io.opencensus.impl.internal

Class DisruptorEventQueue

java.lang.Object

io.opencensus.impl.internal.DisruptorEventQueue

All Implemented Interfaces:

io.opencensus.implcore.internal.EventQueue

@ThreadSafe
public final class DisruptorEventQueue
extends Object
implements io.opencensus.implcore.internal.EventQueue

A low-latency event queue for background updating of (possibly contended) objects. This is intended for use by instrumentation methods to ensure that they do not block foreground activities. To customize the action taken on reading the queue, derive a new class from EventQueue.Entry and pass it to the EventQueue.enqueue(Entry) method. The Entry#process() method of your class will be called and executed in a background thread. This class is a Singleton.

Example Usage: Given a class as follows:

 public class someClass {
   public void doSomething() {
     // Do the work of the method. One result is a measurement of something.
     int measurement = doSomeWork();
     // Make an update to the class state, based on this measurement. This work can take some
     // time, but can be done asynchronously, in the background.
     update(measurement);
   }

   public void update(int arg) {
     // do something
   }
 }
 

The work of calling someClass.update() can be executed in the backgound as follows:

 public class someClass {
   // Add a EventQueueEntry class that will process the update call.
   private static final class SomeClassUpdateEvent implements EventQueueEntry {
     private final SomeClass someClassInstance;
     private final int arg;

     SomeObjectUpdateEvent(SomeObject someClassInstance, int arg) {
       this.someClassInstance = someClassInstance;
       this.arg = arg;
     }

     @Override
     public void process() {
       someClassInstance.update(arg);
     }
   }

   public void doSomething() {
     int measurement = doSomeWork();
     // Instead of calling update() directly, create an event to do the processing, and insert
     // it into the EventQueue. It will be processed in a background thread, and doSomething()
     // can return immediately.
     EventQueue.getInstance.enqueue(new SomeClassUpdateEvent(this, measurement));
   }
 }
 

Nested Class Summary

Nested classes/interfaces inherited from interface io.opencensus.implcore.internal.EventQueue

io.opencensus.implcore.internal.EventQueue.Entry

Method Summary

Modifier and Type	Method and Description
void	enqueue(io.opencensus.implcore.internal.EventQueue.Entry entry) Enqueues an event on the DisruptorEventQueue.
static DisruptorEventQueue	getInstance() Returns the DisruptorEventQueue instance.
void	shutdown() Shuts down the underlying disruptor.

Methods inherited from class java.lang.Object

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

Method Detail

getInstance

public static DisruptorEventQueue getInstance()

Returns the DisruptorEventQueue instance.

Returns:

the singleton EventQueue instance.

enqueue

public void enqueue(io.opencensus.implcore.internal.EventQueue.Entry entry)

Enqueues an event on the DisruptorEventQueue.

Specified by:

enqueue in interface io.opencensus.implcore.internal.EventQueue

Parameters:

entry - a class encapsulating the actions to be taken for event processing.

shutdown

public void shutdown()

Shuts down the underlying disruptor.

Specified by:

shutdown in interface io.opencensus.implcore.internal.EventQueue