程序包 infra.retry.support

类 RetryTemplate

java.lang.Object

infra.retry.support.RetryTemplate

所有已实现的接口:

RetryOperations

public class RetryTemplate
extends Object
implements RetryOperations

Template class that simplifies the execution of operations with retry semantics.

Retryable operations are encapsulated in implementations of the RetryCallback interface and are executed using one of the supplied execute methods.

By default, an operation is retried if is throws any Exception or subclass of Exception. This behaviour can be changed by using the setRetryPolicy(RetryPolicy) method.

Also by default, each operation is retried for a maximum of three attempts with no back off in between. This behaviour can be configured using the setRetryPolicy(RetryPolicy) and setBackOffPolicy(BackOffPolicy) properties. The BackOffPolicy controls how long the pause is between each individual retry attempt.

A new instance can be fluently configured via builder(), e.g:

 
 RetryTemplate.builder()
                 .maxAttempts(10)
                 .fixedBackoff(1000)
                 .build();
 

See RetryTemplateBuilder for more examples and details.

This class is thread-safe and suitable for concurrent access when executing operations and when performing configuration changes. As such, it is possible to change the number of retries on the fly, as well as the BackOffPolicy used and no in progress retryable operations will be affected.

从以下版本开始:

4.0

作者:

Rob Harrop, Dave Syer, Gary Russell, Artem Bilan, Josh Long, Aleksandr Shamukov, Harry Yang

字段概要

字段

修饰符和类型	字段	说明
private BackOffPolicy	backOffPolicy
private static final String	GLOBAL_STATE	Retry context attribute name that indicates the context should be considered global state (never closed).
private RetryListener[]	listeners
protected final infra.logging.Logger	logger
private RetryContextCache	retryContextCache
private RetryPolicy	retryPolicy
private boolean	throwLastExceptionOnExhausted

构造器概要

构造器

构造器	说明
RetryTemplate()

方法概要

修饰符和类型	方法	说明
static RetryTemplateBuilder	builder()	Main entry point to configure RetryTemplate using fluent API.
protected boolean	canRetry(RetryPolicy retryPolicy, RetryContext context)	Decide whether to proceed with the ongoing retry attempt.
protected void	close(RetryPolicy retryPolicy, RetryContext context, RetryState state, boolean succeeded)	Clean up the cache if necessary and close the context provided (if the flag indicates that processing was successful).
static RetryTemplate	defaultInstance()	Creates a new default instance.
private <T, E extends Throwable> void	doCloseInterceptors(RetryCallback<T,E> callback, RetryContext context, Throwable lastException)
protected <T, E extends Throwable> T	doExecute(RetryCallback<T,E> retryCallback, RecoveryCallback<T> recoveryCallback, RetryState state)	Execute the callback once if the policy dictates that we can, otherwise execute the recovery callback.
private <T, E extends Throwable> void	doOnErrorInterceptors(RetryCallback<T,E> callback, RetryContext context, Throwable throwable)
private <T, E extends Throwable> void	doOnSuccessInterceptors(RetryCallback<T,E> callback, RetryContext context, T result)
private <T, E extends Throwable> boolean	doOpenInterceptors(RetryCallback<T,E> callback, RetryContext context)
private RetryContext	doOpenInternal(RetryPolicy retryPolicy)
private RetryContext	doOpenInternal(RetryPolicy retryPolicy, RetryState state)
final <T, E extends Throwable> T	execute(RetryCallback<T,E> retryCallback)	Keep executing the callback until it either succeeds or the policy dictates that we stop, in which case the most recent exception thrown by the callback will be rethrown.
final <T, E extends Throwable> T	execute(RetryCallback<T,E> retryCallback, RecoveryCallback<T> recoveryCallback)	Keep executing the callback until it either succeeds or the policy dictates that we stop, in which case the recovery callback will be executed.
final <T, E extends Throwable> T	execute(RetryCallback<T,E> retryCallback, RecoveryCallback<T> recoveryCallback, RetryState retryState)	Execute the callback once if the policy dictates that we can, re-throwing any exception encountered so that clients can re-present the same task later.
final <T, E extends Throwable> T	execute(RetryCallback<T,E> retryCallback, RetryState retryState)	Execute the callback once if the policy dictates that we can, re-throwing any exception encountered so that clients can re-present the same task later.
protected <T> T	handleRetryExhausted(RecoveryCallback<T> recovery, RetryContext context, RetryState state)	Actions to take after final attempt has failed.
boolean	hasListeners()	Return true if at least one listener is registered.
protected RetryContext	open(RetryPolicy retryPolicy, RetryState state)	Delegate to the RetryPolicy having checked in the cache for an existing value if the state is not null.
private void	registerContext(RetryContext context, RetryState state)
void	registerListener(RetryListener listener)	Register an additional listener at the end of the list.
void	registerListener(RetryListener listener, int index)	Register an additional listener at the specified index.
protected void	registerThrowable(RetryPolicy retryPolicy, RetryState state, RetryContext context, Throwable e)
protected <E extends Throwable> void	rethrow(RetryContext context, String message, boolean wrap)
void	setBackOffPolicy(BackOffPolicy backOffPolicy)	Setter for BackOffPolicy.
void	setListeners(RetryListener[] listeners)	Setter for listeners.
void	setRetryContextCache(RetryContextCache retryContextCache)	Public setter for the RetryContextCache.
void	setRetryPolicy(RetryPolicy retryPolicy)	Setter for RetryPolicy.
void	setThrowLastExceptionOnExhausted(boolean throwLastExceptionOnExhausted)
protected boolean	shouldRethrow(RetryPolicy retryPolicy, RetryContext context, RetryState state)	Extension point for subclasses to decide on behaviour after catching an exception in a RetryCallback.
private static <E extends Throwable> E	wrapIfNecessary(Throwable throwable)	Re-throws the original throwable if it is an Exception, and wraps non-exceptions into RetryException.

