Revert "Revert "Balder/no more fs4 dispatching from fastsearcher""

20 files changed, 28 insertions, 963 deletions

diff --git a/container-search/src/main/java/com/yahoo/prelude/Pong.java b/container-search/src/main/java/com/yahoo/prelude/Pong.java
index a6bc3e7975d..a60fba9a4f7 100644
--- a/container-search/src/main/java/com/yahoo/prelude/Pong.java
+++ b/container-search/src/main/java/com/yahoo/prelude/Pong.java
@@ -1,7 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.prelude;
 
-import com.yahoo.fs4.PongPacket;
 import com.yahoo.search.result.ErrorMessage;
 import com.yahoo.search.statistics.ElapsedTime;
 
@@ -19,28 +18,19 @@ public class Pong {
 
     private String pingInfo="";
     private final List<ErrorMessage> errors = new ArrayList<>(1);
-    private final Optional<PongPacket> pongPacket;
     private ElapsedTime elapsed = new ElapsedTime();
     private final Optional<Long> activeDocuments;
 
     public Pong() {
-        this.pongPacket = Optional.empty();
         this.activeDocuments = Optional.empty();
     }
 
     public Pong(ErrorMessage error) {
         errors.add(error);
-        this.pongPacket = Optional.empty();
-        this.activeDocuments = Optional.empty();
-    }
-
-    public Pong(PongPacket pongPacket) {
-        this.pongPacket = Optional.of(pongPacket);
         this.activeDocuments = Optional.empty();
     }
 
     public Pong(long activeDocuments) {
-        this.pongPacket = Optional.empty();
         this.activeDocuments = Optional.of(activeDocuments);
     }
 
@@ -52,21 +42,14 @@ public class Pong {
         return errors.get(i);
     }
 
-    public int getErrorSize() {
-        return errors.size();
-    }
-
     /** Returns the number of active documents in the backend responding in this Pong, if available */
     public Optional<Long> activeDocuments() {
-        if (activeDocuments.isPresent()) return activeDocuments;
-        if ( ! pongPacket.isPresent()) return Optional.empty();
-        return pongPacket.get().getActiveDocuments();
+        return activeDocuments;
     }
 
     /** Returns the number of nodes which responded to this Pong, if available */
     public Optional<Integer> activeNodes() {
-        if ( ! pongPacket.isPresent()) return Optional.empty();
-        return pongPacket.get().getActiveNodes();
+        return Optional.empty();
     }
 
     public List<ErrorMessage> getErrors() {
@@ -78,16 +61,6 @@ public class Pong {
         return ! errors.isEmpty();
     }
 
-    /** Sets information about the ping used to produce this. This is included when returning the tostring of this. */
-    public void setPingInfo(String pingInfo) {
-        if (pingInfo==null)
-            pingInfo="";
-        this.pingInfo=pingInfo;
-    }
-
-    /** Returns information about the ping use, or "" (never null) if none */
-    public String getPingInfo() { return pingInfo; }
-
     public ElapsedTime getElapsedTime() {
         return elapsed;
     }
diff --git a/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterMonitor.java b/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterMonitor.java
deleted file mode 100644
index c075a0f842b..00000000000
--- a/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterMonitor.java
+++ /dev/null
@@ -1,161 +0,0 @@
-// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.prelude.cluster;
-
-import java.util.Map;
-import java.util.Optional;
-import java.util.concurrent.ScheduledFuture;
-import java.util.concurrent.TimeUnit;
-import java.util.logging.Level;
-import java.util.logging.Logger;
-
-import com.yahoo.component.provider.Freezable;
-import com.yahoo.container.handler.VipStatus;
-import com.yahoo.prelude.fastsearch.VespaBackEndSearcher;
-import com.yahoo.search.result.ErrorMessage;
-
-/**
- * Monitors of a cluster of remote nodes. The monitor uses an internal thread
- * for node monitoring.
- *
- * @author bratseth
- * @author Steinar Knutsen
- */
-public class ClusterMonitor implements Runnable, Freezable {
-
-    // The ping thread wil start using the system, but we cannot be guaranteed that all components
-    // in the system is up. As a workaround for not being able to find out when the system
-    // is ready to be used, we wait some time before starting the ping thread
-    private static final int pingThreadInitialDelayMs = 3000;
-
-    private final MonitorConfiguration configuration;
-
-    private final static Logger log = Logger.getLogger(ClusterMonitor.class.getName());
-
-    private final ClusterSearcher nodeManager;
-
-    private final Optional<VipStatus> vipStatus;
-
-    /** A map from Node to corresponding MonitoredNode */
-    private final Map<VespaBackEndSearcher, NodeMonitor> nodeMonitors = new java.util.IdentityHashMap<>();
-
-    private ScheduledFuture<?>  future;
-
-    private boolean isFrozen = false;
-
-    ClusterMonitor(ClusterSearcher manager, QrMonitorConfig monitorConfig, Optional<VipStatus> vipStatus) {
-        configuration = new MonitorConfiguration(monitorConfig);
-        nodeManager = manager;
-        this.vipStatus = vipStatus;
-        log.fine("checkInterval is " + configuration.getCheckInterval() + " ms");
-    }
-
-    /** Returns the configuration of this cluster monitor */
-    MonitorConfiguration getConfiguration() {
-        return configuration;
-    }
-
-    void startPingThread() {
-        if ( ! isFrozen())
-            throw new IllegalStateException("Do not start the monitoring thread before the set of " +
-                                            "nodes to monitor is complete/the ClusterMonitor is frozen.");
-        future = nodeManager.getScheduledExecutor().scheduleAtFixedRate(this, pingThreadInitialDelayMs, configuration.getCheckInterval(), TimeUnit.MILLISECONDS);
-    }
-
-    /**
-     * Adds a new node for monitoring.
-     */
-    void add(VespaBackEndSearcher node) {
-        if (isFrozen())
-            throw new IllegalStateException("Can not add new nodes after ClusterMonitor has been frozen.");
-        nodeMonitors.put(node, new NodeMonitor(node));
-        updateVipStatus();
-    }
-
-    /** Called from ClusterSearcher/NodeManager when a node failed */
-    void failed(VespaBackEndSearcher node, ErrorMessage error) {
-        NodeMonitor monitor = nodeMonitors.get(node);
-        boolean wasWorking = monitor.isWorking();
-        monitor.failed(error);
-        if (wasWorking && !monitor.isWorking()) {
-            log.info("Failed monitoring node '" + node + "' due to '" + error);
-            nodeManager.failed(node);
-        }
-        updateVipStatus();
-    }
-
-    /** Called when a node responded */
-    void responded(VespaBackEndSearcher node, boolean hasSearchNodesOnline) {
-        NodeMonitor monitor = nodeMonitors.get(node);
-        boolean wasFailing = !monitor.isWorking();
-        monitor.responded(hasSearchNodesOnline);
-        if (wasFailing && monitor.isWorking()) {
-            log.info("Failed node '" + node + "' started working again.");
-            nodeManager.working(node);
-        }
-        updateVipStatus();
-    }
-
-    private void updateVipStatus() {
-        if ( ! vipStatus.isPresent()) return;
-        if ( ! hasInformationAboutAllNodes()) return;
-        
-        if (hasWorkingNodesWithDocumentsOnline()) {
-            vipStatus.get().addToRotation(nodeManager.getId().stringValue());
-        } else {
-            vipStatus.get().removeFromRotation(nodeManager.getId().stringValue());
-        }
-    }
-
-    private boolean hasInformationAboutAllNodes() {
-        for (NodeMonitor monitor : nodeMonitors.values()) {
-            if ( ! monitor.statusIsKnown())
-                return false;
-        }
-        return true;
-    }
-
-    private boolean hasWorkingNodesWithDocumentsOnline() {
-        for (NodeMonitor node : nodeMonitors.values()) {
-            if (node.isWorking() && node.searchNodesOnline())
-                return true;
-        }
-        return false;
-    }
-
-    /**
-     * Ping all nodes which needs pinging to discover state changes
-     */
-    private void ping() throws InterruptedException {
-        for (NodeMonitor monitor : nodeMonitors.values()) {
-            nodeManager.ping(monitor.getNode());
-        }
-    }
-
-    @Override
-    public void run() {
-        log.finest("Activating ping");
-        try {
-            ping();
-        } catch (Exception e) {
-            log.log(Level.WARNING, "Error in monitor thread", e);
-        }
-    }
-
-    public void shutdown() {
-        if (future != null) {
-            future.cancel(true);
-        }
-    }
-
-    @Override
-    public void freeze() {
-        isFrozen  = true;
-
-    }
-
-    @Override
-    public boolean isFrozen() {
-        return isFrozen;
-    }
-
-}
diff --git a/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java b/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java
index 4ffcc0a4330..0780d5e9d65 100644
--- a/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/cluster/ClusterSearcher.java
@@ -2,20 +2,13 @@
 package com.yahoo.prelude.cluster;
 
