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.hc.client5.http.impl.cache;
28
29 import java.util.List;
30
31 import org.apache.hc.client5.http.cache.HeaderConstants;
32 import org.apache.hc.client5.http.cache.HttpCacheEntry;
33 import org.apache.hc.core5.function.Factory;
34 import org.apache.hc.core5.http.Header;
35 import org.apache.hc.core5.http.HttpHeaders;
36 import org.apache.hc.core5.http.HttpRequest;
37 import org.apache.hc.core5.http.message.MessageSupport;
38
39 class ConditionalRequestBuilder<T extends HttpRequest> {
40
41 private final Factory<T, T> messageCopier;
42
43 ConditionalRequestBuilder(final Factory<T, T> messageCopier) {
44 this.messageCopier = messageCopier;
45 }
46
47 /**
48 * When a {@link HttpCacheEntry} is stale but 'might' be used as a response
49 * to an {@link org.apache.hc.core5.http.HttpRequest} we will attempt to revalidate
50 * the entry with the origin. Build the origin {@link org.apache.hc.core5.http.HttpRequest}
51 * here and return it.
52 *
53 * @param cacheControl the cache control directives.
54 * @param request the original request from the caller
55 * @param cacheEntry the entry that needs to be re-validated
56 * @return the wrapped request
57 */
58 public T buildConditionalRequest(final ResponseCacheControl cacheControl, final T request, final HttpCacheEntry cacheEntry) {
59 final T newRequest = messageCopier.create(request);
60
61 final Header eTag = cacheEntry.getFirstHeader(HttpHeaders.ETAG);
62 if (eTag != null) {
63 newRequest.setHeader(HttpHeaders.IF_NONE_MATCH, eTag.getValue());
64 }
65 final Header lastModified = cacheEntry.getFirstHeader(HttpHeaders.LAST_MODIFIED);
66 if (lastModified != null) {
67 newRequest.setHeader(HttpHeaders.IF_MODIFIED_SINCE, lastModified.getValue());
68 }
69 if (cacheControl.isMustRevalidate() || cacheControl.isProxyRevalidate()) {
70 newRequest.addHeader(HttpHeaders.CACHE_CONTROL, HeaderConstants.CACHE_CONTROL_MAX_AGE + "=0");
71 }
72 return newRequest;
73
74 }
75
76 /**
77 * When a {@link HttpCacheEntry} does not exist for a specific
78 * {@link org.apache.hc.core5.http.HttpRequest} we attempt to see if an existing
79 * {@link HttpCacheEntry} is appropriate by building a conditional
80 * {@link org.apache.hc.core5.http.HttpRequest} using the variants' ETag values.
81 * If no such values exist, the request is unmodified
82 *
83 * @param request the original request from the caller
84 * @param variants
85 * @return the wrapped request
86 */
87 public T buildConditionalRequestFromVariants(final T request, final List<String> variants) {
88 final T newRequest = messageCopier.create(request);
89 newRequest.setHeader(MessageSupport.headerOfTokens(HttpHeaders.IF_NONE_MATCH, variants));
90 return newRequest;
91 }
92
93 /**
94 * Returns a request to unconditionally validate a cache entry with
95 * the origin. In certain cases (due to multiple intervening caches)
96 * our cache may actually receive a response to a normal conditional
97 * validation where the Date header is actually older than that of
98 * our current cache entry. In this case, the protocol recommendation
99 * is to retry the validation and force syncup with the origin.
100 * @param request client request we are trying to satisfy
101 * @return an unconditional validation request
102 */
103 public T buildUnconditionalRequest(final T request) {
104 final T newRequest = messageCopier.create(request);
105 newRequest.addHeader(HttpHeaders.CACHE_CONTROL,HeaderConstants.CACHE_CONTROL_NO_CACHE);
106 newRequest.removeHeaders(HttpHeaders.IF_RANGE);
107 newRequest.removeHeaders(HttpHeaders.IF_MATCH);
108 newRequest.removeHeaders(HttpHeaders.IF_NONE_MATCH);
109 newRequest.removeHeaders(HttpHeaders.IF_UNMODIFIED_SINCE);
110 newRequest.removeHeaders(HttpHeaders.IF_MODIFIED_SINCE);
111 return newRequest;
112 }
113
114 }