服务器缓存数据处理的两种方式：循环写入读取和剪切写入读取

来源：互联网发布：java 模拟下载文件编辑：程序博客网时间：2024/05/16 05:18

循环写入读取的原理：在分配的指定大小的内存空间上，首地址开始写入，超出范围之后（未超出整体范围，只是超出当前写入位置之后整体范围的剩余范围）连接超出的范围到缓存的首地址（因为之前的数据比较早，已经被读取），如此循环。

剪切写入读取的原理：在分配的指定大小的内存空间上，首地址开始写入，写入超出整体之后提示报错（缓存空间不足），未超出则正常写入，读取数据时，从当前写位置开始往前读取，读取完之后，将读取的数据从缓存数据中剪切走（将写指针往前指向读的数据长度）。

以下是两种方式的源文件和头文件：（其中还包括线程锁函数）

void *CLoopBuffer::InitLoopBuffer(unsigned long buff_len){    LOOP_BUFFER * lb;    lb =new  LOOP_BUFFER();     if( lb!=NULL )     {        lb->MaxLength = buff_len;        lb->Buffer =new  unsigned char[buff_len];        if (lb->Buffer==NULL)        {            delete lb;            return NULL;        }        lb_ptr = lb;        ResetLoopBuffer();    }    return (void *)lb;}void CLoopBuffer::UnLockLoopBuffer(){    BufferLock.UnLock();}void CLoopBuffer::LockLoopBuffer(){    BufferLock.Lock();}void CLoopBuffer::FreeLoopBuffer(){    LOOP_BUFFER * lb = (LOOP_BUFFER *)lb_ptr;    lb->WritePtr= NULL;    lb->ReadPtr= NULL;    delete []lb->Buffer;    delete lb ;    return;}void CLoopBuffer::ResetLoopBuffer(){    LOOP_BUFFER * lb = (LOOP_BUFFER *)lb_ptr;    lb->CurWritePos = 0;    lb->WritePtr = lb->Buffer;    lb->CurReadPos = 0;    lb->ReadPtr = lb->Buffer;    UnLockLoopBuffer();}//取缓冲的写指针位置，该函数与WriteLoopBuffer配合使用来控制缓冲区的锁问题//即：GetLoopBufferWritePos 置锁//  WriteLoopBuffer 写好后开锁longCLoopBuffer::GetLoopBufferWritePos(){    LOOP_BUFFER * lb = (LOOP_BUFFER *)lb_ptr;    LockLoopBuffer();    return lb->CurWritePos;}longCLoopBuffer::WriteLoopBuffer(unsigned char *data,long len){    try{        LOOP_BUFFER * lb = (LOOP_BUFFER *)lb_ptr;        unsigned char *ptr = lb->WritePtr,*s_ptr;        long r_len,l_len;        if( len + lb->CurWritePos > lb->MaxLength ) //buffer need loop        {            if( len < lb->MaxLength) //added 20080325            {                r_len = lb->MaxLength - lb->CurWritePos;                l_len = len - r_len;                s_ptr=data;                memcpy( ptr , s_ptr , r_len);                s_ptr += r_len;                ptr = lb->Buffer;                memcpy( ptr , s_ptr , l_len);                lb->WritePtr = lb->Buffer;                lb->WritePtr += l_len;                lb->CurWritePos =l_len;            }            else                myTRACE(1,3,"WriteLoopBuffer len is Error !\n");        }        else {//buffer right enought for write,not loop            memcpy( ptr , data , len );            lb->WritePtr += len;            lb->CurWritePos +=len;        }    }    catch(...)    {        myTRACE(1,3,"WriteLoopBuffer Error !\n");    }    UnLockLoopBuffer();    return len;}//取缓冲中的数据，独立开、关锁longCLoopBuffer::GetLoopBufferData(long readpos, char *tagdata , long requestlen ){    if(requestlen<0)return -1;    LOOP_BUFFER * lb = (LOOP_BUFFER *)lb_ptr;    long pos=0,l_len=0,r_len=0;    LockLoopBuffer();    try{        if( readpos >= lb->MaxLength )             pos = readpos % lb->MaxLength;        else             pos = readpos;        char* ptr = (char *)lb->Buffer;        ptr += pos;        if( pos + requestlen > lb->MaxLength )         {            if( requestlen < lb->MaxLength) //added 20080325            {                r_len = lb->MaxLength - pos;                l_len = requestlen - r_len;                memcpy( tagdata , ptr , r_len );                tagdata += r_len ;                ptr = (char *)lb->Buffer;                memcpy( tagdata , ptr , l_len );            }            else                myTRACE(1,3,"GetLoopBufferData requestlen is Error !\n");        }        else         {            memcpy( tagdata , ptr , requestlen );        }    }    catch(...)    {        myTRACE(1,3,"GetLoopBufferData Error !\n");requestlen =-1;    }    UnLockLoopBuffer();    return requestlen;}

