void TCPListenerSocket::ProcessEvent(int /*eventBits*/)
{
//we are executing on the same thread as every other
//socket, so whatever you do here has to be fast.
struct sockaddr_in addr;
#if __Win32__ || __osf__ || __sgi__ || __hpux__
int size = sizeof(addr);
#else
socklen_t size = sizeof(addr);
#endif
Task* theTask = NULL;
TCPSocket* theSocket = NULL;
//fSocket data member of TCPSocket.
int osSocket = accept(fFileDesc, (struct sockaddr*)&addr, &size);
//test osSocket = -1;
if (osSocket == -1)
{
//take a look at what this error is.
int acceptError = OSThread::GetErrno();
if (acceptError == EAGAIN)
{
//If it's EAGAIN, there's nothing on the listen queue right now,
//so modwatch and return
this->RequestEvent(EV_RE);
return;
}
//test acceptError = ENFILE;
//test acceptError = EINTR;
//test acceptError = ENOENT;
//if these error gets returned, we're out of file desciptors,
//the server is going to be failing on sockets, logs, qtgroups and qtuser auth file accesses and movie files. The server is not functional.
if (acceptError == EMFILE || acceptError == ENFILE)
{
#ifndef __Win32__
QTSSModuleUtils::LogErrorStr(qtssFatalVerbosity, "Out of File Descriptors. Set max connections lower and check for competing usage from other processes. Exiting.");
#endif
exit (EXIT_FAILURE);
}
else
{
char errStr[256];
errStr[sizeof(errStr) -1] = 0;
qtss_snprintf(errStr, sizeof(errStr) -1, "accept error = %d '%s' on socket. Clean up and continue.", acceptError, strerror(acceptError));
WarnV( (acceptError == 0), errStr);
theTask = this->GetSessionTask(&theSocket);
if (theTask == NULL)
{
close(osSocket);
}
else
{
theTask->Signal(Task::kKillEvent); // just clean up the task
}
if (theSocket)
theSocket->fState &= ~kConnected; // turn off connected state
return;
}
}
theTask = this->GetSessionTask(&theSocket);
if (theTask == NULL)
{ //this should be a disconnect. do an ioctl call?
close(osSocket);
if (theSocket)
theSocket->fState &= ~kConnected; // turn off connected state
}
else
{
Assert(osSocket != EventContext::kInvalidFileDesc);
//set options on the socket
//we are a server, always disable nagle algorithm
int one = 1;
int err = ::setsockopt(osSocket, IPPROTO_TCP, TCP_NODELAY, (char*)&one, sizeof(int));
AssertV(err == 0, OSThread::GetErrno());
err = ::setsockopt(osSocket, SOL_SOCKET, SO_KEEPALIVE, (char*)&one, sizeof(int));
AssertV(err == 0, OSThread::GetErrno());
int sndBufSize = 96L * 1024L;
err = ::setsockopt(osSocket, SOL_SOCKET, SO_SNDBUF, (char*)&sndBufSize, sizeof(int));
AssertV(err == 0, OSThread::GetErrno());
//setup the socket. When there is data on the socket,
//theTask will get an kReadEvent event
theSocket->Set(osSocket, &addr);
theSocket->InitNonBlocking(osSocket);
theSocket->SetTask(theTask);
theSocket->RequestEvent(EV_RE);
theTask->SetThreadPicker(Task::GetBlockingTaskThreadPicker()); //The RTSP Task processing threads
}
if (fSleepBetweenAccepts)
{
// We are at our maximum supported sockets
// slow down so we have time to process the active ones (we will respond with errors or service).
// wake up and execute again after sleeping. The timer must be reset each time through
//qtss_printf("TCPListenerSocket slowing down\n");
this->SetIdleTimer(kTimeBetweenAcceptsInMsec); //sleep 1 second
}
else
{
// sleep until there is a read event outstanding (another client wants to connect)
//qtss_printf("TCPListenerSocket normal speed\n");
this->RequestEvent(EV_RE);
}
fOutOfDescriptors = false; // always false for now we don't properly handle this elsewhere in the code
}
/* 在TCPListenerSocket中,ProcessEvent 函数(继承EventContext 的ProcessEvent()函数)被重载用来创建Socket和Task 对象得配对 */
void TCPListenerSocket::ProcessEvent(int /*eventBits*/)
{
//we are executing on the same thread as every other
//socket, so whatever you do here has to be fast.
/* 该函数运行于系统唯一的EventThread 线程中，所以要尽量快速，以免占用过多的系统资源 */
/* 在accept()中存放接受的远处客户端的ip地址 */
struct sockaddr_in addr;
socklen_t size = sizeof(addr);
/* 注意theTask(通过派生类TCPSocket)和theSocket都是TCPListenerSocket的基类 */
/**************** 注意:通过子类重载GetSessionTask()使Task(具体说,是RTSPSession)和TCPSocket配对 ***********************/
Task* theTask = NULL;
TCPSocket* theSocket = NULL;
//fSocket data member of TCPSocket.
/* 服务器端的Socket接受客户端的Socket的连接请求,成功后返回服务器新建的接受连接的Socket的描述符,否则返回INVALID_SOCKET */
int osSocket = accept(fFileDesc, (struct sockaddr*)&addr, &size);
//test osSocket = -1;
/* 假如出错了,进行错误处理.以下全是错误处理!! */
if (osSocket == -1)
{
//take a look at what this error is.
