db.h

/**
*    Copyright (C) 2008 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/>.
*/

#pragma once

#include "../pch.h"
#include "../util/net/message.h"
#include "concurrency.h"
#include "pdfile.h"
#include "curop.h"
#include "client.h"

namespace mongo {

//    void jniCallback(Message& m, Message& out);

    /**
     * class to hold path + dbname -> Database
     * might be able to optimizer further
     */
    class DatabaseHolder {
    public:
        typedef map<string,Database*> DBs;
        typedef map<string,DBs> Paths;

        DatabaseHolder() : _size(0) { }

        bool isLoaded( const string& ns , const string& path ) const {
            dbMutex.assertAtLeastReadLocked();
            Paths::const_iterator x = _paths.find( path );
            if ( x == _paths.end() )
                return false;
            const DBs& m = x->second;

            string db = _todb( ns );

            DBs::const_iterator it = m.find(db);
            return it != m.end();
        }

        Database * get( const string& ns , const string& path ) const {
            dbMutex.assertAtLeastReadLocked();
            Paths::const_iterator x = _paths.find( path );
            if ( x == _paths.end() )
                return 0;
            const DBs& m = x->second;

            string db = _todb( ns );

            DBs::const_iterator it = m.find(db);
            if ( it != m.end() )
                return it->second;
            return 0;
        }

        void put( const string& ns , const string& path , Database * db ) {
            dbMutex.assertWriteLocked();
            DBs& m = _paths[path];
            Database*& d = m[_todb(ns)];
            if ( ! d )
                _size++;
            d = db;
        }

        Database* getOrCreate( const string& ns , const string& path , bool& justCreated );

        void erase( const string& ns , const string& path ) {
            dbMutex.assertWriteLocked();
            DBs& m = _paths[path];
            _size -= (int)m.erase( _todb( ns ) );
        }

        /* force - force close even if something underway - use at shutdown */
        bool closeAll( const string& path , BSONObjBuilder& result, bool force );

        int size() {
            return _size;
        }

        void forEach(boost::function<void(Database *)> f) const {
            dbMutex.assertAtLeastReadLocked();
            for ( Paths::const_iterator i=_paths.begin(); i!=_paths.end(); i++ ) {
                DBs m = i->second;
                for( DBs::const_iterator j=m.begin(); j!=m.end(); j++ ) {
                    f(j->second);
                }
            }
        }

        /**
         * gets all unique db names, ignoring paths
         */
        void getAllShortNames( set<string>& all ) const {
            dbMutex.assertAtLeastReadLocked();
            for ( Paths::const_iterator i=_paths.begin(); i!=_paths.end(); i++ ) {
                DBs m = i->second;
                for( DBs::const_iterator j=m.begin(); j!=m.end(); j++ ) {
                    all.insert( j->first );
                }
            }
        }

    private:

        string _todb( const string& ns ) const {
            string d = __todb( ns );
            uassert( 13280 , (string)"invalid db name: " + ns , Database::validDBName( d ) );
            return d;
        }

        string __todb( const string& ns ) const {
            size_t i = ns.find( '.' );
            if ( i == string::npos ) {
                uassert( 13074 , "db name can't be empty" , ns.size() );
                return ns;
            }
            uassert( 13075 , "db name can't be empty" , i > 0 );
            return ns.substr( 0 , i );
        }

        Paths _paths;
        int _size;

    };

    extern DatabaseHolder dbHolder;

    struct dbtemprelease {
        Client::Context * _context;
        int _locktype;

        dbtemprelease() {
            const Client& c = cc();
            _context = c.getContext();
            _locktype = dbMutex.getState();
            assert( _locktype );

            if ( _locktype > 0 ) {
                massert( 10298 , "can't temprelease nested write lock", _locktype == 1);
                if ( _context ) _context->unlocked();
                dbMutex.unlock();
            }
            else {
                massert( 10299 , "can't temprelease nested read lock", _locktype == -1);
                if ( _context ) _context->unlocked();
                dbMutex.unlock_shared();
            }
            
            verify( 14814 , c.curop() );
            c.curop()->yielded();
            
        }
        ~dbtemprelease() {
            if ( _locktype > 0 )
                dbMutex.lock();
            else
                dbMutex.lock_shared();

            if ( _context ) _context->relocked();
        }
    };

    /** must be write locked
        no assert (and no release) if nested write lock 
        a lot like dbtempreleasecond but no malloc so should be a tiny bit faster
    */
    struct dbtempreleasewritelock {
        Client::Context * _context;
        int _locktype;
        dbtempreleasewritelock() {
            const Client& c = cc();
            _context = c.getContext();
            _locktype = dbMutex.getState();
            assert( _locktype >= 1 );
            if( _locktype > 1 ) 
                return; // nested
            if ( _context ) 
                _context->unlocked();
            dbMutex.unlock();
            verify( 14845 , c.curop() );
            c.curop()->yielded();            
        }
        ~dbtempreleasewritelock() {
            if ( _locktype == 1 )
                dbMutex.lock();
            if ( _context ) 
                _context->relocked();
        }
    };

    /**
       only does a temp release if we're not nested and have a lock
     */
    struct dbtempreleasecond {
        dbtemprelease * real;
        int locktype;

        dbtempreleasecond() {
            real = 0;
            locktype = dbMutex.getState();
            if ( locktype == 1 || locktype == -1 )
                real = new dbtemprelease();
        }

        ~dbtempreleasecond() {
            if ( real ) {
                delete real;
                real = 0;
            }
        }

        bool unlocked() {
            return real > 0;
        }
    };

} // namespace mongo

//#include "dbinfo.h"
#include "concurrency.h"