}

    fun flowControlListener(flowControlListener: FlowControlListener) =
      apply {
        this.flowControlListener = flowControlListener
      }

    fun build(): Http2Connection {
      return Http2Connection(this)
    }
  }

  /**
   * Methods in this class must not lock FrameWriter. If a method needs to write a frame, create an
   * async task to do so.
   */

    val http2Connection =
      Http2Connection.Builder(client = true, taskRunner)
        .socket(socket, route.address.url.host, source, sink)
        .listener(this)
        .pingIntervalMillis(pingIntervalMillis)
        .flowControlListener(flowControlListener)
        .build()
    this.http2Connection = http2Connection

    val connection = routePlanner.plans.first().connection
    val http2Connection = connectHttp2(peer, connection, 5)
    setPolicy(pool, address, ConnectionPool.AddressPolicy(5))
    assertThat(pool.connectionCount()).isEqualTo(1)

    // Decrease the connection's max so that another connection is needed
    updateMaxConcurrentStreams(http2Connection, 4)
    assertThat(pool.connectionCount()).isEqualTo(2)

  private fun connect(
    peer: MockHttp2Peer,
    pushObserver: PushObserver = IGNORE,
    listener: Http2Connection.Listener = Http2Connection.Listener.REFUSE_INCOMING_STREAMS,
  ): Http2Connection {
    val connection =
      Http2Connection.Builder(true, TaskRunner.INSTANCE)
        .socket(peer.openSocket())
        .pushObserver(pushObserver)
        .listener(listener)
        .build()

Lokhttp3/internal/http2/Http2Connection$ReaderRunnable$settings$1;
Lokhttp3/internal/http2/Http2Connection$ReaderRunnable;
Lokhttp3/internal/http2/Http2Connection$pushDataLater$1;
Lokhttp3/internal/http2/Http2Connection$pushHeadersLater$1;
Lokhttp3/internal/http2/Http2Connection$pushRequestLater$2;
Lokhttp3/internal/http2/Http2Connection$pushResetLater$1;
Lokhttp3/internal/http2/Http2Connection$sendDegradedPingLater$2;

/** Encode requests and responses using HTTP/2 frames. */
class Http2ExchangeCodec(
  client: OkHttpClient,
  override val carrier: Carrier,
  private val chain: RealInterceptorChain,
  private val http2Connection: Http2Connection,
) : ExchangeCodec {
  @Volatile private var stream: Http2Stream? = null

  private val protocol: Protocol =
    if (Protocol.H2_PRIOR_KNOWLEDGE in client.protocols) {
      Protocol.H2_PRIOR_KNOWLEDGE

import okhttp3.Protocol
import okhttp3.Protocol.Companion.get
import okhttp3.internal.closeQuietly
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.http2.Header
import okhttp3.internal.http2.Http2Connection
import okhttp3.internal.http2.Http2Stream
import okhttp3.internal.platform.Platform
import okhttp3.tls.internal.TlsUtil.localhost
import okio.buffer
import okio.source

import kotlin.concurrent.withLock
import kotlin.contracts.ExperimentalContracts
import kotlin.contracts.InvocationKind
import kotlin.contracts.contract
import okhttp3.Dispatcher
import okhttp3.internal.http2.Http2Connection
import okhttp3.internal.http2.Http2Stream
import okhttp3.internal.http2.Http2Writer

/**
 * Centralisation of central locks according to docs/contribute/concurrency.md
 */
internal object Locks {

              override fun writeTo(sink: BufferedSink) {
                sink.write(postBytes) // push bytes into the stream's buffer
                sink.flush() // Http2Connection.writeData subject to write window
                sink.close() // Http2Connection.writeData empty frame
              }
            },
        ),
      )
    val response = call.execute()
    assertThat(response.body.string()).isEqualTo("ABCDE")

### Locks

We have 3 different things that we synchronize on.

#### Http2Connection

This lock guards internal state of each connection. This lock is never held for blocking operations. That means that we acquire the lock, read or write a few fields and release the lock. No I/O and no application-layer callbacks.