forked from mongodb/mongo
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mongommf.cpp
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/
mongommf.cpp
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// @file mongommf.cpp
/**
* Copyright (C) 2010 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* this module adds some of our layers atop memory mapped files - specifically our handling of private views & such
if you don't care about journaling/durability (temp sort files & such) use MemoryMappedFile class, not this.
*/
#include "pch.h"
#include "cmdline.h"
#include "mongommf.h"
#include "dur.h"
#include "../util/mongoutils/str.h"
using namespace mongoutils;
namespace mongo {
void MongoMMF::remapThePrivateView()
{
assert( cmdLine.dur && !testIntent );
privateViews.remove(_view_private);
_view_private = remapPrivateView(_view_private);
privateViews.add(_view_private, this);
}
void* MongoMMF::getView() {
if( testIntent )
return _view_readonly;
return _view_private;
}
/** register view. threadsafe */
void PointerToMMF::add(void *view, MongoMMF *f) {
mutex::scoped_lock lk(_m);
_views.insert( pair<void*,MongoMMF*>(view,f) );
}
/** de-register view. threadsafe */
void PointerToMMF::remove(void *view) {
if( view ) {
mutex::scoped_lock lk(_m);
_views.erase(view);
}
}
PointerToMMF::PointerToMMF() : _m("PointerToMMF") {
#if defined(SIZE_MAX)
size_t max = SIZE_MAX;
#else
size_t max = ~((size_t)0);
#endif
assert( max > (size_t) this ); // just checking that no one redef'd SIZE_MAX and that it is sane
// this way we don't need any boundary checking in _find()
_views.insert( pair<void*,MongoMMF*>((void*)0,(MongoMMF*)0) );
_views.insert( pair<void*,MongoMMF*>((void*)max,(MongoMMF*)0) );
}
/** underscore version of find is for when you are already locked
@param ofs out return our offset in the view
@return the MongoMMF to which this pointer belongs
*/
MongoMMF* PointerToMMF::_find(void *p, /*out*/ size_t& ofs) {
//
// .................memory..........................
// v1 p v2
// [--------------------] [-------]
//
// e.g., _find(p) == v1
//
const pair<void*,MongoMMF*> x = *(--_views.upper_bound(p));
MongoMMF *mmf = x.second;
if( mmf ) {
size_t o = ((char *)p) - ((char*)x.first);
if( o < mmf->length() ) {
ofs = o;
return mmf;
}
}
return 0;
}
/** find associated MMF object for a given pointer.
threadsafe
@param ofs out returns offset into the view of the pointer, if found.
@return the MongoMMF to which this pointer belongs. null if not found.
*/
MongoMMF* PointerToMMF::find(void *p, /*out*/ size_t& ofs) {
mutex::scoped_lock lk(_m);
return _find(p, ofs);
}
PointerToMMF privateViews;
static PointerToMMF ourReadViews; /// _TESTINTENT (testIntent) build use only (other than existance)
/*static*/ void* MongoMMF::switchToPrivateView(void *readonly_ptr) {
assert( cmdLine.dur );
assert( testIntent );
void *p = readonly_ptr;
{
size_t ofs=0;
MongoMMF *mmf = ourReadViews.find(p, ofs);
if( mmf ) {
void *res = ((char *)mmf->_view_private) + ofs;
return res;
}
}
{
size_t ofs=0;
MongoMMF *mmf = privateViews.find(p, ofs);
if( mmf ) {
log() << "dur: perf warning p=" << p << " is already in the writable view of " << mmf->filename() << endl;
return p;
}
}
// did you call writing() with a pointer that isn't into a datafile?
log() << "dur error switchToPrivateView " << p << endl;
return p;
}
/* switch to _view_write. normally, this is a bad idea since your changes will not
show up in _view_private if there have been changes there; thus the leading underscore
as a tad of a "warning". but useful when done with some care, such as during
initialization.
*/
/*static*/ void* MongoMMF::_switchToWritableView(void *p) {
RARELY log() << "todo dur not done switchtowritable" << endl;
if( debug )
return switchToPrivateView(p);
return p;
}
void MongoMMF::setPath(string f) {
string suffix;
bool ok = str::rSplitOn(f, '.', _filePath, suffix);
uassert(13520, str::stream() << "MongoMMF only supports filenames in a certain format " << f, ok);
if( suffix == "ns" )
_fileSuffixNo = -1;
else
_fileSuffixNo = (int) str::toUnsigned(suffix);
}
bool MongoMMF::open(string fname, bool sequentialHint) {
setPath(fname);
_view_write = mapWithOptions(fname.c_str(), sequentialHint ? SEQUENTIAL : 0);
return finishOpening();
}
bool MongoMMF::create(string fname, unsigned long long& len, bool sequentialHint) {
setPath(fname);
bool preExisting = MemoryMappedFile::exists(fname.c_str());
_view_write = map(fname.c_str(), len, sequentialHint ? SEQUENTIAL : 0);
if( cmdLine.dur && !testIntent && _view_write && !preExisting ) {
getDur().createdFile(fname, len);
}
return finishOpening();
}
bool MongoMMF::finishOpening() {
if( _view_write ) {
if( cmdLine.dur ) {
if( testIntent ) {
_view_private = _view_write;
_view_readonly = MemoryMappedFile::createReadOnlyMap();
ourReadViews.add(_view_readonly, this);
}
else {
_view_private = createPrivateMap();
}
privateViews.add(_view_private, this); // note that testIntent builds use this, even though it points to view_write then...
}
else {
_view_private = _view_write;
}
return true;
}
return false;
}
MongoMMF::MongoMMF() : _willNeedRemap(false) {
_view_write = _view_private = _view_readonly = 0;
}
MongoMMF::~MongoMMF() {
close();
}
namespace dur {
void closingFileNotification();
}
/*virtual*/ void MongoMMF::close() {
#if defined(_DURABLE)
{
if( !testIntent && cmdLine.dur ) {
dur::closingFileNotification();
}
privateViews.remove(_view_private);
if( debug ) {
ourReadViews.remove(_view_readonly);
}
}
#endif
_view_write = _view_private = _view_readonly = 0;
MemoryMappedFile::close();
}
}