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Commit ca35e482 authored by Eric Laurent's avatar Eric Laurent
Browse files

Fix media server restart detection mechanism 

There is a flaw in the mechanism used by AudioService
to detect the fact that mediaserver process did crash and restart.
It relies on polling AudioFlinger service until a successful
connection triggers a callback into AudioSystem JNI and then into AudioService.
But if another thread in system_server process, not attached to the
JNI environment, reconnects before AudioService, the callback is called in
a detached context and dropped.

The fix consists in attaching the thread executing the callback
and detaching it if needed.

Bug: 9693068.
Change-Id: I184308b12a3f87653bf818abf0159e0e45a66ef0
parent 713412fd

core/jni/android_media_AudioSystem.cpp

+31 −1
Original line number Diff line number Diff line
@@ -117,10 +117,36 @@ android_media_AudioSystem_getParameters(JNIEnv *env, jobject thiz, jstring keys) 
    return env->NewStringUTF(AudioSystem::getParameters(0, c_keys8).string());

}



static JNIEnv* AudioSystem_getJNIEnv(bool* needsDetach) {

    *needsDetach = false;

    JNIEnv* env = AndroidRuntime::getJNIEnv();

    if (env == NULL) {

        JavaVMAttachArgs args = {JNI_VERSION_1_4, NULL, NULL};

        JavaVM* vm = AndroidRuntime::getJavaVM();

        int result = vm->AttachCurrentThread(&env, (void*) &args);

        if (result != JNI_OK) {

            ALOGE("thread attach failed: %#x", result);

            return NULL;

        }

        *needsDetach = true;

    }

    return env;

}



static void AudioSystem_detachJNI() {

    JavaVM* vm = AndroidRuntime::getJavaVM();

    int result = vm->DetachCurrentThread();

    if (result != JNI_OK) {

        ALOGE("thread detach failed: %#x", result);

    }

}



static void

android_media_AudioSystem_error_callback(status_t err)

{

    JNIEnv *env = AndroidRuntime::getJNIEnv();

    bool needsDetach = false;

    JNIEnv *env = AudioSystem_getJNIEnv(&needsDetach);



    if (env == NULL) {

        return;

    }
@@ -142,6 +168,10 @@ android_media_AudioSystem_error_callback(status_t err) 
    }



    env->CallStaticVoidMethod(clazz, env->GetStaticMethodID(clazz, "errorCallbackFromNative","(I)V"), error);



    if (needsDetach) {

        AudioSystem_detachJNI();

    }

}



static int