| 1 | package com.hammurapi.store; |
| 2 | |
| 3 | import java.util.Comparator; |
| 4 | import java.util.Iterator; |
| 5 | import java.util.concurrent.locks.ReadWriteLock; |
| 6 | |
| 7 | import com.hammurapi.extract.Extractor; |
| 8 | import com.hammurapi.extract.Predicate; |
| 9 | |
| 10 | /** |
| 11 | * Abstraction of object store. |
| 12 | * @author Pavel Vlasov. |
| 13 | * |
| 14 | * @param <T> Object type. |
| 15 | * @param <PK> Primary key type. |
| 16 | * @param <S> Self-type - sub-type of store. Generic parameter for predicates, extractors, update tasks and views. |
| 17 | */ |
| 18 | public interface Store<T, PK, S extends Store<T,PK,S>> extends ReadWriteLock, Iterable<T> { |
| 19 | |
| 20 | enum ViewType { |
| 21 | /** |
| 22 | * Live perform all operations on the master data, they |
| 23 | * do not create an intermediary store for view data. |
| 24 | */ |
| 25 | LIVE, |
| 26 | /** |
| 27 | * Lazy views create intermediary store which contains only |
| 28 | * data visible by the view. Updates from the main store |
| 29 | * are queued up and get applied to the intermediary store when |
| 30 | * one of view data retrieval methods is invoked. |
| 31 | */ |
| 32 | LAZY, |
| 33 | /** |
| 34 | * Asynchronous views create intermediary store which contains only |
| 35 | * data visible by the view. Updates from the main store |
| 36 | * are queued up and get applied to the intermediary store in a |
| 37 | * background task, or when |
| 38 | * one of view data retrieval methods is invoked. |
| 39 | */ |
| 40 | ASYNCHRONOUS, |
| 41 | /** |
| 42 | * Synchronous views create intermediary store which contains only |
| 43 | * data visible by the view. Updates from the main store |
| 44 | * get applied to the view store as part of update operation. |
| 45 | */ |
| 46 | SYNCHRONOUS |
| 47 | } |
| 48 | |
| 49 | /** |
| 50 | * Object handle. |
| 51 | * @author Pavel Vlasov |
| 52 | * |
| 53 | * @param <T> |
| 54 | */ |
| 55 | interface Handle<T, PK, S extends Store<T,PK,S>> { |
| 56 | |
| 57 | /** |
| 58 | * Updates object referenced by this handle. Clears cache and updates |
| 59 | * indexes. The new object shall have the same primary key if the store |
| 60 | * has primary key extractor. |
| 61 | * @param obj New object for the handle (for immutable objects). |
| 62 | */ |
| 63 | void update(T obj); |
| 64 | |
| 65 | /** |
| 66 | * Clears cache and updates |
| 67 | * indexes. Updated object shall have the same primary key if the store |
| 68 | * has primary key extractor. |
| 69 | */ |
| 70 | void update(); |
| 71 | |
| 72 | /** |
| 73 | * Removes object referenced by this handle. |
| 74 | */ |
| 75 | void remove(); |
| 76 | |
| 77 | /** |
| 78 | * @return Object referenced by this handle. |
| 79 | */ |
| 80 | T get(); |
| 81 | |
| 82 | /** |
| 83 | * @return Primary key if object store is configured with primary |
| 84 | * key extractor. |
| 85 | */ |
| 86 | PK getPrimaryKey(); |
| 87 | |
| 88 | /** |
| 89 | * @return True if object referenced by this handle is present in the store. |
| 90 | */ |
| 91 | boolean isValid(); |
| 92 | |
| 93 | /** |
| 94 | * Extracts value from handle's object using given extractor |
| 95 | * and internal handle's cache. |
| 96 | * @param <V> Value type |
| 97 | * @param extractor Extractor |
| 98 | * @return extracted value. |
| 99 | */ |
| 100 | <V> V extract(Extractor<T, V, S> extractor); |
| 101 | } |
| 102 | |
| 103 | // CRUDI |
| 104 | |
| 105 | /** |
| 106 | * Puts object to the store. |
| 107 | * If object is already present in the store, it gets |
| 108 | * updated in the store. |
| 109 | * @param obj Object to put to the store. |
| 110 | * @param validators Predicate(s) which are checked when object is retrieved from the store. |
| 111 | * If there is more than one predicate, predicates are connected with AND. If validator(s) evaluate to |
| 112 | * false, the object handle is considered invalid, i.e. object is considered removed from the store. |
| 113 | * Once validator(s) evaluate to false, they shall always evaluate to false. One of use of validators |
| 114 | * can be to expire object in the store, i.e. after some time validator returns false and object is cleared |
| 115 | * from the database. If validators evaluate to false at put time, object is not put to the store and |