 import com.yahoo.cloud.config.ClusterInfoConfig;
-import com.yahoo.collections.Tuple2;
 import com.yahoo.component.ComponentId;
-import com.yahoo.component.chain.Chain;
 import com.yahoo.component.chain.dependencies.After;
-import com.yahoo.concurrent.Receiver;
-import com.yahoo.concurrent.Receiver.MessageState;
 import com.yahoo.container.QrSearchersConfig;
 import com.yahoo.container.handler.VipStatus;
-import com.yahoo.fs4.mplex.Backend;
 import com.yahoo.jdisc.Metric;
 import com.yahoo.net.HostName;
 import com.yahoo.prelude.IndexFacts;
-import com.yahoo.prelude.Ping;
-import com.yahoo.prelude.Pong;
 import com.yahoo.prelude.fastsearch.ClusterParams;
 import com.yahoo.prelude.fastsearch.DocumentdbInfoConfig;
 import com.yahoo.prelude.fastsearch.FS4ResourcePool;
@@ -46,11 +39,7 @@ import java.util.HashSet;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
-import java.util.Optional;
 import java.util.Set;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.logging.Logger;
 
 import static com.yahoo.container.QrSearchersConfig.Searchcluster.Indexingmode.STREAMING;
 
@@ -64,10 +53,6 @@ import static com.yahoo.container.QrSearchersConfig.Searchcluster.Indexingmode.S
 @After("*")
 public class ClusterSearcher extends Searcher {
 
-    private final static Logger log = Logger.getLogger(ClusterSearcher.class.getName());
-
-    private final ClusterMonitor monitor;
-
     private final Value cacheHitRatio;
 
     private final String clusterModelName;
@@ -78,8 +63,6 @@ public class ClusterSearcher extends Searcher {
     // Mapping from rank profile names to document types containing them
     private final Map<String, Set<String>> rankProfiles = new HashMap<>();
 
-    private final FS4ResourcePool fs4ResourcePool;
-
     private final long maxQueryTimeout; // in milliseconds
     private final static long DEFAULT_MAX_QUERY_TIMEOUT = 600000L;
 
@@ -88,7 +71,6 @@ public class ClusterSearcher extends Searcher {
 
     private VespaBackEndSearcher server = null;
 
-
     /**
      * Creates a new ClusterSearcher.
      */
@@ -96,7 +78,6 @@ public class ClusterSearcher extends Searcher {
                            QrSearchersConfig qrsConfig,
                            ClusterConfig clusterConfig,
                            DocumentdbInfoConfig documentDbConfig,
-                           QrMonitorConfig monitorConfig,
                            DispatchConfig dispatchConfig,
                            ClusterInfoConfig clusterInfoConfig,
                            Statistics manager,
@@ -104,13 +85,8 @@ public class ClusterSearcher extends Searcher {
                            FS4ResourcePool fs4ResourcePool,
                            VipStatus vipStatus) {
         super(id);
-        this.fs4ResourcePool = fs4ResourcePool;
-
-        Dispatcher dispatcher = Dispatcher.create(id.stringValue(), dispatchConfig, fs4ResourcePool, clusterInfoConfig.nodeCount(), vipStatus, metric);
 
-        monitor = (dispatcher.searchCluster().directDispatchTarget().isPresent()) // dispatcher should decide vip status instead
-                ? new ClusterMonitor(this, monitorConfig, Optional.empty())
-                : new ClusterMonitor(this, monitorConfig, Optional.of(vipStatus));
+        Dispatcher dispatcher = Dispatcher.create(id.stringValue(), dispatchConfig, clusterInfoConfig.nodeCount(), vipStatus, metric);
 
         int searchClusterIndex = clusterConfig.clusterId();
         clusterModelName = clusterConfig.clusterName();
@@ -148,9 +124,8 @@ public class ClusterSearcher extends Searcher {
             for (int dispatcherIndex = 0; dispatcherIndex < searchClusterConfig.dispatcher().size(); dispatcherIndex++) {
                 try {
                     if ( ! isRemote(searchClusterConfig.dispatcher(dispatcherIndex).host())) {
-                        Backend dispatchBackend = createBackend(searchClusterConfig.dispatcher(dispatcherIndex));
-                        FastSearcher searcher = searchDispatch(searchClusterIndex, fs4ResourcePool, docSumParams,
-                                                               documentDbConfig, dispatchBackend, dispatcher, dispatcherIndex);
+                        FastSearcher searcher = searchDispatch(searchClusterIndex, fs4ResourcePool.getServerId(), docSumParams,
+                                                               documentDbConfig, dispatcher, dispatcherIndex);
                         addBackendSearcher(searcher);
                     }
                 } catch (UnknownHostException e) {
@@ -162,8 +137,6 @@ public class ClusterSearcher extends Searcher {
         if ( server == null ) {
             throw new IllegalStateException("ClusterSearcher should have a top level dispatch.");
         }
-        monitor.freeze();
-        monitor.startPingThread();
     }
 
     private static QrSearchersConfig.Searchcluster getSearchClusterConfigFromClusterName(QrSearchersConfig config, String name) {
@@ -189,15 +162,14 @@ public class ClusterSearcher extends Searcher {
     }
 
     private static FastSearcher searchDispatch(int searchclusterIndex,
-                                               FS4ResourcePool fs4ResourcePool,
+                                               String serverId,
                                                SummaryParameters docSumParams,
                                                DocumentdbInfoConfig documentdbInfoConfig,
-                                               Backend backend,
                                                Dispatcher dispatcher,
                                                int dispatcherIndex)
     {
         ClusterParams clusterParams = makeClusterParams(searchclusterIndex, dispatcherIndex);
-        return new FastSearcher(backend, fs4ResourcePool, dispatcher, docSumParams, clusterParams, documentdbInfoConfig);
+        return new FastSearcher(serverId, dispatcher, docSumParams, clusterParams, documentdbInfoConfig);
     }
 
     private static VdsStreamingSearcher vdsCluster(String serverId,
@@ -222,25 +194,14 @@ public class ClusterSearcher extends Searcher {
     /** Do not use, for internal testing purposes only. **/
     ClusterSearcher(Set<String> documentTypes) {
         this.documentTypes = documentTypes;
-        monitor = new ClusterMonitor(this, new QrMonitorConfig(new QrMonitorConfig.Builder()), Optional.of(new VipStatus()));
         cacheHitRatio = new Value("com.yahoo.prelude.cluster.ClusterSearcher.ClusterSearcher().dummy",
                                   Statistics.nullImplementation, new Value.Parameters());
         clusterModelName = "testScenario";
-        fs4ResourcePool = null;
         maxQueryTimeout = DEFAULT_MAX_QUERY_TIMEOUT;
         maxQueryCacheTimeout = DEFAULT_MAX_QUERY_CACHE_TIMEOUT;
     }
 
