1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27 package org.apache.http.impl.client.cache;
28
29 import java.util.Collections;
30 import java.util.HashSet;
31 import java.util.Set;
32 import java.util.concurrent.ArrayBlockingQueue;
33 import java.util.concurrent.ExecutorService;
34 import java.util.concurrent.RejectedExecutionException;
35 import java.util.concurrent.ThreadPoolExecutor;
36 import java.util.concurrent.TimeUnit;
37
38 import org.apache.commons.logging.Log;
39 import org.apache.commons.logging.LogFactory;
40 import org.apache.http.HttpHost;
41 import org.apache.http.client.cache.HttpCacheContext;
42 import org.apache.http.client.cache.HttpCacheEntry;
43 import org.apache.http.client.methods.HttpRequestWrapper;
44
45 /**
46 * Class used for asynchronous revalidations to be used when the "stale-
47 * while-revalidate" directive is present
48 */
49 class AsynchronousAsyncValidator {
50 private final CachingHttpAsyncClient cachingAsyncClient;
51 private final ExecutorService executor;
52 private final Set<String> queued;
53 private final CacheKeyGenerator cacheKeyGenerator;
54
55 private final Log log = LogFactory.getLog(getClass());
56
57 /**
58 * Create AsynchronousValidator which will make revalidation requests using
59 * the supplied {@link CachingHttpAsyncClient}, and a {@link ThreadPoolExecutor}
60 * generated according to the thread pool settings provided in the given
61 * {@link CacheConfig}.
62 *
63 * @param cachingClient
64 * used to execute asynchronous requests
65 * @param config
66 * specifies thread pool settings. See
67 * {@link CacheConfig#getAsynchronousWorkersMax()},
68 * {@link CacheConfig#getAsynchronousWorkersCore()},
69 * {@link CacheConfig#getAsynchronousWorkerIdleLifetimeSecs()},
70 * and {@link CacheConfig#getRevalidationQueueSize()}.
71 */
72 public AsynchronousAsyncValidator(final CachingHttpAsyncClient cachingClient, final CacheConfig config) {
73 this(cachingClient, new ThreadPoolExecutor(config.getAsynchronousWorkersCore(),
74 config.getAsynchronousWorkersMax(), config.getAsynchronousWorkerIdleLifetimeSecs(),
75 TimeUnit.SECONDS, new ArrayBlockingQueue<Runnable>(
76 config.getRevalidationQueueSize())));
77 }
78
79 /**
80 * Create AsynchronousValidator which will make revalidation requests using
81 * the supplied {@link CachingHttpAsyncClient} and {@link ExecutorService}.
82 *
83 * @param cachingClient
84 * used to execute asynchronous requests
85 * @param executor
86 * used to manage a thread pool of revalidation workers
87 */
88 AsynchronousAsyncValidator(final CachingHttpAsyncClient cachingClient, final ExecutorService executor) {
89 this.cachingAsyncClient = cachingClient;
90 this.executor = executor;
91 this.queued = new HashSet<String>();
92 this.cacheKeyGenerator = new CacheKeyGenerator();
93 }
94
95 /**
96 * Schedules an asynchronous revalidation
97 */
98 public synchronized void revalidateCacheEntry(final HttpHost target, final HttpRequestWrapper request,
99 final HttpCacheContext clientContext, final HttpCacheEntry entry) {
100 // getVariantURI will fall back on getURI if no variants exist
101 final String uri = this.cacheKeyGenerator.getVariantURI(target, request, entry);
102
103 if (!this.queued.contains(uri)) {
104 final AsynchronousAsyncValidationRequest asyncRevalidationRequest = new AsynchronousAsyncValidationRequest(
105 this, this.cachingAsyncClient, target, request, clientContext, entry, uri);
106
107 try {
108 this.executor.execute(asyncRevalidationRequest);
109 this.queued.add(uri);
110 } catch (final RejectedExecutionException ree) {
111 this.log.debug("Revalidation for [" + uri + "] not scheduled: " + ree);
112 }
113 }
114 }
115
116 /**
117 * Removes an identifier from the internal list of revalidation jobs in
118 * progress. This is meant to be called by
119 * {@link AsynchronousValidationRequest#run()} once the revalidation is
120 * complete, using the identifier passed in during constructions.
121 */
122 synchronized void markComplete(final String identifier) {
123 this.queued.remove(identifier);
124 }
125
126 Set<String> getScheduledIdentifiers() {
127 return Collections.unmodifiableSet(this.queued);
128 }
129
130 ExecutorService getExecutor() {
131 return this.executor;
132 }
133
134 }