model due to contention
+            if (getNumLoadedModelsLocked() == (mProperties.maxSoundModels - 1)
+                    && !mIsResourceContended) {
+                mGlobalCallbackDispatcher.wrap((ISoundTriggerHwGlobalCallback cb) ->
+                        cb.onResourcesAvailable());
+            }
+
+        }
+    }
+
+    @Override
+    public void startRecognition(int modelHandle, int deviceHandle, int ioHandle,
+            RecognitionConfig config) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to start recognition with invalid handle");
+            }
+
+            if (session.getIsUnloaded()) {
+                // TODO(b/274470274) this is a deficiency in the existing HAL API, there is no way
+                // to handle this race gracefully
+                throw new ServiceSpecificException(Status.RESOURCE_CONTENTION);
+            }
+            ModelSession.RecognitionSession recogSession = session.startRecognitionForModel();
+
+            // TODO(b/274470571) appropriately translate ioHandle to session handle
+            mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                    cb.onRecognitionStarted(-1, config, recogSession, session));
+        }
+    }
+
+    @Override
+    public void stopRecognition(int modelHandle) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to stop recognition with invalid handle");
+            }
+            ModelSession.RecognitionSession recogSession = session.stopRecognitionForModel();
+            mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                    cb.onRecognitionStopped(recogSession));
+        }
+    }
+
+    @Override
+    public void forceRecognitionEvent(int modelHandle) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to force recognition with invalid handle");
+            }
+
+            // TODO(b/274470274) this is a deficiency in the existing HAL API, we could always
+            // get a force request for an already stopped model. The only thing to do is
+            // drop such a request.
+            if (session.getRecogSession() == null) return;
+            session.forceRecognitionForModel();
+        }
+    }
+
+    // TODO(b/274470274) this is a deficiency in the existing HAL API, we could always
+    // get model param API requests after model unload.
+    // For now, succeed anyway to maintain fidelity to existing HALs.
+    @Override
+    public @Nullable ModelParameterRange queryParameter(int modelHandle,
+            /** ModelParameter **/ int modelParam) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to get param with invalid handle");
+            }
+        }
+        if (modelParam == ModelParameter.THRESHOLD_FACTOR) {
+            ModelParameterRange range = new ModelParameterRange();
+            range.minInclusive = THRESHOLD_MIN;
+            range.maxInclusive = THRESHOLD_MAX;
+            return range;
+        } else {
+            return null;
+        }
+    }
+
+    @Override
+    public int getParameter(int modelHandle,
+            /** ModelParameter **/ int modelParam) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to get param with invalid handle");
+            }
+            if (modelParam != ModelParameter.THRESHOLD_FACTOR) {
+                throw new IllegalArgumentException();
+            }
+            return session.getThresholdFactor();
+        }
+    }
+
+    @Override
+    public void setParameter(int modelHandle,
+            /** ModelParameter **/ int modelParam, int value) throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+            ModelSession session = mModelSessionMap.get(modelHandle);
+            if (session == null) {
+                Slog.wtf(TAG, "Attempted to get param with invalid handle");
+            }
+            if ((modelParam == ModelParameter.THRESHOLD_FACTOR)
+                    || (value >= THRESHOLD_MIN && value <= THRESHOLD_MAX)) {
+                session.setThresholdFactor(value);
+            } else {
+                throw new IllegalArgumentException();
+            }
+            mInjectionDispatcher.wrap((ISoundTriggerInjection cb) ->
+                    cb.onParamSet(modelParam, value, session));
+        }
+    }
+
+    @Override
+    public int getInterfaceVersion() throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+        }
+        return super.VERSION;
+    }
+
+    @Override
+    public String getInterfaceHash() throws RemoteException {
+        synchronized (mLock) {
+            if (mIsDead) throw new DeadObjectException();
+        }
+        return super.HASH;
+    }
+
+    // Helpers to follow.
+    @GuardedBy("mLock")
+    private int getNumLoadedModelsLocked() {
