void CheckErrorLogState()
{
//this function makes sure the logging state is in synch with the preferences.
//extern variable declared in QTSSPreferences.h
QTSServerPrefs* thePrefs = QTSServerInterface::GetServer()->GetPrefs();
//check error log.
if ((NULL == sErrorLog) && (thePrefs->IsErrorLogEnabled()))
{
sErrorLog = NEW QTSSErrorLog();
sErrorLog->EnableLog();
}
if ((NULL != sErrorLog) && (!thePrefs->IsErrorLogEnabled()))
{
sErrorLog->Delete(); //sErrorLog is a task object, so don't delete it directly
sErrorLog = NULL;
}
}
QTSS_Error QTSServer::RereadPrefsService(QTSS_ServiceFunctionArgsPtr /*inArgs*/)
{
//
// This function can only be called safely when the server is completely running.
// Ensuring this is a bit complicated because of preemption. Here's how it's done...
QTSServerInterface* theServer = QTSServerInterface::GetServer();
// This is to make sure this function isn't being called before the server is
// completely started up.
if ((theServer == NULL) || (theServer->GetServerState() != qtssRunningState))
return QTSS_OutOfState;
// Because the server must have started up, and because this object always stays
// around (until the process dies), we can now safely get this object.
QTSServerPrefs* thePrefs = theServer->GetPrefs();
// Grab the prefs mutex. We want to make sure that calls to RereadPrefsService
// are serialized. This also prevents the server from shutting down while in
// this function, because the QTSServer destructor grabs this mutex as well.
OSMutexLocker locker(thePrefs->GetMutex());
// Finally, check the server state again. The state may have changed
// to qtssShuttingDownState or qtssFatalErrorState in this time, though
// at this point we have the prefs mutex, so we are guarenteed that the
// server can't actually shut down anymore
if (theServer->GetServerState() != qtssRunningState)
return QTSS_OutOfState;
// Ok, we're ready to reread preferences now.
//
// Reread preferences
sPrefsSource->Parse();
thePrefs->RereadServerPreferences(true);
// Delete all the streams
QTSSModule** theModule = NULL;
UInt32 theLen = 0;
for (int y = 0; QTSServerInterface::GetServer()->GetValuePtr(qtssSvrModuleObjects, y, (void**)&theModule, &theLen) == QTSS_NoErr; y++)
{
Assert(theModule != NULL);
Assert(theLen == sizeof(QTSSModule*));
(*theModule)->GetPrefsDict()->RereadPreferences();
#if DEBUG
theModule = NULL;
theLen = 0;
#endif
}
//
// Go through each module's prefs object and have those reread as well
//
// Now that we are done rereading the prefs, invoke all modules in the RereadPrefs
// role so they can update their internal prefs caches.
for (UInt32 x = 0; x < QTSServerInterface::GetNumModulesInRole(QTSSModule::kRereadPrefsRole); x++)
{
QTSSModule* theModule = QTSServerInterface::GetModule(QTSSModule::kRereadPrefsRole, x);
(void)theModule->CallDispatch(QTSS_RereadPrefs_Role, NULL);
}
return QTSS_NoErr;
}
/* 设置好各种参数后发信号开始触发RTPSession和发送SR包.播放影片,下面是设置步骤:(1)记录并设置相应的播放时间;(2)设置播放状态,播放标志,更新播放的RTPSession总数;
(3)根据电影的平均比特率设置Client Windows size,重置过缓冲窗;(4)遍历RTPSession中的每个RTPStream,设置打薄参数,重置打薄延迟参数,清除上个Play中重传类的RTP包;(5)假如获得的movie
平均比特率>0,就灵活调整TCP RTSP Socket缓存大小以适应movie比特率,且介于预设的最大值和最小值之间;(6)发信号启动该RTP Session任务; */
QTSS_Error RTPSession::Play(RTSPRequestInterface* request, QTSS_PlayFlags inFlags)
{
//first setup the play associated session interface variables
Assert(request != NULL);
/* 假如没有Module数组,立即返回 */
if (fModule == NULL)
return QTSS_RequestFailed;//Can't play if there are no associated streams
//what time is this play being issued(触发) at? 记录Play触发的时刻
fLastBitRateUpdateTime = fNextSendPacketsTime = fPlayTime = OS::Milliseconds();
/* 假如是第一次播放,同步当前播放时间 */
if (fIsFirstPlay)
fFirstPlayTime = fPlayTime;
/* 获取当前播放时间戳和RTSP Request Header Range中的fStartTime的差值 */
fAdjustedPlayTime = fPlayTime - ((SInt64)(request->GetStartTime() * 1000));
//for RTCP SRs(RTCP发送方报告), we also need to store the play time in NTP
fNTPPlayTime = OS::TimeMilli_To_1900Fixed64Secs(fPlayTime);
//we are definitely playing now, so schedule(调度) the object!