从类继承的方法 java.lang.Object

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

字段详细资料

GLOBAL_STATE

private static final String GLOBAL_STATE

Retry context attribute name that indicates the context should be considered global state (never closed). TODO: convert this to a flag in the RetryState.

另请参阅:

• 常量字段值

logger

protected final infra.logging.Logger logger

backOffPolicy

private volatile BackOffPolicy backOffPolicy

retryPolicy

private volatile RetryPolicy retryPolicy

listeners

private volatile RetryListener[] listeners

retryContextCache

private RetryContextCache retryContextCache

throwLastExceptionOnExhausted

private boolean throwLastExceptionOnExhausted

构造器详细资料

RetryTemplate

public RetryTemplate()

方法详细资料

builder

public static RetryTemplateBuilder builder()

Main entry point to configure RetryTemplate using fluent API. See RetryTemplateBuilder for usage examples and details.

返回:

a new instance of RetryTemplateBuilder with preset default behaviour, that can be overwritten during manual configuration

defaultInstance

public static RetryTemplate defaultInstance()

Creates a new default instance. The properties of default instance are described in RetryTemplateBuilder documentation.

返回:

a new instance of RetryTemplate with default behaviour

setThrowLastExceptionOnExhausted

public void setThrowLastExceptionOnExhausted(boolean throwLastExceptionOnExhausted)

参数:

throwLastExceptionOnExhausted - the throwLastExceptionOnExhausted to set

setRetryContextCache

public void setRetryContextCache(RetryContextCache retryContextCache)

Public setter for the RetryContextCache.

参数:

retryContextCache - the RetryContextCache to set.

setListeners

public void setListeners(RetryListener[] listeners)

Setter for listeners. The listeners are executed before and after a retry block (i.e. before and after all the attempts), and on an error (every attempt).

参数:

listeners - the RetryListeners

另请参阅:

• RetryListener

registerListener

public void registerListener(RetryListener listener)

Register an additional listener at the end of the list.

参数:

listener - the RetryListener

另请参阅:

• setListeners(RetryListener[])

registerListener

public void registerListener(RetryListener listener,
 int index)

Register an additional listener at the specified index.