-    private Backend createBackend(QrSearchersConfig.Searchcluster.Dispatcher disp) {
-        return fs4ResourcePool.getBackend(disp.host(), disp.port());
-    }
-
-    ClusterMonitor getMonitor() {
-        return monitor;
-    }
-
     void addBackendSearcher(VespaBackEndSearcher searcher) {
-        monitor.add(searcher);
         server = searcher;
     }
 
@@ -479,77 +440,6 @@ public class ClusterSearcher extends Searcher {
         cacheHitRatio.put(0.0);
     }
 
-    /** NodeManager method, called from ClusterMonitor. */
-    void working(VespaBackEndSearcher node) {
-        server = node;
-    }
-
-    /** Called from ClusterMonitor. */
-    void failed(VespaBackEndSearcher node) {
-        server = null;
-    }
-
-    /**
-     * Pinging a node, called from ClusterMonitor.
-     */
-    void ping(VespaBackEndSearcher node) throws InterruptedException {
-        log.fine("Sending ping to: " + node);
-        Pinger pinger = new Pinger(node);
-
-        getExecutor().execute(pinger);
-        Pong pong = pinger.getPong(); // handles timeout
-        if (pong == null) {
-            monitor.failed(node, ErrorMessage.createNoAnswerWhenPingingNode("Ping thread timed out."));
-        } else if (pong.badResponse()) {
-            monitor.failed(node, pong.getError(0));
-        } else {
-            monitor.responded(node, backendCanServeDocuments(pong));
-        }
-    }
-
-    private boolean backendCanServeDocuments(Pong pong) {
-        if ( ! pong.activeNodes().isPresent()) return true; // no information; assume true
-        return pong.activeNodes().get() > 0;
-    }
-
     @Override
-    public void deconstruct() {
-        monitor.shutdown();
-    }
-
-    ExecutorService getExecutor() {
-        return fs4ResourcePool.getExecutor();
-    }
-
-    ScheduledExecutorService getScheduledExecutor() {
-        return fs4ResourcePool.getScheduledExecutor();
-    }
-
-    private class Pinger implements Runnable {
-
-        private final Searcher searcher;
-        private final Ping pingChallenge = new Ping(monitor.getConfiguration().getRequestTimeout());
-        private final Receiver<Pong> pong = new Receiver<>();
-
-        Pinger(final Searcher searcher) {
-            this.searcher = searcher;
-        }
-
-        @Override
-        public void run() {
-            pong.put(createExecution().ping(pingChallenge));
-        }
-
-        private Execution createExecution() {
-            return new Execution(new Chain<>(searcher),
-                                 new Execution.Context(null, null, null, null, null));
-        }
-
-        public Pong getPong() throws InterruptedException {
-            Tuple2<MessageState, Pong> reply = pong.get(pingChallenge.getTimeout() + 150);
-            return (reply.first != MessageState.VALID) ? null : reply.second;
-        }
-
-    }
-
+    public void deconstruct() { }
 }
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/DataField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/DataField.java
index 524e842eacd..de07839e3e3 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/DataField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/DataField.java
@@ -10,8 +10,6 @@
 
 package com.yahoo.prelude.fastsearch;
 
-import java.nio.ByteBuffer;
-
 import com.yahoo.prelude.hitfield.RawData;
 import com.yahoo.data.access.simple.Value;
 import com.yahoo.data.access.Inspector;
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/DocsumField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/DocsumField.java
index 4f52ef91725..329a9caaf91 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/DocsumField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/DocsumField.java
@@ -6,7 +6,6 @@ import com.yahoo.log.LogLevel;
 
 import java.lang.reflect.Constructor;
 import java.lang.reflect.InvocationTargetException;
-import java.nio.ByteBuffer;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.logging.Logger;
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/DoubleField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/DoubleField.java
index 6b1445229ec..f6f8006d2d2 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/DoubleField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/DoubleField.java
@@ -1,9 +1,6 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.prelude.fastsearch;
 
-
-import java.nio.ByteBuffer;
-
 import com.yahoo.search.result.NanNumber;
 import com.yahoo.data.access.Inspector;
 
