Framing rules make it impractical to implement http/2 correctly on a single blocking thread. The flow-control features introduce feedback between reads and writes, requiring writes to acknowledge reads and reads to throttle writes.

In OkHttp we expose a blocking API over a framed protocol. This document explains the code and policy that makes that work.

  private var nextTcpConnectAtNanos = Long.MIN_VALUE

  /**
   * Plans currently being connected, and that will later be added to [connectResults]. This is
   * mutated by the call thread only. If is accessed by background connect threads.
   */
  private val tcpConnectsInFlight = CopyOnWriteArrayList<Plan>()

  /**
   * Results are posted here as they occur. The find job is done when either one plan completes

import okhttp3.internal.okHttpName

/**
 * A set of tasks that are executed in sequential order.
 *
 * Work within queues is not concurrent. This is equivalent to each queue having a dedicated thread
 * for its work; in practice a set of queues may share a set of threads to save resources.
 */
class TaskQueue internal constructor(
  internal val taskRunner: TaskRunner,
  internal val name: String,
) {
  val lock: ReentrantLock = ReentrantLock()

 * Support asynchronous disconnects by breaking the socket only. This should
   prevent flakiness from multiple threads concurrently accessing a stream.

## Version 1.5.3

_2014-03-29_

 * Fix bug where the Content-Length header was not always dropped when
   following a redirect from a POST to a GET.
 * Implement basic support for `Thread.interrupt()`. OkHttp now checks
   for an interruption before doing a blocking call. If it is interrupted,

      takeEvent()
    }
  }

  private fun logEvent(e: ConnectionEvent) {
    if (e.connection != null) {
      assertThat(Thread.holdsLock(e.connection), "Called with lock $${e.connection}")
        .isFalse()
    }
    for (lock in forbiddenLocks) {
      assertThat(Thread.holdsLock(lock), "Called with lock $lock")
        .isFalse()
    }

    if (enforceOrder) {
      checkForStartEvent(e)
    }

 *
 *  * For asynchronous calls made with [Call.enqueue], an [IOException] is propagated to the caller
 *    indicating that the call was canceled. The interceptor's exception is delivered to the current
 *    thread's [uncaught exception handler][Thread.UncaughtExceptionHandler]. By default this
 *    crashes the application on Android and prints a stacktrace on the JVM. (Crash reporting
 *    libraries may customize this behavior.)
 *

 *
 */
package mockwebserver3.internal

internal fun sleepNanos(nanos: Long) {
  val ms = nanos / 1_000_000L
  val ns = nanos - (ms * 1_000_000L)
  if (ms > 0L || nanos > 0) {
    Thread.sleep(ms, ns.toInt())
  }

   * proceed to read the response body with [Response.body]. The response is still live until its
   * response body is [closed][ResponseBody]. The recipient of the callback may consume the response
   * body on another thread.
   *
   * Note that transport-layer success (receiving a HTTP response code, headers and body) does not
   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP

      assertSetEquals(
        "seqno=$testCase.seqno",
        testCase.headersList,
        hpackReader.getAndResetHeaderList(),
      )
    }
  }

  companion object {
    /**
     * Reads all stories in the folders provided, asserts if no story found.
     */
    @JvmStatic
    protected fun createStories(interopTests: Array<String>): List<Any> {
      if (interopTests.isEmpty()) return listOf<Any>(Story.MISSING)

   * [reader]. For example, if the reader's peeked tag isn't readable by this adapter, it may return
   * a default value.
   *
   * If this does read a value, it starts with the tag and length, and reads an entire value,
   * including any potential composed values.
   *
   * If there's nothing to read and no default value, this will throw an exception.
   */
  fun fromDer(reader: DerReader): T