BESCache.h

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00001 // BESCache.h
00002 
00003 // This file is part of bes, A C++ back-end server implementation framework
00004 // for the OPeNDAP Data Access Protocol.
00005 
00006 // Copyright (c) 2004-2009 University Corporation for Atmospheric Research
00007 // Author: Patrick West <pwest@ucar.edu> and Jose Garcia <jgarcia@ucar.edu>
00008 //
00009 // This library is free software; you can redistribute it and/or
00010 // modify it under the terms of the GNU Lesser General Public
00011 // License as published by the Free Software Foundation; either
00012 // version 2.1 of the License, or (at your option) any later version.
00013 // 
00014 // This library is distributed in the hope that it will be useful,
00015 // but WITHOUT ANY WARRANTY; without even the implied warranty of
00016 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00017 // Lesser General Public License for more details.
00018 // 
00019 // You should have received a copy of the GNU Lesser General Public
00020 // License along with this library; if not, write to the Free Software
00021 // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
00022 //
00023 // You can contact University Corporation for Atmospheric Research at
00024 // 3080 Center Green Drive, Boulder, CO 80301
00025  
00026 // (c) COPYRIGHT University Corporation for Atmospheric Research 2004-2005
00027 // Please read the full copyright statement in the file COPYRIGHT_UCAR.
00028 //
00029 // Authors:
00030 //      pwest       Patrick West <pwest@ucar.edu>
00031 //      jgarcia     Jose Garcia <jgarcia@ucar.edu>
00032 
00033 #ifndef BESCache_h_
00034 #define BESCache_h_ 1
00035 
00036 #include <string>
00037 
00038 using std::string ;
00039 
00040 #include "BESObj.h"
00041 
00042 class BESKeys ;
00043 
00044 #define MAX_LOCK_RETRY_MS 5000  // in microseconds
00045 #define MAX_LOCK_TRIES 16
00046 
00057 class BESCache : public BESObj
00058 {
00059 private:
00060     string                      _cache_dir ;
00061     string                      _prefix ;
00062     unsigned int                _cache_size ;
00063     int                         _lock_fd ;
00064 
00065     void                        check_ctor_params();
00066                                 BESCache() {}
00067 public:
00068                                 BESCache( const string &cache_dir,
00069                                           const string &prefix,
00070                                           unsigned int size ) ;
00071                                 BESCache( BESKeys &keys,
00072                                           const string &cache_dir_key,
00073                                           const string &prefix_key,
00074                                           const string &size_key ) ;
00075     virtual                     ~BESCache() {}
00076 
00077     virtual bool                lock( unsigned int retry_ms,
00078                                       unsigned int num_tries ) ;
00079     virtual bool                unlock() ;
00080 
00081     virtual bool                is_cached( const string &src, string &target ) ;
00082     virtual void                purge( ) ;
00083 
00084     string                      cache_dir( ) { return _cache_dir ; }
00085     string                      prefix( ) { return _prefix ; }
00086     unsigned int                cache_size( ) { return _cache_size ; }
00087 
00088     virtual void                dump( ostream &strm ) const ;
00089 };
00090 
00091 #endif // BESCache_h_
00092 

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