![Events Diagram](../assets/images/events@2x.png)

Here’s a [sample event listener](https://github.com/square/okhttp/blob/master/samples/guide/src/main/java/okhttp3/recipes/PrintEventsNonConcurrent.java) that prints each event with a timestamp.

```java

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.sse.internal

internal data class Event(
  val id: String?,
  val type: String?,
  val data: String,

  }

  /**
   * Enqueues an event to be run on currently known listeners.
   *
   * <p>The {@code toString} method of the Event itself will be used to describe the event in the
   * case of an error.
   *
   * @param event the callback to execute on {@link #dispatch}
   */
  public void enqueue(Event<L> event) {
    enqueueHelper(event, event);
  }

  /**

  }

  fun assertExhausted() {
    assertThat(events).isEmpty()
  }

  fun assertOpen(): WebSocket {
    val event = nextEvent() as Open
    return event.webSocket
  }

  fun assertFailure(t: Throwable?) {
    val event = nextEvent() as Failure
    assertThat(event.response).isNull()
    assertThat(event.t).isSameAs(t)
  }

  fun assertFailure(

  fun assertExhausted() {
    assertThat(events).isEmpty()
  }

  fun assertEvent(
    id: String?,
    type: String?,
    data: String,
  ) {
    assertThat(nextEvent()).isEqualTo(Event(id, type, data))
  }

  fun assertOpen(): EventSource {
    val event = nextEvent() as Open
    return event.eventSource
  }

  fun assertClose() {
    nextEvent() as Closed
  }

  fun assertFailure(

    assertEquals(
        "ReentrantEventHater expected 2 events",
        Lists.<Object>newArrayList(FIRST, SECOND),
        hater.eventsReceived);
  }

  public class ReentrantEventsHater {
    boolean ready = true;
    final List<Object> eventsReceived = new ArrayList<>();

    @Subscribe
    public void listenForStrings(String event) {
      eventsReceived.add(event);
      ready = false;
      try {

   *
   * @param executor Executor to use to dispatch events. It is the caller's responsibility to shut
   *     down the executor after the last event has been posted to this event bus.
   * @param subscriberExceptionHandler Handler used to handle exceptions thrown from subscribers.
   *     See {@link SubscriberExceptionHandler} for more information.
   * @since 16.0
   */

          }
        };

    @Override
    void dispatch(Object event, Iterator<Subscriber> subscribers) {
      checkNotNull(event);
      checkNotNull(subscribers);
      // requireNonNull accommodates Android's @RecentlyNullable annotation on ThreadLocal.get
      Queue<Event> queueForThread = requireNonNull(queue.get());
      queueForThread.offer(new Event(event, subscribers));

      if (!dispatching.get()) {

    }

    /**
     * Rewrites log events by converting ERROR level to WARN level for matching loggers.
     *
     * @param event the log event to potentially rewrite
     * @return the original event or a new event with WARN level if conversion applied
     */
    @Override
    public LogEvent rewrite(final LogEvent event) {
        final String loggerName = event.getLoggerName();
        if (loggerName == null) {

          maxSize = 50L * 1024L * 1024L // 50 MiB
      ))
      .build()
```

## EventListener events 

Cache Events are exposed via the EventListener API.  Typical scenarios are below.

### Cache Hit

In the ideal scenario the cache can fulfill the request without any conditional call to the network.
This will skip the normal events such as DNS, connecting to the network, and downloading the response body.