Chris@334: 
Chris@168: /* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */
Chris@168: 
Chris@168: /*
Chris@168:     Sonic Visualiser
Chris@168:     An audio file viewer and annotation editor.
Chris@168:     Centre for Digital Music, Queen Mary, University of London.
Chris@202:     This file copyright 2006 QMUL.
Chris@168:     
Chris@168:     This program is free software; you can redistribute it and/or
Chris@168:     modify it under the terms of the GNU General Public License as
Chris@168:     published by the Free Software Foundation; either version 2 of the
Chris@168:     License, or (at your option) any later version.  See the file
Chris@168:     COPYING included with this distribution for more information.
Chris@168: */
Chris@168: 
Chris@1276: #ifndef SV_STORAGE_ADVISER_H
Chris@1276: #define SV_STORAGE_ADVISER_H
Chris@168: 
Chris@1038: #include <cstdlib>
Chris@1038: 
Chris@1276: #include <QString>
Chris@1276: 
Chris@168: /**
Chris@168:  * A utility class designed to help decide whether to store cache data
Chris@168:  * (for example FFT outputs) in memory or on disk in the TempDirectory.
Chris@170:  * This is basically a compendium of simple rules of thumb.
Chris@168:  */
Chris@168: 
Chris@168: class StorageAdviser
Chris@168: {
Chris@168: public:
Chris@168:     // pass to recommend() zero or more of these OR'd together
Chris@168:     enum Criteria {
Chris@170:         NoCriteria           = 0,
Chris@170:         SpeedCritical        = 1,
Chris@170:         PrecisionCritical    = 2,
Chris@170:         LongRetentionLikely  = 4,
Chris@170:         FrequentLookupLikely = 8
Chris@168:     };
Chris@168: 
Chris@168:     // recommend() returns one or two of these OR'd together
Chris@168:     enum Recommendation {
Chris@170:         NoRecommendation   = 0,
Chris@170:         UseMemory          = 1, // Disc is strongly contraindicated
Chris@170:         PreferMemory       = 2, // Either would do; memory probably better
Chris@170:         PreferDisc         = 4, // Either would do; disc probably better
Chris@170:         UseDisc            = 8, // Probably won't fit in memory
Chris@170:         ConserveSpace      = 16,// Whatever you choose, keep it compact
Chris@170:         UseAsMuchAsYouLike = 32 // Take my advice and there'll be space for all
Chris@168:     };
Chris@168: 
Chris@169:     /**
Chris@169:      * Recommend where to store some data, given certain storage and
Chris@169:      * recall criteria.  The minimum size is the approximate amount of
Chris@170:      * data in kilobytes that will be stored if the recommendation is
Chris@170:      * to ConserveSpace; the maximum size is approximately the amount
Chris@169:      * that will be used if UseAsMuchAsYouLike is returned.
Chris@170:      *
Chris@170:      * May throw InsufficientDiscSpace exception if there appears to
Chris@170:      * be nowhere the minimum amount of data can be stored.
Chris@169:      */
Chris@168:     static Recommendation recommend(Criteria criteria,
Chris@1038:                                     size_t minimumSize,
Chris@1038:                                     size_t maximumSize);
Chris@205: 
Chris@205:     enum AllocationArea {
Chris@205:         MemoryAllocation,
Chris@205:         DiscAllocation
Chris@205:     };
Chris@205: 
Chris@205:     /**
Chris@205:      * Specify that we are planning to use a given amount of storage
Chris@205:      * (in kilobytes), but haven't allocated it yet.
Chris@205:      */
Chris@1038:     static void notifyPlannedAllocation(AllocationArea area, size_t size);
Chris@205: 
Chris@205:     /**
Chris@205:      * Specify that we have now allocated, or abandoned the allocation
Chris@205:      * of, the given amount (in kilobytes) of a storage area that was
Chris@205:      * previously notified using notifyPlannedAllocation.
Chris@205:      */
Chris@1038:     static void notifyDoneAllocation(AllocationArea area, size_t size);
Chris@205: 
Chris@411:     /**
Chris@411:      * Force all subsequent recommendations to use the (perhaps
Chris@411:      * partial) specification given here.  If NoRecommendation given
Chris@411:      * here, this will reset to the default free behaviour.
Chris@411:      */
Chris@411:     static void setFixedRecommendation(Recommendation recommendation);
Chris@411: 
Chris@205: private:
Chris@1038:     static size_t m_discPlanned;
Chris@1038:     static size_t m_memoryPlanned;
Chris@411:     static Recommendation m_baseRecommendation;
Chris@1276: 
Chris@1276:     enum StorageStatus {
Chris@1276:         Unknown,
Chris@1276:         Insufficient,
Chris@1276:         Marginal,
Chris@1276:         Sufficient
Chris@1276:     };
Chris@1276: 
Chris@1276:     static QString criteriaToString(int);
Chris@1276:     static QString recommendationToString(int);
Chris@1276:     static QString storageStatusToString(StorageStatus);
Chris@168: };
Chris@168: 
Chris@168: #endif
Chris@168: