org.springframework.util.backoff

Class ExponentialBackOff

java.lang.Object

org.springframework.util.backoff.ExponentialBackOff

All Implemented Interfaces:

BackOff

public class ExponentialBackOff
extends Object
implements BackOff

Implementation of BackOff that increases the back off period for each retry attempt. When the interval has reached the max interval, it is no longer increased. Stops retrying once the max elapsed time has been reached.

Example: The default interval is 2000L ms; the default multiplier is 1.5; and the default max interval is 30000L. For 10 attempts the sequence will be as follows:

 request#     back off

  1              2000
  2              3000
  3              4500
  4              6750
  5             10125
  6             15187
  7             22780
  8             30000
  9             30000
 10             30000
 

Note that the default max elapsed time is Long.MAX_VALUE. Use setMaxElapsedTime(long) to limit the maximum length of time that an instance should accumulate before returning BackOffExecution.STOP.

Since:

4.1

Author:

Stephane Nicoll

Field Summary

Fields

Modifier and Type	Field and Description
static long	DEFAULT_INITIAL_INTERVAL The default initial interval.
static long	DEFAULT_MAX_ELAPSED_TIME The default maximum elapsed time.
static long	DEFAULT_MAX_INTERVAL The default maximum back off time.
static double	DEFAULT_MULTIPLIER The default multiplier (increases the interval by 50%).

Constructor Summary

Constructors

Constructor and Description
ExponentialBackOff() Create an instance with the default settings.
ExponentialBackOff(long initialInterval, double multiplier) Create an instance with the supplied settings.

Method Summary

Modifier and Type	Method and Description
long	getInitialInterval() Return the initial interval in milliseconds.
long	getMaxElapsedTime() Return the maximum elapsed time in milliseconds after which a call to BackOffExecution.nextBackOff() returns BackOffExecution.STOP.
long	getMaxInterval() Return the maximum back off time in milliseconds.
double	getMultiplier() Return the value to multiply the current interval by for each retry attempt.
void	setInitialInterval(long initialInterval) Set the initial interval in milliseconds.
void	setMaxElapsedTime(long maxElapsedTime) Set the maximum elapsed time in milliseconds after which a call to BackOffExecution.nextBackOff() returns BackOffExecution.STOP.
void	setMaxInterval(long maxInterval) Set the maximum back off time in milliseconds.
void	setMultiplier(double multiplier) Set the value to multiply the current interval by for each retry attempt.
BackOffExecution	start() Start a new back off execution.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_INITIAL_INTERVAL

public static final long DEFAULT_INITIAL_INTERVAL

The default initial interval.

See Also:

Constant Field Values

DEFAULT_MULTIPLIER

public static final double DEFAULT_MULTIPLIER

The default multiplier (increases the interval by 50%).

See Also:

Constant Field Values

DEFAULT_MAX_INTERVAL

public static final long DEFAULT_MAX_INTERVAL

The default maximum back off time.

See Also:

Constant Field Values

DEFAULT_MAX_ELAPSED_TIME

public static final long DEFAULT_MAX_ELAPSED_TIME

The default maximum elapsed time.

See Also:

Constant Field Values

Constructor Detail

ExponentialBackOff

public ExponentialBackOff()

Create an instance with the default settings.

See Also:

DEFAULT_INITIAL_INTERVAL, DEFAULT_MULTIPLIER, DEFAULT_MAX_INTERVAL, DEFAULT_MAX_ELAPSED_TIME

ExponentialBackOff

public ExponentialBackOff(long initialInterval,
                          double multiplier)

Create an instance with the supplied settings.

Parameters:

initialInterval - the initial interval in milliseconds

multiplier - the multiplier (should be greater than or equal to 1)

Method Detail

setInitialInterval

public void setInitialInterval(long initialInterval)

Set the initial interval in milliseconds.

getInitialInterval

public long getInitialInterval()

Return the initial interval in milliseconds.

setMultiplier

public void setMultiplier(double multiplier)

Set the value to multiply the current interval by for each retry attempt.

getMultiplier

public double getMultiplier()

Return the value to multiply the current interval by for each retry attempt.

setMaxInterval

public void setMaxInterval(long maxInterval)

Set the maximum back off time in milliseconds.

getMaxInterval

public long getMaxInterval()

Return the maximum back off time in milliseconds.

setMaxElapsedTime

public void setMaxElapsedTime(long maxElapsedTime)

Set the maximum elapsed time in milliseconds after which a call to BackOffExecution.nextBackOff() returns BackOffExecution.STOP.

getMaxElapsedTime

public long getMaxElapsedTime()

Return the maximum elapsed time in milliseconds after which a call to BackOffExecution.nextBackOff() returns BackOffExecution.STOP.

start

public BackOffExecution start()

Description copied from interface: BackOff

Start a new back off execution.

Specified by:

start in interface BackOff

Returns:

a fresh BackOffExecution ready to be used