Calls are executed in one of two ways:

 * **Synchronous:** your thread blocks until the response is readable.
 * **Asynchronous:** you enqueue the request on any thread, and get [called back](https://square.github.io/okhttp/5.x/okhttp/okhttp3/-callback/) on another thread when the response is readable.

Events
======

Events allow you to capture metrics on your application’s HTTP calls. Use events to monitor:

 * The size and frequency of the HTTP calls your application makes. If you’re making too many calls, or your calls are too large, you should know about it!
 * The performance of these calls on the underlying network. If the network’s performance isn’t sufficient, you need to either improve the network or use less of it.

### EventListener

   * exception.
   *
   * <p>When the underlying delegate throws an exception then this memoizing supplier will keep
   * delegating calls until it returns valid data.
   *
   * @param duration the length of time after a value is created that it should stop being returned
   *     by subsequent {@code get()} calls
   * @param unit the unit that {@code duration} is expressed in
   * @throws IllegalArgumentException if {@code duration} is not positive

   * exception.
   *
   * <p>When the underlying delegate throws an exception then this memoizing supplier will keep
   * delegating calls until it returns valid data.
   *
   * @param duration the length of time after a value is created that it should stop being returned
   *     by subsequent {@code get()} calls
   * @param unit the unit that {@code duration} is expressed in
   * @throws IllegalArgumentException if {@code duration} is not positive

import java.util.concurrent.Executor;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import org.jspecify.annotations.Nullable;

/**
 * {@link FluentFuture} that forwards all calls to a delegate.
 *
 * <p><b>Warning:</b> The methods of {@code ForwardingFluentFuture} forward <b>indiscriminately</b>
 * to the methods of the delegate. For example, overriding {@link #get(long, TimeUnit)} alone

///

## Other Asynchronous Function Calls { #other-asynchronous-function-calls }

      .build()
    ```

 *  New: Support the `QUERY` HTTP method. You will need to set the `Request.cacheUrlOverride`
    property to cache calls made with this method. The `RequestBody.sha256()` may be helpful here;
    use it to compose a cache URL from the query body.

 *  New: Publish events when calls must wait to execute. `EventListener.dispatcherQueueStart()`

import com.google.common.base.Preconditions;
import java.util.concurrent.Executor;
import org.jspecify.annotations.Nullable;

/**
 * A {@link ListenableFuture} which forwards all its method calls to another future. Subclasses
 * should override one or more methods to modify the behavior of the backing future as desired per
 * the <a href="http://en.wikipedia.org/wiki/Decorator_pattern">decorator pattern</a>.
 *

    assertEquals(0, (int) iter.peek());
    assertEquals(0, (int) iter.next());

    assertEquals(1, (int) iter.peek());
    assertEquals(1, (int) iter.next());

    /*
     * We test peek() after various calls to make sure that one bad call doesn't interfere with its
     * ability to throw the correct exception in the future.
     */
    assertThrows(NoSuchElementException.class, iter::peek);

    assertEquals(0, (int) iter.peek());
    assertEquals(0, (int) iter.next());

    assertEquals(1, (int) iter.peek());
    assertEquals(1, (int) iter.next());

    /*
     * We test peek() after various calls to make sure that one bad call doesn't interfere with its
     * ability to throw the correct exception in the future.
     */
    assertThrows(NoSuchElementException.class, iter::peek);