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114 lines
4.9 KiB
C++
114 lines
4.9 KiB
C++
/*****************************************************************************************
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* *
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* OpenSpace *
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* *
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* Copyright (c) 2014-2017 *
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* *
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* Permission is hereby granted, free of charge, to any person obtaining a copy of this *
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* software and associated documentation files (the "Software"), to deal in the Software *
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* without restriction, including without limitation the rights to use, copy, modify, *
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* merge, publish, distribute, sublicense, and/or sell copies of the Software, and to *
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* permit persons to whom the Software is furnished to do so, subject to the following *
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* conditions: *
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* *
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* The above copyright notice and this permission notice shall be included in all copies *
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* or substantial portions of the Software. *
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* *
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, *
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* INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A *
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* PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT *
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF *
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* CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE *
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* OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. *
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****************************************************************************************/
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#ifndef __OPENSPACE_MODULE_GLOBEBROWSING___MEMORY_AWARE_TILE_CACHE___H__
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#define __OPENSPACE_MODULE_GLOBEBROWSING___MEMORY_AWARE_TILE_CACHE___H__
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#include <modules/globebrowsing/tile/tile.h>
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#include <modules/globebrowsing/tile/tileindex.h>
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#include <modules/globebrowsing/cache/memoryawarelrucache.h>
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#include <memory>
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#include <mutex>
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namespace openspace {
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namespace globebrowsing {
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namespace cache {
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struct ProviderTileKey {
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TileIndex tileIndex;
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unsigned int providerID;
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bool operator==(const ProviderTileKey& r) const {
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return (providerID == r.providerID) &&
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(tileIndex == r.tileIndex);
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}
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};
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struct ProviderTileHasher {
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/**
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Creates a hash which can be used as key in hash maps.
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First set the bits to be unique for all tiles.
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+-------+------------+-------+------------+
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| USAGE | BIT RANGE | #BITS | MAX VALUE |
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+-------+------------+-------+------------+
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| level | 0 - 5 | 5 | 31 |
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| x | 5 - 35 | 30 | 1073741824 |
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| y | 35 - 64 | 29 | 536870912 |
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+-------+------------+-------+------------+
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Bits are then shifted depending on the tile provider used.
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*/
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unsigned long long operator()(const ProviderTileKey& t) const {
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unsigned long long key = 0;
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key |= static_cast<unsigned long long>(t.tileIndex.level);
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key |= static_cast<unsigned long long>(t.tileIndex.x << 5);
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key |= static_cast<unsigned long long>(t.tileIndex.y << 35);
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// Now the key is unique for all tiles, however not for all tile providers.
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// Add to the key depending on the tile provider to avoid some hash collisions.
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// (All hash collisions can not be avoided due to the limit in 64 bit for the
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// hash key)
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// Idea: make some offset in the place of the bits for the x value. Lesser chance
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// of having different x-value than having different tile provider ids.
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key += static_cast<unsigned long long>(t.providerID << 25);
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return key;
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}
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};
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/**
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* Singleton class used to cache tiles for all <code>CachingTileProvider</code>s.
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*/
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class MemoryAwareTileCache {
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public:
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static void create(size_t cacheSize);
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static void destroy();
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void clear();
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bool exist(ProviderTileKey key) const;
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Tile get(ProviderTileKey key);
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void put(ProviderTileKey key, Tile tile);
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void setMaximumSize(size_t maximumSize);
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static MemoryAwareTileCache& ref();
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private:
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/**
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* \param cacheSize is the cache size given in bytes.
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*/
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MemoryAwareTileCache(size_t cacheSize);
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~MemoryAwareTileCache() = default;
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static MemoryAwareTileCache* _singleton;
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MemoryAwareLRUCache<ProviderTileKey, Tile, ProviderTileHasher> _tileCache;
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static std::mutex _mutexLock;
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};
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} // namespace cache
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} // namespace globebrowsing
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} // namespace openspace
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#endif // __OPENSPACE_MODULE_GLOBEBROWSING___MEMORY_AWARE_TILE_CACHE___H__
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