mirror of
https://github.com/mongodb/mongo.git
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111 lines
3.2 KiB
C++
111 lines
3.2 KiB
C++
// mmap_posix.cpp
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/**
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* Copyright (C) 2008 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "stdafx.h"
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#include "mmap.h"
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#include <errno.h>
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#include <sys/mman.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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namespace mongo {
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MemoryMappedFile::MemoryMappedFile() {
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fd = 0;
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maphandle = 0;
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view = 0;
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len = 0;
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created();
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}
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void MemoryMappedFile::close() {
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if ( view )
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munmap(view, len);
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view = 0;
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if ( fd )
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::close(fd);
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fd = 0;
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}
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#ifndef O_NOATIME
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#define O_NOATIME 0
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#endif
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void* MemoryMappedFile::map(const char *filename, int length) {
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updateLength( filename, length );
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len = length;
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fd = open(filename, O_CREAT | O_RDWR | O_NOATIME, S_IRUSR | S_IWUSR);
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if ( fd <= 0 ) {
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out() << "couldn't open " << filename << ' ' << errno << endl;
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return 0;
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}
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/* make sure the file is the full desired length */
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off_t filelen = lseek(fd, 0, SEEK_END);
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if ( filelen < length ) {
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// log() << "map: file length=" << (unsigned) filelen << " want:"
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// << length
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// << endl;
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if ( filelen != 0 ) {
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problem() << "failure mapping new file " << filename << " length:" << length << endl;
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return 0;
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}
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// Check for end of disk.
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lseek(fd, length - 1, SEEK_SET);
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write(fd, "", 1);
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lseek(fd, 0, SEEK_SET);
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Nullstream &l = log();
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l << "new datafile " << filename << " filling with zeroes...";
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l.flush();
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Timer t;
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int z = 8192;
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char buf[z];
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memset(buf, 0, z);
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int left = length;
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while ( 1 ) {
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if ( left <= z ) {
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write(fd, buf, left);
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break;
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}
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write(fd, buf, z);
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left -= z;
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}
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l << "done " << ((double)t.millis())/1000.0 << " secs" << endl;
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}
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view = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
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if ( view == MAP_FAILED ) {
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out() << " mmap() failed for " << filename << " len:" << length << " errno:" << errno << endl;
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return 0;
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}
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return view;
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}
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void MemoryMappedFile::flush(bool sync) {
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if ( msync(view, len, sync ? MS_SYNC : MS_ASYNC) )
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problem() << "msync error " << errno << endl;
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}
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} // namespace mongo
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