elasticSearch6源码分析(5)gateway模块

1.gateway概述

The local gateway module stores the cluster state and shard data across full cluster restarts.

2.gatewaymodule模块

    @Override
    protected void configure() {
        bind(DanglingIndicesState.class).asEagerSingleton();
        bind(GatewayService.class).asEagerSingleton();
        bind(TransportNodesListGatewayMetaState.class).asEagerSingleton();
        bind(TransportNodesListGatewayStartedShards.class).asEagerSingleton();
        bind(LocalAllocateDangledIndices.class).asEagerSingleton();
    }

2.1 DanglingIndicesState

/**
 * The dangling indices state is responsible for finding new dangling indices (indices that have
 * their state written on disk, but don't exists in the metadata of the cluster), and importing
 * them into the cluster.
 */

2.2 GatewayService 

 配置信息

    public static final Setting<Integer> EXPECTED_NODES_SETTING =
        Setting.intSetting("gateway.expected_nodes", -1, -1, Property.NodeScope);
    public static final Setting<Integer> EXPECTED_DATA_NODES_SETTING =
        Setting.intSetting("gateway.expected_data_nodes", -1, -1, Property.NodeScope);
    public static final Setting<Integer> EXPECTED_MASTER_NODES_SETTING =
        Setting.intSetting("gateway.expected_master_nodes", -1, -1, Property.NodeScope);
    public static final Setting<TimeValue> RECOVER_AFTER_TIME_SETTING =
        Setting.positiveTimeSetting("gateway.recover_after_time", TimeValue.timeValueMillis(0), Property.NodeScope);
    public static final Setting<Integer> RECOVER_AFTER_NODES_SETTING =
        Setting.intSetting("gateway.recover_after_nodes", -1, -1, Property.NodeScope);
    public static final Setting<Integer> RECOVER_AFTER_DATA_NODES_SETTING =
        Setting.intSetting("gateway.recover_after_data_nodes", -1, -1, Property.NodeScope);
    public static final Setting<Integer> RECOVER_AFTER_MASTER_NODES_SETTING =
        Setting.intSetting("gateway.recover_after_master_nodes", 0, 0, Property.NodeScope);

2.3 TransportNodesListGatewayStartedShards

/**
 * This transport action is used to fetch the shard version from each node during primary allocation in {@link GatewayAllocator}.
 * We use this to find out which node holds the latest shard version and which of them used to be a primary in order to allocate
 * shards after node or cluster restarts.
 */