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// Copyright Vespa.ai. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.searchers;
import com.yahoo.search.Query;
import com.yahoo.search.Result;
import com.yahoo.search.Searcher;
import com.yahoo.processing.request.CompoundName;
import com.yahoo.search.searchchain.Execution;
/**
* Searcher that sets cache control HTTP headers in response based on query/GET parameters to
* control caching done by proxy/caches such as YSquid and YTS:
* <ul>
* <li>max-age=XXX - set with &cachecontrol.maxage parameter
* <li>stale-while-revalidate=YYY - set with &cachecontrol.staleage
* <li>no-cache - if Vespa &noCache or &cachecontrol.nocache parameter is set to true
* </ul>
*
* <p>This is controlled through the three query parameters <code>cachecontrol.maxage</code>,
* <code>cachecontrol.staleage</code> and <code>cachecontrol.nocache</code>, with the obvious meanings.</p>
*
* Example:
* <ul>
* <li>Request: "?query=foo&cachecontrol.maxage=60&cachecontrol.staleage=3600"
* <li>Response HTTP header: "Cache-Control: max-age=60, revalidate-while-stale=3600"
* </ul>
*
* Further documentation on use of Cache-Control headers:
* http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.9
*
* @author Frode Lundgren
*/
public class CacheControlSearcher extends Searcher {
private static final CompoundName cachecontrolNocache=CompoundName.from("cachecontrol.nocache");
private static final CompoundName cachecontrolMaxage=CompoundName.from("cachecontrol.maxage");
private static final CompoundName cachecontrolStaleage=CompoundName.from("cachecontrol.staleage");
public static final String CACHE_CONTROL_HEADER = "Cache-Control";
@Override
public Result search(Query query, Execution execution) {
query.trace("CacheControlSearcher: Running version $Revision$", false, 6);
Result result = execution.search(query);
query = result.getQuery();
if (result.getHeaders(true) == null) {
query.trace("CacheControlSearcher: No HTTP header map available - skipping searcher.", false, 5);
return result;
}
// If you specify no-cache, no further cache control headers make sense
if (query.properties().getBoolean(cachecontrolNocache, false) || query.getNoCache()) {
result.getHeaders(true).put(CACHE_CONTROL_HEADER, "no-cache");
query.trace("CacheControlSearcher: Added no-cache header", false, 4);
return result;
}
// Handle max-age header
int maxage = query.properties().getInteger(cachecontrolMaxage, -1);
if (maxage > 0) {
result.getHeaders(true).put(CACHE_CONTROL_HEADER, "max-age=" + maxage);
query.trace("CacheControlSearcher: Set max-age header to " + maxage, false, 4);
}
// Handle stale-while-revalidate header
int staleage = query.properties().getInteger(cachecontrolStaleage, -1);
if (staleage > 0) {
result.getHeaders(true).put(CACHE_CONTROL_HEADER, "stale-while-revalidate=" + staleage);
query.trace("CacheControlSearcher: Set stale-while-revalidate header to " + staleage, false, 4);
}
return result;
}
}
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