config-model/src/main/java/com/yahoo/vespa/model/container/search/searchchain/SourceGroup.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.vespa.model.container.search.searchchain;

import com.yahoo.component.ComponentId;

import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Set;

/**
 * A set of sources with the same name,
 * each associated with a different provider,
 * that fills the same role.
 * @author tonytv
 */
final class SourceGroup {
    private final ComponentId id;
    private Source leader;
    private final Set<Source> participants =
            new LinkedHashSet<>();

    private void setLeader(Source leader) {
        assert (validMember(leader));

        if (this.leader != null) {
            throw new IllegalStateException(
                    "There can not be two default providers for the source "
                            + id);
        }

        this.leader = leader;
    }

    private void addParticipant(Source source) {
        assert (validMember(source));
        assert (!source.equals(leader));

        if (!participants.add(source)) {
            throw new RuntimeException("Source added twice to the same group "
                    + source);
        }
    }

    private boolean validMember(Source leader) {
        return leader.getComponentId().equals(id);
    }

    public ComponentId getComponentId() {
        return id;
    }

    public SourceGroup(ComponentId id) {
        this.id = id;
    }

    public void add(Source source) {
        assert source.getComponentId().equals(getComponentId()):
                "Ids differ: " + source.getComponentId() + " -- " + getComponentId();

        if (Source.GroupOption.leader == source.groupOption) {
            setLeader(source);
        } else {
            addParticipant(source);
        }
    }

    public String toString() {
        StringBuilder builder = new StringBuilder();
        builder.append("Source id: ").append(id).append("\n").
                append("Leader provider: ").append(
                leader.getParentProvider().getComponentId()).append("\n").
                append("Participants:");

        for (Source participant : participants) {
            builder.append("\n").append("    Provider: ").append(
                    participant.getParentProvider().getComponentId());
        }
        return builder.toString();
    }

    public Source leader() {
        return leader;
    }

    public Collection<Source> participants() {
        return Collections.unmodifiableCollection(participants);
    }

    public void validate() {
        if (leader == null)
            throw new IllegalStateException("Missing leader for the source " + getComponentId() +
                    ". One of the sources must use the attribute id instead of idref.");
    }
}