C++ 我的mmap代码中的哪些设置将所有文件数据设置为零?
我正在实现流的一半,您应该能够前后跳转X个整数。最重要的是,当我打开一个文件时,它应该保留文件中的数据。在这个实现中,我尝试使用mmap。我的问题是,当我第二次打开一个文件时,映射的数据纯粹是零。我的open方法名为createStream,如下所示:C++ 我的mmap代码中的哪些设置将所有文件数据设置为零?,c++,linux,mmap,C++,Linux,Mmap,我正在实现流的一半,您应该能够前后跳转X个整数。最重要的是,当我打开一个文件时,它应该保留文件中的数据。在这个实现中,我尝试使用mmap。我的问题是,当我第二次打开一个文件时,映射的数据纯粹是零。我的open方法名为createStream,如下所示: void MapperOutForward::createStream(const char* filename) { this->filename = filename; pFile = open(filename, O_
void MapperOutForward::createStream(const char* filename)
{
this->filename = filename;
pFile = open(filename, O_RDWR | O_CREAT | O_SYNC, S_IRWXG|S_IRWXO|S_IRWXU);
if ( pFile == -1)
{
int errsv = errno;
cout << "MappedStreamOut createStream open error: " << strerror( errno ) << endl;
}
//getting file size and making the file big enough
struct stat filestatus;
stat( filename, &filestatus );
if(filestatus.st_size < mapSize + 1)
{
lseek (pFile, mapSize + 1, SEEK_SET);
write (pFile, "", 1);
}
lseek (pFile, 0, SEEK_SET);
map = (int*) mmap (0, mapSize, PROT_WRITE | PROT_READ, MAP_PRIVATE, pFile, 0);
close (pFile);
if ( map == (int*) -1)
{
cout << "MappedStreamOut createStream mmap error: " << strerror(errno) << endl;
}
numberOfOffsets = 1;
numberOfElementsInMap = 0;
cout << "Kopirer 5 før og 4 efter i Create" << endl;
for(int i = 0; i < numberOfElementsInMap + 5; i++)
{
cout << map[i] << endl;
}
cout << "Create numberOfOffsets:numberOfElementsInMap " << numberOfOffsets << ":" << numberOfElementsInMap << endl;
}
void MapperOutForward::createStream(const char*filename)
{
此->文件名=文件名;
pFile=open(文件名,O|RDWR | O|u CREAT | O|u SYNC,S|IRWXG | S|IRWXO | S|IRWXU);
如果(pFile==-1)
{
int errsv=errno;
cout您可能需要MAP\u SHARED
而不是MAP\u PRIVATE
,否则更改不会写入文件,如所指定
MAP\u SHARED
和MAP\u PRIVATE
描述写入的配置
对内存对象的引用。如果指定了MAP\u SHARED
,则写入
引用将更改基础对象。如果MAP\u PRIVATE
为
指定调用进程对映射数据的修改
应仅对呼叫过程可见,且不得改变
底层对象
是的,等3分钟,我才可以给你打上正确的分数。
#include "MapperOutForward.h"
using namespace std;
#include <cstdlib>
#include <iostream>
#include <fcntl.h>
#include <sys/stat.h>
#include <cmath>
MapperOutForward::MapperOutForward(int mapSize) //number of pages
{
pageSize = getpagesize();
this->mapSize = mapSize * pageSize; //we work in pages
numberOfElementsInMap = 0;
numberOfOffsets = 0;
}
MapperOutForward::~MapperOutForward()
{
munmap(map, mapSize);
}
void MapperOutForward::createStream(const char* filename)
{
this->filename = filename;
pFile = open(filename, O_RDWR | O_CREAT | O_SYNC, S_IRWXG|S_IRWXO|S_IRWXU);
if ( pFile == -1)
{
int errsv = errno;
cout << "MappedStreamOut createStream open error: " << strerror( errno ) << endl;
}
//getting file size and making the file big enough
struct stat filestatus;
stat( filename, &filestatus );
if(filestatus.st_size < mapSize + 1)
{
lseek (pFile, mapSize + 1, SEEK_SET);
write (pFile, "", 1);
}
lseek (pFile, 0, SEEK_SET);
map = (int*) mmap (0, mapSize, PROT_WRITE | PROT_READ, MAP_PRIVATE, pFile, 0);
