Android Audio代码分析22 - AudioEffect::getEnabled函数

最新推荐文章于 2024-07-29 15:29:52 发布

最新推荐文章于 2024-07-29 15:29:52 发布 · 126 阅读

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#移动开发 #java

本文探讨了Android AudioEffect类的释放机制及释放后尝试获取启用状态的行为。详细解析了release方法如何清理资源并使后续的getEnabled调用抛出异常。

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今天来看看AudioEffect中enable相关的接口。

*****************************************源码*************************************************

    //Test case 1.3: test getEnabled() failure when called on released effect
    @LargeTest
    public void test1_3GetEnabledAfterRelease() throws Exception {
        boolean result = false;
        String msg = "test1_3GetEnabledAfterRelease()";


        try {
            AudioEffect effect = new AudioEffect(AudioEffect.EFFECT_TYPE_EQUALIZER,
                    AudioEffect.EFFECT_TYPE_NULL,
                    0,
                    0);
            assertNotNull(msg + ": could not create AudioEffect", effect);
            effect.release();
            try {
                effect.getEnabled();
            } catch (IllegalStateException e) {
                result = true;
            }
        } catch (IllegalArgumentException e) {
            msg = msg.concat(": Equalizer not found");
        } catch (UnsupportedOperationException e) {
            msg = msg.concat(": Effect library not loaded");
        }
        assertTrue(msg, result);
    }

**********************************************************************************************
源码路径：
frameworks\base\media\tests\mediaframeworktest\src\com\android\mediaframeworktest\functional\MediaAudioEffectTest.java

#######################说明################################

    //Test case 1.3: test getEnabled() failure when called on released effect
    @LargeTest
    public void test1_3GetEnabledAfterRelease() throws Exception {
        boolean result = false;
        String msg = "test1_3GetEnabledAfterRelease()";


        try {
            AudioEffect effect = new AudioEffect(AudioEffect.EFFECT_TYPE_EQUALIZER,
                    AudioEffect.EFFECT_TYPE_NULL,
                    0,
                    0);
            assertNotNull(msg + ": could not create AudioEffect", effect);
            effect.release();
// ++++++++++++++++++++++++++++++release++++++++++++++++++++++++++++++++++
    /**
     * Releases the native AudioEffect resources. It is a good practice to
     * release the effect engine when not in use as control can be returned to
     * other applications or the native resources released.
     */
    public void release() {
        synchronized (mStateLock) {
            native_release();
// ++++++++++++++++++++++++++++++android_media_AudioEffect_native_release++++++++++++++++++++++++++++++++++
static void android_media_AudioEffect_native_release(JNIEnv *env,  jobject thiz) {


    // do everything a call to finalize would
// 删除创建AudioEffect时，创建的对象
    android_media_AudioEffect_native_finalize(env, thiz);
// ++++++++++++++++++++++++++++++android_media_AudioEffect_native_finalize++++++++++++++++++++++++++++++++++
static void android_media_AudioEffect_native_finalize(JNIEnv *env,  jobject thiz) {
    LOGV("android_media_AudioEffect_native_finalize jobject: %x\n", (int)thiz);


    // delete the AudioEffect object
    AudioEffect* lpAudioEffect = (AudioEffect *)env->GetIntField(
        thiz, fields.fidNativeAudioEffect);
// 此处删除了lpAudioEffect
// getEnabled的时候会调用lpAudioEffect的接口，所以release后再getEnabled会产生异常
    if (lpAudioEffect) {
        LOGV("deleting AudioEffect: %x\n", (int)lpAudioEffect);
        delete lpAudioEffect;
    }