参数:

listener - the RetryListener

index - the position in the list.

另请参阅:

• setListeners(RetryListener[])

hasListeners

public boolean hasListeners()

Return true if at least one listener is registered.

返回:

true if listeners present.

setBackOffPolicy

public void setBackOffPolicy(BackOffPolicy backOffPolicy)

Setter for BackOffPolicy.

参数:

backOffPolicy - the BackOffPolicy

setRetryPolicy

public void setRetryPolicy(RetryPolicy retryPolicy)

Setter for RetryPolicy.

参数:

retryPolicy - the RetryPolicy

execute

public final <T,
E extends Throwable> T execute(RetryCallback<T,E> retryCallback)
                                        throws E

Keep executing the callback until it either succeeds or the policy dictates that we stop, in which case the most recent exception thrown by the callback will be rethrown.

指定者:

execute 在接口中 RetryOperations

类型参数:

T - the return value

E - the exception to throw

参数:

retryCallback - the RetryCallback

返回:

the value returned by the RetryCallback upon successful invocation.

抛出:

TerminatedRetryException - if the retry has been manually terminated by a listener.

E - any Exception raised by the RetryCallback upon unsuccessful retry.

另请参阅:

• RetryOperations.execute(RetryCallback)

execute

public final <T,
E extends Throwable> T execute(RetryCallback<T,E> retryCallback,
 RecoveryCallback<T> recoveryCallback)
                                        throws E

Keep executing the callback until it either succeeds or the policy dictates that we stop, in which case the recovery callback will be executed.

指定者:

execute 在接口中 RetryOperations

类型参数:

T - the type to return

E - the type of the exception

参数:

retryCallback - the RetryCallback

recoveryCallback - the RecoveryCallback

返回:

the value returned by the RetryCallback upon successful invocation, and that returned by the RecoveryCallback otherwise.

抛出:

TerminatedRetryException - if the retry has been manually terminated by a listener.

E - any Exception raised by the unsuccessful retry.

另请参阅:

• RetryOperations.execute(RetryCallback, RecoveryCallback)

execute

public final <T,
E extends Throwable> T execute(RetryCallback<T,E> retryCallback,
 RetryState retryState)
                                        throws E,
ExhaustedRetryException

Execute the callback once if the policy dictates that we can, re-throwing any exception encountered so that clients can re-present the same task later.

指定者:

execute 在接口中 RetryOperations

类型参数:

T - the type of the return value

E - the type of the exception to return

参数:

retryCallback - the RetryCallback

retryState - the RetryState

返回:

the value returned by the RetryCallback upon successful invocation, and that returned by the RecoveryCallback otherwise.

抛出:

ExhaustedRetryException - if the retry has been exhausted.

E - any Exception raised by the RecoveryCallback.

另请参阅:

• RetryOperations.execute(RetryCallback, RetryState)

execute

public final <T,
E extends Throwable> T execute(RetryCallback<T,E> retryCallback,
 RecoveryCallback<T> recoveryCallback,
 RetryState retryState)
                                        throws E,
ExhaustedRetryException

Execute the callback once if the policy dictates that we can, re-throwing any exception encountered so that clients can re-present the same task later.

指定者:

execute 在接口中 RetryOperations

类型参数:

T - the return value type

E - the exception type

参数:

retryCallback - the RetryCallback

recoveryCallback - the RecoveryCallback

retryState - the RetryState

返回:

the value returned by the RetryCallback upon successful invocation, and that returned by the RecoveryCallback otherwise.

抛出:

E - any Exception raised by the RecoveryCallback upon unsuccessful retry.

ExhaustedRetryException

另请参阅:

• RetryOperations.execute(RetryCallback, RetryState)

doExecute

protected <T,
E extends Throwable> T doExecute(RetryCallback<T,E> retryCallback,
 RecoveryCallback<T> recoveryCallback,
 RetryState state)
                                       throws E,
ExhaustedRetryException

Execute the callback once if the policy dictates that we can, otherwise execute the recovery callback.

