src/core/SkStrikeCache.h

/*
 * Copyright 2010 Google Inc.
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#ifndef SkStrikeCache_DEFINED
#define SkStrikeCache_DEFINED

#include <unordered_map>
#include <unordered_set>

#include "include/core/SkDrawable.h"
#include "include/private/SkSpinlock.h"
#include "include/private/SkTemplates.h"
#include "src/core/SkDescriptor.h"
#include "src/core/SkScalerCache.h"
#include "src/core/SkStrikeSpec.h"
#include "src/text/StrikeForGPU.h"

class SkTraceMemoryDump;
class SkStrikeCache;

#ifndef SK_DEFAULT_FONT_CACHE_COUNT_LIMIT
    #define SK_DEFAULT_FONT_CACHE_COUNT_LIMIT   2048
#endif

#ifndef SK_DEFAULT_FONT_CACHE_LIMIT
    #define SK_DEFAULT_FONT_CACHE_LIMIT     (2 * 1024 * 1024)
#endif

///////////////////////////////////////////////////////////////////////////////

class SkStrikePinner {
public:
    virtual ~SkStrikePinner() = default;
    virtual bool canDelete() = 0;
    virtual void assertValid() {}
};

class SkStrike final : public SkRefCnt, public sktext::StrikeForGPU {
public:
    SkStrike(SkStrikeCache* strikeCache,
             const SkStrikeSpec& strikeSpec,
             std::unique_ptr<SkScalerContext> scaler,
             const SkFontMetrics* metrics,
             std::unique_ptr<SkStrikePinner> pinner)
        : fStrikeSpec(strikeSpec)
        , fStrikeCache{strikeCache}
        , fScalerCache{std::move(scaler), metrics}
        , fPinner{std::move(pinner)} {}

    SkGlyph* mergeGlyphAndImage(SkPackedGlyphID toID, const SkGlyph& from) {
        auto [glyph, increase] = fScalerCache.mergeGlyphAndImage(toID, from);
        this->updateDelta(increase);
        return glyph;
    }

    const SkPath* mergePath(SkGlyph* glyph, const SkPath* path, bool hairline) {
        auto [glyphPath, increase] = fScalerCache.mergePath(glyph, path, hairline);
        this->updateDelta(increase);
        return glyphPath;
    }

    const SkDrawable* mergeDrawable(SkGlyph* glyph, sk_sp<SkDrawable> drawable) {
        auto [glyphDrawable, increase] = fScalerCache.mergeDrawable(glyph, std::move(drawable));
        this->updateDelta(increase);
        return glyphDrawable;
    }

    // [[deprecated]]
    SkScalerContext* getScalerContext() const {
        return fScalerCache.getScalerContext();
    }

    void findIntercepts(const SkScalar bounds[2], SkScalar scale, SkScalar xPos,
                        SkGlyph* glyph, SkScalar* array, int* count) {
        fScalerCache.findIntercepts(bounds, scale, xPos, glyph, array, count);
    }

    const SkFontMetrics& getFontMetrics() const {
        return fScalerCache.getFontMetrics();
    }

    SkSpan<const SkGlyph*> metrics(SkSpan<const SkGlyphID> glyphIDs,
                                   const SkGlyph* results[]) {
        auto [glyphs, increase] = fScalerCache.metrics(glyphIDs, results);
        this->updateDelta(increase);
        return glyphs;
    }

    SkSpan<const SkGlyph*> preparePaths(SkSpan<const SkGlyphID> glyphIDs,
                                        const SkGlyph* results[]) {
        auto [glyphs, increase] = fScalerCache.preparePaths(glyphIDs, results);
        this->updateDelta(increase);
        return glyphs;
    }

    SkSpan<const SkGlyph*> prepareImages(SkSpan<const SkPackedGlyphID> glyphIDs,
                                         const SkGlyph* results[]) {
        auto [glyphs, increase] = fScalerCache.prepareImages(glyphIDs, results);
        this->updateDelta(increase);
        return glyphs;
    }