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4FillInvoker.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4FillInvoker.java
deleted file mode 100644
index 59bc781c8b2..00000000000
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4FillInvoker.java
+++ /dev/null
@@ -1,184 +0,0 @@
-// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.prelude.fastsearch;
-
-import com.yahoo.fs4.BasicPacket;
-import com.yahoo.fs4.ChannelTimeoutException;
-import com.yahoo.fs4.GetDocSumsPacket;
-import com.yahoo.fs4.Packet;
-import com.yahoo.fs4.mplex.Backend;
-import com.yahoo.fs4.mplex.FS4Channel;
-import com.yahoo.fs4.mplex.InvalidChannelException;
-import com.yahoo.prelude.fastsearch.VespaBackEndSearcher.FillHitsResult;
-import com.yahoo.search.Query;
-import com.yahoo.search.Result;
-import com.yahoo.search.dispatch.FillInvoker;
-import com.yahoo.search.result.ErrorMessage;
-import com.yahoo.search.result.Hit;
-
-import java.io.IOException;
-import java.util.Iterator;
-
-import static com.yahoo.prelude.fastsearch.VespaBackEndSearcher.hitIterator;
-
-/**
- * {@link FillInvoker} implementation for FS4 nodes and fdispatch
- *
- * @author ollivir
- */
-public class FS4FillInvoker extends FillInvoker {
-    private final VespaBackEndSearcher searcher;
-    private FS4Channel channel;
-
-    private int expectedFillResults = 0;
-
-    // fdispatch code path
-    FS4FillInvoker(VespaBackEndSearcher searcher, Query query, Backend backend) {
-        this.searcher = searcher;
-        this.channel = backend.openChannel();
-        channel.setQuery(query);
-    }
-
-    @Override
-    protected void sendFillRequest(Result result, String summaryClass) {
-
-        if (countUnfilledFastHits(result, summaryClass) > 0) {
-            try {
-                expectedFillResults = requestSummaries(result, summaryClass);
-            } catch (InvalidChannelException e) {
-                result.hits()
-                        .addError(ErrorMessage.createBackendCommunicationError("Invalid channel " + getName() + " (summary fetch)"));
-            } catch (IOException e) {
-                result.hits().addError(ErrorMessage.createBackendCommunicationError(
-                        "IO error while talking on channel " + getName() + " (summary fetch): " + e.getMessage()));
-            }
-        } else {
-            expectedFillResults = 0;
-        }
-    }
-
-
-    @Override
-    protected void getFillResults(Result result, String summaryClass) {
-        if (expectedFillResults == 0) {
-            return;
-        }
-
-        Packet[] receivedPackets;
-        try {
-            receivedPackets = getSummaryResponses(result);
-        } catch (InvalidChannelException e1) {
-            result.hits().addError(ErrorMessage.createBackendCommunicationError("Invalid channel " + getName() + " (summary fetch)"));
-            return;
-        } catch (ChannelTimeoutException e1) {
-            result.hits().addError(ErrorMessage.createTimeout("timeout waiting for summaries from " + getName()));
-            return;
-        }
-
-        if (receivedPackets.length == 0) {
-            result.hits().addError(ErrorMessage.createBackendCommunicationError(getName() + " got no packets back (summary fetch)"));
-            return;
-        }
-
-        int skippedHits;
-        try {
-            FillHitsResult fillHitsResult = searcher.fillHits(result, receivedPackets, summaryClass);
-            skippedHits = fillHitsResult.skippedHits;
-            if (fillHitsResult.error != null) {
-                result.hits().addError(ErrorMessage.createTimeout(fillHitsResult.error));
-                return;
-            }
-        } catch (TimeoutException e) {
-            result.hits().addError(ErrorMessage.createTimeout(e.getMessage()));
-            return;
-        } catch (IOException e) {
-            result.hits().addError(ErrorMessage.createBackendCommunicationError(
-                    "Error filling hits with summary fields, source: " + getName() + " Exception thrown: " + e.getMessage()));
-            return;
-        }
-
-        if (skippedHits > 0)
-            result.hits().addError(
-                    ErrorMessage.createEmptyDocsums("Missing hit data for summary '" + summaryClass + "' for " + skippedHits + " hits"));
-        result.analyzeHits();
-
-        if (channel.getQuery().getTraceLevel() >= 3) {
-            int hitNumber = 0;
-            for (Iterator<com.yahoo.search.result.Hit> i = hitIterator(result); i.hasNext();) {
-                com.yahoo.search.result.Hit hit = i.next();
-                if (!(hit instanceof FastHit))
-                    continue;
-                FastHit fastHit = (FastHit) hit;
-
-                String traceMsg = "Hit: " + (hitNumber++) + " from " + (fastHit.isCached() ? "cache" : "backend");
-                if (!fastHit.isFilled(summaryClass))
-                    traceMsg += ". Error, hit, not filled";
-                channel.getQuery().trace(traceMsg, false, 3);
-            }
-        }
-    }
-
-    @Override
-    public void release() {
-        if (channel != null) {
-            channel.close();
-            channel = null;
-        }
-    }
-
-    private int countUnfilledFastHits(Result result, String summaryClass) {
-        int count = 0;
-        for (Iterator<Hit> i = hitIterator(result); i.hasNext();) {
-            Hit hit = i.next();
-            if (hit instanceof FastHit && !hit.isFilled(summaryClass))
-                count++;
-        }
-        return count;
-    }
-
-    private int requestSummaries(Result result, String summaryClass) throws InvalidChannelException, ClassCastException, IOException {
-
-        boolean summaryNeedsQuery = searcher.summaryNeedsQuery(result.getQuery());
-        if (result.getQuery().getTraceLevel() >= 3)
-            result.getQuery().trace((summaryNeedsQuery ? "FS4: Resending " : "Not resending ") + "query during document summary fetching", 3);
-
-        GetDocSumsPacket docsumsPacket = GetDocSumsPacket.create(result, summaryClass, summaryNeedsQuery);
-        int compressionLimit = result.getQuery().properties().getInteger(FS4SearchInvoker.PACKET_COMPRESSION_LIMIT, 0);
-        docsumsPacket.setCompressionLimit(compressionLimit);
-        if (compressionLimit != 0) {
-            docsumsPacket.setCompressionType(result.getQuery().properties().getString(FS4SearchInvoker.PACKET_COMPRESSION_TYPE, "lz4"));
-        }
-
-        boolean couldSend = channel.sendPacket(docsumsPacket);
-        if (!couldSend)
-            throw new IOException("Could not successfully send GetDocSumsPacket.");
-
-        return docsumsPacket.getNumDocsums() + 1;
-    }
-
-    private Packet[] getSummaryResponses(Result result) throws InvalidChannelException, ChannelTimeoutException {
-        if(expectedFillResults == 0) {
-            return new Packet[0];
-        }
-        BasicPacket[] receivedPackets = channel.receivePackets(result.getQuery().getTimeLeft(), expectedFillResults);
-
-        return convertBasicPackets(receivedPackets);
-    }
-
-    private static Packet[] convertBasicPackets(BasicPacket[] basicPackets) throws ClassCastException {
-        // trying to cast a BasicPacket[] to Packet[] will compile,
-        // but lead to a runtime error. At least that's what I got
-        // from testing and reading the specification. I'm just happy
-        // if someone tells me what's the proper Java way of doing
-        // this. -SK
-        Packet[] packets = new Packet[basicPackets.length];
-
-        for (int i = 0; i < basicPackets.length; i++) {
-            packets[i] = (Packet) basicPackets[i];
-        }
-        return packets;
-    }
-
-    private String getName() {
-        return searcher.getName();
-    }
-}
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4PingFactory.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4PingFactory.java
deleted file mode 100644
index 2abaf341c58..00000000000
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4PingFactory.java
+++ /dev/null
@@ -1,29 +0,0 @@
-// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.prelude.fastsearch;
-
-import com.yahoo.prelude.Pong;
-import com.yahoo.search.cluster.ClusterMonitor;
-import com.yahoo.search.dispatch.searchcluster.Node;
-import com.yahoo.search.dispatch.searchcluster.PingFactory;
-import com.yahoo.search.dispatch.searchcluster.Pinger;
-
-import java.util.concurrent.Callable;
-
-/**
- * FS4PingFactory constructs {@link Pinger} objects that communicate with
- * content nodes or dispatchers over the fnet/FS4 protocol
- *
- * @author ollivir
- */
-public class FS4PingFactory implements PingFactory {
-    private final FS4ResourcePool fs4ResourcePool;
-
-    public FS4PingFactory(FS4ResourcePool fs4ResourcePool) {
-        this.fs4ResourcePool = fs4ResourcePool;
-    }
-
-    @Override
-    public Callable<Pong> createPinger(Node node, ClusterMonitor<Node> monitor) {
-        return new Pinger(node, monitor, fs4ResourcePool);
-    }
-}
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4ResourcePool.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4ResourcePool.java
index f85a4019b78..ed9eb72d7dd 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4ResourcePool.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4ResourcePool.java
@@ -5,14 +5,6 @@ import com.google.inject.Inject;
 import com.yahoo.component.AbstractComponent;
 import com.yahoo.concurrent.ThreadFactoryFactory;
 import com.yahoo.container.QrConfig;
-import com.yahoo.container.search.Fs4Config;
-import com.yahoo.fs4.mplex.Backend;
-import com.yahoo.fs4.mplex.ConnectionPool;
-import com.yahoo.fs4.mplex.ListenerPool;
-
-import java.util.HashMap;
-import java.util.Map;
-import java.util.Timer;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
@@ -22,7 +14,7 @@ import java.util.logging.Level;
 import java.util.logging.Logger;
 
 /**
- * Provider for {@link com.yahoo.fs4.mplex.ListenerPool}. All users will get the same pool instance.
+ * All users will get the same pool instance.
  *
  * @author baldersheim
  */
@@ -32,22 +24,18 @@ public class FS4ResourcePool extends AbstractComponent {
     private static final AtomicInteger instanceCounter = new AtomicInteger(0);
     private final String serverId;
     private final int instanceId;
-    private final ListenerPool listeners;
-    private final Timer timer = new Timer();  // This is a timer for cleaning the closed connections
-    private final Map<String, Backend> connectionPoolMap = new HashMap<>();
     private final ExecutorService executor;
     private final ScheduledExecutorService scheduledExecutor;
 