fState = qtssPlayingState;
fIsFirstPlay = false;/* 现在不是第一次播放 */
fPlayFlags = inFlags;/* 是生成SR包还是AppendServerInfo进SR包 */
/* track how many sessions are playing,see QTSServerInterface.h,使fNumRTPPlayingSessions加1 */
QTSServerInterface::GetServer()-> AlterRTPPlayingSessions(1);
/* set Client window size according to bitrate,,参见RTPBandwidthTracker::SetWindowSize() */
//根据电影的平均比特率设置Client Windows size
UInt32 theWindowSize;
/* 获取电影的平均比特率 */
UInt32 bitRate = this->GetMovieAvgBitrate();
/* 假如电影的平均比特率为0或超过1Mbps,就设置Windowsize 为64Kbytes */
if ((bitRate == 0) || (bitRate > QTSServerInterface::GetServer()->GetPrefs()->GetWindowSizeMaxThreshold() * 1024))
theWindowSize = 1024 * QTSServerInterface::GetServer()->GetPrefs()->GetLargeWindowSizeInK();
/* 假如电影的平均比特率超过200kbps,就设置Windowsize 为48Kbytes */
else if (bitRate > QTSServerInterface::GetServer()->GetPrefs()->GetWindowSizeThreshold() * 1024)
theWindowSize = 1024 * QTSServerInterface::GetServer()->GetPrefs()->GetMediumWindowSizeInK();
/* 否则,,就设置Windowsize 为24Kbytes */
else
theWindowSize = 1024 * QTSServerInterface::GetServer()->GetPrefs()->GetSmallWindowSizeInK();
qtss_printf("bitrate = %d, window size = %d\n", bitRate, theWindowSize);
/* 设置Client窗口大小,参见RTPBandwidthTracker::SetWindowSize() */
this->GetBandwidthTracker()->SetWindowSize(theWindowSize);
/* 重置过缓冲窗 */
this->GetOverbufferWindow()->ResetOverBufferWindow();
// Go through all the streams, setting their thinning params
RTPStream** theStream = NULL;
UInt32 theLen = 0;
/* 遍历RTPSession中的每个RTPStream,设置打薄参数,重置打薄延迟参数,清除上个Play中重传类的RTP包 */
for (int x = 0; this->GetValuePtr(qtssCliSesStreamObjects, x, (void**)&theStream, &theLen) == QTSS_NoErr; x++)
{
Assert(theStream != NULL);
Assert(theLen == sizeof(RTPStream*));
if (*theStream != NULL)
{ /* 设置打薄参数 */
(*theStream)->SetThinningParams();
(*theStream)->ResetThinningDelayParams();
// If we are using reliable UDP, then make sure to clear all the packets from the previous play spurt out of the resender
(*theStream)->GetResender()->ClearOutstandingPackets();
}
}
qtss_printf("movie bitrate = %d, window size = %d\n", this->GetMovieAvgBitrate(), theWindowSize);
Assert(this->GetBandwidthTracker()->BytesInList() == 0);
// Set the size of the RTSPSession's send buffer to an appropriate max size
// based on the bitrate of the movie. This has 2 benefits:
// 1) Each socket normally defaults to 32 K. A smaller buffer prevents the
// system from getting buffer starved if lots of clients get flow-controlled
//
// 2) We may need to scale up buffer sizes for high-bandwidth movies in order
// to maximize thruput, and we may need to scale down buffer sizes for low-bandwidth
// movies to prevent us from buffering lots of data that the client can't use
//
// If we don't know any better, assume maximum buffer size.
/* 获取服务器预设值来得到最大TCP缓冲区大小 */
QTSServerPrefs* thePrefs = QTSServerInterface::GetServer()->GetPrefs();
UInt32 theBufferSize = thePrefs->GetMaxTCPBufferSizeInBytes();
#if RTPSESSION_DEBUGGING
qtss_printf("RTPSession GetMovieAvgBitrate %li\n",(SInt32)this->GetMovieAvgBitrate() );
#endif
/* 假如获得的movie平均比特率>0,就灵活调整TCP Socket缓存大小以适应movie比特率,且介于预设的最大值和最小值之间 */
if (this->GetMovieAvgBitrate() > 0)
{
// We have a bit rate... use it.
/* 由电影比特率和预设的缓存秒数(0.5s),得到实际的缓存大小(字节) */
Float32 realBufferSize = (Float32)this->GetMovieAvgBitrate() * thePrefs->GetTCPSecondsToBuffer();
theBufferSize = (UInt32)realBufferSize;
theBufferSize >>= 3; // Divide by 8 to convert from bits to bytes
// Round down to the next lowest power of 2.
/* 四舍五入到最接近的小于它的2的幂,该函数定义见下面 */
/* 将入参变为2的幂的特殊算法:先将入参表示为十六进制,从第29bit位开始从高到底开始走,若遇到值为1的bit位,就返回该bit位值为1,其它31个bit位值全为0的数;若一直没有1，返回0 */
theBufferSize = this->PowerOf2Floor(theBufferSize);
//下面对缓存大小进行保护,使真实值务必介于预设的最大值和最小值之间
// This is how much data we should buffer based on the scaling factor... if it is lower than the min, raise to min
if (theBufferSize < thePrefs->GetMinTCPBufferSizeInBytes())
theBufferSize = thePrefs->GetMinTCPBufferSizeInBytes();
// Same deal for max buffer size
if (theBufferSize > thePrefs->GetMaxTCPBufferSizeInBytes())
theBufferSize = thePrefs->GetMaxTCPBufferSizeInBytes();
}
QTSS_Error LogError(QTSS_RoleParamPtr inParamBlock)
{
Assert(NULL != inParamBlock->errorParams.inBuffer);
if (inParamBlock->errorParams.inBuffer == NULL)
return QTSS_NoErr;
UInt16 verbLvl = (UInt16) inParamBlock->errorParams.inVerbosity;
if (verbLvl >= qtssIllegalVerbosity)
verbLvl = qtssFatalVerbosity;
QTSServerPrefs* thePrefs = QTSServerInterface::GetServer()->GetPrefs();
OSMutexLocker locker(sLogMutex);
if (thePrefs->GetErrorLogVerbosity() >= inParamBlock->errorParams.inVerbosity)
{
size_t inStringLen = ::strlen(inParamBlock->errorParams.inBuffer);
size_t lastStringLen = ::strlen(sLastErrorString);
Bool16 isDuplicate = true;
if (inStringLen > sizeof(sLastErrorString) -1) //truncate to max char buffer subtract \0 terminator
inStringLen = sizeof(sLastErrorString) -1;
if (lastStringLen != inStringLen) //same size?
