buffer.h

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/*****************************************************************************
written by
   Yunhong Gu, last updated 05/05/2009
*****************************************************************************/

#ifndef __UDT_BUFFER_H__
#define __UDT_BUFFER_H__


#include "udt.h"
#include "list.h"
#include "queue.h"
#include <fstream>

class CSndBuffer
{
public:
   CSndBuffer(int size = 32, int mss = 1500);
   ~CSndBuffer();

      // Functionality:
      //    Insert a user buffer into the sending list.
      // Parameters:
      //    0) [in] data: pointer to the user data block.
      //    1) [in] len: size of the block.
      //    2) [in] ttl: time to live in milliseconds
      //    3) [in] order: if the block should be delivered in order, for DGRAM only
      // Returned value:
      //    None.

   void addBuffer(const char* data, int len, int ttl = -1, bool order = false);

      // Functionality:
      //    Read a block of data from file and insert it into the sending list.
      // Parameters:
      //    0) [in] ifs: input file stream.
      //    1) [in] len: size of the block.
      // Returned value:
      //    actual size of data added from the file.

   int addBufferFromFile(std::fstream& ifs, int len);

      // Functionality:
      //    Find data position to pack a DATA packet from the furthest reading point.
      // Parameters:
      //    0) [out] data: the pointer to the data position.
      //    1) [out] msgno: message number of the packet.
      // Returned value:
      //    Actual length of data read.

   int readData(char** data, int32_t& msgno);

      // Functionality:
      //    Find data position to pack a DATA packet for a retransmission.
      // Parameters:
      //    0) [out] data: the pointer to the data position.
      //    1) [in] offset: offset from the last ACK point.
      //    2) [out] msgno: message number of the packet.
      //    3) [out] msglen: length of the message
      // Returned value:
      //    Actual length of data read.

   int readData(char** data, const int offset, int32_t& msgno, int& msglen);

      // Functionality:
      //    Update the ACK point and may release/unmap/return the user data according to the flag.
      // Parameters:
      //    0) [in] offset: number of packets acknowledged.
      // Returned value:
      //    None.

   void ackData(int offset);

      // Functionality:
      //    Read size of data still in the sending list.
      // Parameters:
      //    None.
      // Returned value:
      //    Current size of the data in the sending list.

   int getCurrBufSize() const;

private:
   void increase();

private:
   std::mutex m_BufLock;           // used to synchronize buffer operation

   struct Block
   {
      char* m_pcData;                   // pointer to the data block
      int m_iLength;                    // length of the block

      int32_t m_iMsgNo;                 // message number
      uint64_t m_OriginTime;            // original request time
      int m_iTTL;                       // time to live (milliseconds)

      Block* m_pNext;                   // next block
   } *m_pBlock, *m_pFirstBlock, *m_pCurrBlock, *m_pLastBlock;

   // m_pBlock:         The head pointer
   // m_pFirstBlock:    The first block
   // m_pCurrBlock:	The current block
   // m_pLastBlock:     The last block (if first == last, buffer is empty)

   struct Buffer
   {
      char* m_pcData;			// buffer
      int m_iSize;			// size
      Buffer* m_pNext;			// next buffer
   } *m_pBuffer;			// physical buffer

   int32_t m_iNextMsgNo;                // next message number

   int m_iSize;				// buffer size (number of packets)
   int m_iMSS;                          // maximum seqment/packet size

   int m_iCount;			// number of used blocks

private:
   CSndBuffer(const CSndBuffer&);
   CSndBuffer& operator=(const CSndBuffer&);
};

////////////////////////////////////////////////////////////////////////////////

class CRcvBuffer
{
public:
   CRcvBuffer(CUnitQueue* queue, int bufsize = 65536);
   ~CRcvBuffer();

      // Functionality:
      //    Write data into the buffer.
      // Parameters:
      //    0) [in] unit: pointer to a data unit containing new packet
      //    1) [in] offset: offset from last ACK point.
      // Returned value:
      //    0 is success, -1 if data is repeated.

   int addData(CUnit* unit, int offset);

      // Functionality:
      //    Read data into a user buffer.
      // Parameters:
      //    0) [in] data: pointer to user buffer.
      //    1) [in] len: length of user buffer.
      // Returned value:
      //    size of data read.

   int readBuffer(char* data, int len);

      // Functionality:
      //    Read data directly into file.
      // Parameters:
      //    0) [in] file: C++ file stream.
      //    1) [in] len: expected length of data to write into the file.
      // Returned value:
      //    size of data read.

   int readBufferToFile(std::fstream& ofs, int len);

      // Functionality:
      //    Update the ACK point of the buffer.
      // Parameters:
      //    0) [in] len: size of data to be acknowledged.
      // Returned value:
      //    1 if a user buffer is fulfilled, otherwise 0.

   void ackData(int len);

      // Functionality:
      //    Query how many buffer space left for data receiving.
      // Parameters:
      //    None.
      // Returned value:
      //    size of available buffer space (including user buffer) for data receiving.

   int getAvailBufSize() const;

      // Functionality:
      //    Query how many data has been continuously received (for reading).
      // Parameters:
      //    None.
      // Returned value:
      //    size of valid (continous) data for reading.

   int getRcvDataSize() const;

      // Functionality:
      //    mark the message to be dropped from the message list.
      // Parameters:
      //    0) [in] msgno: message nuumer.
      // Returned value:
      //    None.

   void dropMsg(int32_t msgno);

      // Functionality:
      //    read a message.
      // Parameters:
      //    0) [out] data: buffer to write the message into.
      //    1) [in] len: size of the buffer.
      // Returned value:
      //    actuall size of data read.

   int readMsg(char* data, int len);

      // Functionality:
      //    Query how many messages are available now.
      // Parameters:
      //    None.
      // Returned value:
      //    number of messages available for recvmsg.

   int getRcvMsgNum();

private:
   bool scanMsg(int& start, int& end, bool& passack);

private:
   CUnit** m_pUnit;                     // pointer to the protocol buffer
   int m_iSize;                         // size of the protocol buffer
   CUnitQueue* m_pUnitQueue;		// the shared unit queue

   int m_iStartPos;                     // the head position for I/O (inclusive)
   int m_iLastAckPos;                   // the last ACKed position (exclusive)
					// EMPTY: m_iStartPos = m_iLastAckPos   FULL: m_iStartPos = m_iLastAckPos + 1
   int m_iMaxPos;			// the furthest data position

   int m_iNotch;			// the starting read point of the first unit

private:
   CRcvBuffer();
   CRcvBuffer(const CRcvBuffer&);
   CRcvBuffer& operator=(const CRcvBuffer&);
};


#endif