commit d9422ccaeceec59b420dac7dcc709df95cd0d574
author xiaotonj <xiaotonj@google.com> Fri Nov 10 18:22:42 2023 -0800
committer xiaotonj <xiaotonj@google.com> Mon Nov 13 12:29:22 2023 -0800
tree c6f14d68d1c6a58f2785e33c021aa0963be48733
parent cf22ed224abc282a4586e835a5b8354e817b5763

Protect audio communication device set/clear operations with a lock.

Currently, when telecom audio stack handle series messages relate to
communication device set/clear operations, these operations will be
completed in random order which will cause unexpected device set as the
communication device. Protect these operations with a lock to avoid race
conditions.

Bug: b/303001133
Test: atest CallAudioRouteStateMachineTest
Change-Id: Ib9fcbc712aaa3583ceea17288fa85ac33c0e7d3c

flags/telecom_callaudioroutestatemachine_flags.aconfig

diff --git a/flags/telecom_callaudioroutestatemachine_flags.aconfig b/flags/telecom_callaudioroutestatemachine_flags.aconfig
index b0f14a4..ab7ec88 100644
--- a/flags/telecom_callaudioroutestatemachine_flags.aconfig
+++ b/flags/telecom_callaudioroutestatemachine_flags.aconfig
@@ -40,4 +40,11 @@
   namespace: "telecom"
   description: "Refactor call audio set/clear communication device and include unsupported routes."
   bug: "308968392"
-}
\ No newline at end of file
+}
+
+flag {
+  name: "communication_device_protected_by_lock"
+  namespace: "telecom"
+  description: "Protect set/clear communication device operation with lock to avoid race condition."
+  bug: "303001133"
+}

src/com/android/server/telecom/CallAudioCommunicationDeviceTracker.java

diff --git a/src/com/android/server/telecom/CallAudioCommunicationDeviceTracker.java b/src/com/android/server/telecom/CallAudioCommunicationDeviceTracker.java
index 38a96eb..4af60f0 100644
--- a/src/com/android/server/telecom/CallAudioCommunicationDeviceTracker.java
+++ b/src/com/android/server/telecom/CallAudioCommunicationDeviceTracker.java
@@ -24,10 +24,12 @@
 
 import com.android.internal.annotations.VisibleForTesting;
 import com.android.server.telecom.bluetooth.BluetoothRouteManager;
+import com.android.server.telecom.flags.Flags;
 
 import java.util.Arrays;
 import java.util.List;
 import java.util.Set;
+import java.util.concurrent.Semaphore;
 
 /**
  * Helper class used to keep track of the requested communication device within Telecom for audio
@@ -50,6 +52,7 @@
     private int mAudioDeviceType = sAUDIO_DEVICE_TYPE_INVALID;
     // Keep track of the locally requested BT audio device if set
     private String mBtAudioDevice = null;
+    private final Semaphore mLock =  new Semaphore(1);
 
     public CallAudioCommunicationDeviceTracker(Context context) {
         mAudioManager = context.getSystemService(AudioManager.class);
@@ -94,6 +97,9 @@
      */
     public boolean setCommunicationDevice(int audioDeviceType,
             BluetoothDevice btDevice) {
+        if (Flags.communicationDeviceProtectedByLock()) {
+            mLock.tryAcquire();
+        }
         // There is only one audio device type associated with each type of BT device.
         boolean isBtDevice = sBT_AUDIO_DEVICE_TYPES.contains(audioDeviceType);
         Log.i(this, "setCommunicationDevice: type = %s, isBtDevice = %s, btDevice = %s",
@@ -155,6 +161,9 @@
                 }
             }
         }
+        if (Flags.communicationDeviceProtectedByLock()) {
+            mLock.release();
+        }
         return result;
     }
 
@@ -164,6 +173,9 @@
      * @param audioDeviceTypes The supported audio device types for the device.
      */
     public void clearCommunicationDevice(int audioDeviceType) {
+        if (Flags.communicationDeviceProtectedByLock()) {
+            mLock.tryAcquire();
+        }
         // There is only one audio device type associated with each type of BT device.
         boolean isBtDevice = sBT_AUDIO_DEVICE_TYPES.contains(audioDeviceType);
         Log.i(this, "clearCommunicationDevice: type = %s, isBtDevice = %s",
@@ -195,6 +207,9 @@
             mBluetoothRouteManager.onAudioLost(mBtAudioDevice);
             mBtAudioDevice = null;
         }
+        if (Flags.communicationDeviceProtectedByLock()) {
+            mLock.release();
+        }
     }
 
     private boolean isUsbHeadsetType(int audioDeviceType, int sourceType) {