AudioFileReaderThread.cpp

/*
    SDL - Simple DirectMedia Layer
    Copyright (C) 1997, 1998, 1999, 2000, 2001, 2002  Sam Lantinga

    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Library General Public
    License as published by the Free Software Foundation; either
    version 2 of the License, or (at your option) any later version.

    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Library General Public License for more details.

    You should have received a copy of the GNU Library General Public
    License along with this library; if not, write to the Free
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

    Sam Lantinga
    slouken@libsdl.org

    This file based on Apple sample code. We haven't changed the file name, 
    so if you want to see the original search for it on apple.com/developer
*/

//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
// AudioFileReaderThread.cpp
//
#include "AudioFilePlayer.h"
#include <mach/mach.h> //used for setting policy of thread
#include "CAGuard.h"
#include <pthread.h>

#include <list>

class FileReaderThread {
public:
	FileReaderThread ();

	CAGuard&					GetGuard() { return mGuard; }
    
	void						AddReader();
	
	void						RemoveReader (const AudioFileReaderThread* inItem);
		
		// returns true if succeeded
	bool						TryNextRead (AudioFileReaderThread* inItem)
	{
		bool didLock = false;
		bool succeeded = false;
		if (mGuard.Try (didLock))
		{
			mFileData.push_back (inItem);
			mGuard.Notify();
			succeeded = true;

			if (didLock)
				mGuard.Unlock();
		}
				
		return succeeded;
	}	
	
    int		mThreadShouldDie;
    
private:
	typedef	std::list<AudioFileReaderThread*> FileData;

	CAGuard				mGuard;
	UInt32				mThreadPriority;
	
	int					mNumReaders;	
	FileData			mFileData;


	void 						ReadNextChunk ();
	
	void 						StartFixedPriorityThread ();
    static UInt32				GetThreadBasePriority (pthread_t inThread);
    
	static void*				DiskReaderEntry (void *inRefCon);
};

FileReaderThread::FileReaderThread ()
	  : mThreadPriority (62),
		mNumReaders (0)
{
}

void	FileReaderThread::AddReader()
{
	if (mNumReaders == 0)
	{
		mThreadShouldDie = false;
	
		StartFixedPriorityThread ();
	}
	mNumReaders++;
}

void	FileReaderThread::RemoveReader (const AudioFileReaderThread* inItem)
{
	if (mNumReaders > 0)
	{
		CAGuard::Locker fileReadLock (mGuard);

		for (FileData::iterator iter = mFileData.begin(); iter != mFileData.end(); ++iter)
		{
			if ((*iter) == inItem) {	
				mFileData.erase (iter);
			}
		}
		
		if (--mNumReaders == 0) {
			mThreadShouldDie = true;
			mGuard.Notify(); // wake up thread so it will quit
            mGuard.Wait();   // wait for thread to die
		}
	}	
}

void 	FileReaderThread::StartFixedPriorityThread ()
{
	pthread_attr_t		theThreadAttrs;
	pthread_t			pThread;
	
	OSStatus result = pthread_attr_init(&theThreadAttrs);
		THROW_RESULT("pthread_attr_init - Thread attributes could not be created.")
	
	result = pthread_attr_setdetachstate(&theThreadAttrs, PTHREAD_CREATE_DETACHED);
		THROW_RESULT("pthread_attr_setdetachstate - Thread attributes could not be detached.")
	
	result = pthread_create (&pThread, &theThreadAttrs, DiskReaderEntry, this);
		THROW_RESULT("pthread_create - Create and start the thread.")
	
	pthread_attr_destroy(&theThreadAttrs);
    
	// we've now created the thread and started it
	// we'll now set the priority of the thread to the nominated priority
	// and we'll also make the thread fixed
    thread_extended_policy_data_t		theFixedPolicy;
    thread_precedence_policy_data_t		thePrecedencePolicy;
    SInt32								relativePriority;
    
    // make thread fixed
    theFixedPolicy.timeshare = false;	// set to true for a non-fixed thread
    result = thread_policy_set (pthread_mach_thread_np(pThread), THREAD_EXTENDED_POLICY, (thread_policy_t)&theFixedPolicy, THREAD_EXTENDED_POLICY_COUNT);
        THROW_RESULT("thread_policy - Couldn't set thread as fixed priority.")
    // set priority
    // precedency policy's "importance" value is relative to spawning thread's priority
    relativePriority = mThreadPriority - FileReaderThread::GetThreadBasePriority (pthread_self());
        
    thePrecedencePolicy.importance = relativePriority;
    result = thread_policy_set (pthread_mach_thread_np(pThread), THREAD_PRECEDENCE_POLICY, (thread_policy_t)&thePrecedencePolicy, THREAD_PRECEDENCE_POLICY_COUNT);
        THROW_RESULT("thread_policy - Couldn't set thread priority.")
}

