fun connectionPreface() {
    this.withLock {
      if (closed) throw IOException("closed")
      if (!client) return // Nothing to write; servers don't send connection headers!
      if (logger.isLoggable(FINE)) {
        logger.fine(format(">> CONNECTION ${CONNECTION_PREFACE.hex()}"))
      }
      sink.write(CONNECTION_PREFACE)
      sink.flush()
    }
  }

  /** Applies `peerSettings` and then sends a settings ACK. */

            startNextTask()
          }
        }
      }
    }
  }

  /**
   * This blocking queue hooks into a fake clock rather than using regular JVM timing for functions
   * like [poll]. It is only usable within task faker tasks.
   */
  private inner class TaskFakerBlockingQueue<T>(
    val delegate: BlockingQueue<T>,
  ) : AbstractQueue<T>(), BlockingQueue<T> {

   * is sent unencrypted to the proxy server, so tunnels include only the minimum set of headers.
   * This avoids sending potentially sensitive data like HTTP cookies to the proxy unencrypted.
   *
   * In order to support preemptive authentication we pass a fake "Auth Failed" response to the

  // performed while holding this lock!
  //
  // Socket writes are guarded by frameWriter.
  //
  // Socket reads are unguarded but are only made by the reader thread.
  //
  // Certain operations (like SYN_STREAM) need to synchronize on both the frameWriter (to do
  // blocking I/O) and this (to create streams). Such operations must synchronize on 'this' last.

      sink.finished -> throw IOException("stream finished")
      errorCode != null -> throw errorException ?: StreamResetException(errorCode!!)
    }
  }

  /**
   * Like [Object.wait], but throws an [InterruptedIOException] when interrupted instead of the more
   * awkward [InterruptedException].
   */
  @Throws(InterruptedIOException::class)
  internal fun waitForIo() {
    try {

      "FINE: Q10000 scheduled after 100 µs: task",
      "FINE: Q10000 starting              : task",
      "FINE: Q10000 run again after  50 µs: task",
      "FINE: Q10000 finished run in   0 µs: task",
      "FINE: Q10000 starting              : task",
      "FINE: Q10000 run again after 150 µs: task",
      "FINE: Q10000 finished run in   0 µs: task",
      "FINE: Q10000 starting              : task",

internal class FastFallbackExchangeFinderTest {
  private val taskFaker = TaskFaker()
  private val taskRunner = taskFaker.taskRunner

  /**
   * Note that we don't use the same [TaskFaker] for this factory. That way off-topic tasks like
   * connection pool maintenance tasks don't add noise to route planning tests.
   */
  private val routePlanner = FakeRoutePlanner(taskFaker = taskFaker)
  private val finder = FastFallbackExchangeFinder(routePlanner, taskRunner)

  }

  /**
   * When writing a set of headers fails due to an `IOException`, make sure the writer is left
   * in a consistent state so the next writer also gets an `IOException` also instead of
   * something worse (like an [IllegalStateException].
   *
   *
   * See https://github.com/square/okhttp/issues/1651
   */
  @Test fun socketExceptionWhileWritingHeaders() {
    peer.acceptFrame() // SYN_STREAM.
    peer.play()