Linux 异步IO 读写编程

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使用AIO读写文件

编译时需连接以下动态库

LIBS += /usr/lib/x86_64-linux-gnu/librt.so
LIBS += -lpthread

#ifndef CAIO_H#define CAIO_H#include <string>#include <aio.h>#include <stdio.h>#include <unistd.h>#include <aio.h>#include <string.h>#include <errno.h>#include <stdlib.h>using namespace std;enum eAIOState{    eBusyState,    eReadyState};typedef void (*FucCallBackAIO)(sigval_t);class CAIO{public:    CAIO();    ~CAIO();    bool Open(string strName, int nMode);    bool  Close();    int Write(const char* buf, int nSize, bool bAppend, eAIOState&  eIOState);    int Read(char* buf );    void SetCallbackFuc(FucCallBackAIO  fAIO);    int  GetFileSize(const char *szFileName);    void Seek(int offset, int __whence);    int Write(const char* buf, int nSize);;    int GetFD();private:    struct aiocb m_aiocb;    int m_fdFile;    string m_strFilename;    int m_nFileSize;        };#endif // CAIO_H

#include <fcntl.h> #include <sys/stat.h>#include "caio.h"using namespace std;CAIO::CAIO(){    m_fdFile =-1;    m_nFileSize=0;}CAIO::~CAIO(){}int CAIO::GetFileSize(const char *szFileName){    int nSize=0;    struct stat buffer;    int         status;    status = stat(szFileName, &buffer);    if(status>=0)    {        nSize=buffer.st_size;    }    return nSize;}bool CAIO::Open(string strName, int nMode){    m_fdFile = open(strName.c_str(), nMode);    if(m_fdFile < 0)    {        printf("Open %s failed\n", strName.c_str());        return false;    }    bzero((void*) &m_aiocb, sizeof(struct aiocb));    m_aiocb.aio_fildes = m_fdFile;    m_aiocb.aio_offset =0;    m_nFileSize= GetFileSize(strName.c_str());    m_aiocb.aio_sigevent.sigev_notify = SIGEV_THREAD;    //  指定回调函数        m_aiocb.aio_sigevent._sigev_un._sigev_thread._attribute = NULL;    //  指定AIO请求        return true;}void CAIO::SetCallbackFuc(FucCallBackAIO  fAIO){    m_aiocb.aio_sigevent._sigev_un._sigev_thread._function =fAIO;    m_aiocb.aio_sigevent.sigev_value.sival_ptr = &m_aiocb;}int CAIO::Write(const char* buf, int nSize, bool bAppend, eAIOState&  eIOState){    m_aiocb.aio_nbytes = nSize;    m_aiocb.aio_buf=(void*)buf;    m_aiocb.aio_offset=0;    m_aiocb.aio_offset+=m_nFileSize;    if(!bAppend)        m_aiocb.aio_offset = 0;    //  发送异步读请求    int ret;    if(eReadyState == eIOState)    {        ret = aio_write(&m_aiocb);        if (ret < 0)              sleep(1);        m_nFileSize +=nSize;        eIOState = eBusyState;    }    return ret;}void CAIO::Seek(int offset, int __whence){    lseek(m_fdFile, offset, SEEK_SET);}int CAIO::Write(const char* buf, int nSize){    write(m_fdFile,buf,nSize);}int CAIO::GetFD(){    return m_fdFile;}bool CAIO::Close(){    if (close(m_fdFile) < 0)    {        return false;    }    return true;}

#include <fcntl.h>#include <aio.h>#include  "caio.h"#include <iostream>using namespace std;void msleep( unsigned int ms ){    int microsecs;    struct timeval tv;    microsecs = ms * 1000;    tv.tv_sec  = microsecs / 1000000;    tv.tv_usec = microsecs % 1000000;    select( 0, NULL, NULL, NULL, &tv );}eAIOState  g_eIOState;void aio_completion_handler( sigval_t sigval ){    int ret;    struct aiocb *tAiocb;    //  获取aiocb结构体指针    tAiocb = (struct aiocb *)sigval.sival_ptr;    //  获取异步读请求的返回值    if ((ret = aio_return(tAiocb)) > 0)    {        //  获取并输出读取的数据        printf("value:%s\n", (char*) (tAiocb->aio_buf));        g_eIOState = eReadyState;    }}#define BUFFER_SIZE 100//  AIO回调函数int main(){        CAIO aio;    bool bOpen= aio.Open("/media/sda1/Videos/20151221/1/155332.mp4",O_WRONLY);    aio.SetCallbackFuc(aio_completion_handler);    if(false == bOpen)        return 1;    string strData="yes tes";    g_eIOState = eReadyState;    for(int i=0 ; i < 10; )    {        if(eReadyState==g_eIOState )        {            aio.Write(strData.c_str(), strData.length(), true, g_eIOState);            i++;        }        msleep(100);    }    aio.Seek(4, 0);    strData="fffff";    msleep(1000);    aio.Write(strData.c_str(), strData.length());    aio.Close();    return 0;}

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