OpenSpace/modules/globebrowsing/cache/memoryawaretilecache.h

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2017                                                               *
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#ifndef __OPENSPACE_MODULE_GLOBEBROWSING___MEMORY_AWARE_TILE_CACHE___H__
#define __OPENSPACE_MODULE_GLOBEBROWSING___MEMORY_AWARE_TILE_CACHE___H__

#include <modules/globebrowsing/cache/lrucache.h>
#include <modules/globebrowsing/cache/texturecontainer.h>
#include <modules/globebrowsing/tile/tile.h>
#include <modules/globebrowsing/tile/tileindex.h>
#include <modules/globebrowsing/tile/rawtile.h>
#include <modules/globebrowsing/tile/rawtiledatareader/iodescription.h>

#include <openspace/properties/propertyowner.h>
#include <openspace/properties/scalar/boolproperty.h>
#include <openspace/properties/scalarproperty.h>
#include <openspace/properties/triggerproperty.h>

#include <memory>
#include <vector>
#include <unordered_map>

namespace openspace::globebrowsing::cache {

struct ProviderTileKey {
    TileIndex tileIndex;
    unsigned int providerID;

    bool operator==(const ProviderTileKey& r) const {
        return (providerID == r.providerID) &&
            (tileIndex == r.tileIndex);
    }
};

struct ProviderTileHasher {
    /**
    Creates a hash which can be used as key in hash maps.
    First set the bits to be unique for all tiles.
    +-------+------------+-------+------------+
    | USAGE | BIT RANGE  | #BITS | MAX VALUE  |
    +-------+------------+-------+------------+
    | level |   0 -  5   |   5   |         31 |
    |     x |   5 - 35   |  30   | 1073741824 |
    |     y |  35 - 64   |  29   |  536870912 |
    +-------+------------+-------+------------+

    Bits are then shifted depending on the tile provider used.
    */
    unsigned long long operator()(const ProviderTileKey& t) const {
        unsigned long long key = 0;
        key |= static_cast<unsigned long long>(t.tileIndex.level);
        key |= static_cast<unsigned long long>(t.tileIndex.x) << 5ULL;
        key |= static_cast<unsigned long long>(t.tileIndex.y) << 35ULL;
        // Now the key is unique for all tiles, however not for all tile providers.
        // Add to the key depending on the tile provider to avoid some hash collisions.
        // (All hash collisions can not be avoided due to the limit in 64 bit for the
        // hash key)
        // Idea: make some offset in the place of the bits for the x value. Lesser chance
        // of having different x-value than having different tile provider ids.
        key += static_cast<unsigned long long>(t.providerID) << 25ULL;
        return key;
    }
};

class MemoryAwareTileCache : public properties::PropertyOwner {
public:
    MemoryAwareTileCache();
    ~MemoryAwareTileCache();

    void clear();
    void setSizeEstimated(size_t estimatedSize);
    bool exist(ProviderTileKey key) const;
    Tile get(ProviderTileKey key);
    ghoul::opengl::Texture* getTexture(const TileTextureInitData& initData);
    void createTileAndPut(ProviderTileKey key, std::shared_ptr<RawTile> rawTile);
    void put(const ProviderTileKey& key,
        const TileTextureInitData::HashKey& initDataKey, Tile tile);
    void update();

    size_t getGPUAllocatedDataSize() const;
    size_t getCPUAllocatedDataSize() const;
    bool shouldUsePbo() const;

private:

    void createDefaultTextureContainers();
    void assureTextureContainerExists(const TileTextureInitData& initData);
    void resetTextureContainerSize(size_t numTexturesPerTextureType);
    
    using TileCache = LRUCache<ProviderTileKey, Tile, ProviderTileHasher>;
    using TextureContainerTileCache =
        std::pair<std::unique_ptr<TextureContainer>, std::unique_ptr<TileCache>>;
    using TextureContainerMap = std::unordered_map<TileTextureInitData::HashKey,
        TextureContainerTileCache>;

    TextureContainerMap _textureContainerMap;
    size_t _numTextureBytesAllocatedOnCPU;

    // Properties
    properties::IntProperty _cpuAllocatedTileData;
    properties::IntProperty _gpuAllocatedTileData;
    properties::IntProperty _tileCacheSize;
    properties::TriggerProperty _applyTileCacheSize;
    properties::TriggerProperty _clearTileCache;

    /// Whether or not pixel buffer objects should be used when uploading tile data
    properties::BoolProperty _usePbo;
};

} // namespace openspace::globebrowsing::cache

#endif // __OPENSPACE_MODULE_GLOBEBROWSING___MEMORY_AWARE_TILE_CACHE___H__