Mercurial > hg > svcore
view base/StorageAdviser.h @ 1038:cc27f35aa75c cxx11
Introducing the signed 64-bit frame index type, and fixing build failures from inclusion of -Wconversion with -Werror. Not finished yet.
author | Chris Cannam |
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date | Tue, 03 Mar 2015 15:18:24 +0000 |
parents | 52303ec15cd2 |
children | adbd16d2c1e8 |
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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*- vi:set ts=8 sts=4 sw=4: */ /* Sonic Visualiser An audio file viewer and annotation editor. Centre for Digital Music, Queen Mary, University of London. This file copyright 2006 QMUL. 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. See the file COPYING included with this distribution for more information. */ #ifndef _STORAGE_ADVISER_H_ #define _STORAGE_ADVISER_H_ #include <cstdlib> /** * A utility class designed to help decide whether to store cache data * (for example FFT outputs) in memory or on disk in the TempDirectory. * This is basically a compendium of simple rules of thumb. */ class StorageAdviser { public: // pass to recommend() zero or more of these OR'd together enum Criteria { NoCriteria = 0, SpeedCritical = 1, PrecisionCritical = 2, LongRetentionLikely = 4, FrequentLookupLikely = 8 }; // recommend() returns one or two of these OR'd together enum Recommendation { NoRecommendation = 0, UseMemory = 1, // Disc is strongly contraindicated PreferMemory = 2, // Either would do; memory probably better PreferDisc = 4, // Either would do; disc probably better UseDisc = 8, // Probably won't fit in memory ConserveSpace = 16,// Whatever you choose, keep it compact UseAsMuchAsYouLike = 32 // Take my advice and there'll be space for all }; /** * Recommend where to store some data, given certain storage and * recall criteria. The minimum size is the approximate amount of * data in kilobytes that will be stored if the recommendation is * to ConserveSpace; the maximum size is approximately the amount * that will be used if UseAsMuchAsYouLike is returned. * * May throw InsufficientDiscSpace exception if there appears to * be nowhere the minimum amount of data can be stored. */ static Recommendation recommend(Criteria criteria, size_t minimumSize, size_t maximumSize); enum AllocationArea { MemoryAllocation, DiscAllocation }; /** * Specify that we are planning to use a given amount of storage * (in kilobytes), but haven't allocated it yet. */ static void notifyPlannedAllocation(AllocationArea area, size_t size); /** * Specify that we have now allocated, or abandoned the allocation * of, the given amount (in kilobytes) of a storage area that was * previously notified using notifyPlannedAllocation. */ static void notifyDoneAllocation(AllocationArea area, size_t size); /** * Force all subsequent recommendations to use the (perhaps * partial) specification given here. If NoRecommendation given * here, this will reset to the default free behaviour. */ static void setFixedRecommendation(Recommendation recommendation); private: static size_t m_discPlanned; static size_t m_memoryPlanned; static Recommendation m_baseRecommendation; }; #endif