UInt32	FileReaderThread::GetThreadBasePriority (pthread_t inThread)
{
    thread_basic_info_data_t			threadInfo;
	policy_info_data_t					thePolicyInfo;
	unsigned int						count;
    
    // get basic info
    count = THREAD_BASIC_INFO_COUNT;
    thread_info (pthread_mach_thread_np (inThread), THREAD_BASIC_INFO, (integer_t*)&threadInfo, &count);
    
	switch (threadInfo.policy) {
		case POLICY_TIMESHARE:
			count = POLICY_TIMESHARE_INFO_COUNT;
			thread_info(pthread_mach_thread_np (inThread), THREAD_SCHED_TIMESHARE_INFO, (integer_t*)&(thePolicyInfo.ts), &count);
			return thePolicyInfo.ts.base_priority;
            break;
            
        case POLICY_FIFO:
			count = POLICY_FIFO_INFO_COUNT;
			thread_info(pthread_mach_thread_np (inThread), THREAD_SCHED_FIFO_INFO, (integer_t*)&(thePolicyInfo.fifo), &count);
            if (thePolicyInfo.fifo.depressed) {
                return thePolicyInfo.fifo.depress_priority;
            } else {
                return thePolicyInfo.fifo.base_priority;
            }
            break;
            
		case POLICY_RR:
			count = POLICY_RR_INFO_COUNT;
			thread_info(pthread_mach_thread_np (inThread), THREAD_SCHED_RR_INFO, (integer_t*)&(thePolicyInfo.rr), &count);
			if (thePolicyInfo.rr.depressed) {
                return thePolicyInfo.rr.depress_priority;
            } else {
                return thePolicyInfo.rr.base_priority;
            }
            break;
	}
    
    return 0;
}

void	*FileReaderThread::DiskReaderEntry (void *inRefCon)
{
	FileReaderThread *This = (FileReaderThread *)inRefCon;
	This->ReadNextChunk();
	#if DEBUG
	printf ("finished with reading file\n");
	#endif
	
	return 0;
}

void 	FileReaderThread::ReadNextChunk ()
{
	OSStatus result;
	UInt32	dataChunkSize;
	AudioFileReaderThread* theItem = 0;

	for (;;) 
	{
		{ // this is a scoped based lock
			CAGuard::Locker fileReadLock (mGuard);
			
			if (this->mThreadShouldDie) {
            
                mGuard.Notify();
                return;
            }
			
			if (mFileData.empty())
			{
				mGuard.Wait();
			}
			            
			// kill thread
			if (this->mThreadShouldDie) {
            
                mGuard.Notify();
                return;
            }

			theItem = mFileData.front();
			mFileData.pop_front();
		}
	
		if ((theItem->mFileLength - theItem->mReadFilePosition) < theItem->mChunkSize)
			dataChunkSize = theItem->mFileLength - theItem->mReadFilePosition;
		else
			dataChunkSize = theItem->mChunkSize;
		
			// this is the exit condition for the thread
		if (dataChunkSize == 0) {
			theItem->mFinishedReadingData = true;
			continue;
		}
			// construct pointer
		char* writePtr = const_cast<char*>(theItem->GetFileBuffer() + 
								(theItem->mWriteToFirstBuffer ? 0 : theItem->mChunkSize));
	
/*
        printf ("AudioFileReadBytes: theItem=%.8X fileID=%.8X pos=%.8X sz=%.8X flen=%.8X ptr=%.8X\n", 
            (unsigned int)theItem, (unsigned int)theItem->GetFileID(),
            (unsigned int)theItem->mReadFilePosition, (unsigned int)dataChunkSize, 
            (unsigned int)theItem->mFileLength, (unsigned int)writePtr);
*/            
		result = AudioFileReadBytes (theItem->GetFileID(), 
									false,
									theItem->mReadFilePosition, 
									&dataChunkSize, 
									writePtr);
		if (result) {
			theItem->GetParent().DoNotification(result);
			continue;
		}
		
		if (dataChunkSize != theItem->mChunkSize)
		{
			writePtr += dataChunkSize;

