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[英]Are AsyncTasks also executed on the same background thread in the SERIAL_EXECUTOR?
[英]C++ serial thread executor
来自Java环境(特别是Android),在不阻塞主线程的情况下在新线程中执行某些代码从未遇到任何问题。 由于我现在必须使用C ++,因此我偶然发现了以下问题。
客户端代码通过JNI执行我的本机(C ++)代码:
JNIEXPORT jbyteArray JNICALL
Java_com_native_project_NativeInterface_processData(JNIEnv *env, jobject instance, jbyteArray inputData_) {
vector<unsigned char> inputData = jbyteArrayToBytes(env, inputData_);
const vector<unsigned char> &result = getDataProcessor(env, instance).processData(inputData);
return bytesTojbyteArray(env, result);
}
DataProcessor getDataProcessor(JNIEnv *env, jobject instance) {
return DataProcessor(env, instance);
}
然后在我的DataProcessor
我想做两个尝试:
示例代码:
class BasicAsync {
private:
void logToDB(const vector<unsigned char> &inputData) {
// connect to DB and write data to it
}
vector<unsigned char> compute(const vector<unsigned char> &inputData) {
vector<unsigned char> result = vector<unsigned char>();
// rocket-science computation in here
return result;
}
public:
vector<unsigned char> processData(const vector<unsigned char> &inputData) {
// perform data computation and produce output
vector<unsigned char> result = compute(inputData);
// create a thread that writes the data to activity log without delaying the response return
logToDB(inputData);
//return result while data is written to activity log
return result;
}
}
我的主要观点是:
DataProcessor
对象会发生什么情况(因为在其生命周期范围结束时,通过JNI返回响应后应该销毁它-也许我在这里丢失了一些东西)? #include <thread>
#include <mutex>
#include <functional>
#include <queue>
class SerialExecutionQueue
{
public:
typedef std::function<void()> QueueItem;
SerialExecutionQueue() :
m_shouldQuit(false),
m_executor([this]()
{
executor();
})
{
}
void enqueueWork(QueueItem item)
{
{
std::lock_guard<std::mutex> l(m_mutex);
m_queue.push(item);
}
m_cv.notify_all();
}
void executor()
{
while (!m_shouldQuit)
{
std::unique_lock<std::mutex> lock(m_mutex);
while (m_queue.size())
{
auto item = m_queue.front();
m_queue.pop();
m_mutex.unlock();
item();
m_mutex.lock();
}
m_cv.wait(lock);
}
}
private:
bool m_shouldQuit;
std::condition_variable m_cv;
std::mutex m_mutex;
std::queue<QueueItem> m_queue;
std::thread m_executor;
};
int main(int argc, const char * argv[])
{
SerialExecutionQueue queue;
queue.enqueueWork([]()
{
std::cout << "Did some work 1" <<std::endl;
});
queue.enqueueWork([]()
{
std::cout << "Did some work 2" <<std::endl;
});
sleep(1);
queue.enqueueWork([]()
{
std::cout << "Did some work 3" <<std::endl;
});
sleep(10);
return 0;
}
输出:
Did some work 1
Did some work 2
Did some work 3
在2011年之前,必须直接使用本机API(例如pthreads)或部署第三方包装器库(如boost中的库),但是自2011年以来,C ++提供了相当丰富的标准化线程接口。
也许您首先自己看看,尝试一下,然后在帖子中添加更具体的问题; 然后,我将相应地扩展此答案。
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