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| 1 /* |
| 2 ****************************************************************************** |
| 3 * Copyright (C) 2014, International Business Machines Corporation and |
| 4 * others. All Rights Reserved. |
| 5 ****************************************************************************** |
| 6 * |
| 7 * File UNIFIEDCACHE.H - The ICU Unified cache. |
| 8 ****************************************************************************** |
| 9 */ |
| 10 |
| 11 #ifndef __UNIFIED_CACHE_H__ |
| 12 #define __UNIFIED_CACHE_H__ |
| 13 |
| 14 #include "utypeinfo.h" // for 'typeid' to work |
| 15 |
| 16 #include "unicode/uobject.h" |
| 17 #include "unicode/locid.h" |
| 18 #include "sharedobject.h" |
| 19 #include "unicode/unistr.h" |
| 20 #include "cstring.h" |
| 21 #include "ustr_imp.h" |
| 22 |
| 23 struct UHashtable; |
| 24 struct UHashElement; |
| 25 |
| 26 U_NAMESPACE_BEGIN |
| 27 |
| 28 class UnifiedCache; |
| 29 |
| 30 /** |
| 31 * A base class for all cache keys |
| 32 */ |
| 33 class U_COMMON_API CacheKeyBase : public UObject { |
| 34 public: |
| 35 CacheKeyBase() : creationStatus(U_ZERO_ERROR) {} |
| 36 |
| 37 /** |
| 38 * Copy constructor. Needed to support cloning. |
| 39 */ |
| 40 CacheKeyBase(const CacheKeyBase &other) |
| 41 : UObject(other), creationStatus(other.creationStatus) { } |
| 42 virtual ~CacheKeyBase(); |
| 43 |
| 44 /** |
| 45 * Returns the hash code for this object. |
| 46 */ |
| 47 virtual int32_t hashCode() const = 0; |
| 48 |
| 49 /** |
| 50 * Clones this object polymorphically. Caller owns returned value. |
| 51 */ |
| 52 virtual CacheKeyBase *clone() const = 0; |
| 53 |
| 54 /** |
| 55 * Equality operator. |
| 56 */ |
| 57 virtual UBool operator == (const CacheKeyBase &other) const = 0; |
| 58 |
| 59 /** |
| 60 * Create a new object for this key. Called by cache on cache miss. |
| 61 * createObject must add a reference to the object it returns. Note |
| 62 * that getting an object from the cache and returning it without calling |
| 63 * removeRef on it satisfies this requirement. It can also return NULL |
| 64 * and set status to an error. |
| 65 * |
| 66 * @param creationContext the context in which the object is being |
| 67 * created. May be NULL. |
| 68 * @param status Implementations can return a failure here. |
| 69 * In addition, implementations may return a |
| 70 * non NULL object and set a warning status. |
| 71 */ |
| 72 virtual const SharedObject *createObject( |
| 73 const void *creationContext, UErrorCode &status) const = 0; |
| 74 |
| 75 /** |
| 76 * Writes a description of this key to buffer and returns buffer. Written |
| 77 * description is NULL terminated. |
| 78 */ |
| 79 virtual char *writeDescription(char *buffer, int32_t bufSize) const = 0; |
| 80 |
| 81 /** |
| 82 * Inequality operator. |
| 83 */ |
| 84 UBool operator != (const CacheKeyBase &other) const { |
| 85 return !(*this == other); |
| 86 } |
| 87 private: |
| 88 mutable UErrorCode creationStatus; |
| 89 friend class UnifiedCache; |
| 90 }; |
| 91 |
| 92 |
| 93 |
| 94 /** |
| 95 * Templated version of CacheKeyBase. |
| 96 * A key of type LocaleCacheKey<T> maps to a value of type T. |
| 97 */ |
| 98 template<typename T> |
| 99 class CacheKey : public CacheKeyBase { |
| 100 public: |
| 101 virtual ~CacheKey() { } |
| 102 /** |
| 103 * The template parameter, T, determines the hash code returned. |
| 104 */ |
| 105 virtual int32_t hashCode() const { |
| 106 const char *s = typeid(T).name(); |
| 107 return ustr_hashCharsN(s, uprv_strlen(s)); |
| 108 } |
| 109 |
| 110 /** |
