cdataadmin.cpp

WINCE下的播放器

// 双缓冲队列之间的互斥操作
// CDataAdmin.cpp
//

#include "stdafx.h"
#include "CDataAdmin.h"

#ifdef _DEBUG
#define new DEBUG_NEW
#undef THIS_FILE
static char THIS_FILE[] = __FILE__;
#endif

///////////////////////////////////////////////////////////////////
CDataAdmin::CDataAdmin()
{
	m_bFlushing = false;
	// Allocate buffers
	m_pMutex = new CMutex(FALSE, NULL);//互斥对象
	for (int i = 0; i < PACK_TOTAL_COUNT; i++)
		PoolList.AddTail(new MPEG1_PACK); 
	// Initialize thread event
	m_hBufEnough = ::CreateEvent(NULL,    // pointer to security attributes 
	    						TRUE,      // flag for manual-reset event 
								FALSE,     // flag for initial state 
								NULL);     // pointer to event-object name
}

CDataAdmin::~CDataAdmin()
{
	// Free data buffers
	PMPEG1_PACK  pData;
	POSITION pos = DataList.GetHeadPosition();//获得队列头位置
	while (pos)
	{
		pData = (PMPEG1_PACK) DataList.GetNext(pos);
		delete pData;
	}
	pos = PoolList.GetHeadPosition();
    while (pos)
	{
		pData = (PMPEG1_PACK) PoolList.GetNext(pos);
		delete pData;
	}
	PoolList.RemoveAll();//删除对列释放内存
	DataList.RemoveAll();

	// Free mutex memory
	if (m_pMutex != NULL)
	{
		delete m_pMutex;
		m_pMutex = NULL;
	}
	if (m_hBufEnough)
	{
		CloseHandle(m_hBufEnough);
		m_hBufEnough = NULL;
	}
}

//重置列表
int CDataAdmin::ResetList(void)
{
	// Initialize the buffer pool
	CSingleLock lock(m_pMutex);
	lock.Lock(1000);
	if (lock.IsLocked())
	{
		while (!DataList.IsEmpty())
		{
			PoolList.AddTail(DataList.RemoveHead());
		}
		lock.Unlock();
	}
	return 1;
}

//获得列表总长度
int CDataAdmin::GetListSize(void)
{
	return (DataList.GetCount() + PoolList.GetCount());
}

// Point to the data list head 
PMPEG1_PACK CDataAdmin::PointToDataHead(void)
{
	if (!DataList.IsEmpty())
		return DataList.GetHead();//获取数据缓冲队列头
	return NULL;
}

// Roll back the data buffer
int CDataAdmin::RollBackDataHead(PMPEG1_PACK pData)//回收读完的数据缓冲队列头
{
	PMPEG1_PACK pPack = GetDataBuffer();
	if (pPack != NULL)
		ReleaseDataBuffer(pPack);
	return 1;
}

// Get a data buffer to read from...
PMPEG1_PACK CDataAdmin::GetDataBuffer(void)
{
	CSingleLock lock(m_pMutex);//互斥对象
	PMPEG1_PACK Result = NULL;
	lock.Lock(1000);//占有互斥
	if (lock.IsLocked())
	{
		if (!DataList.IsEmpty())
			Result = DataList.RemoveHead();//从数据缓冲队列头删除数据包
		lock.Unlock();//释放互斥
	}
	return Result;
}

// Replace the buffer to pool list to receive data...
int CDataAdmin::ReleaseDataBuffer(PMPEG1_PACK pData)//释放数据缓冲队列头
{
	CSingleLock lock(m_pMutex);
	int         nResult = 0;
	lock.Lock(1000);
	if (lock.IsLocked())
	{
		if (pData != NULL)
		{
			PoolList.AddTail(pData);//将读完的数据缓冲队列头加到空闲缓冲队列尾部
			nResult = 1;
		}
		lock.Unlock();
	}
	return nResult;
}

// Get a pool buffer to receive data...
PMPEG1_PACK CDataAdmin::GetPoolBuffer(void)
{
	CSingleLock lock(m_pMutex);
	PMPEG1_PACK Result = NULL;
	lock.Lock(1000);
	if (lock.IsLocked())
	{
		if (!PoolList.IsEmpty())
			Result = PoolList.RemoveHead();//从空闲缓冲队列头删除数据包
		lock.Unlock();
	}	
	return Result;
}

// Place the buffer to data list after receiving data...
int CDataAdmin::ReleasePoolBuffer(PMPEG1_PACK pData)
{
	CSingleLock lock(m_pMutex);
	int         nResult = 0;
	lock.Lock(1000);
	if (lock.IsLocked())
	{
		if (pData != NULL)
		{
			DataList.AddTail(pData);//将空闲缓冲队列头数据包加到数据缓冲队列尾部
			nResult = 1;
		}
		lock.Unlock();
	}
	return nResult;
}

// If no more data available, waiting...
DWORD CDataAdmin::WaitForNext(DWORD  inTimeOut)
{
	//阻塞函数，m_hBufEnough等待对象，inTimeOut等待时间
	return ::WaitForSingleObject(m_hBufEnough, inTimeOut);
}

void CDataAdmin::SetFlushing(bool inFlush)
{
	m_bFlushing = inFlush;
}

bool CDataAdmin::IsFlushing(void)
{
	return m_bFlushing;
}