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. */
  @Throws(IOException::class)

    // flow-control window is fully depleted.
    if (!flushHeaders) {
      this.withLock {
        flushHeaders = (connection.writeBytesTotal >= connection.writeBytesMaximum)
      }
    }

    connection.writeHeaders(id, outFinished, responseHeaders)

    if (flushHeaders) {
      connection.flush()
    }
  }

    in logs. For best security, don't put sensitive information in query parameters.

 *  New: `ConnectionPool.setPolicy()` configures a minimum connection pool size for a target
    address. Use this to proactively open HTTP connections.

    Connections opened to fulfill this policy are subject to the connection pool's
    `keepAliveDuration` but do not count against the pool-wide `maxIdleConnections` limit.

 */
package okhttp3.internal.connection

import java.io.IOException
import java.util.concurrent.CopyOnWriteArrayList
import java.util.concurrent.LinkedBlockingDeque
import java.util.concurrent.TimeUnit
import okhttp3.internal.concurrent.Task
import okhttp3.internal.concurrent.TaskRunner
import okhttp3.internal.connection.RoutePlanner.ConnectResult
import okhttp3.internal.connection.RoutePlanner.Plan

      }
    } else {
      // The server reads the CONNECTION_PREFACE byte string.
      val connectionPreface = source.readByteString(CONNECTION_PREFACE.size.toLong())
      if (logger.isLoggable(FINE)) logger.fine(format("<< CONNECTION ${connectionPreface.hex()}"))
      if (CONNECTION_PREFACE != connectionPreface) {
        throw IOException("Expected a connection header but was ${connectionPreface.utf8()}")
      }
    }
  }

        val http2SocketHandler = Http2SocketHandler(socket, protocol)
        val connection =
          Http2Connection.Builder(false, taskRunner)
            .socket(socket)
            .listener(http2SocketHandler)
            .build()
        connection.start()
        openConnections.add(connection)
        openClientSockets.remove(socket)
        return
      } else if (protocol !== Protocol.HTTP_1_1) {

    clientListener.assertTextMessage("Hello, WebSockets!")
    closeWebSockets(webSocket, server)
  }

  /**
   * We had a bug where web socket connections were leaked if the HTTP connection upgrade was not
   * successful. This test confirms that connections are released back to the connection pool!
   * https://github.com/square/okhttp/issues/4258
   */
  @Test
  @Throws(Exception::class)
  fun webSocketConnectionIsReleased() {

 * Fix: Respect read timeouts on recycled connections.
 * Fix: Transmit multiple cookie values as a single header with delimiter.
 * Fix: Ensure `null` is never returned from a connection's `getHeaderFields()`.
 * Fix: Persist proper `Content-Encoding` header to cache for GZip responses.
 * Fix: Eliminate rare race condition in SPDY streams that would prevent connection reuse.

  )

  override fun connectEnd(
    connection: Connection,
    route: Route,
    call: Call,
  ) {
    logEvent(ConnectionEvent.ConnectEnd(System.nanoTime(), connection, route, call))
  }

  override fun connectionClosed(connection: Connection) = logEvent(ConnectionEvent.ConnectionClosed(System.nanoTime(), connection))

  override fun connectionAcquired(
    connection: Connection,
    call: Call,
  ) {

_2020-03-08_

 *  Fix: Don't reuse a connection on redirect if certs match but DNS does not. For better
    locality and performance OkHttp attempts to use the same pooled connection across redirects and
    follow-ups. It independently shares connections when the IP addresses and certificates match,
    even if the host names do not. In 4.4.0 we introduced a regression where we shared a connection