    SkSpan<const SkGlyph*> prepareDrawables(SkSpan<const SkGlyphID> glyphIDs,
                                            const SkGlyph* results[]) {
        auto [glyphs, increase] = fScalerCache.prepareDrawables(glyphIDs, results);
        this->updateDelta(increase);
        return glyphs;
    }

    void prepareForDrawingMasksCPU(SkDrawableGlyphBuffer* accepted) {
        size_t increase = fScalerCache.prepareForDrawingMasksCPU(accepted);
        this->updateDelta(increase);
    }

    const SkGlyphPositionRoundingSpec& roundingSpec() const override {
        return fScalerCache.roundingSpec();
    }

    const SkDescriptor& getDescriptor() const override {
        return fStrikeSpec.descriptor();
    }

    const SkStrikeSpec& strikeSpec() const {
        return fStrikeSpec;
    }

    void verifyPinnedStrike() const {
        if (fPinner != nullptr) {
            fPinner->assertValid();
        }
    }

#if SK_SUPPORT_GPU
    sk_sp<sktext::gpu::TextStrike> findOrCreateTextStrike(
            sktext::gpu::StrikeCache* gpuStrikeCache) const;
#endif

    SkRect prepareForMaskDrawing(SkScalar strikeToSourceScale,
                                 SkDrawableGlyphBuffer* accepted,
                                 SkSourceGlyphBuffer* rejected) override {
        auto [rect, increase] = fScalerCache.prepareForMaskDrawing(
                strikeToSourceScale, accepted, rejected);
        this->updateDelta(increase);
        return rect;
    }

    SkRect prepareForSDFTDrawing(SkScalar strikeToSourceScale,
                                 SkDrawableGlyphBuffer* accepted,
                                 SkSourceGlyphBuffer* rejected) override {
        auto [rect, increase] = fScalerCache.prepareForSDFTDrawing(
                strikeToSourceScale, accepted, rejected);
        this->updateDelta(increase);
        return rect;
    }

    void prepareForPathDrawing(
            SkDrawableGlyphBuffer* accepted, SkSourceGlyphBuffer* rejected) override {
        size_t increase = fScalerCache.prepareForPathDrawing(accepted, rejected);
        this->updateDelta(increase);
    }

    void glyphIDsToPaths(SkSpan<sktext::IDOrPath> idsOrPaths) {
        size_t increase = fScalerCache.glyphIDsToPaths(idsOrPaths);
        this->updateDelta(increase);
    }

    void prepareForDrawableDrawing(
            SkDrawableGlyphBuffer* accepted, SkSourceGlyphBuffer* rejected) override {
        size_t increase = fScalerCache.prepareForDrawableDrawing(accepted, rejected);
        this->updateDelta(increase);
    }

    SkScalar findMaximumGlyphDimension(SkSpan<const SkGlyphID> glyphs) override {
        auto [maxDimension, increase] = fScalerCache.findMaximumGlyphDimension(glyphs);
        this->updateDelta(increase);
        return maxDimension;
    }

    void onAboutToExitScope() override {
        this->unref();
    }

    sk_sp<SkStrike> getUnderlyingStrike() const override {
        return sk_ref_sp(this);
    }

    void updateDelta(size_t increase);

    const SkStrikeSpec              fStrikeSpec;
    SkStrikeCache* const            fStrikeCache;
    SkStrike*                       fNext{nullptr};
    SkStrike*                       fPrev{nullptr};
    SkScalerCache                   fScalerCache;
    std::unique_ptr<SkStrikePinner> fPinner;
    size_t                          fMemoryUsed{sizeof(SkScalerCache)};
    bool                            fRemoved{false};
};  // SkStrike

class SkStrikeCache final : public sktext::StrikeForGPUCacheInterface {
public:
    SkStrikeCache() = default;

    static SkStrikeCache* GlobalStrikeCache();

