Casarc.h

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//# Casarc.h: Class to read the casa general resource files
//# Copyright (C) 2009
//# Associated Universities, Inc. Washington DC, USA.
//#
//# This library is free software; you can redistribute it and/or modify it
//# under the terms of the GNU Library General Public License as published by
//# the Free Software Foundation; either version 2 of the License, or (at your
//# option) any later version.
//#
//# This library 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 Library General Public
//# License for more details.
//#
//# You should have received a copy of the GNU Library General Public License
//# along with this library; if not, write to the Free Software Foundation,
//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
//#
//# Correspondence concerning AIPS++ should be addressed as follows:
//#        Internet email: aips2-request@nrao.edu.
//#        Postal address: AIPS++ Project Office
//#                        National Radio Astronomy Observatory
//#                        520 Edgemont Road
//#                        Charlottesville, VA 22903-2475 USA
//#
//# $Id$

#ifndef CASA_CASARC_H
#define CASA_CASARC_H

#include <casacore/casa/aips.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <string>
#include <list>
#include <map>

namespace casacore { //# NAMESPACE CASACORE - BEGIN

    class Casarc {

    friend class CasarcCleanup;

    public:

        typedef std::map<std::string,std::string>::const_iterator iterator;

        // return default casarc file, e.g. ~/.casarc
        static Casarc &instance( );

        // set and clear the default casarc path (to something other than ~/.casarc)
        static void setDefaultPath( const std::string &path );
        static void clearDefaultPath( );

        // return a casarc object attached to a particular file
        static Casarc &instance( const std::string &path );

        // return the list of rcfiles that have been loaded
            static const std::list<Casarc*> & list( );

        // adds the keyword->value mapping
        void put( const std::string &keyword, const std::string &value );

        // retrieves the mapping for keyword (or "" if the mapping is not defined)
        std::string get( const std::string &keyword );

        // retrieves the mapping for keyword in value (and returns true if the
        // mapping is defined or false otherwise)
        bool get( const std::string &keyword, std::string &value );

        size_t size( ) const;

        // path to the file that this Casarc mirrors...
        const std::string &path( ) const { return filename; }

        iterator begin( );
        iterator end( );

    private:

        class meta_entry_ {
        public:
        meta_entry_( off_t keys_, int keyl_, off_t vals_, int vall_, off_t times_, int timel_ ) : 
                    key_offset_(keys_), key_len_(keyl_), 
                    val_offset_(vals_), val_len_(vall_),
                    time_offset_(times_), time_len_(timel_) { }

        off_t key_offset( ) const { return key_offset_; }
        int key_length( ) const { return key_len_; }

        off_t value_offset( ) const { return val_offset_; }
        int value_length( ) const { return val_len_; }

        off_t time_offset( ) const { return time_offset_; }
        int time_length( ) const { return time_len_; }

        private:
        off_t key_offset_;
        int key_len_;
        off_t val_offset_;
        int val_len_;
        off_t time_offset_;
        int time_len_;
        };

        char *mapped_file;
        off_t mapped_file_size;

        std::list<int> stale_fds;
        void close( int );

        std::list<pid_t> have_lock;

        enum lock_mode { READ, READ_WRITE, WRITE, APPEND };
        // returns a file descriptor or -1 on error...
        int lock( lock_mode mode );
        void unlock( int fd );

        void sync( );
        double current_modification_time( struct stat &buf );

        std::string filename;
        double timestamp;

        std::map<std::string,std::string> rcmap;
        // this is broken off separate from the rcmap to allow the
        // rcmap to be used for iteration by users of this class...
        std::map<std::string,meta_entry_> rcmetamap;

        void read_file( );

        ino_t inode;

        // singleton Casarcs, (inode->casarc)
        static std::map<ino_t,Casarc*> *rcfiles;
        static std::map<std::string,Casarc*> *filenames;
        static std::list<Casarc*> *rclist;
        static std::string *default_path;
        // path is the path to the .casarc (or .aipsrc file)
        Casarc( const std::string &path );
        static bool initialized;
        static void startup( );
        static void shutdown( );
        ~Casarc( ) { }
    };

    static class CasarcCleanup {
    public:
        CasarcCleanup( ) { creation_count += 1; }
        ~CasarcCleanup( ) { if ( --creation_count == 0 ) { Casarc::shutdown( ); } }
    private:
        static unsigned int creation_count;
    } local_cleanup_object;
  
} //# NAMESPACE CASACORE - END

#endif