| 116 | * put() returns null. Validators evaluation result is not cached. |
| 117 | * @return Object handle or null if validator(s) evaluate to false. |
| 118 | */ |
| 119 | Handle<T, PK, S> put(T obj, Predicate<T, S>... validators); |
| 120 | |
| 121 | /** |
| 122 | * Retrieves all objects from the store. |
| 123 | * @return |
| 124 | */ |
| 125 | Iterable<T> getAll(); |
| 126 | |
| 127 | /** |
| 128 | * Processes all objects in the store. |
| 129 | * @param processor |
| 130 | * @return number of object queried. |
| 131 | */ |
| 132 | int queryAll(QueryTask<T, PK, S> processor); |
| 133 | |
| 134 | /** |
| 135 | * Retrieves object with given primary key. |
| 136 | * @param primaryKey |
| 137 | * @return |
| 138 | * @throws IllegalStateException if object store is configured without |
| 139 | * primary key. |
| 140 | */ |
| 141 | T getByPrimaryKey(PK primaryKey); |
| 142 | |
| 143 | /** |
| 144 | * Some stores may return StoreIterator, which |
| 145 | * needs to be closed if iterator operation is |
| 146 | * terminated before hasNext() returns false. |
| 147 | * @author Pavel Vlasov. |
| 148 | * |
| 149 | * @param <T> |
| 150 | */ |
| 151 | interface StoreIterator<T> extends Iterator<T> { |
| 152 | void close(); |
| 153 | } |
| 154 | |
| 155 | /** |
| 156 | * Retrieves objects matching the predicate. |
| 157 | * @param selector |
| 158 | * @return |
| 159 | */ |
| 160 | Iterable<T> get(Predicate<T, S> selector); |
| 161 | |
| 162 | /** |
| 163 | * Processes objects matching the predicate. |
| 164 | * @param selector |
| 165 | * @return Number of objects queried. |
| 166 | */ |
| 167 | int query(Predicate<T, S> selector, QueryTask<T, PK, S> processor); |
| 168 | |
| 169 | /** |
| 170 | * Processes values extracted from objects matching the predicate. |
| 171 | * @param selector |
| 172 | * @param extractor Extractor. |
| 173 | * @param processor Processor of query results. |
| 174 | * @return Number of objects queried. |
| 175 | */ |
| 176 | <V> int query(Predicate<T, S> selector, Extractor<T, V, S> extractor, QueryTask<V, PK, S> processor); |
| 177 | |
| 178 | /** |
| 179 | * Processes multiple values extracted from objects matching the predicate. |
| 180 | * @param selector Objects shall match this predicate. If null, all objects match. |
| 181 | * @param extractor Extractor |
| 182 | * @param valueSelector Values from matched objects shall match this predicate. If null, all values match. |
| 183 | * Value selectors are executed in separate tasks from extractor. |
| 184 | * Separation of value selection logic from value extraction logic makes |
| 185 | * sense if value selection logic is relatively heavy and parallelization of its |
| 186 | * execution will reduce overall query execution time. |
| 187 | * @param processor Processor of query results. |
| 188 | * @return Number of objects queried. |
| 189 | */ |
| 190 | <V> int queryMultiple(Predicate<T, S> selector, Extractor<T, Iterable<V>, S> extractor, Predicate<V, S> valueSelector, QueryTask<V, PK, S> processor); |
| 191 | |
| 192 | /** |
| 193 | * Retrieves values from objects matching the predicate. |
| 194 | * @param <V> |
| 195 | * @param selector Object selector. |
| 196 | * @param extractor Value extractor. If null, then object itself is returned. |
| 197 | * @param ordered If true, then returned result is ordered by comparator or by natural order if |
| 198 | * comparator is null. |
| 199 | * @param comparator Comparator to use for ordering. |
| 200 | * @return |
| 201 | */ |
| 202 | <V> Iterable<V> get(Predicate<T, S> selector, Extractor<T, V, S> extractor, boolean ordered, Comparator<V> comparator); |
| 203 | |
| 204 | /** |
| 205 | * Retrieves values from objects matching the predicate. Multiple values are retrieved from each object. |
| 206 | * @param <V> |
| 207 | * @param selector Objects shall match this predicate. If null, all objects match. |
| 208 | * @param extractor Value extractor. |
| 209 | * @param valueSelector Values from matched objects shall match this predicate. If null, all values match. |
| 210 | * Value selectors are executed in separate tasks from extractor. |
| 211 | * Separation of value selection logic from value extraction logic makes |
| 212 | * sense if value selection logic is relatively heavy and parallelization of its |
| 213 | * execution will reduce overall query execution time. |