| 111 * Use the value type, T, as the description. |
| 112 */ |
| 113 virtual char *writeDescription(char *buffer, int32_t bufLen) const { |
| 114 const char *s = typeid(T).name(); |
| 115 uprv_strncpy(buffer, s, bufLen); |
| 116 buffer[bufLen - 1] = 0; |
| 117 return buffer; |
| 118 } |
| 119 |
| 120 /** |
| 121 * Two objects are equal if they are of the same type. |
| 122 */ |
| 123 virtual UBool operator == (const CacheKeyBase &other) const { |
| 124 return typeid(*this) == typeid(other); |
| 125 } |
| 126 }; |
| 127 |
| 128 /** |
| 129 * Cache key based on locale. |
| 130 * A key of type LocaleCacheKey<T> maps to a value of type T. |
| 131 */ |
| 132 template<typename T> |
| 133 class LocaleCacheKey : public CacheKey<T> { |
| 134 protected: |
| 135 Locale fLoc; |
| 136 public: |
| 137 LocaleCacheKey(const Locale &loc) : fLoc(loc) {}; |
| 138 LocaleCacheKey(const LocaleCacheKey<T> &other) |
| 139 : CacheKey<T>(other), fLoc(other.fLoc) { } |
| 140 virtual ~LocaleCacheKey() { } |
| 141 virtual int32_t hashCode() const { |
| 142 return 37 *CacheKey<T>::hashCode() + fLoc.hashCode(); |
| 143 } |
| 144 virtual UBool operator == (const CacheKeyBase &other) const { |
| 145 // reflexive |
| 146 if (this == &other) { |
| 147 return TRUE; |
| 148 } |
| 149 if (!CacheKey<T>::operator == (other)) { |
| 150 return FALSE; |
| 151 } |
| 152 // We know this and other are of same class because operator== on |
| 153 // CacheKey returned true. |
| 154 const LocaleCacheKey<T> *fOther = |
| 155 static_cast<const LocaleCacheKey<T> *>(&other); |
| 156 return fLoc == fOther->fLoc; |
| 157 } |
| 158 virtual CacheKeyBase *clone() const { |
| 159 return new LocaleCacheKey<T>(*this); |
| 160 } |
| 161 virtual const T *createObject( |
| 162 const void *creationContext, UErrorCode &status) const; |
| 163 /** |
| 164 * Use the locale id as the description. |
| 165 */ |
| 166 virtual char *writeDescription(char *buffer, int32_t bufLen) const { |
| 167 const char *s = fLoc.getName(); |
| 168 uprv_strncpy(buffer, s, bufLen); |
| 169 buffer[bufLen - 1] = 0; |
| 170 return buffer; |
| 171 } |
| 172 |
| 173 }; |
| 174 |
| 175 /** |
| 176 * The unified cache. A singleton type. |
| 177 */ |
| 178 class U_COMMON_API UnifiedCache : public UObject { |
| 179 public: |
| 180 /** |
| 181 * @internal |
| 182 */ |
| 183 UnifiedCache(UErrorCode &status); |
| 184 |
| 185 /** |
| 186 * Returns the cache instance. |
| 187 */ |
| 188 static const UnifiedCache *getInstance(UErrorCode &status); |
| 189 |
| 190 /** |
| 191 * Fetches a value from the cache by key. Equivalent to |
| 192 * get(key, NULL, ptr, status); |
| 193 */ |
| 194 template<typename T> |
| 195 void get( |
| 196 const CacheKey<T>& key, |
| 197 const T *&ptr, |
| 198 UErrorCode &status) const { |
| 199 get(key, NULL, ptr, status); |
| 200 } |
| 201 |
| 202 /** |
| 203 * Fetches value from the cache by key. |
| 204 * |
| 205 * @param key the cache key. |
| 206 * @param creationContext passed verbatim to createObject method of key |
| 207 * @param ptr On entry, ptr must be NULL or be included if |
| 208 * the reference count of the object it points |
| 209 * to. On exit, ptr points to the fetched object |
| 210 * from the cache or is left unchanged on |
| 211 * failure. Caller must call removeRef on ptr |
| 212 * if set to a non NULL value. |
| 213 * @param status Any error returned here. May be set to a |
| 214 * warning value even if ptr is set. |
| 215 */ |
| 216 template<typename T> |
| 217 void get( |
| 218 const CacheKey<T>& key, |
| 219 const void *creationContext, |
| 220 const T *&ptr, |