+        int numModels = 0;
+        for (ModelSession session : mModelSessionMap.values()) {
+            if (!session.getIsUnloaded()) {
+                numModels++;
+            }
+        }
+        return numModels;
+    }
+
+    private static Properties createDefaultProperties() {
+        Properties properties = new Properties();
+        properties.implementor = "android";
+        properties.description = "AOSP fake STHAL";
+        properties.version = 1;
+        properties.uuid = "00000001-0002-0003-0004-deadbeefabcd";
+        properties.supportedModelArch = ISoundTriggerInjection.FAKE_HAL_ARCH;
+        properties.maxSoundModels = 8;
+        properties.maxKeyPhrases = 2;
+        properties.maxUsers = 2;
+        properties.recognitionModes = RecognitionMode.VOICE_TRIGGER
+                | RecognitionMode.GENERIC_TRIGGER;
+        properties.captureTransition = true;
+        // This is actually not respected, since there is no real AudioRecord
+        properties.maxBufferMs = 5000;
+        properties.concurrentCapture = true;
+        properties.triggerInEvent = false;
+        properties.powerConsumptionMw = 0;
+        properties.audioCapabilities = 0;
+        return properties;
+    }
+
+    private static RecognitionEvent createDefaultEvent(
+            /** RecognitionStatus **/ int status) {
+        RecognitionEvent event = new RecognitionEvent();
+        // Overwrite the event appropriately.
+        event.status = status;
+        event.type = SoundModelType.GENERIC;
+        // TODO(b/274466981) make this configurable.
+        // For now, some plausible defaults
+        event.captureAvailable = true;
+        event.captureDelayMs = 50;
+        event.capturePreambleMs = 200;
+        event.triggerInData = false;
+        event.audioConfig = null; // Nullable within AIDL
+        event.data = new byte[0];
+        // We don't support recognition restart for now
+        event.recognitionStillActive = false;
+        return event;
+    }
+
+    private static PhraseRecognitionEvent createDefaultKeyphraseEvent(
+            /**RecognitionStatus **/ int status) {
+        RecognitionEvent event = createDefaultEvent(status);
+        event.type = SoundModelType.KEYPHRASE;
+        PhraseRecognitionEvent phraseEvent = new PhraseRecognitionEvent();
+        phraseEvent.common = event;
+        phraseEvent.phraseExtras = new PhraseRecognitionExtra[0];
+        return phraseEvent;
+    }
+
+    // Helper classes to dispatch oneway calls to the appropriate callback interfaces to follow.
+    private static class CallbackDispatcher {
+
+        private CallbackDispatcher(ISoundTriggerHwCallback callback) {
+            mCallback = callback;
+        }
+
+        private void wrap(FunctionalUtils.ThrowingConsumer<ISoundTriggerHwCallback> command) {
+            ExecutorHolder.CALLBACK_EXECUTOR.execute(() -> {
+                try {
+                    command.accept(mCallback);
+                } catch (Throwable e) {
+                    Slog.wtf(TAG, "Callback dispatch threw", e);
+                }
+            });
+        }
+
+        private final ISoundTriggerHwCallback mCallback;
+    }
+
+    private static class GlobalCallbackDispatcher {
+
+        private GlobalCallbackDispatcher(ISoundTriggerHwGlobalCallback callback) {
+            mCallback = callback;
+        }
+
+        private void wrap(FunctionalUtils.ThrowingConsumer<ISoundTriggerHwGlobalCallback> command) {
+            ExecutorHolder.CALLBACK_EXECUTOR.execute(() -> {
+                try {
+                    command.accept(mCallback);
+                } catch (Throwable e) {
+                    // We don't expect RemoteException at the moment since we run
+                    // in the same process
+                    Slog.wtf(TAG, "Callback dispatch threw", e);
+                }
+            });
+        }
+
+        private final ISoundTriggerHwGlobalCallback mCallback;
+    }
+
+    private static class InjectionDispatcher {
+
+        private InjectionDispatcher(ISoundTriggerInjection injection) {
+            mInjection = injection;
+        }
+
+        private void wrap(FunctionalUtils.ThrowingConsumer<ISoundTriggerInjection> command) {
+            ExecutorHolder.INJECTION_EXECUTOR.execute(() -> {
+                try {
+                    command.accept(mInjection);
+                } catch (Throwable e) {
+                    // We don't expect RemoteException at the moment since we run
+                    // in the same process
+                    Slog.wtf(TAG, "Callback dispatch threw", e);
+                }
+            });
+        }
+
+        private final ISoundTriggerInjection mInjection;
+    }
+}

