OpenRTMFP/Cumulus效能最佳化(2) PacketWriter的最佳化

前一篇文字http://blog.csdn.net/linyanwen99/article/details/8627430敘述了PacketReader類的部分方法的最佳化，

這節繼續敘述PacketWriter類的部分方法的最佳化

一.PacketWriter.h的定義如下：

#pragma once

#include "Cumulus.h"
#include "MemoryStream.h"
#include "BinaryWriter.h"

#define PACKETSEND_SIZE   1215

namespace Cumulus {

class PacketWriter: public BinaryWriter {
public:
     PacketWriter(const Poco::UInt8* buffer,Poco::UInt32 size);
     PacketWriter(PacketWriter&);

     Poco::UInt8*  begin();
     Poco::UInt32  position();
     void                next(Poco::UInt32 size);
public:
     void  write8(Poco::UInt8 value);
     void  write16(Poco::UInt16 value);
     void  write32(Poco::UInt32 value);
     void  write7BitValue(Poco::UInt32 value);
     void  write7BitLongValue(Poco::UInt64 value);
     void  writeAddress(const Address& address,bool publicFlag);
     void  writeAddress(const Poco::Net::SocketAddress& address,bool publicFlag);
     void  writeRaw(const Poco::UInt8* value,Poco::UInt32 size);
     void  writeRaw(const char* value,Poco::UInt32 size);
     void  writeRaw(const std::string& value);
     void  writeString8(const std::string& value);
     void  writeString8(const char* value,Poco::UInt8 size);
     void  writeString16(const std::string& value);
     void  writeString16(const char* value,Poco::UInt16 size);
private:
     MemoryOutputStream _memory;
     PacketWriter*  _pOther;
     Poco::UInt32  _size;
};
inline Poco::UInt32 PacketWriter::position() {
     return _wppos;//_wppos即寫指標的位置
}

inline Poco::UInt8* PacketWriter::begin() {
     return (Poco::UInt8*)_memory._buf._pBuffer;
}

inline void PacketWriter::next(Poco::UInt32 size){

     _wgpos += size;//_wgpos即讀指標的位置

     _wppos += size;

     return _memory.next(size);

}

} // namespace Cumulus

二.PacketWriter.cpp的實現，如下：

#include "PacketWriter.h"
#include "Util.h"
#include "Logs.h"

using namespace std;
using namespace Poco;
using namespace Poco::Net;

namespace Cumulus {

PacketWriter::PacketWriter(const UInt8* buffer,UInt32 size) : _memory((char*)buffer,size),BinaryWriter(_memory),_pOther(NULL),_size(size) {
}

// Consctruction by copy
PacketWriter::PacketWriter(PacketWriter& other) : _pOther(&other),_memory(other._memory),BinaryWriter(_memory),_size(other._size) {
 
}

void PacketWriter::write8(Poco::UInt8 value){
     *(_memory._buf._pBuffer+_wppos) = value;//直接把該位元組寫入buffer

     _wppos += 1;
     _memory._buf.ppPbump(1);
}

void PacketWriter::write16(Poco::UInt16 value){
     value = htons(value);//轉為網路位元組序
     memcpy(_memory._buf._pBuffer+_wppos,&value,2);
     _wppos += 2;
     _memory._buf.ppPbump(2);
}

void PacketWriter::write32(Poco::UInt32 value){
     value = htonl(value);//轉為網路位元組序
     memcpy(_memory._buf._pBuffer+_wppos,&value,4);
     _wppos += 4;
     _memory._buf.ppPbump(4);

}

void PacketWriter::write7BitValue(UInt32 value) {
     UInt8 shift = (Util::Get7BitValueSize(value)-1)*7;//參考amf3資料格式以便理解
     bool max = false;
     if(shift>=21) { // 4 bytes maximum
          shift = 22;
          max = true;
     }

     while(shift>=7) {
         write8(0x80 | ((value>>shift)&0x7F));
         shift -= 7;
     }
     write8(max ? value&0xFF : value&0x7F);
}

void PacketWriter::write7BitLongValue(UInt64 value) {//與rtmfp協議相關的一些東西
     UInt8 shift = (Util::Get7BitValueSize(value)-1)*7;
     bool max = shift>=63; // Can give 10 bytes!
     if(max)
          ++shift;

     while(shift>=7) {
         write8(0x80 | ((value>>shift)&0x7F));
         shift -= 7;
     }
     write8(max ? value&0xFF : value&0x7F);
}

void PacketWriter::writeAddress(const Address& address,bool publicFlag) {
     UInt8 flag = publicFlag ? 0x02 : 0x01;
     if(address.host.size()==16) // IPv6
         flag |= 0x80;
     write8(flag);
     for(int i=0;i<address.host.size();++i)
         write8(address.host[i]);
     write16(address.port);
}

void PacketWriter::writeAddress(const SocketAddress& address,bool publicFlag) {
     UInt8 flag = publicFlag ? 0x02 : 0x01;
     UInt8 size = 4;
     IPAddress host = address.host();
     if(host.family() == IPAddress::IPv6) {
         flag |= 0x80;
         size = 16;
     }
     const UInt8* bytes = reinterpret_cast<const UInt8*>(host.addr());
     write8(flag);
     for(int i=0;i<size;++i)
         write8(bytes[i]);
     write16(address.port());
}

void PacketWriter::writeRaw(const UInt8* value,UInt32 size){
     writeRaw((char*)value,size);
}

void PacketWriter::writeRaw(const char* value,UInt32 size){//函數的功能即把size大小的位元組數直接寫入buffer，以下方法類似
     for(int i=0;i<size;++i)
         *(_memory._buf._pBuffer+_wppos+i) = *(value+i);

     _wppos += size;
     _memory._buf.ppPbump(size);
}

void PacketWriter::writeRaw(const std::string& value){
     int size = (int)value.length();
     char* ptr = (char*)value.data();
     for(int i=0;i<size;++i)
         *(_memory._buf._pBuffer+_wppos+i) = *(ptr+i);//直接對buffer進行操作

     _wppos += size;                                                    //_wppos進行對應的位移
     _memory._buf.ppPbump(size);
}

void PacketWriter::writeString8(const char* value,UInt8 size){
     write8(size);
     writeRaw(value,size);
}

void PacketWriter::writeString8(const string& value){
     write8(value.size());
     writeRaw(value);
}

void PacketWriter::writeString16(const char* value,UInt16 size){
     write16(size);
     writeRaw(value,size);
}

void PacketWriter::writeString16(const string& value){
     write16(value.size());
     writeRaw(value);
}

} // namespace Cumulus

 

轉載請註明出處：山水間部落格，http://blog.csdn.net/linyanwen99/article/details/8643428