### 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.

#### Http2Stream

        when {
          it.sourceCodePoint1 < codePoint -> -1
          it.sourceCodePoint0 > codePoint -> 1
          else -> 0
        }
      }

    // Code points must be in 0..0x10ffff.
    require(index in mappings.indices) { "unexpected code point: $codePoint" }

    val mapping = mappings[index]
    var result = true

    when (mapping.type) {
      TYPE_IGNORED -> Unit

   * explicitly closed.
   */
  fun truncateLastFrame(length: Int): Http2Writer {
    val lastFrame = outFrames.removeAt(outFrames.size - 1)
    require(length < bytesOut.size - lastFrame.start)

    // Move everything from bytesOut into a new buffer.
    val fullBuffer = Buffer()
    bytesOut.read(fullBuffer, bytesOut.size)

some connectivity failures. In this case, the `connectFailed()` event is not terminal and not followed by `callFailed()`. Event listeners will receive multiple events of the same type when retries are attempted.

A single HTTP call may require follow-up requests to be made to handle authentication challenges, redirects, and HTTP-layer timeouts. In such cases multiple connections, requests, and responses may be attempted. Follow-ups are another reason a single call may trigger multiple events...

  method: String,
  body: RequestBody?,
): Request.Builder =
  apply {
    require(method.isNotEmpty()) {
      "method.isEmpty() == true"
    }
    if (body == null) {
      require(!HttpMethod.requiresRequestBody(method)) {
        "method $method must have a request body."
      }
    } else {
      require(HttpMethod.permitsRequestBody(method)) {
        "method $method must not have a request body."

  val defaultValue: T? = null,
  /** True to set the encoded or decoded value as the type hint for the current SEQUENCE. */
  private val typeHint: Boolean = false,
) : DerAdapter<T> {
  init {
    require(tagClass >= 0)
    require(tag >= 0)
  }

  override fun matches(header: DerHeader): Boolean = header.tagClass == tagClass && header.tag == tag

  override fun fromDer(reader: DerReader): T {

  }

  /**
   * Returns non-null if we don't need to wait for the launched result. In such cases, this result
   * must be processed before whatever is waiting in the queue because we may have already acquired
   * its connection.
   */
  private fun launchTcpConnect(): ConnectResult? {
    val plan =
      when {
        routePlanner.hasNext() -> {
          try {
            routePlanner.plan()

 * accept and which to reject. A reasonable policy is to reject all cookies, though that may
 * interfere with session-based authentication schemes that require cookies.
 *
 * As persistence, implementations of this interface must also provide storage of cookies. Simple
 * implementations may store cookies in memory; sophisticated ones may use the file system or

 * sequence. Returns the unescaped string, or null if the buffer isn't prefixed with a
 * double-quoted string.
 */
@Throws(EOFException::class)
private fun Buffer.readQuotedString(): String? {
  require(readByte() == '\"'.code.toByte())
  val result = Buffer()
  while (true) {
    val i = indexOfElement(QUOTED_STRING_DELIMITERS)
    if (i == -1L) return null // Unterminated quoted string.

  return null
}

internal fun Headers.Builder.commonBuild(): Headers = Headers(namesAndValues.toTypedArray())

internal fun headersCheckName(name: String) {
  require(name.isNotEmpty()) { "name is empty" }
  for (i in name.indices) {
    val c = name[i]
    require(c in '\u0021'..'\u007e') {
      "Unexpected char 0x${c.charCode()} at $i in header name: $name"
    }
  }
}

internal fun headersCheckValue(