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/ISoundTriggerHal.java

@@ -140,6 +140,22 @@ interface ISoundTriggerHal {
      */
     void flushCallbacks();
 
+    /**
+     * Used only for testing purposes. Called when a client attaches to the framework.
+     * Transmitting this event to the fake STHAL allows observation of this event, which is
+     * normally consumed by the framework, and is not communicated to the STHAL.
+     * @param token - A unique binder token associated with this session.
+     */
+    void clientAttached(IBinder token);
+
+    /**
+     * Used only for testing purposes. Called when a client detached from the framework.
+     * Transmitting this event to the fake STHAL allows observation of this event, which is
+     * normally consumed by the framework, and is not communicated to the STHAL.
+     * @param token - The same token passed to the corresponding {@link clientAttached(IBinder)}.
+     */
+    void clientDetached(IBinder token);
+
     /**
      * Kill and restart the HAL instance. This is typically a last resort for error recovery and may
      * result in other related services being killed.

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerHalConcurrentCaptureHandler.java

@@ -283,6 +283,16 @@ public class SoundTriggerHalConcurrentCaptureHandler implements ISoundTriggerHal
         mCallbackThread.flush();
     }
 
+    @Override
+    public void clientAttached(IBinder binder) {
+        mDelegate.clientAttached(binder);
+    }
+
+    @Override
+    public void clientDetached(IBinder binder) {
+        mDelegate.clientDetached(binder);
+    }
+
     /**
      * This is a thread for asynchronous delivery of callback events, having the following features:
      * <ul>

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerHalEnforcer.java

@@ -211,6 +211,16 @@ public class SoundTriggerHalEnforcer implements ISoundTriggerHal {
         mUnderlying.flushCallbacks();
     }
 
+    @Override
+    public void clientAttached(IBinder binder) {
+        mUnderlying.clientAttached(binder);
+    }
+
+    @Override
+    public void clientDetached(IBinder binder) {
+        mUnderlying.clientDetached(binder);
+    }
+
     private RuntimeException handleException(RuntimeException e) {
         if (e instanceof RecoverableException) {
             throw e;

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerHalMaxModelLimiter.java

@@ -165,4 +165,14 @@ public class SoundTriggerHalMaxModelLimiter implements ISoundTriggerHal {
     public void flushCallbacks() {
         mDelegate.flushCallbacks();
     }
+
+    @Override
+    public void clientAttached(IBinder binder) {
+        mDelegate.clientAttached(binder);
+    }
+
+    @Override
+    public void clientDetached(IBinder binder) {
+        mDelegate.clientDetached(binder);
+    }
 }

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerHalWatchdog.java

@@ -142,6 +142,16 @@ public class SoundTriggerHalWatchdog implements ISoundTriggerHal {
         mUnderlying.flushCallbacks();
     }
 
+    @Override
+    public void clientAttached(IBinder binder) {
+        mUnderlying.clientAttached(binder);
+    }
+
+    @Override
+    public void clientDetached(IBinder binder) {
+        mUnderlying.clientDetached(binder);
+    }
+
     @Override
     public void reboot() {
         mUnderlying.reboot();

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerHw2Compat.java

@@ -414,6 +414,16 @@ final class SoundTriggerHw2Compat implements ISoundTriggerHal {
         // This is a no-op. Only implemented for decorators.
     }
 
