[NDK] -POSIX线程学习二

在上篇的基础上添加pthread_join(), 这个函数将会挂起调用线程，直至创建的线程执行完，这时ret_val返回0.

int pthread_join(pthread_t thread, void** ret_val);

• native-thread.cpp

extern "C"
JNIEXPORT void JNICALL
Java_com_zhuhongxi_nativcethreaddemo1_MainActivity_posixThreads(JNIEnv *env, jobject thiz,
                                                                jint threads, jint iterations) {

    //线程句柄
    pthread_t *handles = new pthread_t[threads];

    //为每一个worker创建一个posix线程去执行
    for (jint i = 0; i < threads; i++) {
        //组装每一个worker参数
        NativeWorkerArgs *nativeWorkerArgs = new NativeWorkerArgs();
        nativeWorkerArgs->id = i;
        nativeWorkerArgs->iteration = iterations;
        //创建pthread
        pthread_t thread;
        int result = pthread_create(&handles[i], nullptr, nativeWorkerThread,
                                    (void *) nativeWorkerArgs);
        //如果创建失败就抛出一个java异常
        if (0 != result) {
            jclass exceptionClazz = env->FindClass("java/lang/RuntimeException");
            env->ThrowNew(exceptionClazz, "Unable to create native thread");
            goto exit;
        }
    }

    for (int i = 0; i < threads; ++i) {
        void* result = nullptr;
        if (0 != pthread_join(handles[i], &result))
        {
            jclass exceptionClazz = env->FindClass("java/lang/RuntimeException");
            env->ThrowNew(exceptionClazz, "Unable to join thread");
        }
        else
        {
            char message[26];
            sprintf(message, "Worker %d: Iteration %d", i, result);
            //新建一个字符串
            jstring messageString = env->NewStringUTF(message);
            //调用java中的回调方法
            env->CallVoidMethod(gObj, gOnNativeMessage, messageString);
            if (nullptr != env->ExceptionOccurred())
            {
                goto exit;
            }
        }
    }
exit:
    return;
}