24, 26, 23, 26, 27, 26, 26, 27, 27, 27, 27, 27, 28, 27, 27, 27, 27, 27, 26,
    )

  private val root = Node()

  init {
    for (i in CODE_BIT_COUNTS.indices) {
      addCode(i, CODES[i], CODE_BIT_COUNTS[i].toInt())
    }
  }

  @Throws(IOException::class)
  fun encode(
    source: ByteString,
    sink: BufferedSink,
  ) {
    var accumulator = 0L

    // Compute the next set of routes to attempt.
    val routes = mutableListOf<Route>()
    while (hasNextProxy()) {
      // Postponed routes are always tried last. For example, if we have 2 proxies and all the
      // routes for proxy1 should be postponed, we'll move to proxy2. Only after we've exhausted
      // all the good routes will we attempt the postponed routes.
      val proxy = nextProxy()

In OkHttp some fields of the address come from the URL (scheme, hostname, port) and the rest come from the [OkHttpClient](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-ok-http-client/).

### [Routes](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-route/)

 *     a race in fast follow-up.
 *
 *  4. If there's no existing connection, make a list of routes (which may require blocking DNS
 *     lookups) and attempt a new connection them. When failures occur, retries iterate the list of
 *     available routes.
 *
 * If the pool gains an eligible connection while DNS, TCP, or TLS work is in flight, this finder

      Headers.Builder()
        .add("foo: bar")
        .add(" foo: baz") // Name leading whitespace is trimmed.
        .add("foo : bak") // Name trailing whitespace is trimmed.
        .add("\tkey\t:\tvalue\t") // '\t' also counts as whitespace
        .add("ping:  pong  ") // Value whitespace is trimmed.
        .add("kit:kat") // Space after colon is not required.
        .build()
    assertThat(headers.values("foo")).containsExactly("bar", "baz", "bak")

    server.enqueue(MockResponse(socketPolicy = DisconnectAtStart))
    server.enqueue(MockResponse(socketPolicy = DisconnectAtStart))

    client =
      client.newBuilder()
        .dns(DoubleInetAddressDns()) // Two routes so we get two failures.
        .build()

    val request = Request(server.url("/"))
    assertFailsWith<IOException> {
      client.newCall(request).execute()
    }.also { expected ->

  val responses = mutableListOf<Response>()
  val routes = mutableListOf<Route>()

  fun onlyResponse() = responses.single()

  fun onlyRoute() = routes.single()

  @Throws(IOException::class)
  override fun authenticate(
    route: Route?,
    response: Response,
  ): Request? {
    if (route == null) throw NullPointerException("route == null")
    responses += response
    routes += route

package okhttp3.internal.connection

import okhttp3.Route

/**
 * A denylist of failed routes to avoid when creating a new connection to a target address. This is
 * used so that OkHttp can learn from its mistakes: if there was a failure attempting to connect to
 * a specific IP address or proxy server, that failure is remembered and alternate routes are
 * preferred.
 */
class RouteDatabase {
  private val _failedRoutes = mutableSetOf<Route>()

 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package okhttp3.internal.connection

import java.io.IOException

/** Attempt routes one at a time until one connects. */
internal class SequentialExchangeFinder(
  override val routePlanner: RoutePlanner,
) : ExchangeFinder {
  override fun find(): RealConnection {
    var firstException: IOException? = null

  queue: TaskQueue,
  message: String,
) {
  fine("${queue.name} ${String.format("%-22s", message)}: ${task.name}")
}

/**
 * Returns a duration in the nearest whole-number units like "999 µs" or "  1 s ". This rounds 0.5
 * units away from 0 and 0.499 towards 0. The smallest unit this returns is "µs"; the largest unit
 * it returns is "s". For values in [-499..499] this returns "  0 µs".
 *