+    @Override
+    public void clientAttached(IBinder binder) {
+        // This is a no-op. Only implemented for decorators.
+    }
+
+    @Override
+    public void clientDetached(IBinder binder) {
+        // This is a no-op. Only implemented for decorators.
+    }
+
     private Properties getProperties_2_0()
             throws RemoteException {
         AtomicInteger retval = new AtomicInteger(-1);

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerHw3Compat.java

@@ -185,6 +185,16 @@ public class SoundTriggerHw3Compat implements ISoundTriggerHal {
         // No-op.
     }
 
+    @Override
+    public void clientAttached(IBinder binder) {
+        // No-op. This method is for test purposes, and is intercepted above.
+    }
+
+    @Override
+    public void clientDetached(IBinder binder) {
+        // No-op. This method is for test purposes, and is intercepted above.
+    }
+
     @Override
     public void reboot() {
         mRebootRunnable.run();

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerInjection.java

@@ -0,0 +1,236 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.soundtrigger_middleware;
+
+import android.annotation.Nullable;
+import android.media.soundtrigger.Phrase;
+import android.media.soundtrigger.RecognitionConfig;
+import android.media.soundtrigger.SoundModel;
+import android.media.soundtrigger_middleware.IInjectGlobalEvent;
+import android.media.soundtrigger_middleware.IInjectModelEvent;
+import android.media.soundtrigger_middleware.IInjectRecognitionEvent;
+import android.media.soundtrigger_middleware.ISoundTriggerInjection;
+import android.os.IBinder;
+import android.os.RemoteException;
+import android.util.Slog;
+
+import com.android.internal.annotations.GuardedBy;
+
+import java.util.Objects;
+
+/**
+ * Service side of the injection interface which enforces a single client.
+ * Essentially a facade that presents an ever-present, single injection client to the fake STHAL.
+ * Proxies a binder interface, but should never be called as such.
+ * @hide
+ */
+
+public class SoundTriggerInjection implements ISoundTriggerInjection, IBinder.DeathRecipient {
+
+    private static final String TAG = "SoundTriggerInjection";
+
+    private final Object mClientLock = new Object();
+    @GuardedBy("mClientLock")
+    private ISoundTriggerInjection mClient = null;
+    @GuardedBy("mClientLock")
+    private IInjectGlobalEvent mGlobalEventInjection = null;
+
+    /**
+     * Register a remote injection client.
+     * @param client - The injection client to register
+     */
+    public void registerClient(ISoundTriggerInjection client) {
+        synchronized (mClientLock) {
+            Objects.requireNonNull(client);
+            if (mClient != null) {
+                try {
+                    mClient.onPreempted();
+                } catch (RemoteException e) {
+                    Slog.e(TAG, "RemoteException when handling preemption", e);
+                }
+                mClient.asBinder().unlinkToDeath(this, 0);
+            }
+            mClient = client;
+            // Register cached global event injection interfaces,
+            // in case our client missed them.
+            try {
+                mClient.asBinder().linkToDeath(this, 0);
+                if (mGlobalEventInjection != null) {
+                    mClient.registerGlobalEventInjection(mGlobalEventInjection);
+                }
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+
+        }
+    }
+
+    @Override
+    public void binderDied() {
+        Slog.wtf(TAG, "Binder died without params");
+    }
+
+    // If the binder has died, clear out mClient.
+    @Override
+    public void binderDied(IBinder who) {
+        synchronized (mClientLock) {
+            if (mClient != null && who == mClient.asBinder()) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void registerGlobalEventInjection(IInjectGlobalEvent globalInjection) {
+        synchronized (mClientLock) {
+            // Cache for late attaching clients
+            mGlobalEventInjection = globalInjection;
+            if (mClient == null) return;
+            try {
+                mClient.registerGlobalEventInjection(mGlobalEventInjection);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onRestarted(IInjectGlobalEvent globalSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onRestarted(globalSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onFrameworkDetached(IInjectGlobalEvent globalSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onFrameworkDetached(globalSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onClientAttached(IBinder token, IInjectGlobalEvent globalSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onClientAttached(token, globalSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onClientDetached(IBinder token) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onClientDetached(token);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onSoundModelLoaded(SoundModel model, @Nullable Phrase[] phrases,
+            IInjectModelEvent modelInjection, IInjectGlobalEvent globalSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onSoundModelLoaded(model, phrases, modelInjection, globalSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onParamSet(/** ModelParameter **/ int modelParam, int value,
+            IInjectModelEvent modelSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onParamSet(modelParam, value, modelSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onRecognitionStarted(int audioSessionToken, RecognitionConfig config,
+            IInjectRecognitionEvent recognitionInjection, IInjectModelEvent modelSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onRecognitionStarted(audioSessionToken, config,
+                        recognitionInjection, modelSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onRecognitionStopped(IInjectRecognitionEvent recognitionSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onRecognitionStopped(recognitionSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onSoundModelUnloaded(IInjectModelEvent modelSession) {
+        synchronized (mClientLock) {
+            if (mClient == null) return;
+            try {
+                mClient.onSoundModelUnloaded(modelSession);
+            } catch (RemoteException e) {
+                mClient = null;
+            }
+        }
+    }
+
+    @Override
+    public void onPreempted() {
+        // We are the service, so we can't be preempted.
+        Slog.wtf(TAG, "Unexpected preempted!");
+    }
+
+    @Override
+    public IBinder asBinder() {
+        // This class is not a real binder object
+        Slog.wtf(TAG, "Unexpected asBinder!");
+        throw new UnsupportedOperationException("Calling asBinder on a fake binder object");
+    }
+
+}