     @Inject
-    public FS4ResourcePool(Fs4Config fs4Config, QrConfig config) {
-        this(config.discriminator(), fs4Config.numlistenerthreads());
+    public FS4ResourcePool(QrConfig config) {
+        this(config.discriminator());
     }
     
-    public FS4ResourcePool(String serverId, int listenerThreads) {
+    public FS4ResourcePool(String serverId) {
         this.serverId = serverId;
         instanceId = instanceCounter.getAndIncrement();
         String name = "FS4-" + instanceId;
-        listeners = new ListenerPool(name, listenerThreads);
         executor = Executors.newCachedThreadPool(ThreadFactoryFactory.getDaemonThreadFactory(name));
         scheduledExecutor = Executors.newScheduledThreadPool(1, ThreadFactoryFactory.getDaemonThreadFactory(name + ".scheduled"));
     }
@@ -57,28 +45,10 @@ public class FS4ResourcePool extends AbstractComponent {
     public ExecutorService getExecutor() { return executor; }
     public ScheduledExecutorService getScheduledExecutor() { return scheduledExecutor; }
 
-    public Backend getBackend(String host, int port) {
-        String key = host + ":" + port;
-        synchronized (connectionPoolMap) {
-            Backend pool = connectionPoolMap.get(key);
-            if (pool == null) {
-                pool = new Backend(host, port, serverId, listeners, new ConnectionPool(timer));
-                connectionPoolMap.put(key, pool);
-            }
-            return pool;
-        }
-    }
-
     @Override
     public void deconstruct() {
         logger.log(Level.INFO, "Deconstructing FS4ResourcePool with id '" + instanceId + "'.");
         super.deconstruct();
-        listeners.close();
-        timer.cancel();
-        for (Backend backend : connectionPoolMap.values()) {
-            backend.shutdown();
-            backend.close();
-        }
         executor.shutdown();
         scheduledExecutor.shutdown();
         try {
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4SearchInvoker.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4SearchInvoker.java
deleted file mode 100644
index f3867288b29..00000000000
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FS4SearchInvoker.java
+++ /dev/null
@@ -1,220 +0,0 @@
-// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-package com.yahoo.prelude.fastsearch;
-
-import com.yahoo.data.access.simple.Value;
-import com.yahoo.data.access.slime.SlimeAdapter;
-import com.yahoo.fs4.BasicPacket;
-import com.yahoo.fs4.ChannelTimeoutException;
-import com.yahoo.fs4.DocumentInfo;
-import com.yahoo.fs4.FS4Properties;
-import com.yahoo.fs4.QueryPacket;
-import com.yahoo.fs4.QueryPacketData;
-import com.yahoo.fs4.QueryResultPacket;
-import com.yahoo.fs4.mplex.FS4Channel;
-import com.yahoo.fs4.mplex.InvalidChannelException;
-import com.yahoo.io.GrowableByteBuffer;
-import com.yahoo.log.LogLevel;
-import com.yahoo.prelude.ConfigurationException;
-import com.yahoo.processing.request.CompoundName;
-import com.yahoo.search.Query;
-import com.yahoo.search.Result;
-import com.yahoo.search.dispatch.InvokerResult;
-import com.yahoo.search.dispatch.LeanHit;
-import com.yahoo.search.dispatch.ResponseMonitor;
-import com.yahoo.search.dispatch.SearchInvoker;
-import com.yahoo.search.dispatch.searchcluster.Node;
-import com.yahoo.search.query.Sorting;
-import com.yahoo.search.result.Coverage;
-import com.yahoo.search.result.ErrorMessage;
-import com.yahoo.search.result.Relevance;
-import com.yahoo.search.searchchain.Execution;
-import com.yahoo.searchlib.aggregation.Grouping;
-import com.yahoo.slime.BinaryFormat;
-import com.yahoo.vespa.objects.BufferSerializer;
-
-import java.io.IOException;
-import java.nio.ByteBuffer;
-import java.util.ArrayList;
-import java.util.List;
-import java.util.Optional;
-import java.util.logging.Logger;
-
-/**
- * {@link SearchInvoker} implementation for FS4 nodes and fdispatch
- *
- * @author ollivir
- */
-public class FS4SearchInvoker extends SearchInvoker implements ResponseMonitor<FS4Channel> {
-    static final CompoundName PACKET_COMPRESSION_LIMIT = new CompoundName("packetcompressionlimit");
-    static final CompoundName PACKET_COMPRESSION_TYPE = new CompoundName("packetcompressiontype");
-
-    private static final Logger log = Logger.getLogger(FS4SearchInvoker.class.getName());
-
-    private final VespaBackEndSearcher searcher;
-    private FS4Channel channel;
-
-    private ErrorMessage pendingSearchError = null;
-    private Query query = null;
-    private QueryPacket queryPacket = null;
-
-    public FS4SearchInvoker(VespaBackEndSearcher searcher, Query query, FS4Channel channel, Optional<Node> node) {
-        super(node);
-        this.searcher = searcher;
-        this.channel = channel;
-
-        channel.setQuery(query);
-        channel.setResponseMonitor(this);
-    }
-
-    @Override
-    protected void sendSearchRequest(Query query) throws IOException {
-        log.finest("sending query packet");
-
-        this.query = query;
-        createQueryPacket(searcher.getServerId(), query);
-
-        try {
-            boolean couldSend = channel.sendPacket(queryPacket);
-            if (!couldSend) {
-                setPendingError("Could not reach '" + getName() + "'");
-            }
-        } catch (InvalidChannelException e) {
-            setPendingError("Invalid channel " + getName());
-        } catch (IllegalStateException e) {
-            setPendingError("Illegal state in FS4: " + e.getMessage());
-        }
-    }
-
-    private void setPendingError(String message) {
-        pendingSearchError = ErrorMessage.createBackendCommunicationError(message);
-        responseAvailable();
-    }
-
-    @Override
-    protected InvokerResult getSearchResult(Execution execution) throws IOException {
-        if (pendingSearchError != null) {
-            return errorResult(query, pendingSearchError);
-        }
-        BasicPacket[] basicPackets;
-
-        try {
-            basicPackets = channel.receivePackets(query.getTimeLeft(), 1);
-        } catch (ChannelTimeoutException e) {
-            return errorResult(query, ErrorMessage.createTimeout("Timeout while waiting for " + getName()));
-        } catch (InvalidChannelException e) {
-            return errorResult(query, ErrorMessage.createBackendCommunicationError("Invalid channel for " + getName()));
-        }
-
-        if (basicPackets.length == 0) {
-            return errorResult(query, ErrorMessage.createBackendCommunicationError(getName() + " got no packets back"));
-        }
-
-        log.finest(() -> "got packets " + basicPackets.length + " packets");
-
-        basicPackets[0].ensureInstanceOf(QueryResultPacket.class, getName());
-        QueryResultPacket resultPacket = (QueryResultPacket) basicPackets[0];
-
-        log.finest(() -> "got query packet. " + "docsumClass=" + query.getPresentation().getSummary());
-
-        if (query.getPresentation().getSummary() == null)
-            query.getPresentation().setSummary(searcher.getDefaultDocsumClass());
-
-        InvokerResult result = new InvokerResult(query, resultPacket.getDocumentCount());
-
-        addMetaInfo(query, queryPacket.getQueryPacketData(), resultPacket, result.getResult());
-        addUnfilledHits(result.getLeanHits(), resultPacket.getDocuments(), queryPacket.getQueryPacketData());
-
-        return result;
-    }
-
-    private QueryPacket createQueryPacket(String serverId, Query query) {
-        this.queryPacket = QueryPacket.create(serverId, query);
-        int compressionLimit = query.properties().getInteger(PACKET_COMPRESSION_LIMIT, 0);
-        queryPacket.setCompressionLimit(compressionLimit);
-        if (compressionLimit != 0) {
-            queryPacket.setCompressionType(query.properties().getString(PACKET_COMPRESSION_TYPE, "lz4"));
-        }
-        log.fine(() -> "made QueryPacket: " + queryPacket);
-
-        return queryPacket;
-    }
-
-    private void addMetaInfo(Query query, QueryPacketData queryPacketData, QueryResultPacket resultPacket, Result result) {
-        result.setTotalHitCount(resultPacket.getTotalDocumentCount());
-
-        addBackendTrace(query, resultPacket);
-
-        // Grouping
-        if (resultPacket.getGroupData() != null) {
-            byte[] data = resultPacket.getGroupData();
-            ArrayList<Grouping> list = new ArrayList<>();
-            BufferSerializer buf = new BufferSerializer(new GrowableByteBuffer(ByteBuffer.wrap(data)));
-            int cnt = buf.getInt(null);
-            for (int i = 0; i < cnt; i++) {
-                Grouping g = new Grouping();
-                g.deserialize(buf);
-                list.add(g);
-            }
-            GroupingListHit hit = new GroupingListHit(list, searcher.getDocsumDefinitionSet(query));
-            hit.setQuery(result.getQuery());
-            hit.setSource(getName());
-            hit.setQueryPacketData(queryPacketData);
-            result.hits().add(hit);
-        }
-
-        if (resultPacket.getCoverageFeature()) {
-            result.setCoverage(new Coverage(resultPacket.getCoverageDocs(), resultPacket.getActiveDocs(), resultPacket.getNodesReplied())
-                    .setSoonActive(resultPacket.getSoonActiveDocs())
-                    .setDegradedReason(resultPacket.getDegradedReason())
-                    .setNodesTried(resultPacket.getNodesQueried()));
-        }
-    }
-
-    private void addBackendTrace(Query query, QueryResultPacket resultPacket) {
-        if (resultPacket.propsArray == null) return;
-        Value.ArrayValue traces = new Value.ArrayValue();
-        for (FS4Properties properties : resultPacket.propsArray) {
-            if ( ! properties.getName().equals("trace")) continue;
-            for (FS4Properties.Entry entry : properties.getEntries()) {
-                traces.add(new SlimeAdapter(BinaryFormat.decode(entry.getValue()).get()));
-            }
-        }
-        query.trace(traces, query.getTraceLevel());
-    }
-
-    /**
-     * Creates unfilled hits from a List of DocumentInfo instances.
-     */
-    private void addUnfilledHits(List<LeanHit> result, List<DocumentInfo> documents, QueryPacketData queryPacketData) {
-        Optional<Integer> channelDistributionKey = distributionKey();
-
-        for (DocumentInfo document : documents) {
-             byte [] sortData = document.getSortData();
-             LeanHit hit = (sortData == null)
-                     ? new LeanHit(document.getRawGlobalId(), document.getPartId(), channelDistributionKey.orElse(document.getDistributionKey()), document.getMetric())
-                     : new LeanHit(document.getRawGlobalId(), document.getPartId(), channelDistributionKey.orElse(document.getDistributionKey()), document.getSortData());
-             if (queryPacketData != null) {
-                 hit.setQueryPacketData(queryPacketData);
-             }
-             result.add(hit);
-        }
-    }
-
-    @Override
-    public void release() {
-        if (channel != null) {
-            channel.close();
-            channel = null;
-        }
-    }
-
-    private String getName() {
-        return searcher.getName();
-    }
-
-    @Override
-    public void responseAvailable(FS4Channel from) {
-        responseAvailable();
-    }
-
-}
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java
index f7f2d08d713..244fad4efde 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastHit.java
@@ -3,7 +3,6 @@ package com.yahoo.prelude.fastsearch;
 
