hdf_filecache.h

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/*
 * Author: Grant Tang, 05/01/2012 (gtang@bcm.edu)
 * Copyright (c) 2000-2006 Baylor College of Medicine
 *
 * This software is issued under a joint BSD/GNU license. You may use the
 * source code in this file under either license. However, note that the
 * complete EMAN2 and SPARX software packages have some GPL dependencies,
 * so you are responsible for compliance with the licenses of these packages
 * if you opt to use BSD licensing. The warranty disclaimer below holds
 * in either instance.
 *
 * This complete copyright notice must be included in any revised version of the
 * source code. Additional authorship citations may be added, but existing
 * author citations must be preserved.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 * */
 
#ifndef eman__hdf_filecache__h__
#define eman__hdf_filecache__h__ 1
 
#ifdef  HDFIO_CACHE
 
#include <string>
#include <cstdio>
#include <ctime>
#include <functional>
 
#include "imageio.h"
 
using std::string;
using std::binary_function;
 
const static int CHECK_INTERVAL = 5;    //seconds for thread to check if the opened file need been closed
const static int ACCESS_TIME_THRESHOLD = 30;    //seconds since the last access to close HDF image file
const static int ACCESS_WRITE_TIME_THRESHOLD = 5;       //seconds since the last access to close HDF image file
 
namespace EMAN
{
 
class FileItem {
public:
        FileItem();
        FileItem(const string& fpath, ImageIO* const fimageio, const time_t& ftimestamp, bool freadonly);
        ~FileItem();
 
        int set_path(const string& fpath);
        string get_path() const;
 
        int set_imgio(ImageIO* const fimageio);
        ImageIO * get_imgio() const;
 
        int set_timestamp(const time_t& ftimestamp);
        time_t get_timestamp() const;
 
        int set_readonly(bool freadonly);
        bool get_readonly() const;
 
private:
        string          _path;          //full path name to the opened file
        ImageIO *       _imgio;         //image I/O object to the opened file
        time_t          _timestamp;     //last access time
        bool            _readonly;      //Is the file is opened in read only mode
};
 
class HDFCache {
public:
        static HDFCache *instance();
 
        //file name is a full path name
        FileItem * get_file(const string& filename);
 
        int add_file(FileItem * newfile);
 
private:
        HDFCache();
        HDFCache(const HDFCache&);
        ~HDFCache();
 
        static HDFCache * _instance;
 
        //Primary file handle container for fast accessing by file name
        typedef boost::unordered_map<string, FileItem *> MyHashtable;
        MyHashtable file_pool;
 
        //Secondary file handle container for fast sorting to close those files expired
        vector<FileItem *> file_pool2;
 
        boost::thread   _thread;
        boost::mutex    m_mutex;
 
        size_t CACHESIZE;               //size limit for the HDF file cache, half of the file descriptor limit per process
 
        //These functions are running in the thread
        int purge_file();               //purge the file has last access time >= threshold
        int force_clean();              //close some files when the cache reach it's size limit
        void cache_routine();   //function for background thread
        int close_file(const string& filename);
 
        //functor for sorting file pointer by access time
        struct least_access : public binary_function<FileItem *, FileItem *, bool>{
                bool operator()(FileItem * x, FileItem * y) const {
                        return x->get_timestamp() < y->get_timestamp();
                }
        };
 
        //functor for finding those files have access time over the threshold
        struct access_time_cmp : public binary_function<FileItem *, int, bool>{
                bool operator()(FileItem * f, int interval) const {
                        return f->get_timestamp() < time(0)-ACCESS_TIME_THRESHOLD;
                }
        };
};
 
}
 
#endif  //HDFIO_CACHE
 
#endif  //eman__hdf_filecache__h__