darwin之RTSPSession Run的状态机流程
来源:互联网 发布:geogebra mac 编辑:程序博客网 时间:2024/05/17 14:18
在前几篇文章说到的EventThread事件,我们可以知道EventThread这个线程负责端口的监听,监听的事件主要有两类,第一类是有新的RTSP连接请求事 件,第二类就是在原来已经连接的RTSP连接请求上响应消息事件,比如PALY,Setup,Describe等等。文章参考了http://blog.csdn.net/longlong530/article/details/43451717的文章在这里标示感谢!
那么对于监听到的事件,应该怎么样处理了,就在这个RTSPSession的这个方法中,我们详细的分析下这个方法。
主要看这个RTSPSession::Run()方法 在Run的switch这个语句中有一些状态的判断。
1. 状态机 kReadingFirstRequest
通过fInputStream.ReadRequest()调用Session绑定的socket,获取数据,该函数有两个返回码:
a) QTSS_NoErr,意味着已经收到该socket的完整数据,但是没有收集到本次请求的全部数据,这时需要接着请求监听读事件,获取更多数据组成完整的RTSP请求消息。
b) QTSS_RequestArrived,意味着此时已经收到完整请求的报文,可以正常进入下一状态机了。
c) E2BIG,表示缓存区已经溢出,默认缓存区的大小为( kRequestBufferSizeInBytes = 4096),进入kHaveNonTunnelMessage状态机,然后在改状态机下响应错误
case kReadingFirstRequest: { if ((err = fInputStream.ReadRequest()) == QTSS_NoErr) { // If the RequestStream returns QTSS_NoErr, it means // that we've read all outstanding data off the socket, // and still don't have a full request. Wait for more data. //+rt use the socket that reads the data, may be different now. fInputSocketP->RequestEvent(EV_RE); return 0; } if ((err != QTSS_RequestArrived) && (err != E2BIG)) { // Any other error implies that the client has gone away. At this point, // we can't have 2 sockets, so we don't need to do the "half closed" check // we do below Assert(err > 0); Assert(!this->IsLiveSession()); break; } if (err == QTSS_RequestArrived) fState = kHTTPFilteringRequest; // If we get an E2BIG, it means our buffer was overfilled. // In that case, we can just jump into the following state, and // the code their does a check for this error and returns an error. if (err == E2BIG) fState = kHaveNonTunnelMessage; }
3. 状态机 kHaveNonTunnelMessage
进入此状态,说明请求报文格式是正确的,请求已进入受理状态,具体操作步骤如下:
a) 创建RTSPRequest对象,用于解析RTSP消息;
b) 此状态中对fReadMutex,fSessionMutex进行加锁,禁止在处理报文的过程中接收以RTP Interleaved接收RTP数据或者发出RTSP响应报文
c) 对错误码E2BIG、QTSS_BadArgument进行处理,响应qtssClientBadRequest;
d) 将状态机跳转到kFilteringRequest下;
case kHaveNonTunnelMessage: { // should only get here when fInputStream has a full message built. Assert( fInputStream.GetRequestBuffer() ); Assert(fRequest == NULL); fRequest = NEW RTSPRequest(this); fRoleParams.rtspRequestParams.inRTSPRequest = fRequest; fRoleParams.rtspRequestParams.inRTSPHeaders = fRequest->GetHeaderDictionary(); // We have an RTSP request and are about to begin processing. We need to // make sure that anyone sending interleaved data on this session won't // be allowed to do so until we are done sending our response // We also make sure that a POST session can't snarf in while we're // processing the request. fReadMutex.Lock(); fSessionMutex.Lock(); // The fOutputStream's fBytesWritten counter is used to // count the # of bytes for this RTSP response. So, at // this point, reset it to 0 (we can then just let it increment // until the next