Hystrix: Latency and Fault Tolerance for Distributed Systems

com.netflix.hystrix.strategy.executionhook
Class HystrixCommandExecutionHook

java.lang.Object
  com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook

public abstract class HystrixCommandExecutionHook
extends java.lang.Object

Abstract ExecutionHook with invocations at different lifecycle points of HystrixCommand execution with default no-op implementations.

See HystrixPlugins or the Hystrix GitHub Wiki for information on configuring plugins: https://github.com/Netflix/Hystrix/wiki/Plugins.

Note on thread-safety and performance

A single implementation of this class will be used globally so methods on this class will be invoked concurrently from multiple threads so all functionality must be thread-safe.

Methods are also invoked synchronously and will add to execution time of the commands so all behavior should be fast. If anything time-consuming is to be done it should be spawned asynchronously onto separate worker threads.

Since:

1.2

Constructor Summary

HystrixCommandExecutionHook()

Method Summary

<T> T	onComplete(HystrixCommand<T> commandInstance, T response) Invoked after completion of HystrixCommand execution that results in a response.
<T> java.lang.Exception	onError(HystrixCommand<T> commandInstance, HystrixRuntimeException.FailureType failureType, java.lang.Exception e) Invoked after failed completion of HystrixCommand execution.
<T> java.lang.Exception	onFallbackError(HystrixCommand<T> commandInstance, java.lang.Exception e) Invoked after failed execution of HystrixCommand.getFallback() with thrown exception.
<T> void	onFallbackStart(HystrixCommand<T> commandInstance) Invoked before HystrixCommand.getFallback() is about to be executed.
<T> T	onFallbackSuccess(HystrixCommand<T> commandInstance, T fallbackResponse) Invoked after successful execution of HystrixCommand.getFallback() with response value.
<T> java.lang.Exception	onRunError(HystrixCommand<T> commandInstance, java.lang.Exception e) Invoked after failed execution of HystrixCommand.run() with thrown Exception.
<T> void	onRunStart(HystrixCommand<T> commandInstance) Invoked before HystrixCommand.run() is about to be executed.
<T> T	onRunSuccess(HystrixCommand<T> commandInstance, T response) Invoked after successful execution of HystrixCommand.run() with response value.
<T> void	onStart(HystrixCommand<T> commandInstance) Invoked before HystrixCommand executes.
<T> void	onThreadComplete(HystrixCommand<T> commandInstance) Invoked at completion of thread execution when HystrixCommand is executed using HystrixCommandProperties.ExecutionIsolationStrategy.THREAD.
<T> void	onThreadStart(HystrixCommand<T> commandInstance) Invoked at start of thread execution when HystrixCommand is executed using HystrixCommandProperties.ExecutionIsolationStrategy.THREAD.

Methods inherited from class java.lang.Object

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

Constructor Detail

HystrixCommandExecutionHook

public HystrixCommandExecutionHook()

Method Detail

onRunStart

public <T> void onRunStart(HystrixCommand<T> commandInstance)

Invoked before HystrixCommand.run() is about to be executed.

Parameters:

commandInstance - The executing HystrixCommand instance.

Since:

1.2

onRunSuccess

public <T> T onRunSuccess(HystrixCommand<T> commandInstance,
                          T response)

Invoked after successful execution of HystrixCommand.run() with response value.

Parameters:

commandInstance - The executing HystrixCommand instance.

response - from HystrixCommand.run()

Returns:

T response object that can be modified, decorated, replaced or just returned as a pass-thru.

Since:

1.2

onRunError

public <T> java.lang.Exception onRunError(HystrixCommand<T> commandInstance,
                                          java.lang.Exception e)

Invoked after failed execution of HystrixCommand.run() with thrown Exception.

Parameters:

commandInstance - The executing HystrixCommand instance.

e - Exception thrown by HystrixCommand.run()

Returns:

Exception that can be decorated, replaced or just returned as a pass-thru.

Since:

1.2

onFallbackStart

public <T> void onFallbackStart(HystrixCommand<T> commandInstance)

Invoked before HystrixCommand.getFallback() is about to be executed.

Parameters:

commandInstance - The executing HystrixCommand instance.

Since:

1.2

onFallbackSuccess

public <T> T onFallbackSuccess(HystrixCommand<T> commandInstance,
                               T fallbackResponse)

Invoked after successful execution of HystrixCommand.getFallback() with response value.

Parameters:

commandInstance - The executing HystrixCommand instance.

fallbackResponse - from HystrixCommand.getFallback()

Returns:

T response object that can be modified, decorated, replaced or just returned as a pass-thru.

Since:

1.2

onFallbackError

public <T> java.lang.Exception onFallbackError(HystrixCommand<T> commandInstance,
                                               java.lang.Exception e)

Invoked after failed execution of HystrixCommand.getFallback() with thrown exception.

Parameters:

commandInstance - The executing HystrixCommand instance.

e - Exception thrown by HystrixCommand.getFallback()

Returns:

Exception that can be decorated, replaced or just returned as a pass-thru.

Since:

1.2

onStart

public <T> void onStart(HystrixCommand<T> commandInstance)

Invoked before HystrixCommand executes.

Parameters:

commandInstance - The executing HystrixCommand instance.

Since:

1.2

onComplete

public <T> T onComplete(HystrixCommand<T> commandInstance,
                        T response)

Invoked after completion of HystrixCommand execution that results in a response.

The response can come either from HystrixCommand.run() or HystrixCommand.getFallback().

Parameters:

commandInstance - The executing HystrixCommand instance.

response - from HystrixCommand.run() or HystrixCommand.getFallback().

Returns:

T response object that can be modified, decorated, replaced or just returned as a pass-thru.

Since:

1.2

onError

public <T> java.lang.Exception onError(HystrixCommand<T> commandInstance,
                                       HystrixRuntimeException.FailureType failureType,
                                       java.lang.Exception e)

Invoked after failed completion of HystrixCommand execution.

Parameters:

commandInstance - The executing HystrixCommand instance.

failureType - HystrixRuntimeException.FailureType representing the type of failure that occurred.

See HystrixRuntimeException for more information.

e - Exception thrown by HystrixCommand

Returns:

Exception that can be decorated, replaced or just returned as a pass-thru.

Since:

1.2

onThreadStart

public <T> void onThreadStart(HystrixCommand<T> commandInstance)

Invoked at start of thread execution when HystrixCommand is executed using HystrixCommandProperties.ExecutionIsolationStrategy.THREAD.

Parameters:

commandInstance - The executing HystrixCommand instance.

Since:

1.2

onThreadComplete

public <T> void onThreadComplete(HystrixCommand<T> commandInstance)

Invoked at completion of thread execution when HystrixCommand is executed using HystrixCommandProperties.ExecutionIsolationStrategy.THREAD.

Parameters:

commandInstance - The executing HystrixCommand instance.

Since:

1.2