类型参数:

T - the type of the return value

E - the exception type to throw

参数:

recoveryCallback - the RecoveryCallback

retryCallback - the RetryCallback

state - the RetryState

返回:

T the retried value

抛出:

ExhaustedRetryException - if the retry has been exhausted.

E - an exception if the retry operation fails

另请参阅:

• RetryOperations.execute(RetryCallback, RecoveryCallback, RetryState)

canRetry

protected boolean canRetry(RetryPolicy retryPolicy,
 RetryContext context)

Decide whether to proceed with the ongoing retry attempt. This method is called before the RetryCallback is executed, but after the backoff and open interceptors.

参数:

retryPolicy - the policy to apply

context - the current retry context

返回:

true if we can continue with the attempt

close

protected void close(RetryPolicy retryPolicy,
 RetryContext context,
 RetryState state,
 boolean succeeded)

Clean up the cache if necessary and close the context provided (if the flag indicates that processing was successful).

参数:

retryPolicy - the RetryPolicy

context - the RetryContext

state - the RetryState

succeeded - whether the close succeeded

registerThrowable

protected void registerThrowable(RetryPolicy retryPolicy,
 RetryState state,
 RetryContext context,
 Throwable e)

registerContext

private void registerContext(RetryContext context,
 RetryState state)

open

protected RetryContext open(RetryPolicy retryPolicy,
 RetryState state)

Delegate to the RetryPolicy having checked in the cache for an existing value if the state is not null.

参数:

state - a RetryState

retryPolicy - a RetryPolicy to delegate the context creation

返回:

a retry context, either a new one or the one used last time the same state was encountered

doOpenInternal

private RetryContext doOpenInternal(RetryPolicy retryPolicy,
 RetryState state)

doOpenInternal

private RetryContext doOpenInternal(RetryPolicy retryPolicy)

handleRetryExhausted

protected <T> T handleRetryExhausted(RecoveryCallback<T> recovery,
 RetryContext context,
 RetryState state)
                              throws Throwable

Actions to take after final attempt has failed. If there is state clean up the cache. If there is a recovery callback, execute that and return its result. Otherwise throw an exception.

类型参数:

T - the type to classify

参数:

recovery - the callback for recovery (might be null)

context - the current retry context

state - the RetryState

返回:

T the payload to return

抛出:

Exception - if the callback does, and if there is no callback and the state is null then the last exception from the context

ExhaustedRetryException - if the state is not null and there is no recovery callback

Throwable - if there is an error

rethrow

protected <E extends Throwable> void rethrow(RetryContext context,
 String message,
 boolean wrap)
                                      throws E

抛出:

E extends Throwable

shouldRethrow

protected boolean shouldRethrow(RetryPolicy retryPolicy,
 RetryContext context,
 RetryState state)

Extension point for subclasses to decide on behaviour after catching an exception in a RetryCallback. Normal stateless behaviour is not to rethrow, and if there is state we rethrow.

参数:

retryPolicy - the retry policy

context - the current context

state - the current retryState

返回:

true if the state is not null but subclasses might choose otherwise

doOpenInterceptors

private <T,
E extends Throwable> boolean doOpenInterceptors(RetryCallback<T,E> callback,
 RetryContext context)

doCloseInterceptors

private <T,
E extends Throwable> void doCloseInterceptors(RetryCallback<T,E> callback,
 RetryContext context,
 Throwable lastException)

doOnSuccessInterceptors

private <T,
E extends Throwable> void doOnSuccessInterceptors(RetryCallback<T,E> callback,
 RetryContext context,
 T result)

doOnErrorInterceptors

private <T,
E extends Throwable> void doOnErrorInterceptors(RetryCallback<T,E> callback,
 RetryContext context,
 Throwable throwable)

wrapIfNecessary

private static <E extends Throwable> E wrapIfNecessary(Throwable throwable)
                                                throws RetryException

Re-throws the original throwable if it is an Exception, and wraps non-exceptions into RetryException.

抛出:

RetryException