 import com.yahoo.data.access.ObjectTraverser;
 import com.yahoo.document.GlobalId;
-import com.yahoo.fs4.QueryPacketData;
 import com.yahoo.net.URI;
 import com.yahoo.search.query.Sorting;
 import com.yahoo.search.result.Hit;
@@ -40,9 +39,6 @@ public class FastHit extends Hit {
     /** The global id of this document in the backend node which produced it */
     private byte [] globalId;
 
-    //TODO Remove with fs4
-    private transient QueryPacketData queryPacketData = null;
-
     private transient byte[] sortData = null;
     // TODO I supect this one can be dropped.
     private transient Sorting sortDataSorting = null;
@@ -147,27 +143,6 @@ public class FastHit extends Hit {
     /** Sets the index of the node this hit originated at */
     public void setDistributionKey(int distributionKey) { this.distributionKey = distributionKey; }
 
-    /**
-     * Add the binary data common for the query packet to a Vespa backend and a
-     * summary fetch packet to a Vespa backend. This method can only be called
-     * once for a single hit.
-     *
-     * @param queryPacketData binary data from a query packet resulting in this hit
-     * @throws IllegalStateException if the method is called more than once
-     * @throws NullPointerException if trying to set query packet data to null
-     */
-    public void setQueryPacketData(QueryPacketData queryPacketData) {
-        if (this.queryPacketData != null)
-            throw new IllegalStateException("Query packet data already set to "
-                                            + this.queryPacketData + ", tried to set it to " + queryPacketData);
-        if (queryPacketData == null)
-            throw new NullPointerException("Query packet data reference can not be set to null.");
-        this.queryPacketData = queryPacketData;
-    }
-
-    /** Returns a serial encoding of the query which produced this hit, ot null if not available. */
-    public QueryPacketData getQueryPacketData() { return queryPacketData; }
-
     public void setSortData(byte[] data, Sorting sorting) {
         this.sortData = data;
         this.sortDataSorting = sorting;
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastSearcher.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastSearcher.java
index 6b0041a9e86..b0b3a7800e9 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/FastSearcher.java
@@ -1,23 +1,14 @@
 // Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.prelude.fastsearch;
 
-import com.yahoo.fs4.BasicPacket;
-import com.yahoo.fs4.ChannelTimeoutException;
-import com.yahoo.fs4.PingPacket;
-import com.yahoo.fs4.PongPacket;
-import com.yahoo.fs4.mplex.Backend;
-import com.yahoo.fs4.mplex.FS4Channel;
-import com.yahoo.fs4.mplex.InvalidChannelException;
 import com.yahoo.prelude.Ping;
 import com.yahoo.prelude.Pong;
 import com.yahoo.prelude.querytransform.QueryRewrite;
-import com.yahoo.processing.request.CompoundName;
 import com.yahoo.search.Query;
 import com.yahoo.search.Result;
 import com.yahoo.search.dispatch.Dispatcher;
 import com.yahoo.search.dispatch.FillInvoker;
 import com.yahoo.search.dispatch.SearchInvoker;
-import com.yahoo.search.dispatch.searchcluster.Node;
 import com.yahoo.search.grouping.GroupingRequest;
 import com.yahoo.search.grouping.request.GroupingOperation;
 import com.yahoo.search.query.Ranking;
@@ -46,21 +37,13 @@ import static com.yahoo.container.util.Util.quote;
 // catch and unwrap into a results with an error in high level methods.  -Jon
 public class FastSearcher extends VespaBackEndSearcher {
 
