檔案對映操作類的實現

mmap_file_op.h：

#ifndef qiniu_largefile_mmapfile_op_h_

#define qiniu_largefile_mmapfile_op_h_
#include
"common.h"
#include
"file_op.h"
#include
"mmap_file.h"
namespace qiniu
~mmapfileoperation()
}int
mmap_file
(const mmapoption& mmap_option)
;int
munmap_file()
;int
pread_file
(char
*buf,
const int32_t size,
const int64_t offset)
;int
pwrite_file
(const
char
* buf,
const int32_t sized,
const int64_t offset)
;void
*get_map_data()
const
;int
flush_file()
; 
private:
mmapfile *map_file_;};
}}#endif
//qiniu_largefile_mmapfile_op_h_

#include

"mmap_file_op.h"
#include
"common.h"
//#include "file_op.h"
//#include "mmap_file.h"
static
int debug =1;
namespace qiniu
if(mmap_option.max_mmap_size_ <=0)
int fd =
check_file()
;if(fd <0)
if(map_file_ = new mmapfile
(mmap_option, fd)
;map_file
(true);}
ifelse
}int mmapfileoperation:
:munmap_file()
return tfs_success;
}void
*mmapfileoperation:
:get_map_data()
const
return
null;}
int mmapfileoperation:
:pread_file
(char
*buf,
const int32_t size,
const int64_t offset)
if(offset + size)
<=map_file_->
get_size()
)//情況2，記憶體沒有對映或是要讀取的資料對映不全
return fileoperation:
:pread_file
(buf, size, offset);}
int mmapfileoperation:
:pwrite_file
(const
char
* buf,
const int32_t size,
const int64_t offset)
if(offset + size)
<=map_file_->
get_size()
)//情況2，記憶體沒有對映或是要寫入的資料對映不全
return fileoperation:
:pwrite_file
(buf, size, offset);}
int mmapfileoperation:
:flush_file()
else
}return fileoperation:
:flush_file()
;}}}

#include

"mmap_file_op.h"
#include
using namespace std;
using namespace qiniu;
const
static largefile:
:mmapoption mmap_option=
;//記憶體對映的引數
intmain
(void) 
ret = mmfo->
mmap_file
(mmap_option);if
(ret == largefile:
:tfs_error)
char buffer[
128+1]
;memset
(buffer,
'6',
128)
; buffer[
127]
='\n'; 
ret = mmfo->
pwrite_file
(buffer,
128,8)
;if(ret <0)
else
}memset
(buffer,0,
128)
; ret = mmfo->
pread_file
(buffer,
128,8)
;if(ret <0)
else
}else
ret = mmfo->
flush_file()
;if(ret == largefile:
:tfs_error)
memset
(buffer,
'8',
128)
; buffer[
127]
='\n'
; ret = mmfo->
pwrite_file
(buffer,
128,
4000);
// 即使這裡的偏移量很大，也會自動擴充檔案的
mmfo->
munmap_file()
; mmfo->
close_file()
;return0;
}

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