SocketInputStream 分析

// //文件名稱： SocketInputStream.h //功能描述： 消息數據的接收緩存，提供數據的接收和格式化讀取功能 // // // #ifndef __SOCKETINPUTSTREAM_H__ #define __SOCKETINPUTSTREAM_H__ #include "BaseType.h" #include "Socket.h" //初始化的接收緩存長度 #define DEFAULTSOCKETINPUTBUFFERSIZE 64*1024 //最大可以允許的緩存長度，如果超過此數值，則斷開連接 #define DISCONNECTSOCKETINPUTSIZE 96*1024 class Packet ; class SocketInputStream { public : SocketInputStream( Socket* sock, UINT BufferSize = DEFAULTSOCKETINPUTBUFFERSIZE, UINT MaxBufferSize = DISCONNECTSOCKETINPUTSIZE ) ; virtual ~SocketInputStream( ) ; public : UINT Read( CHAR* buf, UINT len ) ; BOOL ReadPacket( Packet* p ) ; BOOL Peek( CHAR* buf, UINT len ) ; BOOL Find( CHAR* buf ) ; BOOL Skip( UINT len ) ; UINT Fill( ) ; UINT Fill_RAW( ) ; VOID Initsize( ) ; BOOL Resize( INT size ) ; UINT Capacity( )const { return m_BufferLen; } UINT Length( )const ; UINT Size( )const { return Length(); } BOOL IsEmpty( )const { return m_Head==m_Tail; } VOID CleanUp( ) ; UINT GetHead(){return m_Head;} UINT GetTail(){return m_Tail;} UINT GetBuffLen(){return m_BufferLen;} CHAR* GetBuff(){return m_Buffer;} private : Socket* m_pSocket ; CHAR* m_Buffer ; UINT m_BufferLen ; UINT m_MaxBufferLen ; UINT m_Head ; UINT m_Tail ; }; #endif

 

 