request comes in) fOutputStream.ResetBytesWritten(); // Check for an overfilled buffer, and return an error. if (err == E2BIG) { (void)QTSSModuleUtils::SendErrorResponse(fRequest, qtssClientBadRequest, qtssMsgRequestTooLong); fState = kPostProcessingRequest; break; } // Check for a corrupt base64 error, return an error if (err == QTSS_BadArgument) { (void)QTSSModuleUtils::SendErrorResponse(fRequest, qtssClientBadRequest, qtssMsgBadBase64); fState = kPostProcessingRequest; break; } Assert(err == QTSS_RequestArrived); fState = kFilteringRequest; // Note that there is no break here. We'd like to continue onto the next // state at this point. This goes for every case in this case statement }
4. 状态机kFilteringRequest
a) 刷新超时任务fTimeoutTask,运转RTSP会话的超时机制。
b) 通过fIsDataPacket属性进行判断当前数据是否是一个数据包,而不是一个信令消息。该属性判断方法在RTSPRequestStream::ReadRequest()中。RTP包格式以$字符开头,后面紧跟着一个字节是信道标示符,后面两个字节是数字长度,Darwin就用这个字符区分是否为数据包。
c) 这时第一次开始调用module了,角色为kRTSPFilterRole。注册了该角色模块只有一个QTSSRefMovieModule,
d) SetupRequest(),解析RTSP消息,同时创建一个客户会话(RTPSession),和产生当前请求的客户端连接相关联,这个会话会一直保持,直到客户端的流播放结束。
注意:服务器根据被调用的模块是否对请求做了应答来决定后面的调用(方法HasResponseBeenSent()),如果注册了RTSP Filter Role的某一个模块在被调用的时候对请求作出了应答,服务器将立即调用注册了RTSPPostprocessorRole的模块,不再调用其他尚未调用的注册了RTSP Filter Role的模块,否则服务器调用其它注册了RTSP Filter Role的模块。
case kFilteringRequest: { // We received something so auto refresh // The need to auto refresh is because the api doesn't allow a module to refresh at this point // fTimeoutTask.RefreshTimeout(); // // Before we even do this, check to see if this is a *data* packet, // in which case this isn't an RTSP request, so we don't need to go // through any of the remaining steps if (fInputStream.IsDataPacket()) // can this interfere with MP3? { this->HandleIncomingDataPacket(); fState = kCleaningUp; break; } // // In case a module wants to replace the request char* theReplacedRequest = NULL; char* oldReplacedRequest = NULL; // Setup the filter param block QTSS_RoleParams theFilterParams; theFilterParams.rtspFilterParams.inRTSPSession = this; theFilterParams.rtspFilterParams.inRTSPRequest = fRequest; theFilterParams.rtspFilterParams.outNewRequest = &theReplacedRequest; // Invoke filter modules numModules = QTSServerInterface::GetNumModulesInRole(QTSSModule::kRTSPFilterRole); for (; (fCurrentModule < numModules) && ((!fRequest->HasResponseBeenSent()) || fModuleState.eventRequested); fCurrentModule++) { fModuleState.eventRequested = false; fModuleState.idleTime = 0; if (fModuleState.globalLockRequested ) { fModuleState.globalLockRequested = false; fModuleState.isGlobalLocked = true; } theModule = QTSServerInterface::GetModule(QTSSModule::kRTSPFilterRole, fCurrentModule); (void)theModule->CallDispatch(QTSS_RTSPFilter_Role, &theFilterParams); fModuleState.isGlobalLocked = false; // If this module has requested an event, return and wait for