/* 获取具体的出错原因 */
int acceptError = OSThread::GetErrno();
/* 对得出的错误分情形讨论: */
//test acceptError = EAGAIN;
if (acceptError == EAGAIN)
{
//If it's EAGAIN, there's nothing on the listen queue right now,
//so modwatch and return
/* 在同一socket端口上请求监听指定的EV_RE事件 */
this->RequestEvent(EV_RE);
return;
}
//test acceptError = ENFILE;
//test acceptError = EINTR;
//test acceptError = ENOENT;
//if these error gets returned, we're out of file descriptors,
//the server is going to be failing on sockets, logs, qtgroups and qtuser auth file accesses and movie files. The server is not functional.
// 文件描述符用光,这时服务器会丧失功能,直接退出
if (acceptError == EMFILE || acceptError == ENFILE)
{
QTSSModuleUtils::LogErrorStr(qtssFatalVerbosity, "Out of File Descriptors. Set max connections lower and check for competing usage from other processes. Exiting.");
exit (EXIT_FAILURE);
}
else //假如是其它错误(除EAGAIN\EMFILE\ENFILE以外的),在屏幕上显示错误信息,同时将配对的任务和新建的TCPSocket分别删除和关闭,并返回
{
char errStr[256];
/* 确保末尾null-terminated */
errStr[sizeof(errStr) -1] = 0;
/* 得到指定格式的errStr形如"accept error = 1 '*****error' on socket. Clean up and continue." */
qtss_snprintf(errStr, sizeof(errStr) -1, "accept error = %d '%s' on socket. Clean up and continue.", acceptError, strerror(acceptError));
/* 当条件不成立时,在屏幕上显示错误信息 */
WarnV( (acceptError == 0), errStr);
/**************** 注意:通过子类重载GetSessionTask()使Task和TCPSocket配对 ***********************/
/* 用RTSPListenerSocket::GetSessionTask()获取Session Task和socket,并对结果分析 */
theTask = this->GetSessionTask(&theSocket);
if (theTask == NULL)
{
/* 若没有获取任务,就关闭Socket */
close(osSocket);
}
else
{
theTask->Signal(Task::kKillEvent); // just clean up the task
}
/* 假如RTSPSession中相对应的theSocket非空,就将其状态设为非连接 */
if (theSocket)
theSocket->fState &= ~kConnected; // turn off connected state
return;
}
}/* errors handling */
/* 得到Session Task并作错误处理 */
/* 注意以后的派生类(当是RTSPListenerSocket)去获取任务,并设置好Task和outSocket */
/**************** 注意:通过子类重载GetSessionTask()使Task和TCPSocket配对 ***********************/
theTask = this->GetSessionTask(&theSocket);
/* 如果没有获得任务,将已接受连接的服务器端的osSocket关闭,将服务器上RTSPSession中相对应的theSocket关闭 */
if (theTask == NULL)
{ //this should be a disconnect. do an ioctl call?
close(osSocket);
if (theSocket)
theSocket->fState &= ~kConnected; // turn off connected state
}
/* 假如成功获取到任务,就分别设置这相对应的两个Socket的相关属性 */
else//创建Task成功,接着创建Socket 对象
{
/* 确保接受连接的服务器端Socket不是初始状态 */
Assert(osSocket != EventContext::kInvalidFileDesc);
//set options on the socket
//we are a server, always disable NAGLE ALGORITHM
/* 设置接受连接的服务器端Socket是:非延迟的,保持活跃,指定大小的传送缓存 */
int one = 1;
int err = ::setsockopt(osSocket, IPPROTO_TCP, TCP_NODELAY, (char*)&one, sizeof(int));
AssertV(err == 0, OSThread::GetErrno());
err = ::setsockopt(osSocket, SOL_SOCKET, SO_KEEPALIVE, (char*)&one, sizeof(int));
AssertV(err == 0, OSThread::GetErrno());
/* 设置服务器端传送缓存大小96K字节 */
int sndBufSize = 96L * 1024L;
err = ::setsockopt(osSocket, SOL_SOCKET, SO_SNDBUF, (char*)&sndBufSize, sizeof(int));
AssertV(err == 0, OSThread::GetErrno());
//setup the socket. When there is data on the socket, theTask will get an kReadEvent event
//
/* 用服务器接受连接时新建的Socket和连接它的客户端的IP地址等初始化RTSPSession中的TCPSocket数据成员 */
theSocket->Set(osSocket, &addr);
/* 设置RTSPSession中的TCPSocket为非阻塞的 */
theSocket->InitNonBlocking(osSocket);
/**************** 注意:通过子类重载GetSessionTask()使Task和TCPSocket配对 ***********************/
/* 给RTSPSession中的TCPSocket数据成员设定任务,就是它所在的RTSPSession对象实例,使RTSPSession和TCPSocket紧密配对配对 */
theSocket->SetTask(theTask);
// 完成上述设置后,刚建立连接的这个RTSPSession对象实例的TCPSocket向TaskThread请求读入Client发送的数据
theSocket->RequestEvent(EV_RE);
}
/* 在两次accept()间休眠吗?进行速度调整! */
if (fSleepBetweenAccepts)
{
// We are at our maximum supported sockets
// slow down so we have time to process the active ones (we will respond with errors or service).
// wake up and execute again after sleeping. The timer must be reset each time through
//qtss_printf("TCPListenerSocket slowing down\n");
// 我们已经用光文件描述符,此处需要设置空闲任务计时器,让当前线程休眠1s
this->SetIdleTimer(kTimeBetweenAcceptsInMsec); //sleep 1 second
}
else
{
// sleep until there is a read event outstanding (another client wants to connect)
//qtss_printf("TCPListenerSocket normal speed\n");
//处理完一次连接请求后,服务器端的侦听TCPListenerSocket对象还要接着监听,等待接入新的Client连接
this->RequestEvent(EV_RE);
}
fOutOfDescriptors = false; // always false for now we don't properly handle this elsewhere in the code
}
