我在需要读写的地方实现了游戏服务器。所以我接受传入的连接并开始使用aio_read()从中读取,但是当我需要发送一些东西时,我停止使用aio_cancel()读取,然后使用aio_write()。在 write 的回调中,我继续阅读。所以,我确实一直在阅读,但是当我需要发送一些东西时——我会暂停阅读。
它的工作时间约为 20% - 在其他情况下,对aio_cancel()的调用失败并显示“正在进行操作” - 我无法取消它(即使在永久循环内)。所以,我添加的写操作永远不会发生。
如何用好这些功能?我错过了什么?
编辑:在 Linux 2.6.35 下使用。Ubuntu 10 - 32 位。
示例代码:
void handle_read(union sigval sigev_value) { /* handle data or disconnection */ }
void handle_write(union sigval sigev_value) { /* free writing buffer memory */ }
void start()
{
const int acceptorSocket = socket(AF_INET, SOCK_STREAM, 0);
struct sockaddr_in addr;
memset(&addr, 0, sizeof(struct sockaddr_in));
addr.sin_family = AF_INET;
addr.sin_addr.s_addr = INADDR_ANY;
addr.sin_port = htons(port);
bind(acceptorSocket, (struct sockaddr*)&addr, sizeof(struct sockaddr_in));
listen(acceptorSocket, SOMAXCONN);
struct sockaddr_in address;
socklen_t addressLen = sizeof(struct sockaddr_in);
for(;;)
{
const int incomingSocket = accept(acceptorSocket, (struct sockaddr*)&address, &addressLen);
if(incomingSocket == -1)
{ /* handle error ... */}
else
{
//say socket to append outcoming messages at writing:
const int currentFlags = fcntl(incomingSocket, F_GETFL, 0);
if(currentFlags < 0) { /* handle error ... */ }
if(fcntl(incomingSocket, F_SETFL, currentFlags | O_APPEND) == -1) { /* handle another error ... */ }
//start reading:
struct aiocb* readingAiocb = new struct aiocb;
memset(readingAiocb, 0, sizeof(struct aiocb));
readingAiocb->aio_nbytes = MY_SOME_BUFFER_SIZE;
readingAiocb->aio_fildes = socketDesc;
readingAiocb->aio_buf = mySomeReadBuffer;
readingAiocb->aio_sigevent.sigev_notify = SIGEV_THREAD;
readingAiocb->aio_sigevent.sigev_value.sival_ptr = (void*)mySomeData;
readingAiocb->aio_sigevent.sigev_notify_function = handle_read;
if(aio_read(readingAiocb) != 0) { /* handle error ... */ }
}
}
}
//called at any time from server side:
send(void* data, const size_t dataLength)
{
//... some thread-safety precautions not needed here ...
const int cancellingResult = aio_cancel(socketDesc, readingAiocb);
if(cancellingResult != AIO_CANCELED)
{
//this one happens ~80% of the time - embracing previous call to permanent while cycle does not help:
if(cancellingResult == AIO_NOTCANCELED)
{
puts(strerror(aio_return(readingAiocb))); // "Operation now in progress"
/* don't know what to do... */
}
}
//otherwise it's okay to send:
else
{
aio_write(...);
}
}