commit 6e463ce6fc456a3c185b80086d3605e2189eccd6
author Phil Burk <philburk@google.com> Mon Apr 13 10:20:20 2020 -0700
committer Phil Burk <philburk@google.com> Tue May 05 02:54:41 2020 -0700
tree 5c897c19218b6ab714ad781076018079ef2b0240
parent 4756a9f78b39c7aad0bd79c18b97bf8ed00b4bc6

aaudio: steal exclusive streams

An app (B) that asks for an exclusive stream can steal
an exclusive stream from an earlier app (A).
App B will be given the MMAP resource as a SHARED stream.
The stream for app A will be disconnected and released
by the service.
If app A reopens a stream then it will get a SHARED
stream.

The order of the opening of the streams is controlled by using a
recursive_mutex in AAudioService::openStream().

Bug: 129846760
Test: media/libaaudio/tests/test_steal_exclusive.cpp
Test: also
Test: Launch AudioTroubleMaker. It should say "EXCLUSIVE".
Test: Press Home button.
Test: Siren sound from AudioTroubleMaker should continue.
Test: Launch OboeTester
Test: TEST OUTPUT, then Open, Start
Test: You should get an MMAP SHARED stream on Pixel.
Test: Go back to AudioTroubleMaker. It should say "SHARED".
Change-Id: I7f8339d8ed62546520a9b46ed398418b41ca2832

media/libaaudio/src/client/AudioStreamInternal.cpp

diff --git a/media/libaaudio/src/client/AudioStreamInternal.cpp b/media/libaaudio/src/client/AudioStreamInternal.cpp
index 3db0099..79fa5ed 100644
--- a/media/libaaudio/src/client/AudioStreamInternal.cpp
+++ b/media/libaaudio/src/client/AudioStreamInternal.cpp
@@ -354,6 +354,12 @@
     drainTimestampsFromService();
 
     aaudio_result_t result = mServiceInterface.startStream(mServiceStreamHandle);
+    if (result == AAUDIO_ERROR_INVALID_HANDLE) {
+        ALOGD("%s() INVALID_HANDLE, stream was probably stolen", __func__);
+        // Stealing was added in R. Coerce result to improve backward compatibility.
+        result = AAUDIO_ERROR_DISCONNECTED;
+        setState(AAUDIO_STREAM_STATE_DISCONNECTED);
+    }
 
     startTime = AudioClock::getNanoseconds();
     mClockModel.start(startTime);
@@ -397,7 +403,12 @@
     if (isDataCallbackSet()
             && (isActive() || getState() == AAUDIO_STREAM_STATE_DISCONNECTED)) {
         mCallbackEnabled.store(false);
-        return joinThread(NULL); // may temporarily unlock mStreamLock
+        aaudio_result_t result = joinThread(NULL); // may temporarily unlock mStreamLock
+        if (result == AAUDIO_ERROR_INVALID_HANDLE) {
+            ALOGD("%s() INVALID_HANDLE, stream was probably stolen", __func__);
+            result = AAUDIO_OK;
+        }
+        return result;
     } else {
         return AAUDIO_OK;
     }
@@ -427,7 +438,12 @@
     setState(AAUDIO_STREAM_STATE_STOPPING);
     mAtomicInternalTimestamp.clear();
 
-    return mServiceInterface.stopStream(mServiceStreamHandle);
+    result = mServiceInterface.stopStream(mServiceStreamHandle);
+    if (result == AAUDIO_ERROR_INVALID_HANDLE) {
+        ALOGD("%s() INVALID_HANDLE, stream was probably stolen", __func__);
+        result = AAUDIO_OK;
+    }
+    return result;
 }
 
 aaudio_result_t AudioStreamInternal::registerThread() {