close (pFile);
if ( map == (int*) -1)
{
cout << "MappedStreamOut createStream mmap error: " << strerror(errno) << endl;
}
numberOfOffsets = 1;
numberOfElementsInMap = 0;
cout << "Kopirer 5 før og 4 efter i Create" << endl;
for(int i = 0; i < numberOfElementsInMap + 5; i++)
{
cout << map[i] << endl;
}
cout << "Create numberOfOffsets:numberOfElementsInMap " << numberOfOffsets << ":" << numberOfElementsInMap << endl;
}
void MapperOutForward::writeNext(int* data, int numberOfElements)
{
for(int i = 0; i < numberOfElements; i++)
{
writeHelper(data[i]);
}
cout << "Kopirer 5 før og 4 efter i writeNext" << endl;
for(int i = numberOfElementsInMap - 5; i < numberOfElementsInMap + 5; i++)
{
cout << map[i] << endl;
}
//cout << "WriteNext numberOfOffsets:numberOfElementsInMap " << numberOfOffsets << ":" << numberOfElementsInMap << endl;
}
void MapperOutForward::writeHelper(int data)
{
int sizeOfInt = 4; //bytes
if(numberOfElementsInMap >= mapSize / sizeOfInt) //We need to create the next part of the file
{
munmap(map, mapSize);
pFile = open(filename, O_RDWR | O_CREAT | O_SYNC, S_IRWXG|S_IRWXO|S_IRWXU);
if ( pFile == -1)
{
std::cout<<"filename: "<<filename<<std::endl;
std::cout<<"mapSize: "<<mapSize<<std::endl;
int errsv = errno;
cout << "MappedStreamOut writeNext open error: " << strerror( errno ) << endl;
}
numberOfOffsets++;
//Make the file bigger
lseek (pFile, mapSize * numberOfOffsets, SEEK_SET);
write (pFile, "", 1);
lseek (pFile, 0, SEEK_SET);
map = (int*) mmap (0, mapSize, PROT_WRITE | PROT_READ, MAP_PRIVATE, pFile, mapSize * (numberOfOffsets - 1));
close (pFile);
if ( map == (int*) -1)
{
cout << "MappedStreamOut writeNext mmap error: " << strerror(errno) << endl;
}
numberOfElementsInMap = 0;
}
map[numberOfElementsInMap] = data;
numberOfElementsInMap++;
}
void MapperOutForward::jumpTo(int offset)
{
int sizeOfInt = 4; //bytes
//cout << "numberOfElementsInMap + offset " << numberOfElementsInMap + offset << endl;
//cout << "mapSize / sizeOfInt " << mapSize / sizeOfInt << endl;
if(numberOfElementsInMap + offset >= mapSize / sizeOfInt)
{
munmap(map, mapSize);
pFile = open(filename, O_RDWR | O_CREAT | O_SYNC, S_IRWXG|S_IRWXO|S_IRWXU);
if ( pFile == -1)
{
std::cout<<"filename: "<<filename<<std::endl;
std::cout<<"mapSize: "<<mapSize<<std::endl;
int errsv = errno;
cout << "MappedStreamOut writeNext open error: " << strerror( errno ) << endl;
}
numberOfOffsets += (int) ceil( (double) (numberOfElementsInMap + offset - (mapSize / sizeOfInt)) / (mapSize / sizeOfInt)); // rundet op ((resterende antal ints ud over mapSize) / (Antal ints i en mapsize)) = Antal offsets der skal springes
//Make the file bigger
lseek (pFile, mapSize * numberOfOffsets, SEEK_SET);
write (pFile, "", 1);
lseek (pFile, 0, SEEK_SET);
map = (int*) mmap (0, mapSize, PROT_WRITE | PROT_READ, MAP_PRIVATE, pFile, mapSize * (numberOfOffsets - 1));
close (pFile);
