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/4.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

  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code containsKey(null)},
   * {@code get(null)}, {@code keySet().contains(null)} or {@code remove(null)}.
   */
  ALLOWS_NULL_KEY_QUERIES,
  ALLOWS_NULL_KEYS(ALLOWS_NULL_KEY_QUERIES),
  /**
   * The map does not throw {@code NullPointerException} on calls such as {@code

import javax.net.ssl.HostnameVerifier
import javax.net.ssl.SSLSession

class RecordingHostnameVerifier : HostnameVerifier {
  @JvmField
  val calls: MutableList<String> = mutableListOf()

  @Synchronized override fun verify(
    hostname: String,
    session: SSLSession,
  ): Boolean {
    calls.add("verify $hostname")
    return true
  }

) : AbstractExecutorService() {
  private var shutdown: Boolean = false
  private val calls = mutableListOf<RealCall.AsyncCall>()

  override fun execute(command: Runnable) {
    if (shutdown) throw RejectedExecutionException()
    calls.add(command as RealCall.AsyncCall)
  }

  fun assertJobs(vararg expectedUrls: String) {
    val actualUrls = calls.map { it.request.url.toString() }
    assertThat(actualUrls).containsExactly(*expectedUrls)

  /**
   * Invoked when the HTTP connection has been closed normally.
   *
   * No further calls to this listener will be made.
   */
  open fun onClosed(eventSource: EventSource) {
  }

  /**
   * Invoked when an event source has been closed due to an error reading from or writing to the
   * network. Incoming events may have been lost. No further calls to this listener will be made.
   */
  open fun onFailure(
    eventSource: EventSource,

 */
@NullMarked
@GwtCompatible
public class SuppliersTest extends TestCase {

  static class CountingSupplier implements Supplier<Integer> {
    int calls = 0;

    @Override
    public Integer get() {
      calls++;
      return calls * 10;
    }

    @Override
    public String toString() {
      return "CountingSupplier";
    }
  }

      alternate_style: true
  - tables

plugins:
  - search
  - redirects:
      redirect_maps:
        # Redirect all feature pages to features/*
        'caching.md': 'features/caching.md'
        'calls.md': 'features/calls.md'
        'connections.md': 'features/connections.md'
        'events.md': 'features/events.md'
        'https.md': 'features/events.md'
        'interceptors.md': 'features/interceptors.md'

    return capacityWithoutIt >= addressState.policy.minimumConcurrentCalls
  }

  /**
   * Prunes any leaked calls and then returns the number of remaining live calls on [connection].
   * Calls are leaked if the connection is tracking them but the application code has abandoned
   * them. Leak detection is imprecise and relies on garbage collection.
   */

   * 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