156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson/* 256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Copyright (C) 2010 Google Inc. 356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Licensed under the Apache License, Version 2.0 (the "License"); 556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * you may not use this file except in compliance with the License. 656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * You may obtain a copy of the License at 756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * http://www.apache.org/licenses/LICENSE-2.0 956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 1056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Unless required by applicable law or agreed to in writing, software 1156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * distributed under the License is distributed on an "AS IS" BASIS, 1256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 1356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * See the License for the specific language governing permissions and 1456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * limitations under the License. 1556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 1656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 1756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonpackage com.google.clearsilver.jsilver.adaptor; 1856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 1956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonimport java.util.LinkedHashMap; 2056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonimport java.util.List; 2156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonimport java.util.Map; 2256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonimport java.util.concurrent.locks.ReadWriteLock; 2356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonimport java.util.concurrent.locks.ReentrantReadWriteLock; 2456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 2556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson/** 2656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * This class implements a cache of a list of loadpaths and a file name to the absolute file name 2756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * where the file is located on the filesystem. The purpose is to avoid filesystem calls for common 2856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * operations, like in which of these directories does this file exist? This class is threadsafe. 2956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 3056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Some of this code is copied from {@link com.google.clearsilver.base.CSFileCache}. 3156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 3256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodsonpublic class LoadPathToFileCache { 3356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 3456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson private final LRUCache<String, String> cache; 3556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson private final ReadWriteLock cacheLock = new ReentrantReadWriteLock(); 3656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 3756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson public LoadPathToFileCache(int capacity) { 3856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson cache = new LRUCache<String, String>(capacity); 3956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 4056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 4156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson /** 4256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Lookup in the cache to see if we have a mapping from the given loadpaths and filename to an 4356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * absolute file path. 4456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 4556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param loadPaths the ordered list of directories to search for the file. 4656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param filename the name of the file. 4756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @return the absolute filepath location of the file, or {@code null} if not in the cache. 4856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 4956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson public String lookup(List<String> loadPaths, String filename) { 5056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson String filePathMapKey = makeCacheKey(loadPaths, filename); 5156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson cacheLock.readLock().lock(); 5256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson try { 5356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson return cache.get(filePathMapKey); 5456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } finally { 5556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson cacheLock.readLock().unlock(); 5656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 5756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 5856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 5956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson /** 6056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Add a new mapping to the cache. 6156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 6256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param loadPaths the ordered list of directories to search for the file. 6356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param filename the name of the file. 6456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param filePath the absolute filepath location of the file 6556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 6656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson public void add(List<String> loadPaths, String filename, String filePath) { 6756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson String filePathMapKey = makeCacheKey(loadPaths, filename); 6856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson cacheLock.writeLock().lock(); 6956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson try { 7056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson cache.put(filePathMapKey, filePath); 7156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } finally { 7256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson cacheLock.writeLock().unlock(); 7356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 7456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 7556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 7656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson public static String makeCacheKey(List<String> loadPaths, String filename) { 7756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson if (loadPaths == null) { 7856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson throw new NullPointerException("Loadpaths cannot be null"); 7956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 8056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson if (filename == null) { 8156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson throw new NullPointerException("Filename cannot be null"); 8256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 8356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson String loadPathsHash = Long.toHexString(hashLoadPath(loadPaths)); 8456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson StringBuilder sb = new StringBuilder(loadPathsHash); 8556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson sb.append('|').append(filename); 8656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson return sb.toString(); 8756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 8856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 8956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson /** 9056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Generate a hashCode to represent the ordered list of loadpaths. Used as a key into the fileMap 9156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * since a concatenation of the loadpaths is likely to be huge (greater than 1K) but very 9256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * repetitive. Algorithm comes from Effective Java by Joshua Bloch. 9356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * <p> 9456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * We don't use the builtin hashCode because it is only 32-bits, and while the expect different 9556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * values of loadpaths is very small, we want to minimize any chance of collision since we use the 9656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * hash as the key and throw away the loadpath list 9756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 9856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param list an ordered list of loadpaths. 9956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @return a long representing a hash of the loadpaths. 10056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 10156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson static long hashLoadPath(List<String> list) { 10256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson long hash = 17; 10356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson for (String path : list) { 10456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson hash = 37 * hash + path.hashCode(); 10556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 10656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson return hash; 10756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 10856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 10956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson /** 11056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * This code is copied from {@link com.google.common.cache.LRUCache} but is distilled to basics in 11156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * order to not require importing Google code. Hopefully there is an open-source implementation, 11256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * although given the design of LinkHashMap, this is trivial. 11356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 11456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson static class LRUCache<K, V> extends LinkedHashMap<K, V> { 11556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 11656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson private final int capacity; 11756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 11856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson LRUCache(int capacity) { 11956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson super(capacity, 0.75f, true); 12056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson this.capacity = capacity; 12156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 12256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 12356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson /** 12456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * {@inheritDoc} 12556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * <p> 12656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * Necessary to override because HashMap increases the capacity of the hashtable before 12756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * inserting the elements. However, here we have set the max capacity already and will instead 12856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * remove eldest elements instead of increasing capacity. 12956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 13056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson @Override 13156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson public void putAll(Map<? extends K, ? extends V> m) { 13256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson for (Map.Entry<? extends K, ? extends V> e : m.entrySet()) { 13356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson put(e.getKey(), e.getValue()); 13456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 13556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 13656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson 13756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson /** 13856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * This method is called by LinkedHashMap to check whether the eldest entry should be removed. 13956ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * 14056ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @param eldest 14156ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson * @return true if element should be removed. 14256ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson */ 14356ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson @Override 14456ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson protected boolean removeEldestEntry(Map.Entry<K, V> eldest) { 14556ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson return size() > capacity; 14656ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 14756ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson } 14856ed4167b942ec265f9cee70ac4d71d10b3835ceBen Dodson} 149