okhttp3.internal.cache.CacheInterceptor Maven / Gradle / Ivy
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* 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.
*/
package okhttp3.internal.cache;
import java.io.IOException;
import java.util.Date;
import okhttp3.Headers;
import okhttp3.Interceptor;
import okhttp3.MediaType;
import okhttp3.Protocol;
import okhttp3.Request;
import okhttp3.Response;
import okhttp3.ResponseBody;
import okhttp3.internal.Internal;
import okhttp3.internal.http.HttpHeaders;
import okhttp3.internal.http.HttpMethod;
import okhttp3.internal.http.HttpStream;
import okhttp3.internal.http.RealResponseBody;
import okio.Buffer;
import okio.BufferedSink;
import okio.BufferedSource;
import okio.Okio;
import okio.Sink;
import okio.Source;
import okio.Timeout;
import static java.net.HttpURLConnection.HTTP_NOT_MODIFIED;
import static java.util.concurrent.TimeUnit.MILLISECONDS;
import static okhttp3.internal.Util.closeQuietly;
import static okhttp3.internal.Util.discard;
/** Serves requests from the cache and writes responses to the cache. */
public final class CacheInterceptor implements Interceptor {
private static final ResponseBody EMPTY_BODY = new ResponseBody() {
@Override public MediaType contentType() {
return null;
}
@Override public long contentLength() {
return 0;
}
@Override public BufferedSource source() {
return new Buffer();
}
};
final InternalCache cache;
public CacheInterceptor(InternalCache cache) {
this.cache = cache;
}
@Override public Response intercept(Chain chain) throws IOException {
Response cacheCandidate = cache != null
? cache.get(chain.request())
: null;
long now = System.currentTimeMillis();
CacheStrategy strategy = new CacheStrategy.Factory(now, chain.request(), cacheCandidate).get();
Request networkRequest = strategy.networkRequest;
Response cacheResponse = strategy.cacheResponse;
if (cache != null) {
cache.trackResponse(strategy);
}
if (cacheCandidate != null && cacheResponse == null) {
closeQuietly(cacheCandidate.body()); // The cache candidate wasn't applicable. Close it.
}
// If we're forbidden from using the network and the cache is insufficient, fail.
if (networkRequest == null && cacheResponse == null) {
return new Response.Builder()
.request(chain.request())
.protocol(Protocol.HTTP_1_1)
.code(504)
.message("Unsatisfiable Request (only-if-cached)")
.body(EMPTY_BODY)
.sentRequestAtMillis(-1L)
.receivedResponseAtMillis(System.currentTimeMillis())
.build();
}
// If we don't need the network, we're done.
if (networkRequest == null) {
return cacheResponse.newBuilder()
.cacheResponse(stripBody(cacheResponse))
.build();
}
Response networkResponse = null;
try {
networkResponse = chain.proceed(networkRequest);
} finally {
// If we're crashing on I/O or otherwise, don't leak the cache body.
if (networkResponse == null && cacheCandidate != null) {
closeQuietly(cacheCandidate.body());
}
}
// If we have a cache response too, then we're doing a conditional get.
if (cacheResponse != null) {
if (validate(cacheResponse, networkResponse)) {
Response response = cacheResponse.newBuilder()
.headers(combine(cacheResponse.headers(), networkResponse.headers()))
.cacheResponse(stripBody(cacheResponse))
.networkResponse(stripBody(networkResponse))
.build();
networkResponse.body().close();
// Update the cache after combining headers but before stripping the
// Content-Encoding header (as performed by initContentStream()).
cache.trackConditionalCacheHit();
cache.update(cacheResponse, response);
return response;
} else {
closeQuietly(cacheResponse.body());
}
}
Response response = networkResponse.newBuilder()
.cacheResponse(stripBody(cacheResponse))
.networkResponse(stripBody(networkResponse))
.build();
if (HttpHeaders.hasBody(response)) {
CacheRequest cacheRequest = maybeCache(response, networkResponse.request(), cache);
response = cacheWritingResponse(cacheRequest, response);
}
return response;
}
private static Response stripBody(Response response) {
return response != null && response.body() != null
? response.newBuilder().body(null).build()
: response;
}
private CacheRequest maybeCache(Response userResponse, Request networkRequest,
InternalCache responseCache) throws IOException {
if (responseCache == null) return null;
// Should we cache this response for this request?
if (!CacheStrategy.isCacheable(userResponse, networkRequest)) {
if (HttpMethod.invalidatesCache(networkRequest.method())) {
try {
responseCache.remove(networkRequest);
} catch (IOException ignored) {
// The cache cannot be written.
