return executorServiceOrNull!!
      }

  /** Ready async calls in the order they'll be run. */
  private val readyAsyncCalls = ArrayDeque<AsyncCall>()

  /** Running asynchronous calls. Includes canceled calls that haven't finished yet. */
  private val runningAsyncCalls = ArrayDeque<AsyncCall>()

  /** Running synchronous calls. Includes canceled calls that haven't finished yet. */

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
  }

   * connection has been successfully released. No further calls to this listener will be made.
   */
  open fun onClosed(
    webSocket: WebSocket,
    code: Int,
    reason: String,
  ) {
  }

  /**
   * Invoked when a web socket has been closed due to an error reading from or writing to the
   * network. Both outgoing and incoming messages may have been lost. No further calls to this
   * listener will be made.
   */

configured to fall back for broad connectivity.

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It
supports both synchronous blocking calls and async calls with callbacks.


Get a URL
---------

This program downloads a URL and prints its contents as a string. [Full source][get_example].

```java
OkHttpClient client = new OkHttpClient();

import javax.net.ssl.SSLPeerUnverifiedException
import javax.net.ssl.SSLSession
import javax.net.ssl.SSLSessionContext
import javax.security.cert.X509Certificate

/** An [SSLSession] that delegates all calls.  */
abstract class DelegatingSSLSession(protected val delegate: SSLSession?) : SSLSession {
  override fun getId(): ByteArray {
    return delegate!!.id
  }

  override fun getSessionContext(): SSLSessionContext {

Interceptors
============

Interceptors are a powerful mechanism that can monitor, rewrite, and retry calls. Here's a simple interceptor that logs the outgoing request and the incoming response.

```java
class LoggingInterceptor implements Interceptor {
  @Override public Response intercept(Interceptor.Chain chain) throws IOException {
    Request request = chain.request();

    long t1 = System.nanoTime();

   * in the **API contract** between OkHttp and the application.
   *
   * This method returns false unless it is overridden by a subclass.
   *
   * ### Duplex Transmission
   *
   * With regular HTTP calls the request always completes sending before the response may begin
   * receiving. With duplex the request and response may be interleaved! That is, request body bytes

import okhttp3.HttpUrl;
import okhttp3.OkHttpClient;
import okhttp3.Protocol;
import okhttp3.Request;
import okhttp3.Response;

/**
 * This prints events for a single in-flight call. It won't work for multiple concurrent calls
 * because we don't know what callStartNanos refers to.
 */
public final class PrintEventsNonConcurrent {
  private final OkHttpClient client = new OkHttpClient.Builder()
      .eventListener(new PrintingEventListener())

 * [OkHttp Profiler](https://plugins.jetbrains.com/plugin/11249-okhttp-profiler): An IntelliJ plugin for monitoring OkHttp calls.
 * [OkReplay](https://github.com/airbnb/okreplay): Record and replay OkHttp network interaction in your tests.
 * [okhttp-signpost](https://github.com/pakerfeldt/okhttp-signpost): OAuth signing with signpost and OkHttp.

import java.util.function.BiFunction
import javax.net.ssl.HandshakeCompletedListener
import javax.net.ssl.SSLParameters
import javax.net.ssl.SSLSession
import javax.net.ssl.SSLSocket

/** An [SSLSocket] that delegates all calls.  */
abstract class DelegatingSSLSocket(protected val delegate: SSLSocket?) : SSLSocket() {
  @Throws(IOException::class)
  override fun shutdownInput() {
    delegate!!.shutdownInput()
  }