the event to transpire if (fModuleState.globalLockRequested) // call this request back locked return this->CallLocked(); if (fModuleState.eventRequested) { this->ForceSameThread(); // We are holding mutexes, so we need to force // the same thread to be used for next Run() return fModuleState.idleTime; // If the module has requested idle time... } // // Check to see if this module has replaced the request. If so, check // to see if there is an old replacement that we should delete if (theReplacedRequest != NULL) { if (oldReplacedRequest != NULL) delete [] oldReplacedRequest; fRequest->SetVal(qtssRTSPReqFullRequest, theReplacedRequest, ::strlen(theReplacedRequest)); oldReplacedRequest = theReplacedRequest; theReplacedRequest = NULL; } } fCurrentModule = 0; if (fRequest->HasResponseBeenSent()) { fState = kPostProcessingRequest; break; } if (fSentOptionsRequest && this->ParseOptionsResponse()) { fRoundTripTime = (SInt32) (OS::Milliseconds() - fOptionsRequestSendTime); //qtss_printf("RTSPSession::Run RTT time = %"_S32BITARG_" msec\n", fRoundTripTime); fState = kSendingResponse; break; } else // Otherwise, this is a normal request, so parse it and get the RTPSession. this->SetupRequest(); // This might happen if there is some syntax or other error, // or if it is an OPTIONS request if (fRequest->HasResponseBeenSent()) { fState = kPostProcessingRequest; break; } fState = kRoutingRequest; }
5. 状态机kPreprocessingRequest
遍历调用所有注册了QTSS_RTSPPreProcessor_Role角色的模块。在这个角色模式下,分别处理了每种RTSP消息,比如本次的点播请求的Describe、Setup、Play指令,模块中针对各种消息都有对应的单独函数处理。 处理完每次RTSP请求后即进入下一状态kPostProcessingRequest,待下轮循环进入本状态机再处理下一个RTSP消息。
case kPreprocessingRequest: { // Invoke preprocessor modules numModules = QTSServerInterface::GetNumModulesInRole(QTSSModule::kRTSPPreProcessorRole); { // Manipulation of the RTPSession from the point of view of // a module is guarenteed to be atomic by the API. Assert(fRTPSession != NULL); OSMutexLocker locker(fRTPSession->GetSessionMutex()); for (; (fCurrentModule < numModules) && ((!fRequest->HasResponseBeenSent()) || fModuleState.eventRequested); fCurrentModule++) { fModuleState.eventRequested = false; fModuleState.idleTime = 0; if (fModuleState.globalLockRequested ) { fModuleState.globalLockRequested = false; fModuleState.isGlobalLocked = true; } theModule = QTSServerInterface::GetModule(QTSSModule::kRTSPPreProcessorRole, fCurrentModule); (void)theModule->CallDispatch(QTSS_RTSPPreProcessor_Role, &fRoleParams); fModuleState.isGlobalLocked = false; // The way the API is set up currently, the first module that adds a stream // to the session is responsible for sending RTP packets for the session. if (fRTPSession->HasAnRTPStream() && (fRTPSession->GetPacketSendingModule() == NULL)) fRTPSession->SetPacketSendingModule(theModule); if (fModuleState.globalLockRequested) // call this request