}
}
return null;
}
// Offer this request to the cache.
return responseCache.put(userResponse);
}
/**
* Returns a new source that writes bytes to {@code cacheRequest} as they are read by the source
* consumer. This is careful to discard bytes left over when the stream is closed; otherwise we
* may never exhaust the source stream and therefore not complete the cached response.
*/
private Response cacheWritingResponse(final CacheRequest cacheRequest, Response response)
throws IOException {
// Some apps return a null body; for compatibility we treat that like a null cache request.
if (cacheRequest == null) return response;
Sink cacheBodyUnbuffered = cacheRequest.body();
if (cacheBodyUnbuffered == null) return response;
final BufferedSource source = response.body().source();
final BufferedSink cacheBody = Okio.buffer(cacheBodyUnbuffered);
Source cacheWritingSource = new Source() {
boolean cacheRequestClosed;
@Override public long read(Buffer sink, long byteCount) throws IOException {
long bytesRead;
try {
bytesRead = source.read(sink, byteCount);
} catch (IOException e) {
if (!cacheRequestClosed) {
cacheRequestClosed = true;
cacheRequest.abort(); // Failed to write a complete cache response.
}
throw e;
}
if (bytesRead == -1) {
if (!cacheRequestClosed) {
cacheRequestClosed = true;
cacheBody.close(); // The cache response is complete!
}
return -1;
}
sink.copyTo(cacheBody.buffer(), sink.size() - bytesRead, bytesRead);
cacheBody.emitCompleteSegments();
return bytesRead;
}
@Override public Timeout timeout() {
return source.timeout();
}
@Override public void close() throws IOException {
if (!cacheRequestClosed
&& !discard(this, HttpStream.DISCARD_STREAM_TIMEOUT_MILLIS, MILLISECONDS)) {
cacheRequestClosed = true;
cacheRequest.abort();
}
source.close();
}
};
return response.newBuilder()
.body(new RealResponseBody(response.headers(), Okio.buffer(cacheWritingSource)))
.build();
}
/**
* Returns true if {@code cached} should be used; false if {@code network} response should be
* used.
*/
private static boolean validate(Response cached, Response network) {
if (network.code() == HTTP_NOT_MODIFIED) return true;
// The HTTP spec says that if the network's response is older than our
// cached response, we may return the cache's response. Like Chrome (but
// unlike Firefox), this client prefers to return the newer response.
Date lastModified = cached.headers().getDate("Last-Modified");
if (lastModified != null) {
Date networkLastModified = network.headers().getDate("Last-Modified");
if (networkLastModified != null
&& networkLastModified.getTime() < lastModified.getTime()) {
return true;
}
}
return false;
}
/** Combines cached headers with a network headers as defined by RFC 2616, 13.5.3. */
private static Headers combine(Headers cachedHeaders, Headers networkHeaders) {
Headers.Builder result = new Headers.Builder();
for (int i = 0, size = cachedHeaders.size(); i < size; i++) {
String fieldName = cachedHeaders.name(i);
String value = cachedHeaders.value(i);
if ("Warning".equalsIgnoreCase(fieldName) && value.startsWith("1")) {
continue; // Drop 100-level freshness warnings.
}
if (!isEndToEnd(fieldName) || networkHeaders.get(fieldName) == null) {
Internal.instance.addLenient(result, fieldName, value);
}
}
for (int i = 0, size = networkHeaders.size(); i < size; i++) {
String fieldName = networkHeaders.name(i);
if ("Content-Length".equalsIgnoreCase(fieldName)) {
continue; // Ignore content-length headers of validating responses.
}
if (isEndToEnd(fieldName)) {
Internal.instance.addLenient(result, fieldName, networkHeaders.value(i));
}
}
return result.build();
}
/**
* Returns true if {@code fieldName} is an end-to-end HTTP header, as defined by RFC 2616,
* 13.5.1.
*/
static boolean isEndToEnd(String fieldName) {
return !"Connection".equalsIgnoreCase(fieldName)
&& !"Keep-Alive".equalsIgnoreCase(fieldName)
&& !"Proxy-Authenticate".equalsIgnoreCase(fieldName)
&& !"Proxy-Authorization".equalsIgnoreCase(fieldName)
&& !"TE".equalsIgnoreCase(fieldName)
&& !"Trailers".equalsIgnoreCase(fieldName)
&& !"Transfer-Encoding".equalsIgnoreCase(fieldName)
&& !"Upgrade".equalsIgnoreCase(fieldName);
}
}
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