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// mmap_posix.cpp
/* Copyright 2009 10gen Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "stdafx.h"
#include "mmap.h"
#include "file_allocator.h"
#include <errno.h>
#include <sys/mman.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
namespace mongo {
MemoryMappedFile::MemoryMappedFile() {
fd = 0;
maphandle = 0;
view = 0;
len = 0;
created();
}
void MemoryMappedFile::close() {
if ( view )
munmap(view, len);
view = 0;
if ( fd )
::close(fd);
fd = 0;
}
#ifndef O_NOATIME
#define O_NOATIME 0
#endif
void* MemoryMappedFile::map(const char *filename, long &length, int options) {
// length may be updated by callee.
theFileAllocator().allocateAsap( filename, length );
len = length;
fd = open(filename, O_RDWR | O_NOATIME);
if ( fd <= 0 ) {
out() << "couldn't open " << filename << ' ' << errno << endl;
return 0;
}
off_t filelen = lseek(fd, 0, SEEK_END);
if ( filelen != length ){
cout << "wanted length: " << length << " filelen: " << filelen << endl;
cout << sizeof(size_t) << endl;
massert( "file size allocation failed", filelen == length );
}
lseek( fd, 0, SEEK_SET );
view = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if ( view == MAP_FAILED ) {
out() << " mmap() failed for " << filename << " len:" << length << " errno:" << errno << endl;
if ( errno == ENOMEM ){
out() << " mmap failed with out of memory, if you're using 32-bits, then you probably need to upgrade to 64" << endl;
}
return 0;
}
if ( options & SEQUENTIAL ){
if ( madvise( view , length , MADV_SEQUENTIAL ) ){
out() << " madvise failed for " << filename << " " << errno << endl;
}
}
return view;
}
void MemoryMappedFile::flush(bool sync) {
if ( view == 0 || fd == 0 )
return;
if ( msync(view, len, sync ? MS_SYNC : MS_ASYNC) )
problem() << "msync error " << errno << endl;
}
} // namespace mongo
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