| 221 UErrorCode &status) const { |
| 222 if (U_FAILURE(status)) { |
| 223 return; |
| 224 } |
| 225 UErrorCode creationStatus = U_ZERO_ERROR; |
| 226 const SharedObject *value = NULL; |
| 227 _get(key, value, creationContext, creationStatus); |
| 228 const T *tvalue = (const T *) value; |
| 229 if (U_SUCCESS(creationStatus)) { |
| 230 SharedObject::copyPtr(tvalue, ptr); |
| 231 } |
| 232 SharedObject::clearPtr(tvalue); |
| 233 // Take care not to overwrite a warning status passed in with |
| 234 // another warning or U_ZERO_ERROR. |
| 235 if (status == U_ZERO_ERROR || U_FAILURE(creationStatus)) { |
| 236 status = creationStatus; |
| 237 } |
| 238 } |
| 239 |
| 240 #ifdef UNIFIED_CACHE_DEBUG |
| 241 /** |
| 242 * Dumps the contents of this cache to standard error. Used for testing of |
| 243 * cache only. |
| 244 */ |
| 245 void dumpContents() const; |
| 246 #endif |
| 247 |
| 248 /** |
| 249 * Convenience method to get a value of type T from cache for a |
| 250 * particular locale with creationContext == NULL. |
| 251 * @param loc the locale |
| 252 * @param ptr On entry, must be NULL or included in the ref count |
| 253 * of the object to which it points. |
| 254 * On exit, fetched value stored here or is left |
| 255 * unchanged on failure. Caller must call removeRef on |
| 256 * ptr if set to a non NULL value. |
| 257 * @param status Any error returned here. May be set to a |
| 258 * warning value even if ptr is set. |
| 259 */ |
| 260 template<typename T> |
| 261 static void getByLocale( |
| 262 const Locale &loc, const T *&ptr, UErrorCode &status) { |
| 263 const UnifiedCache *cache = getInstance(status); |
| 264 if (U_FAILURE(status)) { |
| 265 return; |
| 266 } |
| 267 cache->get(LocaleCacheKey<T>(loc), ptr, status); |
| 268 } |
| 269 |
| 270 #ifdef UNIFIED_CACHE_DEBUG |
| 271 /** |
| 272 * Dumps the cache contents to stderr. For testing only. |
| 273 */ |
| 274 static void dump(); |
| 275 #endif |
| 276 |
| 277 /** |
| 278 * Returns the number of keys in this cache. For testing only. |
| 279 */ |
| 280 int32_t keyCount() const; |
| 281 |
| 282 /** |
| 283 * Removes any values from cache that are not referenced outside |
| 284 * the cache. |
| 285 */ |
| 286 void flush() const; |
| 287 |
| 288 virtual ~UnifiedCache(); |
| 289 private: |
| 290 UHashtable *fHashtable; |
| 291 UnifiedCache(const UnifiedCache &other); |
| 292 UnifiedCache &operator=(const UnifiedCache &other); |
| 293 UBool _flush(UBool all) const; |
| 294 void _get( |
| 295 const CacheKeyBase &key, |
| 296 const SharedObject *&value, |
| 297 const void *creationContext, |
| 298 UErrorCode &status) const; |
| 299 UBool _poll( |
| 300 const CacheKeyBase &key, |
| 301 const SharedObject *&value, |
| 302 UErrorCode &status) const; |
| 303 void _putNew( |
| 304 const CacheKeyBase &key, |
| 305 const SharedObject *value, |
| 306 const UErrorCode creationStatus, |
| 307 UErrorCode &status) const; |
| 308 void _putIfAbsentAndGet( |
| 309 const CacheKeyBase &key, |
| 310 const SharedObject *&value, |
| 311 UErrorCode &status) const; |
| 312 #ifdef UNIFIED_CACHE_DEBUG |
| 313 void _dumpContents() const; |
| 314 #endif |
| 315 static void _put( |
| 316 const UHashElement *element, |
| 317 const SharedObject *value, |
| 318 const UErrorCode status); |
| 319 static void _fetch( |
| 320 const UHashElement *element, |
| 321 const SharedObject *&value, |
| 322 UErrorCode &status); |
| 323 static UBool _inProgress(const UHashElement *element); |
| 324 }; |
| 325 |
| 326 U_NAMESPACE_END |
| 327 |
| 328 #endif |
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