 #include "stdafx.h" #include "SocketInputStream.h" #include "Packet.h" SocketInputStream::SocketInputStream( Socket* sock, UINT BufferLen, UINT MaxBufferLen ) { __ENTER_FUNCTION_FOXNET m_pSocket = sock ; m_BufferLen = BufferLen ; m_MaxBufferLen = MaxBufferLen ; // Assert( m_pSocket != NULL ); // Assert( m_BufferLen > 0 ); m_Head = 0 ; m_Tail = 0 ; m_Buffer = new CHAR[ m_BufferLen ]; // Assert( m_Buffer ) ; memset( m_Buffer, 0, m_BufferLen ) ; __LEAVE_FUNCTION_FOXNET } SocketInputStream::~SocketInputStream( ) { __ENTER_FUNCTION_FOXNET SAFE_DELETE_ARRAY(m_Buffer); __LEAVE_FUNCTION_FOXNET } UINT SocketInputStream::Length( )const { __ENTER_FUNCTION_FOXNET if( m_Head<m_Tail ) return m_Tail-m_Head; else if( m_Head>m_Tail ) return m_BufferLen-m_Head+m_Tail ; return 0 ; __LEAVE_FUNCTION_FOXNET return 0 ; } //返回0表示沒有讀到數據 UINT SocketInputStream::Read( CHAR* buf, UINT len ) { __ENTER_FUNCTION_FOXNET // Assert( buf != NULL ); if ( len == 0 ) return 0 ; if ( len > Length() ) return 0 ; //讀指針位於寫指針之前，直接從讀的位置開始，讀取Len長度的數據 if ( m_Head < m_Tail ) { memcpy( buf, &m_Buffer[m_Head], len ) ; } //讀指針位於寫指針之後 else { //計算讀指針到緩衝區尾部還有多少數據可讀 UINT rightLen = m_BufferLen-m_Head ; //如果有足夠的數據可讀 if( len<=rightLen ) { memcpy( buf, &m_Buffer[m_Head], len ) ; } //沒有足夠的數據可讀，則先讀取讀指針到緩衝區尾部的數據，再從緩衝區頭開始讀未完的數據 else { memcpy( buf, &m_Buffer[m_Head], rightLen ) ; memcpy( &buf[rightLen], m_Buffer, len-rightLen ) ; } } //移動讀的位置 m_Head = (m_Head+len)%m_BufferLen ; return len ; __LEAVE_FUNCTION_FOXNET return 0 ; } BOOL SocketInputStream::ReadPacket( Packet* pPacket ) { __ENTER_FUNCTION_FOXNET BOOL ret ; //讀取8個字節的包頭長度 ret = Skip( PACKET_HEADER_SIZE ) ; if( !ret ) return FALSE ; //讀取包的內容 return pPacket->Read( *this ) ; __LEAVE_FUNCTION_FOXNET return FALSE ; } //讀取數據，但不移動讀指針 BOOL SocketInputStream::Peek( CHAR* buf, UINT len ) { __ENTER_FUNCTION_FOXNET // Assert( buf!=NULL ) ; if( len==0 ) return FALSE ; if( len>Length() ) return FALSE ; if( m_Head<m_Tail ) { memcpy( buf , &m_Buffer[m_Head] , len ); } else { UINT rightLen = m_BufferLen-m_Head ; if( len<=rightLen ) { memcpy( &buf[0], &m_Buffer[m_Head], len ) ; } else { memcpy( &buf[0], &m_Buffer[m_Head], rightLen ) ; memcpy( &buf[rightLen], &m_Buffer[0], len-rightLen ) ; } } return TRUE ; __LEAVE_FUNCTION_FOXNET return FALSE ; } BOOL SocketInputStream::Find( CHAR* buf ) { __ENTER_FUNCTION_FOXNET // Assert( buf!=NULL ) ; BOOL IsFind = FALSE; //可讀數據(到緩衝區尾部)大於 "$-$" 的長度 while ( Length() > PACK_COMPART_SIZE ) { if( m_Head<m_Tail ) { memcpy( buf , &m_Buffer[m_Head] , PACK_COMPART_SIZE ); } else { UINT rightLen = m_BufferLen-m_Head ; if( PACK_COMPART_SIZE<=rightLen ) { memcpy( &buf[0], &m_Buffer[m_Head], PACK_COMPART_SIZE ) ; } else { //否則，先從讀指針到尾部爲止的數據，再從緩衝區頭開始讀 memcpy( &buf[0], &m_Buffer[m_Head], rightLen ) ; memcpy( &buf[rightLen], &m_Buffer[0], PACK_COMPART_SIZE-rightLen ) ; } } //在字符串中查找 $-$，如果未找到，讀指針向後移動一個位置 //在此處需要便利整個緩衝區直到找到"$-$"爲止,找到的話，將讀指針指向包分隔符的下一個位置，即數據內容的位置 if (strstr(buf, PACK_COMPART) == NULL){ m_Head++; if (m_Head >= m_BufferLen){ m_Head -= m_BufferLen; } continue; } else{ IsFind = TRUE; break; } } if (!IsFind){ return FALSE; } m_Head += (UINT)PACK_COMPART_SIZE; if (m_Head >= m_BufferLen){ m_Head -= m_BufferLen; } return TRUE ; __LEAVE_FUNCTION_FOXNET return FALSE ; } BOOL SocketInputStream::Skip( UINT len ) { __ENTER_FUNCTION_FOXNET if( len == 0 ) return FALSE ; if( len>Length( ) ) return FALSE ; m_Head = (m_Head+len)%m_BufferLen ; return TRUE ; __LEAVE_FUNCTION_FOXNET return FALSE ; } VOID SocketInputStream::Initsize( ) { m_Head = 0 ; m_Tail = 0 ; SAFE_DELETE_ARRAY( m_Buffer ) ; m_Buffer = new CHAR[DEFAULTSOCKETINPUTBUFFERSIZE] ; // Assert(m_Buffer) ; m_BufferLen = DEFAULTSOCKETINPUTBUFFERSIZE ; memset( m_Buffer, 0, m_BufferLen ) ; } UINT SocketInputStream::Fill( ) { __ENTER_FUNCTION_FOXNET UINT nFilled = 0 ; UINT nReceived = 0 ; UINT nFree = 0 ; //讀指針 <= 寫指針,即緩衝區的讀數據的位置在前，寫數據的位置在後，還未追尾 if ( m_Head <= m_Tail ) { //如果還沒有開始讀數據 if ( m_Head == 0 ) { // // H T LEN=10 // 0123456789 // abcd...... // nReceived = 0 ; //可寫字節數 nFree = m_BufferLen-m_Tail-1 ; if( nFree != 0 ) { //根據可寫的長度來接收數據，不會導致緩衝區溢出，也可能套接字中並沒有nFree大小的數據可讀，nReceived是實際讀到的數據大小 nReceived = m_pSocket->receive( &m_Buffer[m_Tail] , nFree ); if (nReceived==SOCKET_ERROR_WOULDBLOCK) return 0 ; if (nReceived==SOCKET_ERROR) return SOCKET_ERROR-1 ; if (nReceived==0) return SOCKET_ERROR-2 ; //寫指針向後移動nReceived的字節數 m_Tail += nReceived; //填充字節數 nFilled += nReceived; } //如果接收的數據剛好等於緩衝可寫的數據長度 if( nReceived == nFree ) { //計算套接字中還有多少可讀數據 UINT available = m_pSocket->available(); if ( available > 0 ) { //如果套接字還有可讀的數據,並且現有的緩衝區長度加上將要接收的數據長度大於最大緩衝區長度（大於此長度即斷開連接）,重新初始化緩衝區 if( (m_BufferLen+available+1)>m_MaxBufferLen ) { Initsize( ) ; return SOCKET_ERROR-3 ; } //否則的話，重新分配緩衝區(m_BufferLen+available+1) if( !Resize( available+1 ) ) return 0 ; //接收套接字中剩餘的數據 nReceived = m_pSocket->receive( &m_Buffer[m_Tail] , available ); if (nReceived==SOCKET_ERROR_WOULDBLOCK) return 0 ; if (nReceived==SOCKET_ERROR) return SOCKET_ERROR-4 ; if (nReceived==0) return SOCKET_ERROR-5; m_Tail += nReceived; nFilled += nReceived; } } } //讀指針不爲0， 已讀部分數據 else { // // H T LEN=10 // 0123456789 // ...abcd... // //緩衝區還有多少可寫數據的空間，僅僅計算到緩衝區尾部爲止 nFree = m_BufferLen-m_Tail ; //從套接字中讀取nFree大小的數據， nReceived = m_pSocket->receive( &m_Buffer[m_Tail], nFree ); if( nReceived==SOCKET_ERROR_WOULDBLOCK ) return 0 ; if( nReceived==SOCKET_ERROR ) return SOCKET_ERROR-6 ; if( nReceived==0 ) return SOCKET_ERROR-7 ; //寫指針向後移動nReceived個位置，當遇到緩衝區結尾的時候，轉到緩衝區頭，此時的情況是剛好數據寫到緩衝區尾部了 //^_^考慮：如果超出的數據大小大於讀指針的位置？或者這個跟拆包時的設計有關，拆包的時候是以某個標記來分隔包的，所以允許存在丟包的情況，這樣的情況也不會太多。 m_Tail = (m_Tail+nReceived)%m_BufferLen ; nFilled += nReceived ; //如果套接字的數據未讀取完 if( nReceived==nFree ) { // Assert( m_Tail == 0 ); nReceived = 0 ; //到讀指針所在的位置還有多少數據可寫 nFree = m_Head-1 ; if( nFree!