## HTTP/2 Connections

The HttpURLConnection API is a blocking API. You make a blocking write to send a request, and a blocking read to receive the response.

#### Blocking APIs

    assumeTrue(Build.VERSION.SDK_INT >= 23)

    val request = Request.Builder().url("http://squareup.com/robots.txt").build()

    try {
      client.newCall(request).execute()
      fail<Any>("expected cleartext blocking")
    } catch (_: java.net.UnknownServiceException) {
    }
  }

  data class HowsMySslResults(
    val unknown_cipher_suite_supported: Boolean,
    val beast_vuln: Boolean,

 * Fix bug where the Content-Length header was not always dropped when
   following a redirect from a POST to a GET.
 * Implement basic support for `Thread.interrupt()`. OkHttp now checks
   for an interruption before doing a blocking call. If it is interrupted,
   it throws an `InterruptedIOException`.

## Version 1.5.2

_2014-03-17_

 * Fix bug where deleting a file that was absent from the `HttpResponseCache`
   caused an IOException.

        } finally {
          taskRunner.lock.withLock {
            activeThreads--
            startNextTask()
          }
        }
      }
    }
  }

  /**
   * This blocking queue hooks into a fake clock rather than using regular JVM timing for functions
   * like [poll]. It is only usable within task faker tasks.
   */
  private inner class TaskFakerBlockingQueue<T>(

  // Internal state of this connection is guarded by 'lock'. No blocking operations may be
  // performed while holding this lock!
  //
  // Socket writes are guarded by frameWriter.
  //
  // Socket reads are unguarded but are only made by the reader thread.
  //
  // Certain operations (like SYN_STREAM) need to synchronize on both the frameWriter (to do

 *     failed connect attempts (such as trying the next [ConnectionSpec]), or as attempts that lost
 *     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.
 *

configured to fall back for broad connectivity.

Using OkHttp is easy. Its request/response API is designed with fluent builders and immutability. It
supports both synchronous blocking calls and async calls with callbacks.


Get a URL
---------

This program downloads a URL and prints its contents as a string. [Full source][get_example].

```java
OkHttpClient client = new OkHttpClient();

    val pooled1 = planReusePooledConnection()
    if (pooled1 != null) return pooled1

    // Attempt a deferred plan before new routes.
    if (deferredPlans.isNotEmpty()) return deferredPlans.removeFirst()

    // Do blocking calls to plan a route for a new connection.
    val connect = planConnect()

    // Now that we have a set of IP addresses, make another attempt at getting a connection from

requests, responses, headers, and calls. It uses modern Java patterns like
immutability and chained builders. The API now offers asynchronous callbacks
in addition to synchronous blocking calls.

#### API Changes

 *  **New Request and Response types,** each with their own builder. There's also
    a `RequestBody` class to write the request body to the network and a

  headers: Headers?,
) {
  internal val lock: ReentrantLock = ReentrantLock()
  val condition: Condition = lock.newCondition()

  // Internal state is guarded by [lock]. No long-running or potentially blocking operations are
  // performed while the lock is held.

  /** The bytes consumed and acknowledged by the stream. */
  val readBytes: WindowCounter = WindowCounter(id)