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/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

/**
 * nsIClassOfService.idl
 *
 * Used to express class dependencies and characteristics - complimentary to
 * nsISupportsPriority which is used to express weight
 *
 * Channels that implement this interface may make use of this
 * information in different ways.
 *
 * The default gecko HTTP/1 stack makes Followers wait for Leaders to
 * complete before dispatching followers. Other classes run in
 * parallel - neither being blocked nor blocking. All grouping is done
 * based on the Load Group - separate load groups proceed
 * independently.
 *
 * HTTP/2 does not use the load group, but prioritization is done per
 * HTTP/2 session. HTTP/2 dispatches all the requests as soon as
 * possible.
 * The various classes are assigned logical priority
 * dependency groups and then transactions of that class depend on the
 * group. In this model Followers block on Leaders and Speculative
 * depends on Background. See Http2Stream.cpp for weighting details.
 *
 */

[scriptable, uuid(1ccb58ec-5e07-4cf9-a30d-ac5490d23b41)]
interface nsIClassOfService : nsISupports
{
  attribute unsigned long classFlags;

  void clearClassFlags(in unsigned long flags);
  void addClassFlags(in unsigned long flags);

  const unsigned long Leader = 1 << 0;
  const unsigned long Follower = 1 << 1;
  const unsigned long Speculative = 1 << 2;
  const unsigned long Background = 1 << 3;
  const unsigned long Unblocked = 1 << 4;
  const unsigned long Throttleable = 1 << 5;
  const unsigned long UrgentStart = 1 << 6;
  const unsigned long DontThrottle = 1 << 7;
  // Enforce tailing on this load; any of Leader, Unblocked, UrgentStart, TailForbidden
  // overrule this flag (disable tailing.)
  const unsigned long Tail = 1 << 8;
  // Tailing may be engaged regardless if the load is marked Unblocked when
  // some other conditions are met later, like when the load is found to be
  // a tracker.
  const unsigned long TailAllowed = 1 << 9;
  // Tailing not allowed under any circumstances or combination of flags.
  const unsigned long TailForbidden = 1 << 10;
};