| 214 | * @param ordered If true, then returned result is ordered by comparator or by natural order if |
| 215 | * comparator is null. |
| 216 | * @param comparator Comparator to use for ordering. |
| 217 | * @return |
| 218 | */ |
| 219 | <V> Iterable<V> getMultiple(Predicate<T, S> selector, Extractor<T, Iterable<V>, S> extractor, Predicate<V, S> valueSelector, boolean ordered, Comparator<V> comparator); |
| 220 | |
| 221 | /** |
| 222 | * Removes all entries from the store. |
| 223 | */ |
| 224 | void clear(); |
| 225 | |
| 226 | /** |
| 227 | * Removes specified object from the store. |
| 228 | * @param obj Object to remove. |
| 229 | * @return true if object was removed. |
| 230 | */ |
| 231 | boolean remove(T obj); |
| 232 | |
| 233 | /** |
| 234 | * Removes object by primary key. |
| 235 | * @param primaryKey |
| 236 | * @return |
| 237 | */ |
| 238 | boolean removeByPrimaryKey(PK primaryKey); |
| 239 | |
| 240 | /** |
| 241 | * Removes objects matching the predicate. |
| 242 | * @param predicate |
| 243 | * @return number of returned objects or -1 if number is unknown. |
| 244 | */ |
| 245 | int remove(Predicate<T, S> selector); |
| 246 | |
| 247 | |
| 248 | /** |
| 249 | * Task to update objects. |
| 250 | * @author Pavel Vlasov. |
| 251 | * |
| 252 | * @param <T> Object type. |
| 253 | */ |
| 254 | interface UpdateTask<T, PK, S extends Store<T,PK,S>> { |
| 255 | |
| 256 | /** |
| 257 | * Executes update. |
| 258 | * @param store Store to perform joins, sub-queries, etc. |
| 259 | * @param obj |
| 260 | * @param primaryKey |
| 261 | * @return Undo task to rollback changes done by this task or null if there are no changes. |
| 262 | */ |
| 263 | Runnable execute(S store, Handle<T,PK,S> handle); |
| 264 | } |
| 265 | |
| 266 | /** |
| 267 | * Task to perform processing on objects (without updating). |
| 268 | * @author Pavel Vlasov. |
| 269 | * |
| 270 | * @param <T> Object type. |
| 271 | */ |
| 272 | interface QueryTask<T, PK, S extends Store<?,PK,S>> { |
| 273 | |
| 274 | /** |
| 275 | * Performs querying. |
| 276 | * @param store Store to perform joins, sub-queries, etc. |
| 277 | * @param obj |
| 278 | * @param primaryKey |
| 279 | */ |
| 280 | void execute(S store, T obj, PK primaryKey); |
| 281 | } |
| 282 | |
| 283 | /** |
| 284 | * Updates objects matching the predicate. |
| 285 | * @param selector |
| 286 | * @param updater |
| 287 | * @return |
| 288 | */ |
| 289 | int update(Predicate<T, S> selector, UpdateTask<T, PK, S> updater); |
| 290 | |
| 291 | /** |
| 292 | * Adds index to the store to speed-up extraction operations. |
| 293 | * @param predicate Only store items matching the predicate are indexed. |
| 294 | * @param extractor Extractor of the index key. |
| 295 | * @param Index type. |
| 296 | * @param ordered If true index is ordered. |
| 297 | * @param comparator Comparator to use for ordering. If null, then natural order is used. |
| 298 | * @return A "mix" of Index sub-interfaces corresponding to the |
| 299 | * index creation parameters. |
| 300 | */ |
| 301 | <V> Index<T,PK,V,S> addIndex( |
| 302 | Predicate<T, S> predicate, |
| 303 | Extractor<T, V, S> extractor, |
| 304 | Index.Type type, |
| 305 | boolean ordered, |
| 306 | Comparator<V> comparator); |
| 307 | |
| 308 | /** |
| 309 | * If primary key is set, then the store shall use equals on the |
| 310 | * value returned from the primaryKeyExtractor |
| 311 | * instead of equals on the object to compare objects for removal and update (put). |
| 312 | * @param primaryKeyExtractor Primary key extractor. |
| 313 | * @throws IllegalStateException If primary key is already set. |
| 314 | */ |
| 315 | Extractor<T, PK, S> getPrimaryKeyExtractor(); |
| 316 | |
| 317 | /** |
| 318 | * Creates a view - a store which sees only objects matching the given selector. |
| 319 | * @param selector View selector. |
| 320 | * @param materialized If true, view elements are calculated at modify time instead of query time. |
| 321 | * @return Store which sees only objects matching give selector. The returned store is backed by the master store. |
| 322 | */ |
| 323 | S createView(Predicate<T, S> selector, ViewType viewType); |
| 324 | |
| 325 | /** |
| 326 | * Creates unmodifiable facade for this store. |
| 327 | * @return |
| 328 | */ |
| 329 | S createUnmodifiableFacade(); |
| 330 | |
| 331 | } |