org.apache.hadoop.hbase.client

Class RpcRetryingCallerWithReadReplicas

java.lang.Object

org.apache.hadoop.hbase.client.RpcRetryingCallerWithReadReplicas

@InterfaceAudience.Private
public class RpcRetryingCallerWithReadReplicas
extends Object

Caller that goes to replica if the primary region does no answer within a configurable timeout. If the timeout is reached, it calls all the secondary replicas, and returns the first answer. If the answer comes from one of the secondary replica, it will be marked as stale.

Field Summary

Fields

Modifier and Type	Field and Description
protected ClusterConnection	cConnection
protected org.apache.hadoop.conf.Configuration	conf
protected Get	get
protected ExecutorService	pool
protected org.apache.hadoop.hbase.TableName	tableName
protected int	timeBeforeReplicas

Constructor Summary

Constructors

Constructor and Description
RpcRetryingCallerWithReadReplicas(RpcControllerFactory rpcControllerFactory, org.apache.hadoop.hbase.TableName tableName, ClusterConnection cConnection, Get get, ExecutorService pool, int retries, int callTimeout, int timeBeforeReplicas)

Method Summary

Modifier and Type	Method and Description
Result	call() Algo: - we put the query into the execution pool.

Methods inherited from class java.lang.Object

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

Field Detail

pool

protected final ExecutorService pool

cConnection

protected final ClusterConnection cConnection

conf

protected final org.apache.hadoop.conf.Configuration conf

get

protected final Get get

tableName

protected final org.apache.hadoop.hbase.TableName tableName

timeBeforeReplicas

protected final int timeBeforeReplicas

Constructor Detail

RpcRetryingCallerWithReadReplicas

public RpcRetryingCallerWithReadReplicas(RpcControllerFactory rpcControllerFactory,
                                         org.apache.hadoop.hbase.TableName tableName,
                                         ClusterConnection cConnection,
                                         Get get,
                                         ExecutorService pool,
                                         int retries,
                                         int callTimeout,
                                         int timeBeforeReplicas)

Method Detail

call

public Result call()
            throws DoNotRetryIOException,
                   InterruptedIOException,
                   RetriesExhaustedException

Algo: - we put the query into the execution pool. - after x ms, if we don't have a result, we add the queries for the secondary replicas - we take the first answer - when done, we cancel what's left. Cancelling means: - removing from the pool if the actual call was not started - interrupting the call if it has started Client side, we need to take into account - a call is not executed immediately after being put into the pool - a call is a thread. Let's not multiply the number of thread by the number of replicas. Server side, if we can cancel when it's still in the handler pool, it's much better, as a call can take some i/o.

Globally, the number of retries, timeout and so on still applies, but it's per replica, not global. We continue until all retries are done, or all timeouts are exceeded.

Throws:

DoNotRetryIOException

InterruptedIOException

RetriesExhaustedException