*  Fix: Don't crash if a TLS tunnel's response body is truncated.
 *  Fix: Don't track unusable routes beyond their usefulness. We had a bug where we could track
    certain bad routes indefinitely; now we only track the ones that could be necessary.
 *  Fix: Defer proxy selection until a proxy is required. This saves calls to `ProxySelector` on
    calls that use a pooled connection.


## Version 4.3.1

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

import okio.IOException

interface Callback {
  /**
   * Called when the request could not be executed due to cancellation, a connectivity problem or
   * timeout. Because networks can fail during an exchange, it is possible that the remote server
   * accepted the request before the failure.
   */
  fun onFailure(

  /**
   * If true, this connection may not be used for coalesced requests. These are requests that could
   * share the same connection without sharing the same hostname.
   */
  private var noCoalescedConnections = false

  /**
   * The number of times there was a problem establishing a stream that could be due to route
   * chosen. Guarded by this.
   */
  internal var routeFailureCount = 0

          fileToClose = file
          file = null
        }
      }

      fileToClose?.closeQuietly()
    }
  }

  companion object {
    // TODO(jwilson): what to do about timeouts? They could be different and unfortunately when any
    //     timeout is hit we like to tear down the whole stream.

    private const val SOURCE_UPSTREAM = 1
    private const val SOURCE_FILE = 2

    could use new flow control capacity before acknowledging it, causing strict HTTP/2 servers to
    fail the call.

 *  Fix: Recover gracefully when a coalesced connection immediately goes unhealthy.

## Version 3.14.2

_2019-05-19_

 *  Fix: Lock in a route when recovering from an HTTP/2 connection error. We had a bug where two
    calls that failed at the same time could cause OkHttp to crash with a `NoSuchElementException`

   * necessarily indicate application-layer success: `response` may still indicate an unhappy HTTP
   * response code like 404 or 500.
   *
   * @throws IOException if the request could not be executed due to cancellation, a connectivity
   *     problem or timeout. Because networks can fail during an exchange, it is possible that the
   *     remote server accepted the request before the failure.

    ```

 *  **New APIs to permit easy certificate pinning.** Be warned, certificate
    pinning is dangerous and could prevent your application from trusting your
    server!

 *  **Cache improvements.** This release fixes some severe cache problems
    including a bug where the cache could be corrupted upon certain access
    patterns. We also fixed a bug where the cache was being cleared due to a

Similarly, the reader thread must never block on writing because this can deadlock the connection. Consider a client and server that both violate this rule. If you get unlucky, they could fill up their TCP buffers (so that writes block) and then use their reader threads to write a frame. Nobody is reading on either end, and the buffers are never drained.

#### Do-stuff-later pool

 * `server_max_window_bits`. This harms our ability to support these parameters:
 *
 *  * If `client_max_window_bits` is less than 15, OkHttp must close the web socket with code 1010.
 *    Otherwise it would compress values in a way that servers could not decompress.
 *  * If `server_max_window_bits` is less than 15, OkHttp will waste memory on an oversized buffer.
 *
 * See [RFC 7692, 7.1][rfc_7692] for details on negotiation process.
 *

 * Fix problems where spdy/3.1 headers may not have been compressed properly.
 * Fix problems with spdy/3.1 and http/2 where the wrong window size was being
   used.
 * Fix 1.5.0 regression where conditional cache responses could corrupt the
   connection pool.


## Version 1.5.0

_2014-03-07_


##### OkHttp no longer uses the default SSL context.