*
 * <p>Except as noted, the orderings returned by the factory methods of this class are serializable
 * if and only if the provided instances that back them are. For example, if {@code ordering} and
 * {@code function} can themselves be serialized, then {@code ordering.onResultOf(function)} can as
 * well.
 *
 * <h3>Java 8+ users</h3>
 *
 * <p>If you are using Java 8+, this class is now obsolete. Most of its functionality is now

  int getHash();

  /** Returns the key for this entry. */
  @Nullable K getKey();

  /*
   * Used by entries that use access order. Access entries are maintained in a doubly-linked list.
   * New entries are added at the tail of the list at write time; stale entries are expired from
   * the head of the list.
   */

  /** Returns the time that this entry was last accessed, in ns. */
  @SuppressWarnings("GoodTime")

/**
 * A semi-persistent mapping from keys to values. Cache entries are manually added using {@link
 * #get(Object, Callable)} or {@link #put(Object, Object)}, and are stored in the cache until either
 * evicted or manually invalidated. The common way to build instances is using {@link CacheBuilder}.
 *
 * <p>Implementations of this interface are expected to be thread-safe, and can be safely accessed
 * by multiple concurrent threads.
 *

   * safe to do so. The exact circumstances under which a copy will or will not be performed are
   * undocumented and subject to change.
   *
   * <p>This method is not type-safe, as it may be called on elements that are not mutually
   * comparable.
   *
   * @throws ClassCastException if the elements are not mutually comparable
   * @throws NullPointerException if any of {@code elements} is null
   */

	<dd>
		You can search any field by typing the field name followed by a colon
		":" and then the term you are looking for. If you want to find
		documents which has "Fess" as the document title, you can enter:
		<pre>title:Fess</pre>
		The available fields are "url", "host", "site", "title", "content",
		"content_length", "last_modified" and "mimetype", and they are
		customizable.
	</dd>
	<dt>Sort</dt>
	<dd>

   * tags are computed.
   */
  fun <T : Any> tag(type: KClass<T>): T?

  /**
   * Returns the tag attached with [type] as a key, or null if no tag is attached with that key.
   *
   * The tags on a call are seeded from the [request tags][Request.tag]. This set will grow if new
   * tags are computed.
   */
  fun <T> tag(type: Class<out T>): T?

  /**

to mitigate the impact.

NOTE: Breaking changes introduced in minor versions are
normally limited to security and bug fixes.
Significant changes in behavior are deprecated in a minor release and
the old behavior is supported until the next major release.
To find out if you are using any deprecated functionality,
enable <<deprecation-logging, deprecation logging>>.
<%
[true, false].each { isNotable ->

allows you to use these configurations arbitrarily. Here are some of the most
common configurations in our build and how we use them:

<dl>
<dt>`implementation`</dt><dd>Dependencies that are used by the project
at compile and runtime but are not exposed as a compile dependency to other dependent projects.
Dependencies added to the `implementation` configuration are considered an implementation detail

 *       <b>This may change in the future.</b>
 * </ul>
 *
 * <h3>Other notes</h3>
 *
 * <ul>
 *   <li>All ranges are shallow-immutable.
 *   <li>Instances of this type are obtained using the static factory methods in this class.
 *   <li>Ranges are <i>convex</i>: whenever two values are contained, all values in between them
 *       must also be contained. More formally, for any {@code c1 <= c2 <= c3} of type {@code C},

#### Http2Writer

Socket writes are guarded by the Http2Writer. Only one stream can write at a time so that messages are not interleaved. Writes are either made by application-layer threads or the do-stuff-later pool.

### Holding multiple locks