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerMiddlewareService.java

@@ -20,6 +20,7 @@ import static android.Manifest.permission.SOUNDTRIGGER_DELEGATE_IDENTITY;
 
 import android.annotation.NonNull;
 import android.content.Context;
+import android.content.PermissionChecker;
 import android.media.permission.ClearCallingIdentityContext;
 import android.media.permission.Identity;
 import android.media.permission.PermissionUtil;
@@ -29,6 +30,7 @@ import android.media.soundtrigger.PhraseSoundModel;
 import android.media.soundtrigger.RecognitionConfig;
 import android.media.soundtrigger.SoundModel;
 import android.media.soundtrigger_middleware.ISoundTriggerCallback;
+import android.media.soundtrigger_middleware.ISoundTriggerInjection;
 import android.media.soundtrigger_middleware.ISoundTriggerMiddlewareService;
 import android.media.soundtrigger_middleware.ISoundTriggerModule;
 import android.media.soundtrigger_middleware.SoundTriggerModuleDescriptor;
@@ -68,15 +70,18 @@ public class SoundTriggerMiddlewareService extends ISoundTriggerMiddlewareServic
 
     private final @NonNull ISoundTriggerMiddlewareInternal mDelegate;
     private final @NonNull Context mContext;
+    // Lightweight object used to delegate injection events to the fake STHAL
+    private final @NonNull SoundTriggerInjection mInjection;
 
     /**
      * Constructor for internal use only. Could be exposed for testing purposes in the future.
      * Users should access this class via {@link Lifecycle}.
      */
     private SoundTriggerMiddlewareService(@NonNull ISoundTriggerMiddlewareInternal delegate,
-            @NonNull Context context) {
+            @NonNull Context context, @NonNull SoundTriggerInjection injection) {
         mDelegate = Objects.requireNonNull(delegate);
         mContext = context;
+        mInjection = injection;
     }
 
     @Override
@@ -113,6 +118,16 @@ public class SoundTriggerMiddlewareService extends ISoundTriggerMiddlewareServic
         }
     }
 
