From 7c279747beb43c7e88633a6228a155a30e6834f7 Mon Sep 17 00:00:00 2001 From: Benjamin Culkin Date: Mon, 27 May 2024 11:38:33 -0400 Subject: Initial import --- .../foundation/caching/GenericFetcherCache.java | 124 +++++++++++++++++++++ 1 file changed, 124 insertions(+) create mode 100644 israfil-foundation-cache/src/main/java/net/israfil/foundation/caching/GenericFetcherCache.java (limited to 'israfil-foundation-cache/src/main/java/net/israfil/foundation/caching/GenericFetcherCache.java') diff --git a/israfil-foundation-cache/src/main/java/net/israfil/foundation/caching/GenericFetcherCache.java b/israfil-foundation-cache/src/main/java/net/israfil/foundation/caching/GenericFetcherCache.java new file mode 100644 index 0000000..ce42bc2 --- /dev/null +++ b/israfil-foundation-cache/src/main/java/net/israfil/foundation/caching/GenericFetcherCache.java @@ -0,0 +1,124 @@ +/* + * Copyright (c) 2006 Israfil Consulting Services Corporation + * Copyright (c) 2006 Christian Edward Gruber + * All Rights Reserved + * + * This software is licensed under the Berkeley Standard Distribution license, + * (BSD license), as defined below: + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are met: + * + * 1. Redistributions of source code must retain the above copyright notice, this + * list of conditions and the following disclaimer. + * 2. 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. + * 3. Neither the name of Israfil Consulting Services nor the names of its contributors + * may be used to endorse or promote products derived from this software without + * specific prior written permission. + * + * 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 OWNER 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. + * + * $Id: GenericCache.java 129 2006-12-31 23:20:02Z cgruber $ + */ +package net.israfil.foundation.caching; + +import java.util.ArrayList; +import java.util.Arrays; +import java.util.HashMap; +import java.util.List; +import java.util.Map; + + +/** + * A non-thread-safe cache object + * + * @author Christian Edward Gruber + */ +public class GenericFetcherCache implements FetcherCache { + + private Map _caches = new HashMap(); + + /** + * Retrieves an object from a path in the cache + * @param cacheName A string identifying from which cache the object will be retrieved + * @param An array of path items identifying the path through the map keys. + */ + public Object get(Fetcher fetcher, String cacheName, String itemKey, String ... path) { + + // Fetch the map containing the item. + Map cache = _getLocationInMap(_caches,new ArrayList(_prepPathList(cacheName,path))); + + // Get the item from the map + Object o = cache.get((itemKey==null) ? "__NULL__" : itemKey); + if (o == null) { + // Item doesn't exist, so try to fetch, then retrieve again. + fetcher.fetch(); + o = cache.get((itemKey==null) ? "__NULL__" : itemKey); + } + return o; + } + + + /** + * A method to set values within the cache, to be used by Fetcher implementations + * in setting up the cache when they fetch. + */ + public void set(String cacheName, String itemKey, Object value, String ... path) { + List pathList = _prepPathList(cacheName,path); + Map cache = _getLocationInMap(_caches,new ArrayList(pathList)); + cache.put(itemKey,value); + } + + /** + * Creates a List that contains the pathelements, starting from the + * cache name down to the bottom, but excluding the actual final path + * item. + */ + static List _prepPathList(String cacheName,String[] pathElements) { + List pathList; + if (pathElements == null || pathElements.length < 1) { + pathList = new ArrayList(); + } else { + // Need to make this explicitly an arrayList, so that + // add(index,value) will work. + pathList = new ArrayList(Arrays.asList(pathElements)); + } + pathList.add(0,cacheName); + return pathList; + } + + /** + * Recursively traverses the cache map, creating maps at path locations + * where they do not already exist. + */ + @SuppressWarnings("unchecked") + static Map _getLocationInMap( + Map currentMap, List cachePath) { + if (cachePath == null || cachePath.size() < 1) return currentMap; + String cacheName = (String)cachePath.remove(0); // pull the first one + + Object cacheObject = (Map)currentMap.get(cacheName); + if (cacheObject == null) { + cacheObject = new HashMap(); + currentMap.put(cacheName,cacheObject); + } + if (! (cacheObject instanceof Map)) + throw new IllegalArgumentException("Attempted to find a map at location ("+cachePath+") in cache ("+cacheName+"), but found a " + cacheObject.getClass().getName() + "."); + Map cache = (Map)cacheObject; + + return _getLocationInMap(cache,cachePath); + } + + +} -- cgit v1.2.3