#if !defined(LOOP_BUFFER__H)#define LOOP_BUFFER__H#include "ThreadLock.h"typedef struct {long PacketPos;//this media packet position on MediaBufferlong PacketLenfth;//this media packet length}PACKET_PARSE;typedef struct {    longMaxLength;    longCurWritePos;    longCurReadPos;    unsigned char*Buffer;    unsigned char*ReadPtr;    unsigned char*WritePtr;}LOOP_BUFFER;class CLoopBuffer{public:    void*InitLoopBuffer(unsigned long buff_len);    voidFreeLoopBuffer();    longWriteLoopBuffer(unsigned char *data,long len);    voidResetLoopBuffer();    longGetLoopBufferWritePos();    longGetLoopBufferData(long readpos, char *tagdata , long requestlen );    //char*GetLoopBufferAviliDataPtr(long startpos,long requestlen,long *ret_len);    //voidGetLoopBufferAviliDataPtrEnd();    voidLockLoopBuffer();    voidUnLockLoopBuffer();    void*lb_ptr;private :    CThreadLockBufferLock;};#endif

void *CCutBuffer::InitCutBuffer(long buff_len){    CUT_BUFFER * cb;    cb = new CUT_BUFFER();    cb->MaxLength = buff_len;    cb->Buffer = new char[buff_len];    memset(cb->Buffer,0,buff_len);    cb->CurWritePos = 0;    cb->WritePtr = cb->Buffer;    cb_ptr = (void *)cb;    return (void *)cb;}void CCutBuffer::FreeCutBuffer(){    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    cb->WritePtr= NULL;    delete []cb->Buffer;    delete cb;    return;}void CCutBuffer::LockCutBuffer(){    BufferLock.Lock();}void CCutBuffer::UnLockCutBuffer(){    BufferLock.UnLock();}longCCutBuffer::WriteCutBuffer(unsigned char  *data,long len){    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    if(len<=0 || len> cb->MaxLength)  //added 20080325    {        myTRACE(1,3,"WriteCutBuffer len is Error !\n");        return -1;    }    BufferLock.Lock();    unsigned char  *ptr = (unsigned char  *)cb->WritePtr;    if( len + cb->CurWritePos > cb->MaxLength ) //buffer not enought for write    {        myTRACE(0,3,"WriteCutBuffer buffer not enought for write,Clear the Buffer \n");        cb->CurWritePos = 0;        cb->WritePtr = cb->Buffer;        BufferLock.UnLock();        return -1;    }    else  //buffer right enought for write,not loop    {        memcpy( ptr , data , len );        cb->WritePtr += len;        cb->CurWritePos +=len;    }    BufferLock.UnLock();    return len;}unsigned char *CCutBuffer::GetCutBufferWritePtr(long *len){    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    BufferLock.Lock();    long al = cb->MaxLength - cb->CurWritePos;    *len = al;    if( al <= 0 )    {        BufferLock.UnLock();    }       return (unsigned char  *)cb->WritePtr;}void CCutBuffer::UpdateCutBufferWrite(long len){    if( len <= 0 ) {        BufferLock.UnLock();        return;    }    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    cb->CurWritePos += len;    cb->WritePtr += len;    BufferLock.UnLock();}unsigned char *CCutBuffer::GetCutBufferReadPtr(long *len){    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    BufferLock.Lock();    *len = cb->CurWritePos;    if( cb->CurWritePos <= 0 )    {        cb->CurWritePos = 0;        cb->WritePtr = cb->Buffer; //added 20080325        BufferLock.UnLock();    }    return (unsigned char  *)cb->Buffer;}void CCutBuffer::UpdateCutBufferRead(long len){    if( len <= 0 ) {        BufferLock.UnLock();        return;    }    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    if( cb->CurWritePos > len ) {        unsigned char* sptr = (unsigned char  *)cb->Buffer;        unsigned char* tptr = (unsigned char  *)cb->Buffer;        sptr += len;        memcpy( tptr , sptr , cb->CurWritePos - len );//memmove保险些，memcpy效率高些    }    cb->CurWritePos -= len;    cb->WritePtr -= len;    BufferLock.UnLock();}void CCutBuffer::ResetCutBuffer(){    CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    cb->CurWritePos = 0;    cb->WritePtr = cb->Buffer;    BufferLock.UnLock();}bool CCutBuffer::NoData() {     CUT_BUFFER * cb = (CUT_BUFFER *)cb_ptr;    if( cb->CurWritePos == 0 )         return true;    return false;}

#if !defined(CUT_BUFFER_H)#define CUT_BUFFER_H#include "ThreadLock.h"typedef struct {longMaxLength;longCurWritePos;char*Buffer;char*WritePtr;}CUT_BUFFER;class CCutBuffer{public:voidLockCutBuffer();voidUnLockCutBuffer();void*InitCutBuffer(long buff_len);voidFreeCutBuffer();longWriteCutBuffer(unsigned char  *data,long len);//longDirectWriteCutBuffer(unsigned char *data,long len);unsigned char *GetCutBufferWritePtr(long *len);voidUpdateCutBufferWrite(long len);unsigned char *GetCutBufferReadPtr(long *len);voidUpdateCutBufferRead(long len);voidResetCutBuffer();boolNoData();void *cb_ptr;private:    CThreadLockBufferLock;};#endif

#include "StdAfx.h"#include "ThreadLock.h"//#include "stream_svr.h"CThreadLock::CThreadLock(void){#ifdef WIN32    ThreadLockHandle = CreateMutex (NULL, FALSE, NULL);#elsepthread_mutex_init(&ThreadLockHandle,NULL);#endif}CThreadLock::~CThreadLock(void){#ifdef WIN32    CloseHandle(ThreadLockHandle);#else    pthread_mutex_destroy(&ThreadLockHandle);#endif}void CThreadLock::Lock(){#ifdef WIN32WaitForSingleObject(ThreadLockHandle, INFINITE); #elsepthread_mutex_lock(&ThreadLockHandle); #endif}void CThreadLock::UnLock(){#ifdef WIN32ReleaseMutex(ThreadLockHandle);#elsepthread_mutex_unlock(&ThreadLockHandle); #endif}

#ifndef THREAD_LOCK_H#define THREAD_LOCK_H//#include "stream_svr.h"#ifndef WIN32#include <pthread.h>#endifclass CThreadLock{public:CThreadLock(void);~CThreadLock(void);void Lock();void UnLock();#ifdef WIN32HANDLE             ThreadLockHandle;#else    pthread_mutex_t    ThreadLockHandle;#endif};#endif

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