var idleAtNs = Long.MAX_VALUE

  /**
   * Returns true if this is an HTTP/2 connection. Such connections can be used in multiple HTTP
   * requests simultaneously.
   */
  internal val isMultiplexed: Boolean
    get() = http2Connection != null

  /** Prevent further exchanges from being created on this connection. */
  override fun noNewExchanges() {

    )
  }

  /**
   * Holding the lock of the connection being added or removed when mutating this, and check its
   * [RealConnection.noNewExchanges] property. This defends against races where a connection is
   * simultaneously adopted and removed.
   */
  private val connections = ConcurrentLinkedQueue<RealConnection>()

  init {
    // Put a floor on the keep alive duration, otherwise cleanup will spin loop.

 * Since connections may be reused, the proxy selection, DNS, and connect events may not be present
 * for a call. In future releases of OkHttp these events may also occur concurrently to permit
 * multiple routes to be attempted simultaneously.
 *
 * Events and sequences of events may be repeated for retries and follow-ups.
 *
 * All event methods must execute fast, without external locking, cannot throw exceptions, attempt

   * The reason why this stream was closed, or null if it closed normally or has not yet been
   * closed.
   *
   * If there are multiple reasons to abnormally close this stream (such as both peers closing it
   * near-simultaneously) then this is the first reason known to this peer.
   */
  internal var errorCode: ErrorCode? = null
    get() = this.withLock { field }

Use an HTTP POST to send a request body to a service. This example posts a markdown document to a web service that renders markdown as HTML. Because the entire request body is in memory simultaneously, avoid posting large (greater than 1 MiB) documents using this API.

=== ":material-language-kotlin: Kotlin"
    ```kotlin
      private val client = OkHttpClient()

      fun run() {

    assertEvents(
      "plan 3 TCP connect canceled",
    )

    taskFaker.assertNoMoreTasks()
  }

  /**
   * This test causes two connections to become available simultaneously, one from a TCP connect and
   * one from the pool. We must take the pooled connection because by taking it from the pool, we've
   * fully acquired it.
   *

 *  **OkHttp now supports duplex calls over HTTP/2.** With normal HTTP calls the request must finish
    before the response starts. With duplex, request and response bodies are transmitted
    simultaneously. This can be used to implement interactive conversations within a single HTTP
    call.

    Create duplex calls by overriding the new `RequestBody.isDuplex()` method to return true.

## Dispatch

For synchronous calls, you bring your own thread and are responsible for managing how many simultaneous requests you make. Too many simultaneous connections wastes resources; too few harms latency.

 * typically false on Windows.
 *
 * If this returns false we won't permit simultaneous reads and writes. When writes commit we need
 * to delete the previous snapshots, and that won't succeed if the file is open. (We do permit
 * multiple simultaneous reads.)
 *
 * @param file a file in the directory to check. This file shouldn't already exist!
 */