环形缓冲

shake863

/** * Copyright (c) 2008, ×××研发中心 * All rights reserved. *  * 名    称： * 摘    要： * 作    者：test * 版    本：1.0 * 时    间：08.08.27 16:21:55 */#include <stdio.h>#include <string.h>#include <stdlib.h>#include <iostream>#include <pthread.h>#include <time.h>#define INITBUFSIZE        10 /*环型缓冲区初始单元个数*/#define UNITSIZE        200/*每单元大小*/using namespace std;/*global data*//*Cirbuf chain 写进程可能很快 以至于不只有1个或2个环形缓冲，可能有多个*/struct Cirbuf* packetCirbuf;/*环形缓冲的一个单元*/struct CirUnit{    int flag; /*0 表明可写,1表明可读*/    char unit[UNITSIZE];};/*环形缓冲*/struct Cirbuf{    struct Cirbuf * newBuf; /*point to new Cirbuf*/    int readPoint; /*for reading thread*/    int writePoint; /*for writing thread*/    int bufSize;        /*buf char array's size*/    struct CirUnit *buf;                /*point to unit array*/};struct Cirbuf* GetNewCirbuf(int bufSize,struct Cirbuf* oldBuf){    if(bufSize>30000)    {            printf("oh my god,the bufSize is out of my league,I cannot handle it,exit");            exit(1);    }    struct Cirbuf* newBuf = new Cirbuf();        printf("new buffer %d\n",bufSize);    usleep(1000000);    if(oldBuf != NULL)            oldBuf->newBuf = newBuf;    newBuf->newBuf = NULL;    newBuf->readPoint = newBuf->writePoint = 0;    newBuf->bufSize = bufSize;    newBuf->buf = new CirUnit[bufSize];    memset(newBuf->buf,0,sizeof(CirUnit)*bufSize); /*初始化单元为0*/    return newBuf;}int FreeCirbuf(struct Cirbuf* bufPoint){    delete bufPoint->buf;    delete bufPoint;    printf("delete buffer \n");    return 1;}void DoWrite(struct Cirbuf* latestBuf,char flag){    latestBuf->buf[latestBuf->writePoint].unit[0] = flag;    printf("write %d \n",flag);}void DoRead(){    printf("read %d \n",packetCirbuf->buf[packetCirbuf->readPoint].unit[0]);}extern "C" void* ReadThread(void *arg){    while(1)    {        usleep(200000);        if(packetCirbuf->buf[packetCirbuf->readPoint].flag == 0)        {            if(packetCirbuf->newBuf != NULL)            {                    /*表明readthread已经处理完旧的缓冲区并且已经有新的缓冲区，这时应该释放旧缓冲*/                    struct Cirbuf *temp = packetCirbuf;                    packetCirbuf = packetCirbuf->newBuf;                    FreeCirbuf(temp);                    continue;            }            /* delay*/            pthread_cond_t mycond = PTHREAD_COND_INITIALIZER;             pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER;             struct timespec ts;             int rv;             ts.tv_sec = 0;             ts.tv_nsec = 50000; /* 500,00 nanoseconds = 50 ms */             pthread_mutex_lock(&mymutex);             rv = pthread_cond_timedwait(&mycond, &mymutex, &ts);             pthread_mutex_unlock(&mymutex);            continue;        }        DoRead();        packetCirbuf->buf[packetCirbuf->readPoint].flag = 0;        if(++packetCirbuf->readPoint == packetCirbuf->bufSize)                packetCirbuf->readPoint = 0;    }    return NULL;}extern "C" void* WriteThread(void *arg){    struct Cirbuf* latestBuf;    /*进写进程后，初始化latestBuf指针 使其指向packetCirbuf，这时的packetCirbuf是由主线程函数创建的初始buf*/    latestBuf = packetCirbuf;    if(latestBuf == NULL)    {            cout << "packet capture buffer NULL error" << endl;            exit(0);    }    /*进入循环*/    char test=0;    while(1)    {        usleep(100000);        if (latestBuf->buf[latestBuf->writePoint].flag == 1)        {                /*we need a larger buf*/                latestBuf = GetNewCirbuf(latestBuf->bufSize * 2,latestBuf);        }        else        {                DoWrite(latestBuf,test++);                latestBuf->buf[latestBuf->writePoint].flag = 1;                if(++latestBuf->writePoint == latestBuf->bufSize)                    latestBuf->writePoint = 0;        }        if(test == 127)            break;    }    return NULL;}int main(int argc, char *argv[]){    pthread_t threadNum[2];    packetCirbuf = GetNewCirbuf(INITBUFSIZE,NULL);    pthread_create(&threadNum[0],NULL,WriteThread,NULL);    pthread_create(&threadNum[1],NULL,ReadThread,NULL);    pthread_join(threadNum[0],NULL);    pthread_join(threadNum[1],NULL);    FreeCirbuf(packetCirbuf);} 
 
   见到的一个不错的环形缓冲。