From a533b9942dd7a93804953d633eb842f0b7cd0ede Mon Sep 17 00:00:00 2001
From: Chris Thornton <thorntonc@google.com>
Date: Fri, 24 Mar 2017 17:30:29 -0700
Subject: [PATCH] SoundTriggerHelper: Remove unused models onLoad

If some process tries to start a recognition, the STH will now check to
see if there are any other models that have been loaded and either:
 - Have a callback that's died (determined by pinging the binder)
 - Don't have a callback at all (meaning they didn't clean up after the
   last detection and didn't start it again).
If it finds such a model, it will be stopped and unloaded, freeing up
resources in the HAL.

Test: Manually load model/kill the process and make sure that it is
unloaded the next time some other model is loaded. Also made sure
running models aren't evicted.

Change-Id: Ia1139b47afe5f88102a3773d90f4f056ea3cdc92
---
 .../soundtrigger/SoundTriggerHelper.java      | 51 ++++++++++++++++++-
 1 file changed, 49 insertions(+), 2 deletions(-)

diff --git a/services/voiceinteraction/java/com/android/server/soundtrigger/SoundTriggerHelper.java b/services/voiceinteraction/java/com/android/server/soundtrigger/SoundTriggerHelper.java
index 1aa952cd58b9e..cb44471e3c0cf 100644
--- a/services/voiceinteraction/java/com/android/server/soundtrigger/SoundTriggerHelper.java
+++ b/services/voiceinteraction/java/com/android/server/soundtrigger/SoundTriggerHelper.java
@@ -300,7 +300,11 @@ public class SoundTriggerHelper implements SoundTrigger.StatusListener {
 
             // Load the model if it is not loaded.
             if (!modelData.isModelLoaded()) {
-                // Load the model
+                // Before we try and load this model, we should first make sure that any other
+                // models that don't have an active recognition/dead callback are unloaded. Since
+                // there is a finite limit on the number of models that the hardware may be able to
+                // have loaded, we want to make sure there's room for our model.
+                stopAndUnloadDeadModelsLocked();
                 int[] handle = new int[] { INVALID_VALUE };
                 int status = mModule.loadSoundModel(soundModel, handle);
                 if (status != SoundTrigger.STATUS_OK) {
@@ -899,7 +903,29 @@ public class SoundTriggerHelper implements SoundTrigger.StatusListener {
         }
     }
 
+    /**
+     * Stops and unloads a sound model, and removes any reference to the model if successful.
+     *
+     * @param modelData The model data to remove.
+     * @param exception Optional exception to print in logcat. May be null.
+     */
     private void forceStopAndUnloadModel(ModelData modelData, Exception exception) {
+      forceStopAndUnloadModel(modelData, exception, null /* modelDataIterator */);
+    }
+
+    /**
+     * Stops and unloads a sound model, and removes any reference to the model if successful.
+     *
+     * @param modelData The model data to remove.
+     * @param exception Optional exception to print in logcat. May be null.
+     * @param modelDataIterator If this function is to be used while iterating over the
+     *        mModelDataMap, you can provide the iterator for the current model data to be used to
+     *        remove the modelData from the map. This avoids generating a
+     *        ConcurrentModificationException, since this function will try and remove the model
+     *        data from the mModelDataMap when it can successfully unload the model.
+     */
+    private void forceStopAndUnloadModel(ModelData modelData, Exception exception,
+            Iterator modelDataIterator) {
         if (exception != null) {
           Slog.e(TAG, "forceStopAndUnloadModel", exception);
         }
@@ -916,7 +942,11 @@ public class SoundTriggerHelper implements SoundTrigger.StatusListener {
             Slog.d(TAG, "Unloading previously loaded dangling model " + modelData.getHandle());
             if (mModule.unloadSoundModel(modelData.getHandle()) == STATUS_OK) {
                 // Remove the model data from existence.
-                mModelDataMap.remove(modelData.getModelId());
+                if (modelDataIterator != null) {
+                    modelDataIterator.remove();
+                } else {
+                    mModelDataMap.remove(modelData.getModelId());
+                }
                 Iterator it = mKeyphraseUuidMap.entrySet().iterator();
                 while (it.hasNext()) {
                     Map.Entry pair = (Map.Entry) it.next();
@@ -931,6 +961,23 @@ public class SoundTriggerHelper implements SoundTrigger.StatusListener {
         }
     }
 
+    private void stopAndUnloadDeadModelsLocked() {
+        Iterator it = mModelDataMap.entrySet().iterator();
+        while (it.hasNext()) {
+            ModelData modelData = (ModelData) ((Map.Entry) it.next()).getValue();
+            if (!modelData.isModelLoaded()) {
+                continue;
+            }
+            if (modelData.getCallback() == null
+                    || (modelData.getCallback().asBinder() != null
+                        && !modelData.getCallback().asBinder().pingBinder())) {
+                // No one is listening on this model, so we might as well evict it.
+                Slog.w(TAG, "Removing model " + modelData.getHandle() + " that has no clients");
+                forceStopAndUnloadModel(modelData, null /* exception */, it);
+            }
+        }
+    }
+
     private ModelData getOrCreateGenericModelDataLocked(UUID modelId) {
         ModelData modelData = mModelDataMap.get(modelId);
         if (modelData == null) {