back locked return this->CallLocked(); // If this module has requested an event, return and wait for the event to transpire if (fModuleState.eventRequested) { this->ForceSameThread(); // We are holding mutexes, so we need to force // the same thread to be used for next Run() return fModuleState.idleTime; // If the module has requested idle time... } } } fCurrentModule = 0; if (fRequest->HasResponseBeenSent()) { fState = kPostProcessingRequest; break; } fState = kProcessingRequest; }
今天详细的看了下RTSPSession的会话处理代码,该模块主要是Run方法内对会话的状态机进行管理,实现对RTSP会话的处理,我以点播Movie文件夹下的视频文件为例,深入的学习了(Describe、Setup、Play的点播流程),并按照状态机的处理顺序对他们进行一一解析,如下:
【转载请注明出处】:http://blog.csdn.net/longlong530
1. 状态机 kReadingFirstRequest
通过fInputStream.ReadRequest()调用Session绑定的socket,获取数据,该函数有两个返回码:
a) QTSS_NoErr,意味着已经收到该socket的完整数据,但是没有收集到本次请求的全部数据,这时需要接着请求监听读事件,获取更多数据组成完整的RTSP请求消息。
b) QTSS_RequestArrived,意味着此时已经收到完整请求的报文,可以正常进入下一状态机了。
c) E2BIG,表示缓存区已经溢出,默认缓存区的大小为( kRequestBufferSizeInBytes = 4096),进入kHaveNonTunnelMessage状态机,然后在改状态机下响应错误
2. 状态机 kHTTPFilteringRequest
该状态机下检测是否为RTSP-over-HTTP tunneling,并直接切换到kHaveNonTunnelMessage状态。由于与RTSP无关,该部分的函数PreFilterForHTTPProxyTunnel(),暂时就不深入研究了。
3. 状态机 kHaveNonTunnelMessage
进入此状态,说明请求报文格式是正确的,请求已进入受理状态,具体操作步骤如下:
a) 创建RTSPRequest对象,用于解析RTSP消息;
b) 此状态中对fReadMutex,fSessionMutex进行加锁,禁止在处理报文的过程中接收以RTP Interleaved接收RTP数据或者发出RTSP响应报文
c) 对错误码E2BIG、QTSS_BadArgument进行处理,响应qtssClientBadRequest;
d) 将状态机跳转到kFilteringRequest下;
4. 状态机kFilteringRequest
a) 刷新超时任务fTimeoutTask,运转RTSP会话的超时机制。
b) 通过fIsDataPacket属性进行判断当前数据是否是一个数据包,而不是一个信令消息。该属性判断方法在RTSPRequestStream::ReadRequest()中。RTP包格式以$字符开头,后面紧跟着一个字节是信道标示符,后面两个字节是数字长度,Darwin就用这个字符区分是否为数据包。
c) 这时第一次开始调用module了,角色为kRTSPFilterRole。注册了该角色模块只有一个QTSSRefMovieModule,
d) SetupRequest(),解析RTSP消息,同时创建一个客户会话(RTPSession),和产生当前请求的客户端连接相关联,这个会话会一直保持,直到客户端的流播放结束。
注意:服务器根据被调用的模块是否对请求做了应答来决定后面的调用(方法HasResponseBeenSent()),如果注册了RTSP Filter Role的某一个模块在被调用的时候对请求作出了应答,服务器将立即调用注册了RTSPPostprocessorRole的模块,不再调用其他尚未调用的注册了RTSP Filter Role的模块,否则服务器调用其它注册了RTSP Filter Role的模块。
5. 状态机kRoutingRequest
这里只走到一个模块QTSSReflectorModule中,调用其RedirectBroadcast()方法,主要是增加两个字段到inParams->inRTSPRequest中。key值分别为qtssRTSPReqRootDir、qtssRTSPReqFilePath。 配置文件中如下两个字段并未设置,上面设置的路径逻辑就不会走到。 最后跳转到鉴权状态机kAuthenticatingRequest
6. 状态机kAuthenticatingRequest、kAuthorizingRequest。
这里对鉴权方面后续会单独深入研究,目前项目也不涉及。 鉴权完成后,跳转到核心的状态机kPreprocessingRequest中。
7. 状态机kPreprocessingRequest
遍历调用所有注册了QTSS_RTSPPreProcessor_Role角色的模块。在这个角色模式下,分别处理了每种RTSP消息,比如本次的点播请求的Describe、Setup、Play指令,模块中针对各种消息都有对应的单独函数处理。 处理完每次RTSP请求后即进入下一状态kPostProcessingRequest,待下轮循环进入本状态机再处理下一个RTSP消息。
(以下状态后续补充)
8. 状态机kPostProcessingRequest
9. 状态机kSendingResponse
10.状态机kCleaningUp
清理数据,同时释放kHaveNonTunnelMessage状态中获取的锁。
11.状态机kReadingRequest【转载请注明出处】:http://blog.csdn.net/longlong530
简单的画了下RTSPSession的状态机流程,如下图:
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