1 | /**********************************************************************
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2 | *
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3 | * CacheMan.h
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4 | * Copyright (C) 2003 UNESCO
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5 | *
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6 | * A component of the Greenstone digital library software
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7 | * from the New Zealand Digital Library Project at the
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8 | * University of Waikato, New Zealand.
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9 | *
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10 | * This program is free software; you can redistribute it and/or modify
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11 | * it under the terms of the GNU General Public License as published by
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12 | * the Free Software Foundation; either version 2 of the License, or
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13 | * (at your option) any later version.
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14 | *
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15 | * This program is distributed in the hope that it will be useful,
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16 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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17 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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18 | * GNU General Public License for more details.
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19 | *
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20 | * You should have received a copy of the GNU General Public License
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21 | * along with this program; if not, write to the Free Software
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22 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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23 | *
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24 | *********************************************************************/
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25 |
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26 | #ifndef __CACHEMAN_H__
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27 | #define __CACHEMAN_H__
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28 |
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29 |
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30 | #include "File.h"
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31 |
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32 | class CacheManager
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33 | {
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34 | private:
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35 |
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36 | CFileBase* theFile_;
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37 | unsigned maxblocks_; // Max # blocks in buff_er
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38 | unsigned nused_; // Number being used.
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39 | unsigned blocksize_; // Size of a block
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40 | FileSystem::FAU_t* diskAddrs_; // Its disk address
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41 | unsigned* useCounts_; // Use count for the block
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42 | char* buff_; // The set of blocks.
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43 |
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44 | public:
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45 |
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46 | CacheManager();
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47 | CacheManager::CacheManager(unsigned blocksz, unsigned mxblks);
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48 |
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49 | ~CacheManager();
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50 |
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51 | void Create(unsigned blocksz, unsigned mxblks = 10);
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52 | void Erase();
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53 |
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54 | void Connect(CFileBase* file);
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55 | void Disconnect();
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56 | bool Flush(); // Perform any pending writes.
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57 | void Invalidate(); // Invalidate the entire cache
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58 | bool Read (FileSystem::FAU_t locn, void* dat);
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59 | bool Write(FileSystem::FAU_t locn, void* dat);
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60 |
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61 | private:
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62 |
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63 | CacheManager(const CacheManager&); // Private to insure no copies
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64 | void operator=(const CacheManager&); // Ditto
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65 | size_t AgeAndFindSlot(FileSystem::FAU_t);
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66 | bool Flush(unsigned);
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67 | size_t GetFreeSlot();
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68 | size_t LRU() const; // Find least recently used block
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69 | };
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70 |
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71 | #endif
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