com.netflix.hystrix.util
Class HystrixTimer

java.lang.Object
  com.netflix.hystrix.util.HystrixTimer

public class HystrixTimer
extends java.lang.Object

Timer used by the HystrixCollapser to trigger batch executions.

Used instead of java.util.Timer because:

• Creating a large number of tasks that then need to be cancelled is inefficient with java.util.Timer and requires the use of purge() to prevent memory leaks which is synchronized and iterates all items in queue.
• We can use non-blocking data structures now that didn't exist when java.util.Timer was written.
• We can optimize for the specific use case of HystrixCollapser instead of being generic to any tasks being submitted. Specifically, we can 'tick' every 10ms (for example) and fire all HystrixCollapser interested in that time, rather than each instance needing a separate task that gets scheduled independently.
• We can use a simple add/remove listener model rather than a Task which gets submitted but has no way to explicitly remove itself other than cancel and wait to eventually be cleaned out - or have to use purge() to force it out
• We can use soft-references to ensure we don't cause memory leaks even if cleanup doesn't occur.

Nested Class Summary

static interface

HystrixTimer.TimerListener

Method Summary

java.lang.ref.Reference<HystrixTimer.TimerListener>	addTimerListener(HystrixTimer.TimerListener listener) Add a HystrixTimer.TimerListener that will be executed until it is garbage collected or removed by clearing the returned Reference.
static HystrixTimer	getInstance() Retrieve the global instance with a single backing thread.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static HystrixTimer getInstance()

Retrieve the global instance with a single backing thread.

addTimerListener

public java.lang.ref.Reference<HystrixTimer.TimerListener> addTimerListener(HystrixTimer.TimerListener listener)

Add a HystrixTimer.TimerListener that will be executed until it is garbage collected or removed by clearing the returned Reference.

NOTE: It is the responsibility of code that adds a listener via this method to clear this listener when completed.

 // add a TimerListener 
 Reference<TimerListener> listener = HystrixTimer.getInstance().addTimerListener(listenerImpl);
 
 // sometime later, often in a thread shutdown, request cleanup, servlet filter or something similar the listener must be shutdown via the clear() method
 listener.clear();
 

Parameters:

listener - TimerListener implementation that will be triggered according to its getIntervalTimeInMilliseconds() method implementation.

Returns:

reference to the TimerListener that allows cleanup via the clear() method