=0 ) { nReceived = m_pSocket->receive( &m_Buffer[0] , nFree ); if( nReceived==SOCKET_ERROR_WOULDBLOCK ) return 0 ; if( nReceived==SOCKET_ERROR ) return SOCKET_ERROR -8; if( nReceived==0 ) return SOCKET_ERROR-9 ; m_Tail += nReceived; nFilled += nReceived; } //如果此時套接字還有數據未讀完 if( nReceived==nFree ) { //計算還有多少數據可讀 UINT available = m_pSocket->available(); if ( available > 0 ) { if( (m_BufferLen+available+1)>m_MaxBufferLen ) { Initsize( ) ; return SOCKET_ERROR-10 ; } if( !Resize( available+1 ) ) return 0 ; nReceived = m_pSocket->receive( &m_Buffer[m_Tail] , available ); if (nReceived==SOCKET_ERROR_WOULDBLOCK) return 0 ; if (nReceived==SOCKET_ERROR) return SOCKET_ERROR-11 ; if (nReceived==0) return SOCKET_ERROR-12; m_Tail += nReceived; nFilled += nReceived; } } } } } //讀指針 > 寫指針,即緩衝區的讀數據的位置在後，寫數據的位置在前，還未追尾 else { // // T H LEN=10 // 0123456789 // abcd...efg // nReceived = 0 ; //首先計算讀指針到緩衝區尾部還有多少可寫的空間 nFree = m_Head-m_Tail-1 ; if( nFree!=0 ) { nReceived = m_pSocket->receive( &m_Buffer[m_Tail], nFree ) ; if( nReceived==SOCKET_ERROR_WOULDBLOCK ) return 0 ; if( nReceived==SOCKET_ERROR ) return SOCKET_ERROR-13 ; if( nReceived==0 ) return SOCKET_ERROR-14 ; m_Tail += nReceived ; nFilled += nReceived ; } //如果套接字的數據還未讀完 if( nReceived==nFree ) { //計算套接字還有多少數據可讀 UINT available = m_pSocket->available( ) ; if ( available>0 ) { if( (m_BufferLen+available+1)>m_MaxBufferLen ) { Initsize( ) ; return SOCKET_ERROR-15 ; } //直接在緩衝區尾部擴充，重新分配內存,保證讀完套接字所有的數據 if( !Resize( available+1 ) ) return 0 ; nReceived = m_pSocket->receive( &m_Buffer[m_Tail], available ) ; if( nReceived==SOCKET_ERROR_WOULDBLOCK ) return 0 ; if( nReceived==SOCKET_ERROR ) return SOCKET_ERROR-16 ; if( nReceived==0 ) return SOCKET_ERROR-17 ; m_Tail += nReceived ; nFilled += nReceived ; } } } return nFilled ; __LEAVE_FUNCTION_FOXNET return 0 ; } BOOL SocketInputStream::Resize( INT size ) { __ENTER_FUNCTION_FOXNET // Assert( size != 0 ) ; size = max(size, (int)(m_BufferLen>>1)); UINT newBufferLen = m_BufferLen + size; UINT len = Length(); if ( size < 0 ) { if ( newBufferLen < 0 || newBufferLen < len ) return FALSE ; } CHAR * newBuffer = new CHAR[ newBufferLen ]; // Assert( newBuffer ) ; //僅僅拷貝未讀的數據 if ( m_Head < m_Tail ) { memcpy( newBuffer , &m_Buffer[m_Head] , m_Tail - m_Head ); } //此情況是讀指針已讀取部分數據，寫指針已經寫完一圈，又從頭開始寫，但還沒有追尾 //先將讀指針後到緩衝區尾部未讀的數據拷貝，然後再拷貝緩衝區頭部未讀的數據 else if ( m_Head > m_Tail ) { memcpy( newBuffer , &m_Buffer[m_Head] , m_BufferLen - m_Head ); memcpy( &newBuffer[ m_BufferLen - m_Head ] , m_Buffer , m_Tail ); } delete [] m_Buffer ; m_Buffer = newBuffer ; m_BufferLen = newBufferLen ; m_Head = 0 ; m_Tail = len ; return TRUE ; __LEAVE_FUNCTION_FOXNET return FALSE ; } VOID SocketInputStream::CleanUp( ) { __ENTER_FUNCTION_FOXNET m_Head = 0 ; m_Tail = 0 ; __LEAVE_FUNCTION_FOXNET }

 

網絡層的拆包使用環形緩衝區，包由包頭+內容組成，每個包之間使用"$-$"做爲分隔符，包頭包括 PACKET ID，消息序列號，消息長度組成

在實際設計中，每個玩家關聯一個套接字，一個輸入緩衝區，一個輸入緩衝區，通過BOOL  ReadPacket( Packet* p ) ; 這個接口，從輸入緩衝區SocketInputStream中讀取數據，先取包頭，然後取包內容，通過在緩衝區中查找"$-$"來分隔每一個數據包。

消息都是以Packet爲基類，通過虛函數機制，找到對應的數據包，讀取數據。

值得一提的是，在使用環形緩衝接收數據包的時候，可以根據套接字讀取相關聯.首先計算環形緩衝區中還有多少可寫數據空間，從套接字中取多少數據並寫到緩衝區中；然後判斷套接字中數據是否已經讀完，然後讀取剩餘數據，並對緩衝區大小進行調節。

 

另外，數據包發送前也有次打包的過程，這樣適合於大量小數據包發送，這個由SocketOutputStream來處理。