OpenSpace/modules/globebrowsing/src/asynctiledataprovider.h

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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2024                                                               *
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#ifndef __OPENSPACE_MODULE_GLOBEBROWSING___ASYNC_TILE_DATAPROVIDER___H__
#define __OPENSPACE_MODULE_GLOBEBROWSING___ASYNC_TILE_DATAPROVIDER___H__

#include <modules/globebrowsing/src/prioritizingconcurrentjobmanager.h>
#include <modules/globebrowsing/src/rawtiledatareader.h>
#include <modules/globebrowsing/src/tileindex.h>
#include <ghoul/misc/boolean.h>
#include <map>
#include <optional>
#include <set>

namespace openspace::globebrowsing {

struct RawTile;

/**
 * The responsibility of this class is to enqueue tile requests and fetching finished
 * `RawTile`s that has been asynchronously loaded.
 */
class AsyncTileDataProvider {
public:
    /**
     * \param name is the name for this provider
     * \param rawTileDataReader is the reader that will be used for the asynchronous tile
     *        loading
     */
    AsyncTileDataProvider(std::string name,
        std::unique_ptr<RawTileDataReader> rawTileDataReader);

    /**
     * Creates a job which asynchronously loads a raw tile. This job is enqueued.
     */
    bool enqueueTileIO(const TileIndex& tileIndex);

    /**
     * Get one finished job.
     */
    std::optional<RawTile> popFinishedRawTile();

    void update();
    void reset();
    void prepareToBeDeleted();

    bool shouldBeDeleted() const;

    const RawTileDataReader& rawTileDataReader() const;
    float noDataValueAsFloat() const;

protected:
    BooleanType(ResetRawTileDataReader);

    enum class ResetMode {
        ShouldResetAll,
        ShouldResetAllButRawTileDataReader,
        ShouldBeDeleted,
        ShouldNotReset
    };

    /**
     * \return `true` if tile of index \p tileIndex is not already enqueued
     */
    bool satisfiesEnqueueCriteria(const TileIndex& tileIndex);

    /**
     * An unfinished job is a load tile job that has been popped from the thread pool due
     * to its low priority. Once it has been popped, it is marked as unfinished and needs
     * to be explicitly ended.
     */
    void endUnfinishedJobs();

    void clearTiles();

    void endEnqueuedJobs();

    void performReset(ResetRawTileDataReader resetRawTileDataReader);

private:
    const std::string _name;
    /// The reader used for asynchronous reading
    std::unique_ptr<RawTileDataReader> _rawTileDataReader;

    PrioritizingConcurrentJobManager<RawTile, TileIndex::TileHashKey>
        _concurrentJobManager;

    std::set<TileIndex::TileHashKey> _enqueuedTileRequests;

    ResetMode _resetMode = ResetMode::ShouldResetAllButRawTileDataReader;
    bool _shouldBeDeleted = false;
};

} // namespace openspace::globebrowsing

#endif // __OPENSPACE_MODULE_GLOBEBROWSING___ASYNC_TILE_DATAPROVIDER___H__