icuSources/common/lrucache.h

   1 /*
   2 ******************************************************************************
   3 * Copyright (C) 2014, International Business Machines Corporation and
   4 * others. All Rights Reserved.
   5 ******************************************************************************
   6 *
   7 * File LRUCACHE.H
   8 ******************************************************************************
   9 */
  10
  11 #ifndef __LRU_CACHE_H__
  12 #define __LRU_CACHE_H__
  13
  14 #include "unicode/uobject.h"
  15 #include "sharedobject.h"
  16
  17 struct UHashtable;
  18
  19 U_NAMESPACE_BEGIN
  20
  21 /**
  22  * LRUCache keyed by locale ID.
  23  */
  24
  25 class U_COMMON_API LRUCache : public UObject {
  26 public:
  27     template<typename T>
  28     void get(const char *localeId, const T *&ptr, UErrorCode &status) {
  29         const T *value = (const T *) _get(localeId, status);
  30         if (U_FAILURE(status)) {
  31             return;
  32         }
  33         SharedObject::copyPtr(value, ptr);
  34     }
  35     UBool contains(const char *localeId) const;
  36     virtual ~LRUCache();
  37 protected:
  38     virtual SharedObject *create(const char *localeId, UErrorCode &status)=0;
  39     LRUCache(int32_t maxSize, UErrorCode &status);
  40 private:
  41     class CacheEntry : public UMemory {
  42     public:
  43         CacheEntry *moreRecent;
  44         CacheEntry *lessRecent;
  45         char *localeId;
  46         const SharedObject *cachedData;
  47         UErrorCode status;  // This is the error if any from creating
  48                             // cachedData.
  49         CacheEntry();
  50         ~CacheEntry();
  51
  52         void unlink();
  53         void reset();
  54         void init(
  55                char *adoptedLocId, SharedObject *dataToAdopt, UErrorCode err);
  56     private:
  57         CacheEntry(const CacheEntry& other);
  58         CacheEntry &operator=(const CacheEntry& other);
  59     };
  60     LRUCache();
  61     LRUCache(const LRUCache &other);
  62     LRUCache &operator=(const LRUCache &other);
  63
  64     // TODO (Travis Keep): Consider replacing both of these end nodes with a
  65     // single sentinel.
  66     CacheEntry *mostRecentlyUsedMarker;
  67     CacheEntry *leastRecentlyUsedMarker;
  68     UHashtable *localeIdToEntries;
  69     int32_t maxSize;
  70
  71     void moveToMostRecent(CacheEntry *cacheEntry);
  72     void init(char *localeId, CacheEntry *cacheEntry);
  73     const SharedObject *_get(const char *localeId, UErrorCode &status);
  74 };
  75
  76 typedef SharedObject *CreateFunc(const char *localeId, UErrorCode &status);
  77
  78 class U_COMMON_API SimpleLRUCache : public LRUCache {
  79 public:
  80     SimpleLRUCache(
  81         int32_t maxSize,
  82         CreateFunc cf,
  83         UErrorCode &status) :
  84             LRUCache(maxSize, status), createFunc(cf) {
  85     }
  86     virtual ~SimpleLRUCache();
  87 protected:
  88     virtual SharedObject *create(const char *localeId, UErrorCode &status);
  89 private:
  90     CreateFunc *createFunc;
  91 };
  92
  93 U_NAMESPACE_END
  94
  95 #endif