org.elasticsearch.gateway

Class AsyncShardFetch<T extends BaseNodeResponse>

java.lang.Object

org.elasticsearch.gateway.AsyncShardFetch<T>

All Implemented Interfaces:

AutoCloseable, Releasable

public abstract class AsyncShardFetch<T extends BaseNodeResponse>
extends Object
implements Releasable

Allows to asynchronously fetch shard related data from other nodes for allocation, without blocking the cluster update thread.

The async fetch logic maintains a map of which nodes are being fetched from in an async manner, and once the results are back, it makes sure to schedule a reroute to make sure those results will be taken into account.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	AsyncShardFetch.FetchResult<T extends BaseNodeResponse> The result of a fetch operation.
static interface	AsyncShardFetch.List<NodesResponse extends BaseNodesResponse<NodeResponse>,NodeResponse extends BaseNodeResponse> An action that lists the relevant shard data that needs to be fetched.

Field Summary

Fields

Modifier and Type	Field and Description
protected ESLogger	logger
protected String	type

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AsyncShardFetch(ESLogger logger, String type, ShardId shardId, AsyncShardFetch.List<? extends BaseNodesResponse<T>,T> action)

Method Summary

Methods

Modifier and Type	Method and Description
void	close()
AsyncShardFetch.FetchResult<T>	fetchData(DiscoveryNodes nodes, MetaData metaData, Set<String> ignoreNodes) Fetches the data for the relevant shard.
int	getNumberOfInFlightFetches() Returns the number of async fetches that are currently ongoing.
protected void	processAsyncFetch(ShardId shardId, T[] responses, FailedNodeException[] failures) Called by the response handler of the async action to fetch data.
protected abstract void	reroute(ShardId shardId, String reason) Implement this in order to scheduled another round that causes a call to fetch data.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

logger

protected final ESLogger logger

type

protected final String type

Constructor Detail

AsyncShardFetch

protected AsyncShardFetch(ESLogger logger,
               String type,
               ShardId shardId,
               AsyncShardFetch.List<? extends BaseNodesResponse<T>,T> action)

Method Detail

close

public void close()

Specified by:

close in interface AutoCloseable

Specified by:

close in interface Releasable

getNumberOfInFlightFetches

public int getNumberOfInFlightFetches()

Returns the number of async fetches that are currently ongoing.

fetchData

public AsyncShardFetch.FetchResult<T> fetchData(DiscoveryNodes nodes,
                                       MetaData metaData,
                                       Set<String> ignoreNodes)

Fetches the data for the relevant shard. If there any ongoing async fetches going on, or new ones have been initiated by this call, the result will have no data.

The ignoreNodes are nodes that are supposed to be ignored for this round, since fetching is async, we need to keep them around and make sure we add them back when all the responses are fetched and returned.

processAsyncFetch

protected void processAsyncFetch(ShardId shardId,
                     T[] responses,
                     FailedNodeException[] failures)

Called by the response handler of the async action to fetch data. Verifies that its still working on the same cache generation, otherwise the results are discarded. It then goes and fills the relevant data for the shard (response + failures), issueing a reroute at the end of it to make sure there will be another round of allocations taking this new data into account.

reroute

protected abstract void reroute(ShardId shardId,
           String reason)

Implement this in order to scheduled another round that causes a call to fetch data.