## Version 5.0.0-alpha.4

_2022-02-01_

**This release introduces fast fallback to better support mixed IPv4+IPv6 networks.** Fast fallback
is what we're calling our implementation of Happy Eyeballs, [RFC 8305][rfc_8305]. With this
feature OkHttp will attempt both IPv6 and IPv4 connections concurrently, keeping whichever connects
first. Fast fallback gives IPv6 connections a 250 ms head start so IPv6 is preferred on networks

    client.newCall(Request.Builder().url(server.url("/a")).build()).enqueue(callback)
    callback.await(server.url("/a")).assertBody("abc")
    client.newCall(Request.Builder().url(server.url("/b")).build()).enqueue(callback)
    callback.await(server.url("/b")).assertBody("def")
    client.newCall(Request.Builder().url(server.url("/c")).build()).enqueue(callback)
    callback.await(server.url("/c")).assertBody("ghi")

          responseCallback.onResponse(this@RealCall, response)
        } catch (e: IOException) {
          if (signalledCallback) {
            // Do not signal the callback twice!
            Platform.get().log("Callback failure for ${toLoggableString()}", Platform.INFO, e)
          } else {
            responseCallback.onFailure(this@RealCall, e)
          }
        } catch (t: Throwable) {
          cancel()

suspend fun Call.executeAsync(): Response =
  suspendCancellableCoroutine { continuation ->
    continuation.invokeOnCancellation {
      this.cancel()
    }
    this.enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          continuation.resumeWithException(e)
        }

        override fun onResponse(
          call: Call,

	public synthetic fun <init> (Lokhttp3/AsyncDns$DnsClass;Landroid/net/Network;ILkotlin/jvm/internal/DefaultConstructorMarker;)V
	public fun query (Ljava/lang/String;Lokhttp3/AsyncDns$Callback;)V
}

public final class okhttp3/android/AndroidAsyncDns$Companion {
	public final fun getIPv4 ()Lokhttp3/android/AndroidAsyncDns;
	public final fun getIPv6 ()Lokhttp3/android/AndroidAsyncDns;
}

    scheduling. In your debugger you will see new thread names and more use of daemon threads.

 *  Fix: Don't drop callbacks on unexpected exceptions. When an interceptor throws an unchecked
    exception the callback is now notified that the call was canceled. The exception is still sent
    to the uncaught exception handler for reporting and recovery.

        if (cacheResponse.code != HttpURLConnection.HTTP_GATEWAY_TIMEOUT) {
          return cacheResponse
        }
      } catch (ioe: IOException) {
        // Failures are ignored as we can fallback to the network
        // and hopefully repopulate the cache.
      }
    }

    return null
  }

  @Throws(Exception::class)
  private fun readResponse(
    hostname: String,

package okhttp3.coroutines

import kotlin.coroutines.resumeWithException
import kotlinx.coroutines.ExperimentalCoroutinesApi
import kotlinx.coroutines.suspendCancellableCoroutine
import okhttp3.Call
import okhttp3.Callback
import okhttp3.Response
import okhttp3.internal.closeQuietly
import okio.IOException

@ExperimentalCoroutinesApi // resume with a resource cleanup.
suspend fun Call.executeAsync(): Response =

import android.net.http.DnsOptions
import android.net.http.HttpEngine
import android.net.http.HttpException
import android.net.http.QuicOptions
import android.net.http.UrlRequest
import android.net.http.UrlRequest.Callback
import android.net.http.UrlRequest.REQUEST_PRIORITY_MEDIUM
import android.net.http.UrlResponseInfo
import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.filters.SdkSuppress

import okio.Timeout

open class FailingCall : Call {
  override fun request(): Request = error("unexpected")

  override fun execute(): Response = error("unexpected")

  override fun enqueue(responseCallback: Callback): Unit = error("unexpected")

  override fun cancel(): Unit = error("unexpected")

  override fun isExecuted(): Boolean = error("unexpected")

  override fun isCanceled(): Boolean = error("unexpected")