/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/* 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"

%{C++
// Forward-declare mozilla::net::SpdyPushCache
namespace mozilla {
namespace net {
class SpdyPushCache;
}
}
%}

interface nsILoadGroup;
interface nsIChannel;
interface nsIStreamListener;

[ptr] native SpdyPushCachePtr(mozilla::net::SpdyPushCache);

/**
 * Requests capable of tail-blocking must implement this
 * interfaces (typically channels).
 * If the request is tail-blocked, it will be held in its request
 * context queue until unblocked.
 */
[uuid(7EB361D4-37A5-42C9-AFAE-F6C88FE7C394)]
interface nsIRequestTailUnblockCallback : nsISupports
{
  /**
   * Called when the requests is unblocked and proceed.
   * @param result
   *    NS_OK - the request is OK to go, unblocking is not
   *            caused by cancelation of the request.
   *    any error - the request must behave as it were canceled
   *                with the result as status.
   */
  void onTailUnblock(in nsresult aResult);
};

/**
 * The nsIRequestContext is used to maintain state about connections
 * that are in some way associated with each other (often by being part
 * of the same load group) and how they interact with blocking items like
 * HEAD css/js loads.
 *
 * This used to be known as nsILoadGroupConnectionInfo and nsISchedulingContext.
 */
[uuid(658e3e6e-8633-4b1a-8d66-fa9f72293e63)]
interface nsIRequestContext : nsISupports
{
  /**
   * A unique identifier for this request context
   */
  [notxpcom, nostdcall] readonly attribute unsigned long long ID;

  /**
   * Called by the associated document when its load starts.  This resets
   * context's internal states.
   */
  void beginLoad();

  /**
  * Called when the associated document notified the DOMContentLoaded event.
  */
  void DOMContentLoaded();

  /**
   * Number of active blocking transactions associated with this context
   */
  readonly attribute unsigned long blockingTransactionCount;

  /**
   * Increase the number of active blocking transactions associated
   * with this context by one.
   */
  void addBlockingTransaction();

  /**
   * Decrease the number of active blocking transactions associated
   * with this context by one. The return value is the number of remaining
   * blockers.
   */
  unsigned long removeBlockingTransaction();

  /**
   * This gives out a weak pointer to the push cache.
   * The nsIRequestContext implementation owns the cache
   * and will destroy it when overwritten or when the context
   * ends.
   */
  [notxpcom,nostdcall] attribute SpdyPushCachePtr spdyPushCache;

  /**
   * Increases/decrease the number of non-tailed requests in this context.
   * If the count drops to zero, all tail-blocked callbacks are notified
   * shortly after that to be unblocked.
   */
  void addNonTailRequest();
  void removeNonTailRequest();

  /**
   * If the request context is in tail-blocked state, the callback
   * is queued and result is true.  The callback will be notified
   * about tail-unblocking or when the request context is canceled.
   */
  [must_use] boolean isContextTailBlocked(in nsIRequestTailUnblockCallback callback);

  /**
   * Called when the request is sitting in the tail queue but has been
   * canceled before untailing.  This just removes the request from the
   * queue so that it is not notified on untail and not referenced.
   */
  void cancelTailedRequest(in nsIRequestTailUnblockCallback request);

  /**
   * This notifies all queued tail-blocked requests, they will be notified
   * aResult and released afterwards.  Called by the load group when
   * it's canceled.
   */
  void cancelTailPendingRequests(in nsresult aResult);
};

/**
 * The nsIRequestContextService is how anyone gets access to a request
 * context when they haven't been explicitly given a strong reference to an
 * existing one. It is responsible for creating and handing out strong
 * references to nsIRequestContexts, but only keeps weak references itself.
 * The shared request context will go away once no one else is keeping a
 * reference to it. If you ask for a request context that has no one else
 * holding a reference to it, you'll get a brand new request context. Anyone
 * who asks for the same request context while you're holding a reference
 * will get a reference to the same request context you have.
 */
[uuid(7fcbf4da-d828-4acc-b144-e5435198f727)]
interface nsIRequestContextService : nsISupports
{
  /**
   * Get an existing request context from its ID
   */
  nsIRequestContext getRequestContext(in unsigned long long id);
  /**
   * Shorthand to get request context from a load group
   */
  nsIRequestContext getRequestContextFromLoadGroup(in nsILoadGroup lg);

  /**
   * Create a new request context
   */
  nsIRequestContext newRequestContext();

  /**
   * Remove an existing request context from its ID
   */
  void removeRequestContext(in unsigned long long id);
};