ParagraphCache.h

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// Copyright 2019 Google LLC.
#ifndef ParagraphCache_DEFINED
#define ParagraphCache_DEFINED
 
#include "include/private/base/SkMutex.h"
#include "src/core/SkLRUCache.h"
#include <functional>  // std::function
 
#define PARAGRAPH_CACHE_STATS
 
namespace skia {
namespace textlayout {
 
class ParagraphImpl;
class ParagraphCacheKey;
class ParagraphCacheValue;
 
class ParagraphCache {
public:
    ParagraphCache();
    ~ParagraphCache();
 
    void abandon();
    void reset();
    bool updateParagraph(ParagraphImpl* paragraph);
    bool findParagraph(ParagraphImpl* paragraph);
 
    // For testing
    void setChecker(std::function<void(ParagraphImpl* impl, const char*, bool)> checker) {
        fChecker = std::move(checker);
    }
    void printStatistics();
    void turnOn(bool value) { fCacheIsOn = value; }
    int count() { return fLRUCacheMap.count(); }
 
    bool isPossiblyTextEditing(ParagraphImpl* paragraph);
 
 private:
 
    struct Entry;
    void updateFrom(const ParagraphImpl* paragraph, Entry* entry);
    void updateTo(ParagraphImpl* paragraph, const Entry* entry);
 
     mutable SkMutex fParagraphMutex;
     std::function<void(ParagraphImpl* impl, const char*, bool)> fChecker;
 
    static const int kMaxEntries = 128;
 
    struct KeyHash {
        uint32_t operator()(const ParagraphCacheKey& key) const;
    };
 
    SkLRUCache<ParagraphCacheKey, std::unique_ptr<Entry>, KeyHash> fLRUCacheMap;
    bool fCacheIsOn;
    ParagraphCacheValue* fLastCachedValue;
 
#ifdef PARAGRAPH_CACHE_STATS
    int fTotalRequests;
    int fCacheMisses;
    int fHashMisses; // cache hit but hash table missed
#endif
};
 
}  // namespace textlayout
}  // namespace skia
 
#endif  // ParagraphCache_DEFINED