Package org.apache.hadoop.tools.util

Class RetriableCommand

java.lang.Object

org.apache.hadoop.tools.util.RetriableCommand

Direct Known Subclasses:

RetriableDirectoryCreateCommand, RetriableFileCopyCommand

public abstract class RetriableCommand
extends java.lang.Object

This class represents commands that be retried on failure, in a configurable manner.

Field Summary

Fields

Modifier and Type	Field	Description
protected java.lang.String	description

Constructor Summary

Constructors

Constructor	Description
RetriableCommand(java.lang.String description)	Constructor.
RetriableCommand(java.lang.String description, org.apache.hadoop.io.retry.RetryPolicy retryPolicy)	Constructor.

Method Summary

Modifier and Type	Method	Description
protected abstract java.lang.Object	doExecute(java.lang.Object... arguments)	Implement this interface-method define the command-logic that will be retried on failure (i.e.
java.lang.Object	execute(java.lang.Object... arguments)	The execute() method invokes doExecute() until either: 1.
RetriableCommand	setRetryPolicy(org.apache.hadoop.io.retry.RetryPolicy retryHandler)	Fluent-interface to change the RetryHandler.

Methods inherited from class java.lang.Object

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

Field Detail

description

protected java.lang.String description

Constructor Detail

RetriableCommand

public RetriableCommand(java.lang.String description)

Constructor.

Parameters:

description - The human-readable description of the command.

RetriableCommand

public RetriableCommand(java.lang.String description,
                        org.apache.hadoop.io.retry.RetryPolicy retryPolicy)

Constructor.

Parameters:

description - The human-readable description of the command.

retryPolicy - The RetryHandler to be used to compute retries.

Method Detail

doExecute

protected abstract java.lang.Object doExecute(java.lang.Object... arguments)
                                       throws java.lang.Exception

Implement this interface-method define the command-logic that will be retried on failure (i.e. with Exception).

Parameters:

arguments - Argument-list to the command.

Returns:

Generic "Object".

Throws:

java.lang.Exception - Throws Exception on complete failure.

execute

public java.lang.Object execute(java.lang.Object... arguments)
                         throws java.lang.Exception

The execute() method invokes doExecute() until either: 1. doExecute() succeeds, or 2. the command may no longer be retried (e.g. runs out of retry-attempts).

Parameters:

arguments - The list of arguments for the command.

Returns:

Generic "Object" from doExecute(), on success.

Throws:

java.lang.Exception

setRetryPolicy

public RetriableCommand setRetryPolicy(org.apache.hadoop.io.retry.RetryPolicy retryHandler)

Fluent-interface to change the RetryHandler.

Parameters:

retryHandler - The new RetryHandler instance to be used.

Returns:

Self.