BasicHttpCacheStorage.java

/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
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package com.apigee.sdk.apm.http.impl.client.cache;

import java.io.IOException;
import java.util.LinkedHashMap;

import com.apigee.sdk.apm.http.annotation.ThreadSafe;
import com.apigee.sdk.apm.http.client.cache.HttpCacheEntry;
import com.apigee.sdk.apm.http.client.cache.HttpCacheStorage;
import com.apigee.sdk.apm.http.client.cache.HttpCacheUpdateCallback;

/**
 * Basic {@link HttpCacheStorage} implementation backed by an instance of
 * {@link LinkedHashMap}. This cache does NOT deallocate resources associated
 * with the cache entries. It is intended for use with {@link HeapResource} and
 * similar.
 * 
 * @since 4.1
 */
@ThreadSafe
public class BasicHttpCacheStorage implements HttpCacheStorage {

	private final CacheMap entries;

	public BasicHttpCacheStorage(CacheConfig config) {
		super();
		this.entries = new CacheMap(config.getMaxCacheEntries());
	}

	/**
	 * Places a HttpCacheEntry in the cache
	 * 
	 * @param url
	 *            Url to use as the cache key
	 * @param entry
	 *            HttpCacheEntry to place in the cache
	 */
	public synchronized void putEntry(String url, HttpCacheEntry entry)
			throws IOException {
		entries.put(url, entry);
	}

	/**
	 * Gets an entry from the cache, if it exists
	 * 
	 * @param url
	 *            Url that is the cache key
	 * @return HttpCacheEntry if one exists, or null for cache miss
	 */
	public synchronized HttpCacheEntry getEntry(String url) throws IOException {
		return entries.get(url);
	}

	/**
	 * Removes a HttpCacheEntry from the cache
	 * 
	 * @param url
	 *            Url that is the cache key
	 */
	public synchronized void removeEntry(String url) throws IOException {
		entries.remove(url);
	}

	public synchronized void updateEntry(String url,
			HttpCacheUpdateCallback callback) throws IOException {
		HttpCacheEntry existingEntry = entries.get(url);
		entries.put(url, callback.update(existingEntry));
	}

}