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1 files changed, 75 insertions, 0 deletions

diff --git a/container-search/src/main/java/com/yahoo/search/searchers/CacheControlSearcher.java b/container-search/src/main/java/com/yahoo/search/searchers/CacheControlSearcher.java
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+// Copyright 2016 Yahoo Inc. 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 &amp;cachecontrol.maxage parameter
+ *    <li>stale-while-revalidate=YYY - set with &amp;cachecontrol.staleage
+ *    <li>no-cache - if Vespa &amp;noCache or &amp;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&amp;cachecontrol.maxage=60&amp;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=new CompoundName("cachecontrol.nocache");
+    private static final CompoundName cachecontrolMaxage=new CompoundName("cachecontrol.maxage");
+    private static final CompoundName cachecontrolStaleage=new CompoundName("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 " + maxage, false, 4);
+        }
+
+        return result;
+    }
+}