mongodb/util/mmap.cpp

// mmap.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 "pch.h"
#include "mmap.h"
#include "processinfo.h"
#include "concurrency/rwlock.h"
#include "../db/namespace.h"
#include "../db/cmdline.h"

namespace mongo {

    set<MongoFile*> MongoFile::mmfiles;
    map<string,MongoFile*> MongoFile::pathToFile;

    /* Create. Must not exist.
    @param zero fill file with zeros when true
    */
    void* MemoryMappedFile::create(string filename, unsigned long long len, bool zero) {
        uassert( 13468, string("can't create file already exists ") + filename, !exists(filename) );
        void *p = map(filename.c_str(), len);
        if( p && zero ) {
            size_t sz = (size_t) len;
            assert( len == sz );
            memset(p, 0, sz);
        }
        return p;
    }

    /*static*/ void MemoryMappedFile::updateLength( const char *filename, unsigned long long &length ) {
        if ( !boost::filesystem::exists( filename ) )
            return;
        // make sure we map full length if preexisting file.
        boost::uintmax_t l = boost::filesystem::file_size( filename );
        length = l;
    }

    void* MemoryMappedFile::map(const char *filename) {
        unsigned long long l = boost::filesystem::file_size( filename );
        return map( filename , l );
    }
    void* MemoryMappedFile::mapWithOptions(const char *filename, int options) {
        unsigned long long l = boost::filesystem::file_size( filename );
        return map( filename , l, options );
    }

    /* --- MongoFile -------------------------------------------------
       this is the administrative stuff
    */

    RWLockRecursive MongoFile::mmmutex("mmmutex",10*60*1000 /* 10 minutes */);

    /* subclass must call in destructor (or at close).
        removes this from pathToFile and other maps
        safe to call more than once, albeit might be wasted work
        ideal to call close to the close, if the close is well before object destruction
    */
    void MongoFile::destroyed() {
        mmmutex.assertExclusivelyLocked();
        mmfiles.erase(this);
        pathToFile.erase( filename() );
    }

    /*static*/
    void MongoFile::closeAllFiles( stringstream &message ) {
        static int closingAllFiles = 0;
        if ( closingAllFiles ) {
            message << "warning closingAllFiles=" << closingAllFiles << endl;
            return;
        }
        ++closingAllFiles;

        RWLockRecursive::Exclusive lk(mmmutex);

        ProgressMeter pm( mmfiles.size() , 2 , 1 );
        set<MongoFile*> temp = mmfiles;
        for ( set<MongoFile*>::iterator i = temp.begin(); i != temp.end(); i++ ) {
            (*i)->close(); // close() now removes from mmfiles
            pm.hit();
        }
        message << "closeAllFiles() finished";
        --closingAllFiles;
    }

    /*static*/ long long MongoFile::totalMappedLength() {
        unsigned long long total = 0;

        RWLockRecursive::Shared lk(mmmutex);
        for ( set<MongoFile*>::iterator i = mmfiles.begin(); i != mmfiles.end(); i++ )
            total += (*i)->length();

        return total;
    }

    void nullFunc() { }

    // callback notifications
    void (*MongoFile::notifyPreFlush)() = nullFunc;
    void (*MongoFile::notifyPostFlush)() = nullFunc;

    /*static*/ int MongoFile::flushAll( bool sync ) {
        notifyPreFlush();
        int x = _flushAll(sync);
        notifyPostFlush();
        return x;
    }

    /*static*/ int MongoFile::_flushAll( bool sync ) {
        if ( ! sync ) {
            int num = 0;
            RWLockRecursive::Shared lk(mmmutex);
            for ( set<MongoFile*>::iterator i = mmfiles.begin(); i != mmfiles.end(); i++ ) {
                num++;
                MongoFile * mmf = *i;
                if ( ! mmf )
                    continue;

                mmf->flush( sync );
            }
            return num;
        }

        // want to do it sync
        set<MongoFile*> seen;
        while ( true ) {
            auto_ptr<Flushable> f;
            {
                RWLockRecursive::Shared lk(mmmutex);
                for ( set<MongoFile*>::iterator i = mmfiles.begin(); i != mmfiles.end(); i++ ) {
                    MongoFile * mmf = *i;
                    if ( ! mmf )
                        continue;
                    if ( seen.count( mmf ) )
                        continue;
                    f.reset( mmf->prepareFlush() );
                    seen.insert( mmf );
                    break;
                }
            }
            if ( ! f.get() )
                break;

            f->flush();
        }
        return seen.size();
    }

    void MongoFile::created() {
        RWLockRecursive::Exclusive lk(mmmutex);
        mmfiles.insert(this);
    }

    void MongoFile::setFilename(string fn) {
        RWLockRecursive::Exclusive lk(mmmutex);
        assert( _filename.empty() );
        _filename = fn;
        MongoFile *&ptf = pathToFile[fn];
        massert(13617, "MongoFile : multiple opens of same filename", ptf == 0);
        ptf = this;
    }

#if defined(_DEBUG)
    void MongoFile::markAllWritable() {
      if( cmdLine.dur )
          return;
        RWLockRecursive::Shared lk(mmmutex);
        for ( set<MongoFile*>::iterator i = mmfiles.begin(); i != mmfiles.end(); i++ ) {
            MongoFile * mmf = *i;
            if (mmf) mmf->_lock();
        }
    }

    void MongoFile::unmarkAllWritable() {
        if( cmdLine.dur )
            return;
        RWLockRecursive::Shared lk(mmmutex);
        for ( set<MongoFile*>::iterator i = mmfiles.begin(); i != mmfiles.end(); i++ ) {
            MongoFile * mmf = *i;
            if (mmf) mmf->_unlock();
        }
    }
#endif
} // namespace mongo