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// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.search.dispatch;
import com.yahoo.component.AbstractComponent;
import com.yahoo.container.handler.VipStatus;
import com.yahoo.prelude.fastsearch.DocumentDatabase;
import com.yahoo.prelude.fastsearch.FS4InvokerFactory;
import com.yahoo.prelude.fastsearch.FS4ResourcePool;
import com.yahoo.prelude.fastsearch.VespaBackEndSearcher;
import com.yahoo.processing.request.CompoundName;
import com.yahoo.search.Query;
import com.yahoo.search.Result;
import com.yahoo.search.dispatch.SearchPath.InvalidSearchPathException;
import com.yahoo.search.dispatch.searchcluster.Group;
import com.yahoo.search.dispatch.searchcluster.Node;
import com.yahoo.search.dispatch.searchcluster.SearchCluster;
import com.yahoo.vespa.config.search.DispatchConfig;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
/**
* A dispatcher communicates with search nodes to perform queries and fill hits.
*
* This class allocates {@link SearchInvoker} and {@link FillInvoker} objects based
* on query properties and general system status. The caller can then use the provided
* invocation object to execute the search or fill.
*
* This class is multithread safe.
*
* @author bratseth
* @author ollvir
*/
public class Dispatcher extends AbstractComponent {
private static final int MAX_GROUP_SELECTION_ATTEMPTS = 3;
/** If enabled, this internal dispatcher will be preferred over fdispatch whenever possible */
private static final CompoundName dispatchInternal = new CompoundName("dispatch.internal");
/** A model of the search cluster this dispatches to */
private final SearchCluster searchCluster;
private final LoadBalancer loadBalancer;
private final RpcResourcePool rpcResourcePool;
public Dispatcher(DispatchConfig dispatchConfig, FS4ResourcePool fs4ResourcePool, int containerClusterSize, VipStatus vipStatus) {
this.searchCluster = new SearchCluster(dispatchConfig, fs4ResourcePool, containerClusterSize, vipStatus);
this.loadBalancer = new LoadBalancer(searchCluster,
dispatchConfig.distributionPolicy() == DispatchConfig.DistributionPolicy.ROUNDROBIN);
this.rpcResourcePool = new RpcResourcePool(dispatchConfig);
}
/** For testing */
public Dispatcher(Map<Integer, Client.NodeConnection> nodeConnections, Client client) {
this.searchCluster = null;
this.loadBalancer = new LoadBalancer(searchCluster, true);
this.rpcResourcePool = new RpcResourcePool(client, nodeConnections);
}
/** Returns the search cluster this dispatches to */
public SearchCluster searchCluster() {
return searchCluster;
}
@Override
public void deconstruct() {
rpcResourcePool.release();
}
public Optional<FillInvoker> getFillInvoker(Result result, VespaBackEndSearcher searcher, DocumentDatabase documentDb,
FS4InvokerFactory fs4InvokerFactory) {
Optional<FillInvoker> rpcInvoker = rpcResourcePool.getFillInvoker(result.getQuery(), searcher, documentDb);
if (rpcInvoker.isPresent()) {
return rpcInvoker;
}
if (result.getQuery().properties().getBoolean(dispatchInternal, false)) {
Optional<FillInvoker> fs4Invoker = fs4InvokerFactory.getFillInvoker(result);
if (fs4Invoker.isPresent()) {
return fs4Invoker;
}
}
return Optional.empty();
}
public Optional<SearchInvoker> getSearchInvoker(Query query, FS4InvokerFactory fs4InvokerFactory) {
if (query.properties().getBoolean(dispatchInternal, false)) {
Optional<SearchInvoker> invoker = getSearchPathInvoker(query, fs4InvokerFactory::getSearchInvoker);
if(! invoker.isPresent()) {
invoker = getInternalInvoker(query, fs4InvokerFactory::getSearchInvoker);
}
if(invoker.isPresent() && query.properties().getBoolean(com.yahoo.search.query.Model.ESTIMATE)) {
query.setHits(0);
query.setOffset(0);
}
return invoker;
}
return Optional.empty();
}
@FunctionalInterface
private interface SearchInvokerSupplier {
Optional<SearchInvoker> supply(Query query, int groupId, List<Node> nodes, boolean acceptIncompleteCoverage);
}
// build invoker based on searchpath
private Optional<SearchInvoker> getSearchPathInvoker(Query query, SearchInvokerSupplier invokerFactory) {
String searchPath = query.getModel().getSearchPath();
if(searchPath == null) {
return Optional.empty();
}
try {
List<Node> nodes = SearchPath.selectNodes(searchPath, searchCluster);
if (nodes.isEmpty()) {
return Optional.empty();
} else {
return invokerFactory.supply(query, -1, nodes, true);
}
} catch (InvalidSearchPathException e) {
return Optional.of(new SearchErrorInvoker(e.getMessage()));
}
}
private Optional<SearchInvoker> getInternalInvoker(Query query, SearchInvokerSupplier invokerFactory) {
Optional<Node> directNode = searchCluster.directDispatchTarget();
if (directNode.isPresent()) {
Node node = directNode.get();
query.trace(false, 2, "Dispatching directly to ", node);
return invokerFactory.supply(query, -1, Arrays.asList(node), true);
}
int max = Integer.min(searchCluster.orderedGroups().size(), MAX_GROUP_SELECTION_ATTEMPTS);
Set<Integer> rejected = null;
for (int i = 0; i < max; i++) {
Optional<Group> groupInCluster = loadBalancer.takeGroupForQuery(query, rejected);
if (!groupInCluster.isPresent()) {
// No groups available
break;
}
Group group = groupInCluster.get();
boolean acceptIncompleteCoverage = (i == max - 1);
Optional<SearchInvoker> invoker = invokerFactory.supply(query, group.id(), group.nodes(), acceptIncompleteCoverage);
if (invoker.isPresent()) {
query.trace(false, 2, "Dispatching internally to ", group);
invoker.get().teardown(() -> loadBalancer.releaseGroup(group));
return invoker;
} else {
loadBalancer.releaseGroup(group);
if (rejected == null) {
rejected = new HashSet<>();
}
rejected.add(group.id());
}
}
return Optional.empty();
}
}
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