StopGapEventTarget.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

/* vim: set ts=8 sts=2 et sw=2 tw=80: */

/* 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/. */

#ifndef mozilla_StopGapEventTarget_h

#define mozilla_StopGapEventTarget_h

#include "nsISerialEventTarget.h"

#include "nsCOMPtr.h"

#include "nsISupports.h"

#include "nsTArray.h"

#include "mozilla/Mutex.h"

#include "mozilla/Queue.h"

namespace mozilla {

// This is an event target that buffers events until a "real" event target is

// connected to it. This is for situations where events must be dispatched, but

// we don't know *where* yet.

// Note: GetCurrentSerialEventTarget and friends will return the *real* event

// target for tasks that are dispatched to this.

class StopGapEventTarget final : public nsISerialEventTarget {

 public:

  StopGapEventTarget();

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_DECL_NSIEVENTTARGET_FULL

  // Call this when you know the real event target. Dispatches all queued

  // events right away, and passes subsequent events straight through.

  nsresult SetRealEventTarget(nsISerialEventTarget* aRealEventTarget);

 private:

  virtual ~StopGapEventTarget();

  typedef struct TaskStruct {

    nsCOMPtr<nsIRunnable> event;

    nsIEventTarget::DispatchFlags flags;

  } TaskStruct;

  Mutex mMutex;

  nsCOMPtr<nsISerialEventTarget> mRealEventTarget MOZ_GUARDED_BY(mMutex);

  nsTArray<TaskStruct> mTasks MOZ_GUARDED_BY(mMutex);

};

}  // namespace mozilla

#endif  // mozilla_StopGapEventTarget_h