    sk_sp<SkStrike> findStrike(const SkDescriptor& desc) SK_EXCLUDES(fLock);

    sk_sp<SkStrike> createStrike(
            const SkStrikeSpec& strikeSpec,
            SkFontMetrics* maybeMetrics = nullptr,
            std::unique_ptr<SkStrikePinner> = nullptr) SK_EXCLUDES(fLock);

    sk_sp<SkStrike> findOrCreateStrike(const SkStrikeSpec& strikeSpec) SK_EXCLUDES(fLock);

    sktext::ScopedStrikeForGPU findOrCreateScopedStrike(
            const SkStrikeSpec& strikeSpec) override SK_EXCLUDES(fLock);

    sktext::StrikeRef findOrCreateStrikeRef(
            const SkStrikeSpec& strikeSpec) override SK_EXCLUDES(fLock);

    static void PurgeAll();
    static void Dump();

    // Dump memory usage statistics of all the attaches caches in the process using the
    // SkTraceMemoryDump interface.
    static void DumpMemoryStatistics(SkTraceMemoryDump* dump);

    void purgeAll() SK_EXCLUDES(fLock); // does not change budget

    int getCacheCountLimit() const SK_EXCLUDES(fLock);
    int setCacheCountLimit(int limit) SK_EXCLUDES(fLock);
    int getCacheCountUsed() const SK_EXCLUDES(fLock);

    size_t getCacheSizeLimit() const SK_EXCLUDES(fLock);
    size_t setCacheSizeLimit(size_t limit) SK_EXCLUDES(fLock);
    size_t getTotalMemoryUsed() const SK_EXCLUDES(fLock);

private:
    friend class SkStrike;  // for SkStrike::updateDelta
    sk_sp<SkStrike> internalFindStrikeOrNull(const SkDescriptor& desc) SK_REQUIRES(fLock);
    sk_sp<SkStrike> internalCreateStrike(
            const SkStrikeSpec& strikeSpec,
            SkFontMetrics* maybeMetrics = nullptr,
            std::unique_ptr<SkStrikePinner> = nullptr) SK_REQUIRES(fLock);

    // The following methods can only be called when mutex is already held.
    void internalRemoveStrike(SkStrike* strike) SK_REQUIRES(fLock);
    void internalAttachToHead(sk_sp<SkStrike> strike) SK_REQUIRES(fLock);

    // Checkout budgets, modulated by the specified min-bytes-needed-to-purge,
    // and attempt to purge caches to match.
    // Returns number of bytes freed.
    size_t internalPurge(size_t minBytesNeeded = 0) SK_REQUIRES(fLock);

    // A simple accounting of what each glyph cache reports and the strike cache total.
    void validate() const SK_REQUIRES(fLock);

    void forEachStrike(std::function<void(const SkStrike&)> visitor) const SK_EXCLUDES(fLock);

    mutable SkMutex fLock;
    SkStrike* fHead SK_GUARDED_BY(fLock) {nullptr};
    SkStrike* fTail SK_GUARDED_BY(fLock) {nullptr};
    struct StrikeTraits {
        static const SkDescriptor& GetKey(const sk_sp<SkStrike>& strike) {
            return strike->getDescriptor();
        }
        static uint32_t Hash(const SkDescriptor& descriptor) {
            return descriptor.getChecksum();
        }
    };
    SkTHashTable<sk_sp<SkStrike>, SkDescriptor, StrikeTraits> fStrikeLookup SK_GUARDED_BY(fLock);

    size_t  fCacheSizeLimit{SK_DEFAULT_FONT_CACHE_LIMIT};
    size_t  fTotalMemoryUsed SK_GUARDED_BY(fLock) {0};
    int32_t fCacheCountLimit{SK_DEFAULT_FONT_CACHE_COUNT_LIMIT};
    int32_t fCacheCount SK_GUARDED_BY(fLock) {0};
};

#endif  // SkStrikeCache_DEFINED