0002 0.554 connectionReleased
0002 0.554 callEnd
0001 0.624 responseBodyEnd
0001 0.624 connectionReleased
0001 0.624 callEnd
```

The `EventListener.Factory` also makes it possible to limit metrics to a subset of calls. This one captures metrics on a random 10%:

```java
class MetricsEventListener extends EventListener {
  private static final Factory FACTORY = new Factory() {
    @Override public EventListener create(Call call) {

        .build()
    ```

 *  New: Add `cacheHit`, `cacheMiss`, and `cacheConditionalHit()` events to `EventListener`. Use
    these in logs, metrics, and even test cases to confirm your cache headers are configured as
    expected.

 *  New: Constant string `okhttp3.VERSION`. This is a string like "4.5.0-RC1", "4.5.0", or

 * both.
 *
 * Applications may configure OkHttp with an authenticator for origin servers, or proxy servers,
 * or both.
 *
 * ## Authentication Retries
 *
 * If your authentication may be flaky and requires retries you should apply some policy
 * to limit the retries by the class of errors and number of attempts.  To get the number of
 * attempts to the current point use this function.
 *
 * ```java

## Version 3.14.1

_2019-04-10_

 *  Fix: Don't crash when an interceptor retries when there are no more routes. This was an
    edge-case regression introduced with the events cleanup in 3.14.0.

 *  Fix: Provide actionable advice when the exchange is non-null. Prior to 3.14, OkHttp would
    silently leak connections when an interceptor retries without closing the response body. With

 * limitations under the License.
 */
package okhttp3

import java.io.IOException
import java.net.InetAddress
import java.net.InetSocketAddress
import java.net.Proxy

/**
 * Listener for metrics events. Extend this class to monitor the quantity, size, and duration of
 * your application's HTTP calls.
 *
 * All start/connect/acquire events will eventually receive a matching end/release event, either

  /**
   * Returns the number of bytes required to encode these headers using HTTP/1.1. This is also the
   * approximate size of HTTP/2 headers before they are compressed with HPACK. This value is
   * intended to be used as a metric: smaller headers are more efficient to encode and transmit.
   */
  fun byteCount(): Long {
    // Each header name has 2 bytes of overhead for ': ' and every header value has 2 bytes of
    // overhead for '\r\n'.

events_with_failures_and_retries@2x.png...

  /**
   * Returns a timeout that spans the entire call: resolving DNS, connecting, writing the request
   * body, server processing, and reading the response body. If the call requires redirects or
   * retries all must complete within one timeout period.
   *
   * Configure the client's default timeout with [OkHttpClient.Builder.callTimeout].
   */
  fun timeout(): Timeout

  /**

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

   *
   * https://github.com/square/okhttp/pull/7190
   */
  @Test
  fun preferCallConnectionOverDeferredConnection() {
    // Make sure we have enough connection options to permit retries.
    dnsResults =
      listOf(
        localhostIpv4,
        localhostIpv6,
        TestUtil.UNREACHABLE_ADDRESS_IPV4.address,
      )
    serverIpv4.protocols = listOf(Protocol.H2_PRIOR_KNOWLEDGE)