-    /** If this is turned on this will make search queries directly to the local search node when possible */
-    private final static CompoundName dispatchDirect = new CompoundName("dispatch.direct");
-
     /** Used to dispatch directly to search nodes over RPC, replacing the old fnet communication path */
     private final Dispatcher dispatcher;
 
-    private final Backend dispatchBackend;
-    private final FS4ResourcePool fs4ResourcePool;
-
     /**
      * Creates a Fastsearcher.
      *
-     * @param dispatchBackend       The backend object containing the connection to the dispatch node this should talk to
-     *                      over the fs4 protocol
-     * @param fs4ResourcePool the resource pool used to create direct connections to the local search nodes when
+     * @param serverId the resource pool used to create direct connections to the local search nodes when
      *                        bypassing the dispatch node
      * @param dispatcher the dispatcher used (when enabled) to send summary requests over the rpc protocol.
      *                   Eventually we will move everything to this protocol and never use dispatch nodes.
@@ -70,13 +53,11 @@ public class FastSearcher extends VespaBackEndSearcher {
      * @param clusterParams the cluster number, and other cluster backend parameters
      * @param documentdbInfoConfig document database parameters
      */
-    public FastSearcher(Backend dispatchBackend, FS4ResourcePool fs4ResourcePool, Dispatcher dispatcher,
+    public FastSearcher(String serverId, Dispatcher dispatcher,
                         SummaryParameters docSumParams, ClusterParams clusterParams,
                         DocumentdbInfoConfig documentdbInfoConfig) {
-        init(fs4ResourcePool.getServerId(), docSumParams, clusterParams, documentdbInfoConfig);
-        this.dispatchBackend = dispatchBackend;
+        init(serverId, docSumParams, clusterParams, documentdbInfoConfig);
         this.dispatcher = dispatcher;
-        this.fs4ResourcePool = fs4ResourcePool;
     }
 
     /**
@@ -84,58 +65,7 @@ public class FastSearcher extends VespaBackEndSearcher {
      */
     @Override
     public Pong ping(Ping ping, Execution execution) {
-        return ping(ping, dispatchBackend, getName());
-    }
-
-    public static Pong ping(Ping ping, Backend backend, String name) {
-        FS4Channel channel = backend.openPingChannel();
-
-        // If you want to change this code, you need to understand
-        // com.yahoo.prelude.cluster.ClusterSearcher.ping(Searcher) and
-        // com.yahoo.prelude.cluster.TrafficNodeMonitor.failed(ErrorMessage)
-        try {
-            PingPacket pingPacket = new PingPacket();
-            try {
-                boolean couldSend = channel.sendPacket(pingPacket);
-                if ( ! couldSend) {
-                    return new Pong(ErrorMessage.createBackendCommunicationError("Could not ping " + name));
-                }
-            } catch (InvalidChannelException e) {
-                return new Pong(ErrorMessage.createBackendCommunicationError("Invalid channel " + name));
-            } catch (IllegalStateException e) {
-                return new Pong(ErrorMessage.createBackendCommunicationError("Illegal state in FS4: " + e.getMessage()));
-            } catch (IOException e) {
-                return new Pong(ErrorMessage.createBackendCommunicationError("IO error while sending ping: " + e.getMessage()));
-            }
-
-            // We should only get a single packet
-            BasicPacket[] packets;
-
-            try {
-                packets = channel.receivePackets(ping.getTimeout(), 1);
-            } catch (ChannelTimeoutException e) {
-                return new Pong(ErrorMessage.createNoAnswerWhenPingingNode("timeout while waiting for fdispatch for " + name));
-            } catch (InvalidChannelException e) {
-                return new Pong(ErrorMessage.createBackendCommunicationError("Invalid channel for " + name));
-            }
-
-            if (packets.length == 0) {
-                return new Pong(ErrorMessage.createBackendCommunicationError(name + " got no packets back"));
-            }
-
-            try {
-                packets[0].ensureInstanceOf(PongPacket.class, name);
-            } catch (TimeoutException e) {
-                return new Pong(ErrorMessage.createTimeout(e.getMessage()));
-            } catch (IOException e) {
-                return new Pong(ErrorMessage.createBackendCommunicationError("Unexpected packet class returned after ping: " + e.getMessage()));
-            }
-            return new Pong((PongPacket)packets[0]);
-        } finally {
-            if (channel != null) {
-                channel.close();
-            }
-        }
+        throw new IllegalStateException("This ping should not have been called.");
     }
 
     @Override
@@ -217,18 +147,7 @@ public class FastSearcher extends VespaBackEndSearcher {
      * on the same host.
      */
     private SearchInvoker getSearchInvoker(Query query) {
-        Optional<SearchInvoker> invoker = dispatcher.getSearchInvoker(query, this);
-        if (invoker.isPresent()) {
-            return invoker.get();
-        }
-
-        Optional<Node> direct = getDirectNode(query);
-        if(direct.isPresent()) {
-            var node = direct.get();
-            Backend backend = fs4ResourcePool.getBackend(node.hostname(), node.fs4port());
-            return new FS4SearchInvoker(this, query, backend.openChannel(), direct);
-        }
-        return new FS4SearchInvoker(this, query, dispatchBackend.openChannel(), Optional.empty());
+        return dispatcher.getSearchInvoker(query, this).get();
     }
 
     /**
@@ -237,47 +156,17 @@ public class FastSearcher extends VespaBackEndSearcher {
      * content nodes.
      */
     private FillInvoker getFillInvoker(Result result) {
-        Query query = result.getQuery();
-        Optional<FillInvoker> invoker = dispatcher.getFillInvoker(result, this);
-        if (invoker.isPresent()) {
-            return invoker.get();
-        }
-
-        Optional<Node> direct = getDirectNode(query);
-        if (direct.isPresent()) {
-            var node = direct.get();
-            Backend backend = fs4ResourcePool.getBackend(node.hostname(), node.fs4port());
-            return new FS4FillInvoker(this, query, backend);
-        }
-        return new FS4FillInvoker(this, query, dispatchBackend);
+        return dispatcher.getFillInvoker(result, this).get();
     }
 
-    /**
-     * If the query can be directed to a single local content node, returns that node. Otherwise,
-     * returns an empty value.
-     */
-    private Optional<Node> getDirectNode(Query query) {
-        if (!query.properties().getBoolean(dispatchDirect, true))
-            return Optional.empty();
-        if (query.properties().getBoolean(com.yahoo.search.query.Model.ESTIMATE))
-            return Optional.empty();
-
-        Optional<Node> directDispatchRecipient = dispatcher.searchCluster().directDispatchTarget();
-        if (!directDispatchRecipient.isPresent())
-            return Optional.empty();
 
-        // Dispatch directly to the single, local search node
-        Node local = directDispatchRecipient.get();
-        query.trace(false, 2, "Dispatching directly to ", local);
-        return Optional.of(local);
-    }
 
     private static Optional<String> quotedSummaryClass(String summaryClass) {
         return Optional.of(summaryClass == null ? "[null]" : quote(summaryClass));
     }
 
     public String toString() {
-        return "fast searcher (" + getName() + ") " + dispatchBackend;
+        return "fast searcher (" + getName() + ") ";
     }
 
     protected boolean isLoggingFine() {
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/GroupingListHit.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/GroupingListHit.java
index e0d569c6ae1..740b9592efc 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/GroupingListHit.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/GroupingListHit.java
@@ -3,7 +3,6 @@ package com.yahoo.prelude.fastsearch;
 
 import java.util.List;
 
-import com.yahoo.fs4.QueryPacketData;
 import com.yahoo.search.result.Hit;
 import com.yahoo.searchlib.aggregation.Grouping;
 