isDuplicate = false; // different sizes
else if (::strncmp(inParamBlock->errorParams.inBuffer, sLastErrorString, lastStringLen ) != 0 ) //same chars?
isDuplicate = false; //different chars
//is this error message the same as the last one we received?
if ( isDuplicate )
{ //yes? increment count and bail if it's not the first time we've seen this message (otherwise fall thourhg and write it to the log)
sDupErrorStringCount++;
return QTSS_NoErr;
}
else
{
//we have a new error message, write a "previous line" message before writing the new log entry
if ( sDupErrorStringCount >= 1 )
{
/*** clean this up - lots of duplicate code ***/
//The error logger is the bottleneck for any and all messages printed by the server.
//For debugging purposes, these messages can be printed to stdout as well.
if (thePrefs->IsScreenLoggingEnabled())
qtss_printf("--last message repeated %d times\n", sDupErrorStringCount);
CheckErrorLogState();
if (sErrorLog == NULL)
return QTSS_NoErr;
//timestamp the error
char theDateBuffer[QTSSRollingLog::kMaxDateBufferSizeInBytes];
Bool16 result = QTSSRollingLog::FormatDate(theDateBuffer, false);
//for now, just ignore the error.
if (!result)
theDateBuffer[0] = '\0';
char tempBuffer[kMaxLogStringLen];
qtss_snprintf(tempBuffer,sizeof(tempBuffer), "%s: --last message repeated %d times\n", theDateBuffer, sDupErrorStringCount);
sErrorLog->WriteToLog(tempBuffer, kAllowLogToRoll);
sDupErrorStringCount = 0;
}
::strncpy(sLastErrorString, inParamBlock->errorParams.inBuffer, sizeof(sLastErrorString));
sLastErrorString[sizeof(sLastErrorString)-1] = '\0';
}
//The error logger is the bottleneck for any and all messages printed by the server.
//For debugging purposes, these messages can be printed to stdout as well.
if (thePrefs->IsScreenLoggingEnabled())
qtss_printf("%s %s\n", sErrorLevel[verbLvl], inParamBlock->errorParams.inBuffer);
CheckErrorLogState();
if (sErrorLog == NULL)
return QTSS_NoErr;
//timestamp the error
char theDateBuffer[QTSSRollingLog::kMaxDateBufferSizeInBytes];
Bool16 result = QTSSRollingLog::FormatDate(theDateBuffer, false);
//for now, just ignore the error.
if (!result)
theDateBuffer[0] = '\0';
char tempBuffer[kMaxLogStringLen];
qtss_snprintf(tempBuffer,sizeof(tempBuffer), "%s: %s %s\n", theDateBuffer, sErrorLevel[verbLvl], inParamBlock->errorParams.inBuffer);
tempBuffer[sizeof(tempBuffer)-2] = '\n'; //make sure the entry has a line feed before the \0 terminator
tempBuffer[sizeof(tempBuffer)-1] = '\0'; //make sure it is 0 terminated.
sErrorLog->WriteToLog(tempBuffer, kAllowLogToRoll);
}
return QTSS_NoErr;
}
QTSS_Error RTPSession::Play(RTSPRequestInterface* request, QTSS_PlayFlags inFlags)
{
//first setup the play associated session interface variables
Assert(request != NULL);
if (fModule == NULL)
return QTSS_RequestFailed;//Can't play if there are no associated streams
//what time is this play being issued at?
fLastBitRateUpdateTime = fNextSendPacketsTime = fPlayTime = OS::Milliseconds();
if (fIsFirstPlay)
fFirstPlayTime = fPlayTime;
fAdjustedPlayTime = fPlayTime - ((SInt64)(request->GetStartTime() * 1000));
//for RTCP SRs, we also need to store the play time in NTP
fNTPPlayTime = OS::TimeMilli_To_1900Fixed64Secs(fPlayTime);
//we are definitely playing now, so schedule the object!
