1 files changed, 106 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/federation/ForwardingSearcher.java b/container-search/src/main/java/com/yahoo/search/federation/ForwardingSearcher.java
new file mode 100644
index 00000000000..b43798113de
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/federation/ForwardingSearcher.java
@@ -0,0 +1,106 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.federation;
+
+import com.yahoo.component.ComponentSpecification;
+import com.yahoo.component.chain.Chain;
+import com.yahoo.component.chain.dependencies.After;
+import com.yahoo.prelude.Ping;
+import com.yahoo.prelude.Pong;
+import com.yahoo.search.Query;
+import com.yahoo.search.Result;
+import com.yahoo.search.Searcher;
+import com.yahoo.search.cluster.PingableSearcher;
+import com.yahoo.search.result.ErrorMessage;
+import com.yahoo.search.result.HitGroup;
+import com.yahoo.search.searchchain.Execution;
+
+/**
+ * A lightweight searcher to forward all incoming requests to a single search
+ * chain defined in config. An alternative to federation searcher when standard
+ * semantics are not necessary for the application.
+ *
+ * @see FederationSearcher
+ * @since 5.0.13
+ * @author <a href="mailto:steinar@yahoo-inc.com">Steinar Knutsen</a>
+ */
+@After("*")
+public class ForwardingSearcher extends PingableSearcher {
+    private final ComponentSpecification target;
+
+    public ForwardingSearcher(final SearchchainForwardConfig config) {
+        if (config.target() == null) {
+            throw new RuntimeException(
+                    "Configuration value searchchain-forward.target was null.");
+        }
+        try {
+            target = new ComponentSpecification(config.target());
+        } catch (RuntimeException e) {
+            throw new RuntimeException(
+                    "Failed constructing the component specification from searchchain-forward.target: "
+                            + config.target(), e);
+        }
+    }
+
+    @Override
+    public Result search(final Query query, final Execution execution) {
+        Execution next = createForward(execution);
+
+        if (next == null) {
+            return badResult(query);
+        } else {
+            return next.search(query);
+        }
+    }
+
+    private Result badResult(final Query query) {
+        final ErrorMessage error = noSearchchain();
+        return new Result(query, error);
+    }
+
+    @Override
+    public Pong ping(final Ping ping, final Execution execution) {
+        Execution next = createForward(execution);
+
+        if (next == null) {
+            return badPong();
+        } else {
+            return next.ping(ping);
+        }
+    }
+
+    private Pong badPong() {
+        final Pong pong = new Pong();
+        pong.addError(noSearchchain());
+        return pong;
+    }
+
+    @Override
+    public void fill(final Result result, final String summaryClass,
+            final Execution execution) {
+        Execution next = createForward(execution);
+        if (next == null) {
+            badFill(result.hits());
+            return;
+        } else {
+            next.fill(result, summaryClass);
+        }
+    }
+
+    private void badFill(HitGroup hits) {
+        hits.addError(noSearchchain());
+    }
+
+    private Execution createForward(Execution execution) {
+        Chain<Searcher> targetChain = execution.context().searchChainRegistry()
+                .getComponent(target);
+        if (targetChain == null) {
+            return null;
+        }
+        return new Execution(targetChain, execution.context());
+    }
+
+    private ErrorMessage noSearchchain() {
+        return ErrorMessage
+                .createServerIsMisconfigured("Could not get search chain matching component specification: " + target);
+    }
+}