@@ -27,15 +26,4 @@ public class GroupingListHit extends Hit {
 
     private final List<Grouping> groupingList;
     private final DocsumDefinitionSet defs;
-    private QueryPacketData queryPacketData;
-
-    public void setQueryPacketData(QueryPacketData queryPacketData) {
-        this.queryPacketData = queryPacketData;
-    }
-
-    /** Returns encoded query data from the query used to create this, or null if none present */
-    public QueryPacketData getQueryPacketData() {
-        return queryPacketData;
-    }
-
 }
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/Int64Field.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/Int64Field.java
index f690d9d4da4..396a84a28bd 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/Int64Field.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/Int64Field.java
@@ -5,9 +5,6 @@
  */
 package com.yahoo.prelude.fastsearch;
 
-
-import java.nio.ByteBuffer;
-
 import com.yahoo.search.result.NanNumber;
 import com.yahoo.data.access.Inspector;
 
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/IntegerField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/IntegerField.java
index a02d9813793..bec39393359 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/IntegerField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/IntegerField.java
@@ -5,9 +5,6 @@
  */
 package com.yahoo.prelude.fastsearch;
 
-
-import java.nio.ByteBuffer;
-
 import com.yahoo.search.result.NanNumber;
 import com.yahoo.data.access.Inspector;
 
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/LongdataField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/LongdataField.java
index bf77c517d50..388c96b453d 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/LongdataField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/LongdataField.java
@@ -5,9 +5,6 @@
  */
 package com.yahoo.prelude.fastsearch;
 
-import java.nio.ByteBuffer;
-
-import com.yahoo.io.SlowInflate;
 import com.yahoo.prelude.hitfield.RawData;
 import com.yahoo.data.access.simple.Value;
 import com.yahoo.data.access.Inspector;
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/ShortField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/ShortField.java
index 5e3d0babe98..b94c902693a 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/ShortField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/ShortField.java
@@ -5,9 +5,6 @@
  */
 package com.yahoo.prelude.fastsearch;
 
-
-import java.nio.ByteBuffer;
-
 import com.yahoo.search.result.NanNumber;
 import com.yahoo.data.access.Inspector;
 
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/StringField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/StringField.java
index 408cbbbb62d..4df12bd82bd 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/StringField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/StringField.java
@@ -5,10 +5,6 @@
  */
 package com.yahoo.prelude.fastsearch;
 
-
-import java.nio.ByteBuffer;
-
-import com.yahoo.text.Utf8;
 import com.yahoo.data.access.Inspector;
 
 
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/VespaBackEndSearcher.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/VespaBackEndSearcher.java
index 430ad015493..c98cf23ec61 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/VespaBackEndSearcher.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/VespaBackEndSearcher.java
@@ -3,7 +3,6 @@ package com.yahoo.prelude.fastsearch;
 
 import com.yahoo.collections.TinyIdentitySet;
 import com.yahoo.fs4.DocsumPacket;
-import com.yahoo.fs4.Packet;
 import com.yahoo.prelude.query.Item;
 import com.yahoo.prelude.query.NullItem;
 import com.yahoo.prelude.query.textualrepresentation.TextualQueryRepresentation;
@@ -20,7 +19,6 @@ import com.yahoo.search.result.Hit;
 import com.yahoo.search.searchchain.Execution;
 import com.yahoo.searchlib.aggregation.Grouping;
 
-import java.io.IOException;
 import java.lang.reflect.Constructor;
 import java.util.ArrayList;
 import java.util.Iterator;
@@ -51,7 +49,7 @@ public abstract class VespaBackEndSearcher extends PingableSearcher {
     private String defaultDocsumClass = null;
 
     /** Returns an iterator which returns all hits below this result **/
-    static Iterator<Hit> hitIterator(Result result) {
+    private static Iterator<Hit> hitIterator(Result result) {
         return result.hits().unorderedDeepIterator();
     }
 
@@ -230,7 +228,7 @@ public abstract class VespaBackEndSearcher extends PingableSearcher {
         if ((query.getTraceLevel()<level) || query.properties().getBoolean(TRACE_DISABLE)) return;
 
         StringBuilder s = new StringBuilder();
-        s.append(sourceName).append(" " + type + " to dispatch: ")
+        s.append(sourceName).append(" ").append(type).append(" to dispatch: ")
                 .append("query=[")
                 .append(query.getModel().getQueryTree().getRoot().toString())
                 .append("]");
@@ -320,7 +318,7 @@ public abstract class VespaBackEndSearcher extends PingableSearcher {
         }
     }
 
-    FillHitResult fillHit(FastHit hit, DocsumPacket packet, String summaryClass) {
+    private FillHitResult fillHit(FastHit hit, DocsumPacket packet, String summaryClass) {
         if (packet != null) {
             byte[] docsumdata = packet.getData();
             if (docsumdata.length > 0) {
@@ -344,7 +342,7 @@ public abstract class VespaBackEndSearcher extends PingableSearcher {
      * @return the number of hits that we did not return data for, and an optional error message.
      *         when things are working normally we return 0.
      */
-     public FillHitsResult fillHits(Result result, Packet[] packets, String summaryClass) throws IOException {
+     protected FillHitsResult fillHits(Result result, DocsumPacket[] packets, String summaryClass) {
         int skippedHits = 0;
         String lastError = null;
         int packetIndex = 0;
@@ -354,8 +352,7 @@ public abstract class VespaBackEndSearcher extends PingableSearcher {
             if (hit instanceof FastHit && ! hit.isFilled(summaryClass)) {
                 FastHit fastHit = (FastHit) hit;
 
-                packets[packetIndex].ensureInstanceOf(DocsumPacket.class, getName());
-                DocsumPacket docsum = (DocsumPacket) packets[packetIndex];
+                DocsumPacket docsum = packets[packetIndex];
 
                 packetIndex++;
                 FillHitResult fr = fillHit(fastHit, docsum, summaryClass);
@@ -384,7 +381,7 @@ public abstract class VespaBackEndSearcher extends PingableSearcher {
         return decodeSummary(summaryClass, hit, docsumdata, db.getDocsumDefinitionSet());
     }
 
-    private String decodeSummary(String summaryClass, FastHit hit, byte[] docsumdata, DocsumDefinitionSet docsumSet) {
+    private static String decodeSummary(String summaryClass, FastHit hit, byte[] docsumdata, DocsumDefinitionSet docsumSet) {
         String error = docsumSet.lazyDecode(summaryClass, docsumdata, hit);
         if (error == null) {
             hit.setFilled(summaryClass);
diff --git a/container-search/src/main/java/com/yahoo/prelude/fastsearch/XMLField.java b/container-search/src/main/java/com/yahoo/prelude/fastsearch/XMLField.java
index d768dda2657..00bdc474119 100644
--- a/container-search/src/main/java/com/yahoo/prelude/fastsearch/XMLField.java
+++ b/container-search/src/main/java/com/yahoo/prelude/fastsearch/XMLField.java
@@ -1,8 +1,5 @@
 // Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
-/**
- * Class converting data (historically XML-encoded) from a document summary field.
- * This has only been used to represent geographical positions.
- */
+
 package com.yahoo.prelude.fastsearch;
 
 import com.yahoo.data.access.Inspector;
@@ -11,6 +8,8 @@ import com.yahoo.prelude.hitfield.XMLString;
 import com.yahoo.search.result.PositionsData;
 
 /**
+ * Class converting data (historically XML-encoded) from a document summary field.
+ * This has only been used to represent geographical positions.
  * @author Steinar Knutsen
  */
 public class XMLField extends DocsumField {