* 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.

 * by holding a lock on the connection.
 */
class RealConnection(
  val taskRunner: TaskRunner,
  val connectionPool: RealConnectionPool,
  override val route: Route,
  /** The low-level TCP socket. */
  private var rawSocket: Socket?,
  /**
   * The application layer socket. Either an [SSLSocket] layered over [rawSocket], or [rawSocket]
   * itself if this connection does not use SSL.
   */

import okio.BufferedSink
import okio.BufferedSource
import okio.buffer
import okio.sink
import okio.source

/**
 * A single attempt to connect to a remote server, including these steps:
 *
 *  * [TCP handshake][connectSocket]
 *  * Optional [CONNECT tunnels][connectTunnel]. When using an HTTP proxy to reach an HTTPS server
 *    we must send a `CONNECT` request, and handle authorization challenges from the proxy.

        if (connectResult == null) {
          connectResult = awaitTcpConnect(awaitTimeoutNanos, TimeUnit.NANOSECONDS) ?: continue
        }

        if (connectResult.isSuccess) {
          // We have a connected TCP connection. Cancel and defer the racing connects that all lost.
          cancelInFlightConnects()

          // Finish connecting. We won't have to if the winner is from the connection pool.

      check(connectState == ConnectState.READY)
      events += "plan $id TCP connecting..."

      taskFaker.sleep(tcpConnectDelayNanos)

      if (yieldBeforeTcpConnectReturns) {
        taskFaker.yield()
      }

      return when {
        tcpConnectThrowable != null -> {
          events += "plan $id TCP connect failed"

Similarly, the reader thread must never block on writing because this can deadlock the connection. Consider a client and server that both violate this rule. If you get unlucky, they could fill up their TCP buffers (so that writes block) and then use their reader threads to write a frame. Nobody is reading on either end, and the buffers are never drained.

#### Do-stuff-later pool

    assertThat(get("h3")).isEqualTo(Protocol.HTTP_3)
    assertThat(get("h3-29")).isEqualTo(Protocol.HTTP_3)
  }

  @Test
  fun testGetUnknown() {
    assertThrows(IOException::class.java) { get("tcp") }
  }

  @Test
  fun testToString() {
    assertThat(Protocol.HTTP_1_0.toString()).isEqualTo("http/1.0")
    assertThat(Protocol.HTTP_1_1.toString()).isEqualTo("http/1.1")

 *     lookups) and attempt a new connection them. When failures occur, retries iterate the list of
 *     available routes.
 *
 * If the pool gains an eligible connection while DNS, TCP, or TLS work is in flight, this finder
 * will prefer pooled connections. Only pooled HTTP/2 connections are used for such de-duplication.
 *
 * It is possible to cancel the finding process by canceling its call.
 *

     * otherwise values must be between 1 and [Integer.MAX_VALUE] when converted to milliseconds.
     *
     * The connect timeout is applied when connecting a TCP socket to the target host. The default
     * value is 10 seconds.
     */
    fun connectTimeout(
      timeout: Long,
      unit: TimeUnit,
    ) = apply {

   * this address.
   *
   * If [planToReplace] is non-null, this will swap it for a pooled connection if that pooled
   * connection uses HTTP/2. That results in fewer sockets overall and thus fewer TCP slow starts.
   */
  internal fun planReusePooledConnection(
    planToReplace: ConnectPlan? = null,
    routes: List<Route>? = null,
  ): ReusePlan? {
    val result =