if ( map == (int*) -1)
{
cout << "MappedStreamOut writeNext mmap error: " << strerror(errno) << endl;
}
numberOfElementsInMap = (numberOfElementsInMap + offset - (mapSize / sizeOfInt)) % (mapSize / sizeOfInt); //(resterende antal ints ud over mapSize) % (Antal ints i en mapsize) = Antal elementer ind i offsettet
//cout << "JumpTo offsetForward numberOfOffsets:numberOfElementsInMap " << numberOfOffsets << ":" << numberOfElementsInMap << endl;
}
else if(numberOfElementsInMap + offset < 0)
{
munmap(map, mapSize);
pFile = open(filename, O_RDWR | O_CREAT | O_SYNC, S_IRWXG|S_IRWXO|S_IRWXU);
if ( pFile == -1)
{
std::cout<<"filename: "<<filename<<std::endl;
std::cout<<"mapSize: "<<mapSize<<std::endl;
int errsv = errno;
cout << "MappedStreamOut writeNext open error: " << strerror( errno ) << endl;
}
numberOfOffsets += (int) floor( (double) (numberOfElementsInMap + offset) / (mapSize / sizeOfInt)); // rundet op ((resterende antal ints ud over mapSize) / (Antal ints i en mapsize)) = Antal offsets der skal springes
//Make the file bigger
lseek (pFile, mapSize * numberOfOffsets, SEEK_SET);
write (pFile, "", 1);
lseek (pFile, 0, SEEK_SET);
map = (int*) mmap (0, mapSize, PROT_WRITE | PROT_READ, MAP_PRIVATE, pFile, mapSize * (numberOfOffsets - 1));
close (pFile);
if ( map == (int*) -1)
{
cout << "MappedStreamOut writeNext mmap error: " << strerror(errno) << endl;
}
numberOfElementsInMap = (mapSize + (numberOfElementsInMap + offset)) % (mapSize / sizeOfInt); //(resterende antal ints ud over mapSize) % (Antal ints i en mapsize) = Antal elementer ind i offsettet
//cout << "JumpTo offsetBacward numberOfOffsets:numberOfElementsInMap " << numberOfOffsets << ":" << numberOfElementsInMap << endl;
}
else
{
numberOfElementsInMap += offset;
//cout << "JumpTo else numberOfOffsets:numberOfElementsInMap " << numberOfOffsets << ":" << numberOfElementsInMap << endl;
}
}
void MapperOutForward::closeStream()
{
munmap(map, mapSize);
}
#include "MapperInForward.h"
#include "MapperOutForward.h"
//#include "MapperOutBackward.h"
//#include "MapperInBackward.h"
//#include "MapperStreamFactory.h"
#include <functional>
int main( int argc, const char* argv[] )
{
/*********************Tester Buffer Stream*************************************/
close(open((char*) "mapperTest", O_WRONLY | O_CREAT | O_SYNC | O_TRUNC, S_IRWXG|S_IRWXO|S_IRWXU));
//BufferStreamFactory* bsf = new BufferStreamFactory(3);
MapperOutForward* mso = new MapperOutForward(1);
mso->createStream((char*) "mapperTest");
int data[4000];
for(int i = 0; i < 4000; i++)
{
data[i] = i + 1;
}
mso->writeNext(data, 4000);
mso->closeStream();
MapperOutForward* mso1 = new MapperOutForward(1);
mso1->createStream((char*) "mapperTest");
data[0] = 9999;
mso1->jumpTo(0);
mso1->jumpTo(100);
mso1->writeNext(data, 1);
mso1->jumpTo(1000);
mso1->writeNext(data, 1);
mso1->jumpTo(-900);
mso1->writeNext(data, 1);
mso1->closeStream();
}