fState = qtssPlayingState;
fIsFirstPlay = false;
fPlayFlags = inFlags;
QTSServerInterface::GetServer()-> AlterRTPPlayingSessions(1);
UInt32 theWindowSize;
UInt32 bitRate = this->GetMovieAvgBitrate();
if ((bitRate == 0) || (bitRate > QTSServerInterface::GetServer()->GetPrefs()->GetWindowSizeMaxThreshold() * 1024))
theWindowSize = 1024 * QTSServerInterface::GetServer()->GetPrefs()->GetLargeWindowSizeInK();
else if (bitRate > QTSServerInterface::GetServer()->GetPrefs()->GetWindowSizeThreshold() * 1024)
theWindowSize = 1024 * QTSServerInterface::GetServer()->GetPrefs()->GetMediumWindowSizeInK();
else
theWindowSize = 1024 * QTSServerInterface::GetServer()->GetPrefs()->GetSmallWindowSizeInK();
// qtss_printf("bitrate = %d, window size = %d\n", bitRate, theWindowSize);
this->GetBandwidthTracker()->SetWindowSize(theWindowSize);
this->GetOverbufferWindow()->ResetOverBufferWindow();
//
// Go through all the streams, setting their thinning params
RTPStream** theStream = NULL;
UInt32 theLen = 0;
for (int x = 0; this->GetValuePtr(qtssCliSesStreamObjects, x, (void**)&theStream, &theLen) == QTSS_NoErr; x++)
{
Assert(theStream != NULL);
Assert(theLen == sizeof(RTPStream*));
if (*theStream != NULL)
{
(*theStream)->SetThinningParams();
(*theStream)->ResetThinningDelayParams();
//
// If we are using reliable UDP, then make sure to clear all the packets
// from the previous play spurt out of the resender
(*theStream)->GetResender()->ClearOutstandingPackets();
}
}
// qtss_printf("movie bitrate = %d, window size = %d\n", this->GetMovieAvgBitrate(), theWindowSize);
Assert(this->GetBandwidthTracker()->BytesInList() == 0);
// Set the size of the RTSPSession's send buffer to an appropriate max size
// based on the bitrate of the movie. This has 2 benefits:
// 1) Each socket normally defaults to 32 K. A smaller buffer prevents the
// system from getting buffer starved if lots of clients get flow-controlled
//
// 2) We may need to scale up buffer sizes for high-bandwidth movies in order
// to maximize thruput, and we may need to scale down buffer sizes for low-bandwidth
// movies to prevent us from buffering lots of data that the client can't use
// If we don't know any better, assume maximum buffer size.
QTSServerPrefs* thePrefs = QTSServerInterface::GetServer()->GetPrefs();
UInt32 theBufferSize = thePrefs->GetMaxTCPBufferSizeInBytes();
#if RTPSESSION_DEBUGGING
qtss_printf("RTPSession GetMovieAvgBitrate %li\n",(SInt32)this->GetMovieAvgBitrate() );
#endif
if (this->GetMovieAvgBitrate() > 0)
{
// We have a bit rate... use it.
Float32 realBufferSize = (Float32)this->GetMovieAvgBitrate() * thePrefs->GetTCPSecondsToBuffer();
theBufferSize = (UInt32)realBufferSize;
theBufferSize >>= 3; // Divide by 8 to convert from bits to bytes
// Round down to the next lowest power of 2.
theBufferSize = this->PowerOf2Floor(theBufferSize);
// This is how much data we should buffer based on the scaling factor... if it is
// lower than the min, raise to min
if (theBufferSize < thePrefs->GetMinTCPBufferSizeInBytes())
theBufferSize = thePrefs->GetMinTCPBufferSizeInBytes();
// Same deal for max buffer size
if (theBufferSize > thePrefs->GetMaxTCPBufferSizeInBytes())
theBufferSize = thePrefs->GetMaxTCPBufferSizeInBytes();
}