+++ /dev/null
-/*
- * Copyright (c) 2009, Takeyuki Nagao
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or
- * without modification, are permitted provided that the
- * following conditions are met:
- *
- * * Redistributions of source code must retain the above
- * copyright notice, this list of conditions and the
- * following disclaimer.
- * * Redistributions in binary form must reproduce the above
- * copyright notice, this list of conditions and the
- * following disclaimer in the documentation and/or other
- * materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
- * CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
- * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
- * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
- * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
- * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
- * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
- * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY
- * OF SUCH DAMAGE.
- */
-
-package jp.sourceforge.dvibrowser.dvicore.util.concurrent;
-import java.util.Collections;
-import java.util.LinkedHashMap;
-import java.util.Map;
-import java.util.concurrent.Future;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-import jp.sourceforge.dvibrowser.dvicore.util.DviUtils;
-
-
-
-public class CachedComputer<K, V> implements Computer<K, V>
-{
- private final class LinkedHashMapExtension extends
- LinkedHashMap<K, CacheEntry<K, V>> {
- private static final long serialVersionUID = 1L;
-
- @Override
- protected boolean removeEldestEntry(Map.Entry<K,CacheEntry<K, V>> eldest)
- {
- boolean doRemove = CachedComputer.this.removeEldestEntry(eldest);
- LOGGER.finer("doRemove = " + doRemove);
- return doRemove;
- }
- }
-
- private static final Logger LOGGER = Logger.getLogger(CachedComputer.class.getName());
- private final Map<K, CacheEntry<K, V>> map;
- private final Computer<K, V> computer;
-
- public CachedComputer(final Computer<K, V> computer)
- {
- this.computer = computer;
- map = Collections.synchronizedMap(createCache());
- }
-
- protected Map<K, CacheEntry<K, V>> createCache()
- {
- return new LinkedHashMapExtension();
- }
-
- protected boolean removeEldestEntry(Map.Entry<K, CacheEntry<K, V>> entry)
- {
- return false;
- }
-
- protected synchronized Future<V> startComputation(final Computation<K, V> computable)
- {
- final Future<V> future = computer.compute(new Computation<K, V>() {
- public V call() throws Exception {
- try {
- return computable.call();
- } catch (Throwable e) {
- // We would like to associate any exception with the return value of null.
- DviUtils.logStackTrace(LOGGER, Level.SEVERE, e);
- return null;
- }
- }
-
- public K getCacheKey() {
- return computable.getCacheKey();
- }
-
- });
- return future;
- }
-
- /* (non-Javadoc)
- * @see Computer#compute(Computation, java.util.concurrent.ExecutorService)
- */
- public synchronized Future<V> compute(Computation<K, V> computable)
- {
- K key = computable.getCacheKey();
- if (key == null) {
- LOGGER.finer("Key is null: " + computable);
- final Future<V> future = startComputation(computable);
- return future;
- }
- CacheEntry<K, V> cacheEntry = map.get(key);
- if (cacheEntry == null) {
- LOGGER.finer("Cache miss: " + key);
- final Future<V> future = startComputation(computable);
- cacheEntry = new CacheEntry<K, V>(this, computable, future);
- getCache().put(key, cacheEntry);
- LOGGER.finer("Wrote cache: key=" + key + " value=" + future);
- } else {
- LOGGER.finest("Cache hit: " + key);
- }
- return cacheEntry.getFuture();
- }
-
- public synchronized Future<V> getCachedResult(Computation<K, V> computable)
- {
- K key = computable.getCacheKey();
- if (key == null) {
- return null;
- }
- CacheEntry<K, V> cacheEntry = map.get(key);
- if (cacheEntry == null) {
- return null;
- } else {
- return cacheEntry.getFuture();
- }
- }
-
- public Map<K, CacheEntry<K, V>> getCache()
- {
- return map;
- }
-}
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