*/
package okhttp3

import okio.IOException
import okio.Timeout

/**
 * A call is a request that has been prepared for execution. A call can be canceled. As this object
 * represents a single request/response pair (stream), it cannot be executed twice.
 */
interface Call : Cloneable {
  /** Returns the original request that initiated this call. */
  fun request(): Request

  /**

_2019-09-29_

 *  Fix: Cancel calls that fail due to unexpected exceptions. We had a bug where an enqueued call
    would never call back if it crashed with an unchecked throwable, such as a
    `NullPointerException` or `OutOfMemoryError`. We now call `Callback.onFailure()` with an
    `IOException` that reports the call as canceled. The triggering exception is still delivered to
    the thread's `UncaughtExceptionHandler`.

    check(exchange == null) { "Timeouts can't be adjusted in a network interceptor" }

    return copy(writeTimeoutMillis = checkDuration("writeTimeout", timeout.toLong(), unit))
  }

  override fun call(): Call = call

  override fun request(): Request = request

  @Throws(IOException::class)
  override fun proceed(request: Request): Response {
    check(index < interceptors.size)

    calls++

    route: Route,
    call: Call,
  ) {}

  /**
   * Invoked when a connection fails to be established.
   */
  open fun connectFailed(
    route: Route,
    call: Call,
    failure: IOException,
  ) {}

  /**
   * Invoked as soon as a connection is successfully established.
   */
  open fun connectEnd(
    connection: Connection,
    route: Route,
    call: Call,
  ) {}

  /**

 * Prefer to alternate IP addresses from different address families, (IPv6 / IPv4), starting with IPv6.
 * Don't start a new attempt until 250 ms after the most recent attempt was started.
 * Keep whichever TCP connection succeeds first and cancel all the others.
 * Race TCP only. Only attempt a TLS handshake on the winning TCP connection.

    val client =
      OkHttpClient.Builder()
        .connectionPool(poolApi)
        .build()
    val call = client.newCall(Request(addressA.url)) as RealCall
    call.enterNetworkInterceptorExchange(call.request(), true, factory.newChain(call))
    c1.withLock { call.acquireConnectionNoEvents(c1) }

    // Running at time 50, the pool returns that nothing can be evicted until time 150.

    val routes = mutableListOf<Route>()
    while (hasNextProxy()) {
      // Postponed routes are always tried last. For example, if we have 2 proxies and all the
      // routes for proxy1 should be postponed, we'll move to proxy2. Only after we've exhausted
      // all the good routes will we attempt the postponed routes.
      val proxy = nextProxy()
      for (inetSocketAddress in inetSocketAddresses) {

          call: Call,
          e: IOException,
        ) {
          latch.countDown()
        }

        override fun onResponse(
          call: Call,
          response: Response,
        ) {
          fail("")
        }
      },
    )
    assertThat(server.takeRequest().sequenceNumber)
      .isEqualTo(expectedSequenceNumber)
    responseDequeuedLatch!!.await()
    call.cancel()

 * until [nextPart] returns null. After calling [nextPart] any preceding parts should not be read.
 *
 * Typical use loops over the parts in sequence:
 *
 * ```kotlin
 * val response: Response = call.execute()
 * val multipartReader = MultipartReader(response.body!!)
 *
 * multipartReader.use {
 *   while (true) {
 *     val part = multipartReader.nextPart() ?: break
 *     process(part.headers, part.body)
 *   }

    /** Do this task's work, and then start another, such as by calling [startNextTask]. */
    fun start()
  }

  private object TestThreadSerialTask : SerialTask {
    override fun start() = error("unexpected call")
  }

  inner class RunnableSerialTask(
    private val runnable: Runnable,
  ) : SerialTask {
    override fun start() {
      taskRunner.assertThreadHoldsLock()
      require(currentTask == this)