    // delete the JNI data
    AudioEffectJniStorage* lpJniStorage = (AudioEffectJniStorage *)env->GetIntField(
        thiz, fields.fidJniData);
    if (lpJniStorage) {
        LOGV("deleting pJniStorage: %x\n", (int)lpJniStorage);
        delete lpJniStorage;
    }
}
// ------------------------------android_media_AudioEffect_native_finalize----------------------------------
    // + reset the native resources in the Java object so any attempt to access
    // them after a call to release fails.
    env->SetIntField(thiz, fields.fidNativeAudioEffect, 0);
    env->SetIntField(thiz, fields.fidJniData, 0);
}
// ------------------------------android_media_AudioEffect_native_release----------------------------------
            mState = STATE_UNINITIALIZED;
        }
    }
// ------------------------------release----------------------------------
            try {
                effect.getEnabled();
// ++++++++++++++++++++++++++++++++getEnabled++++++++++++++++++++++++++++++++
    /**
     * Returns effect enabled state
     *
     * @return true if the effect is enabled, false otherwise.
     * @throws IllegalStateException
     */
    public boolean getEnabled() throws IllegalStateException {
        checkState("getEnabled()");
        return native_getEnabled();
// ++++++++++++++++++++++++++++++android_media_AudioEffect_native_getEnabled++++++++++++++++++++++++++++++++++
static jboolean
android_media_AudioEffect_native_getEnabled(JNIEnv *env, jobject thiz)
{
    // retrieve the AudioEffect object
    AudioEffect* lpAudioEffect = (AudioEffect *)env->GetIntField(
        thiz, fields.fidNativeAudioEffect);


    if (lpAudioEffect == NULL) {
        jniThrowException(env, "java/lang/IllegalStateException",
            "Unable to retrieve AudioEffect pointer for getEnabled()");
        return false;
    }


    return (jboolean)lpAudioEffect->getEnabled();
// ++++++++++++++++++++++++++++AudioEffect::getEnabled++++++++++++++++++++++++++++++++++++
bool AudioEffect::getEnabled() const
{
// mEnabled在函数AudioEffect::set中被赋值：mEnabled = (volatile int32_t)enabled;


// enabled产生于对函数AudioFlinger::createEffect的调用
//    iEffect = audioFlinger->createEffect(getpid(), (effect_descriptor_t *)&mDescriptor,
//            mIEffectClient, priority, output, mSessionId, &mStatus, &mId, &enabled);


// 又将地址传给了函数AudioFlinger::PlaybackThread::createEffect_l
        // create effect on selected output trhead
//        handle = thread->createEffect_l(client, effectClient, priority, sessionId,
//                &desc, enabled, &lStatus);


// 调用函数AudioFlinger::EffectModule::isEnabled
//            *enabled = (int)effect->isEnabled();
// ++++++++++++++++++++++++++++AudioFlinger::EffectModule::isEnabled++++++++++++++++++++++++++++++++++++
bool AudioFlinger::EffectModule::isEnabled()
{
// EffectModule构造函数中会将mState设为IDLE
// 函数updateState和函数setEnabled都会改变mState。
// 函数AudioFlinger::EffectChain::process_l会调用函数updateState来更新状态
    switch (mState) {
    case RESTART:
    case STARTING:
    case ACTIVE:
        return true;
    case IDLE:
    case STOPPING:
    case STOPPED:
    default:
        return false;
    }
}
// ----------------------------AudioFlinger::EffectModule::isEnabled------------------------------------
    return (mEnabled != 0);
}
// ----------------------------AudioEffect::getEnabled------------------------------------
}
// ------------------------------android_media_AudioEffect_native_getEnabled----------------------------------
    }
// --------------------------------getEnabled--------------------------------
            } catch (IllegalStateException e) {
                result = true;
            }
        } catch (IllegalArgumentException e) {
            msg = msg.concat(": Equalizer not found");
        } catch (UnsupportedOperationException e) {
            msg = msg.concat(": Effect library not loaded");
        }
        assertTrue(msg, result);
    }

###########################################################

&&&&&&&&&&&&&&&&&&&&&&&总结&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&
release时会删除native中创建的AudioEffectJniStorage对象和AudioEffect对象。
getEnabled是根据EffectModule的状态返回的。
release之后，再调用getEnabled函数，由于AudioEffect对象已被删除，所以会产生异常。
&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&