            // can't exit yet.. we still have to pass the partial buffer back
            memset (writePtr, 0, (theItem->mChunkSize - dataChunkSize));
        }
		
		theItem->mWriteToFirstBuffer = !theItem->mWriteToFirstBuffer;	// switch buffers
		
		theItem->mReadFilePosition += dataChunkSize;		// increment count
	}
}


static FileReaderThread sReaderThread;

AudioFileReaderThread::AudioFileReaderThread (AudioFilePlayer	&inParent, 
										AudioFileID 			&inFile, 
										SInt64 					inFileLength,
										UInt32					inChunkSize)
	: AudioFileManager (inParent, inFile),
	  mChunkSize (inChunkSize),
	  mFileLength (inFileLength),
	  mReadFilePosition (0),
	  mWriteToFirstBuffer (false),
	  mFinishedReadingData (false),

	  mLockUnsuccessful (false),
	  mIsEngaged (false)
{
	mFileBuffer = (char*) malloc (mChunkSize * 2);
    assert (mFileBuffer != NULL);
}

void	AudioFileReaderThread::DoConnect ()
{
	if (!mIsEngaged)
	{
		//mReadFilePosition = 0;
		mFinishedReadingData = false;

		mNumTimesAskedSinceFinished = -1;
		mLockUnsuccessful = false;
		
		UInt32 dataChunkSize;
        
        if ((mFileLength - mReadFilePosition) < mChunkSize)
			dataChunkSize = mFileLength - mReadFilePosition;
		else
			dataChunkSize = mChunkSize;
        
		OSStatus result = AudioFileReadBytes ( mAudioFileID, 
												false, 
												mReadFilePosition, 
												&dataChunkSize, 
												mFileBuffer);
            THROW_RESULT("AudioFileReadBytes")
            
		mReadFilePosition += dataChunkSize;
				
		mWriteToFirstBuffer = false;
		mReadFromFirstBuffer = true;

		sReaderThread.AddReader();
		
		mIsEngaged = true;
	}
	else
		throw static_cast<OSStatus>(-1); //thread has already been started
}

void	AudioFileReaderThread::Disconnect ()
{
	if (mIsEngaged) 
	{
		sReaderThread.RemoveReader (this);
		mIsEngaged = false;
	}
}

OSStatus AudioFileReaderThread::GetFileData (void** inOutData, UInt32 *inOutDataSize)
{
	if (mFinishedReadingData) 
	{
		++mNumTimesAskedSinceFinished;
		*inOutDataSize = 0;
		*inOutData = 0;
		return noErr;
	}
	
	if (mReadFromFirstBuffer == mWriteToFirstBuffer) {
		#if DEBUG
		printf ("* * * * * * * Can't keep up with reading file:%ld\n", mParent.GetBusNumber());
		#endif
		
		mParent.DoNotification (kAudioFilePlayErr_FilePlayUnderrun);
		*inOutDataSize = 0;
		*inOutData = 0;
	} else {
		*inOutDataSize = mChunkSize;
		*inOutData = mReadFromFirstBuffer ? mFileBuffer : (mFileBuffer + mChunkSize);
	}

	mLockUnsuccessful = !sReaderThread.TryNextRead (this);
	
	mReadFromFirstBuffer = !mReadFromFirstBuffer;

	return noErr;
}

void 	AudioFileReaderThread::AfterRender ()
{
	if (mNumTimesAskedSinceFinished > 0)
	{
		bool didLock = false;
		if (sReaderThread.GetGuard().Try (didLock)) {
			mParent.DoNotification (kAudioFilePlay_FileIsFinished);
			if (didLock)
				sReaderThread.GetGuard().Unlock();
		}
	}

	if (mLockUnsuccessful)
		mLockUnsuccessful = !sReaderThread.TryNextRead (this);
}

void 	AudioFileReaderThread::SetPosition (SInt64 pos)
{
    if (pos < 0 || pos >= mFileLength) {
        SDL_SetError ("AudioFileReaderThread::SetPosition - position invalid: %d filelen=%d\n", 
            (unsigned int)pos, (unsigned int)mFileLength);
        pos = 0;
    }
        
    mReadFilePosition = pos;
}
    
void 	AudioFileReaderThread::SetEndOfFile (SInt64 pos)
{
    if (pos <= 0 || pos > mFileLength) {
        SDL_SetError ("AudioFileReaderThread::SetEndOfFile - position beyond actual eof\n");
        pos = mFileLength;
    }
    
    mFileLength = pos;
}