From 4e850d1cff074d06abe721cdc922f299015b37ea Mon Sep 17 00:00:00 2001
From: Jan Sebechlebsky <jsebechlebsky@google.com>
Date: Wed, 22 Mar 2023 14:05:34 +0100
Subject: Fix flaky failures when re-registering AudioPolicy.

The failures were caused by mix address being out of sync with
registered mix address because the mix ids were advanced during
unregistration of the mix and access to the mix config config
was not properly synchronized.

This cl:
 * Moves resetting the mix ids (mConfig.reset call) to synchronized
   section.
 * Changes mix counter behavior so it's incremented only during
   registration (and not unregistration) and fixes the comment.
 * Makes mStatusListener, mIsFocusPolicy and mIsTestFocusPolicy final
   since they never change since construction.
 * Removes unnecessary synchronization when accessing mStatusListener
   callback.

Bug: 247788804
Test: atest AudioHostTest --iterations 15
Change-Id: I1544329654cec5c13ec5e20a983d8d318ab3549d
---
 .../java/android/media/audiopolicy/AudioPolicy.java  | 20 +++++++++-----------
 .../android/media/audiopolicy/AudioPolicyConfig.java |  7 ++-----
 2 files changed, 11 insertions(+), 16 deletions(-)

diff --git a/media/java/android/media/audiopolicy/AudioPolicy.java b/media/java/android/media/audiopolicy/AudioPolicy.java
index 3ba1d1f0eca2..c1ee74a70a15 100644
--- a/media/java/android/media/audiopolicy/AudioPolicy.java
+++ b/media/java/android/media/audiopolicy/AudioPolicy.java
@@ -75,11 +75,13 @@ public class AudioPolicy {
      */
     public static final int POLICY_STATUS_REGISTERED = 2;
 
+    @GuardedBy("mLock")
     private int mStatus;
+    @GuardedBy("mLock")
     private String mRegistrationId;
-    private AudioPolicyStatusListener mStatusListener;
-    private boolean mIsFocusPolicy;
-    private boolean mIsTestFocusPolicy;
+    private final AudioPolicyStatusListener mStatusListener;
+    private final boolean mIsFocusPolicy;
+    private final boolean mIsTestFocusPolicy;
 
     /**
      * The list of AudioTrack instances created to inject audio into the associated mixes
@@ -115,6 +117,7 @@ public class AudioPolicy {
 
     private Context mContext;
 
+    @GuardedBy("mLock")
     private AudioPolicyConfig mConfig;
 
     private final MediaProjection mProjection;
@@ -552,7 +555,6 @@ public class AudioPolicy {
     /** @hide */
     public void reset() {
         setRegistration(null);
-        mConfig.reset();
     }
 
     public void setRegistration(String regId) {
@@ -563,6 +565,7 @@ public class AudioPolicy {
                 mStatus = POLICY_STATUS_REGISTERED;
             } else {
                 mStatus = POLICY_STATUS_UNREGISTERED;
+                mConfig.reset();
             }
         }
         sendMsg(MSG_POLICY_STATUS_CHANGE);
@@ -940,14 +943,9 @@ public class AudioPolicy {
     }
 
     private void onPolicyStatusChange() {
-        AudioPolicyStatusListener l;
-        synchronized (mLock) {
-            if (mStatusListener == null) {
-                return;
-            }
-            l = mStatusListener;
+        if (mStatusListener != null) {
+            mStatusListener.onStatusChange();
         }
-        l.onStatusChange();
     }
 
     //==================================================
diff --git a/media/java/android/media/audiopolicy/AudioPolicyConfig.java b/media/java/android/media/audiopolicy/AudioPolicyConfig.java
index ce9773312a10..7a85d21bf144 100644
--- a/media/java/android/media/audiopolicy/AudioPolicyConfig.java
+++ b/media/java/android/media/audiopolicy/AudioPolicyConfig.java
@@ -42,9 +42,7 @@ public class AudioPolicyConfig implements Parcelable {
 
     private String mRegistrationId = null;
 
-    /** counter for the mixes that are / have been in the list of AudioMix
-     *  e.g. register 4 mixes (counter is 3), remove 1 (counter is 3), add 1 (counter is 4)
-     */
+    // Corresponds to id of next mix to be registered.
     private int mMixCounter = 0;
 
     protected AudioPolicyConfig(AudioPolicyConfig conf) {
@@ -286,7 +284,7 @@ public class AudioPolicyConfig implements Parcelable {
             if ((mix.getRouteFlags() & AudioMix.ROUTE_FLAG_LOOP_BACK) ==
                     AudioMix.ROUTE_FLAG_LOOP_BACK) {
                 mix.setRegistration(mRegistrationId + "mix" + mixTypeId(mix.getMixType()) + ":"
-                        + mMixCounter);
+                        + mMixCounter++);
             } else if ((mix.getRouteFlags() & AudioMix.ROUTE_FLAG_RENDER) ==
                     AudioMix.ROUTE_FLAG_RENDER) {
                 mix.setRegistration(mix.mDeviceAddress);
@@ -294,7 +292,6 @@ public class AudioPolicyConfig implements Parcelable {
         } else {
             mix.setRegistration("");
         }
-        mMixCounter++;
     }
 
     @GuardedBy("mMixes")
-- 
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