+    @Override
+    @android.annotation.RequiresPermission(android.Manifest.permission.MANAGE_SOUND_TRIGGER)
+    public void attachFakeHalInjection(@NonNull ISoundTriggerInjection injection) {
+        PermissionChecker.checkCallingOrSelfPermissionForPreflight(
+                mContext, android.Manifest.permission.MANAGE_SOUND_TRIGGER);
+        try (SafeCloseable ignored = ClearCallingIdentityContext.create()) {
+            mInjection.registerClient(Objects.requireNonNull(injection));
+        }
+    }
+
     @Override
     protected void dump(FileDescriptor fd, PrintWriter fout, String[] args) {
         if (mDelegate instanceof Dumpable) {
@@ -223,7 +238,9 @@ public class SoundTriggerMiddlewareService extends ISoundTriggerMiddlewareServic
 
         @Override
         public void onStart() {
-            HalFactory[] factories = new HalFactory[]{new DefaultHalFactory()};
+            final SoundTriggerInjection injection = new SoundTriggerInjection();
+            HalFactory[] factories = new HalFactory[]{new DefaultHalFactory(),
+                    new FakeHalFactory(injection)};
 
             publishBinderService(Context.SOUND_TRIGGER_MIDDLEWARE_SERVICE,
                     new SoundTriggerMiddlewareService(
@@ -232,7 +249,8 @@ public class SoundTriggerMiddlewareService extends ISoundTriggerMiddlewareServic
                                         new SoundTriggerMiddlewareValidation(
                                                 new SoundTriggerMiddlewareImpl(factories,
                                                         new AudioSessionProviderImpl())),
-                                        getContext())), getContext()));
+                                        getContext())), getContext(),
+                                        injection));
         }
     }
 }

services/voiceinteraction/java/com/android/server/soundtrigger_middleware/SoundTriggerModule.java

@@ -29,6 +29,7 @@ import android.media.soundtrigger.SoundModelType;
 import android.media.soundtrigger.Status;
 import android.media.soundtrigger_middleware.ISoundTriggerCallback;
 import android.media.soundtrigger_middleware.ISoundTriggerModule;
+import android.os.Binder;
 import android.os.IBinder;
 import android.os.RemoteException;
 import android.util.Log;
@@ -38,6 +39,7 @@ import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
 
 /**
@@ -92,13 +94,14 @@ class SoundTriggerModule implements IBinder.DeathRecipient, ISoundTriggerHal.Glo
     /**
      * Ctor.
      *
-     * @param halFactory A factory for the underlying HAL driver.
+     * @param halFactory - A factory for the underlying HAL driver.
+     * @param audioSessionProvider - Creates a session token + device id/port pair used to
+     * associate recognition events with the audio stream used to access data.
      */
     SoundTriggerModule(@NonNull HalFactory halFactory,
             @NonNull SoundTriggerMiddlewareImpl.AudioSessionProvider audioSessionProvider) {
-        assert halFactory != null;
-        mHalFactory = halFactory;
-        mAudioSessionProvider = audioSessionProvider;
+        mHalFactory = Objects.requireNonNull(halFactory);
+        mAudioSessionProvider = Objects.requireNonNull(audioSessionProvider);
 
         attachToHal();
     }
@@ -218,6 +221,7 @@ class SoundTriggerModule implements IBinder.DeathRecipient, ISoundTriggerHal.Glo
      */
     private class Session implements ISoundTriggerModule {
         private ISoundTriggerCallback mCallback;
+        private final IBinder mToken = new Binder();
         private final Map<Integer, Model> mLoadedModels = new HashMap<>();
 
         /**
@@ -227,6 +231,7 @@ class SoundTriggerModule implements IBinder.DeathRecipient, ISoundTriggerHal.Glo
          */
         private Session(@NonNull ISoundTriggerCallback callback) {
             mCallback = callback;
+            mHalService.clientAttached(mToken);
         }
 
         @Override
@@ -237,6 +242,7 @@ class SoundTriggerModule implements IBinder.DeathRecipient, ISoundTriggerHal.Glo
                 }
                 removeSession(this);
                 mCallback = null;
+                mHalService.clientDetached(mToken);
             }
         }