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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.jdisc.Metric;
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.rpc.RpcInvokerFactory;
import com.yahoo.search.dispatch.rpc.RpcResourcePool;
import com.yahoo.search.dispatch.searchcluster.Group;
import com.yahoo.search.dispatch.searchcluster.Node;
import com.yahoo.search.dispatch.searchcluster.PingFactory;
import com.yahoo.search.dispatch.searchcluster.SearchCluster;
import com.yahoo.search.query.profile.types.FieldDescription;
import com.yahoo.search.query.profile.types.FieldType;
import com.yahoo.search.query.profile.types.QueryProfileType;
import com.yahoo.search.result.ErrorMessage;
import com.yahoo.vespa.config.search.DispatchConfig;
import java.util.Arrays;
import java.util.HashSet;
import java.util.List;
import java.util.Optional;
import java.util.OptionalInt;
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 {
public static final String DISPATCH = "dispatch";
private static final String INTERNAL = "internal";
private static final String PROTOBUF = "protobuf";
private static final String FDISPATCH_METRIC = "dispatch_fdispatch";
private static final String INTERNAL_METRIC = "dispatch_internal";
private static final int MAX_GROUP_SELECTION_ATTEMPTS = 3;
/** If enabled, search queries will use protobuf rpc */
public static final CompoundName dispatchProtobuf = CompoundName.fromComponents(DISPATCH, PROTOBUF);
/** A model of the search cluster this dispatches to */
private final SearchCluster searchCluster;
private final LoadBalancer loadBalancer;
private final boolean multilevelDispatch;
private final InvokerFactory invokerFactory;
private final Metric metric;
private final Metric.Context metricContext;
private static final QueryProfileType argumentType;
static {
argumentType = new QueryProfileType(DISPATCH);
argumentType.setStrict(true);
argumentType.setBuiltin(true);
argumentType.addField(new FieldDescription(INTERNAL, FieldType.booleanType));
argumentType.addField(new FieldDescription(PROTOBUF, FieldType.booleanType));
argumentType.freeze();
}
public static QueryProfileType getArgumentType() { return argumentType; }
public static Dispatcher create(String clusterId,
DispatchConfig dispatchConfig,
int containerClusterSize,
VipStatus vipStatus,
Metric metric) {
var searchCluster = new SearchCluster(clusterId, dispatchConfig, containerClusterSize, vipStatus);
var rpcFactory = new RpcInvokerFactory(new RpcResourcePool(dispatchConfig), searchCluster);
return new Dispatcher(searchCluster, dispatchConfig, rpcFactory, rpcFactory, metric);
}
public Dispatcher(SearchCluster searchCluster,
DispatchConfig dispatchConfig,
InvokerFactory invokerFactory,
PingFactory pingFactory,
Metric metric) {
this.searchCluster = searchCluster;
this.loadBalancer = new LoadBalancer(searchCluster,
dispatchConfig.distributionPolicy() == DispatchConfig.DistributionPolicy.ROUNDROBIN);
this.invokerFactory = invokerFactory;
this.multilevelDispatch = dispatchConfig.useMultilevelDispatch();
this.metric = metric;
this.metricContext = metric.createContext(null);
searchCluster.startClusterMonitoring(pingFactory);
}
/** Returns the search cluster this dispatches to */
public SearchCluster searchCluster() {
return searchCluster;
}
@Override
public void deconstruct() {
invokerFactory.release();
}
public Optional<FillInvoker> getFillInvoker(Result result, VespaBackEndSearcher searcher) {
return invokerFactory.createFillInvoker(searcher, result);
}
public Optional<SearchInvoker> getSearchInvoker(Query query, VespaBackEndSearcher searcher) {
if (multilevelDispatch) {
emitDispatchMetric(Optional.empty());
return Optional.empty();
}
Optional<SearchInvoker> invoker = getSearchPathInvoker(query, searcher);
if (invoker.isEmpty()) {
invoker = getInternalInvoker(query, searcher);
}
if (invoker.isPresent() && query.properties().getBoolean(com.yahoo.search.query.Model.ESTIMATE)) {
query.setHits(0);
query.setOffset(0);
}
emitDispatchMetric(invoker);
return invoker;
}
/** Builds an invoker based on searchpath */
private Optional<SearchInvoker> getSearchPathInvoker(Query query, VespaBackEndSearcher searcher) {
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();
query.trace(false, 2, "Dispatching internally with search path ", searchPath);
return invokerFactory.createSearchInvoker(searcher, query, OptionalInt.empty(), nodes, true);
} catch (InvalidSearchPathException e) {
return Optional.of(new SearchErrorInvoker(ErrorMessage.createIllegalQuery(e.getMessage())));
}
}
private Optional<SearchInvoker> getInternalInvoker(Query query, VespaBackEndSearcher searcher) {
Optional<Node> directNode = searchCluster.localCorpusDispatchTarget();
if (directNode.isPresent()) {
Node node = directNode.get();
query.trace(false, 2, "Dispatching directly to ", node);
return invokerFactory.createSearchInvoker(searcher, query, OptionalInt.empty(), Arrays.asList(node), true);
}
int covered = searchCluster.groupsWithSufficientCoverage();
int groups = searchCluster.orderedGroups().size();
int max = Integer.min(Integer.min(covered + 1, groups), MAX_GROUP_SELECTION_ATTEMPTS);
Set<Integer> rejected = null;
for (int i = 0; i < max; i++) {
Optional<Group> groupInCluster = loadBalancer.takeGroup(rejected);
if (groupInCluster.isEmpty()) break; // No groups available
Group group = groupInCluster.get();
boolean acceptIncompleteCoverage = (i == max - 1);
Optional<SearchInvoker> invoker = invokerFactory.createSearchInvoker(searcher,
query,
OptionalInt.of(group.id()),
group.nodes(),
acceptIncompleteCoverage);
if (invoker.isPresent()) {
query.trace(false, 2, "Dispatching internally to search group ", group.id());
query.getModel().setSearchPath("/" + group.id());
invoker.get().teardown((success, time) -> loadBalancer.releaseGroup(group, success, time));
return invoker;
} else {
loadBalancer.releaseGroup(group, false, 0);
if (rejected == null) {
rejected = new HashSet<>();
}
rejected.add(group.id());
}
}
return Optional.empty();
}
private void emitDispatchMetric(Optional<SearchInvoker> invoker) {
if (invoker.isEmpty()) {
metric.add(FDISPATCH_METRIC, 1, metricContext);
} else {
metric.add(INTERNAL_METRIC, 1, metricContext);
}
}
}
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