Bug 1413606 P1 Add ClientThing base class. r=baku

/* -*- 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_dom_ClientThing_h

#define _mozilla_dom_ClientThing_h

#include "nsTArray.h"

namespace mozilla {

namespace dom {

// Base class representing various Client "things" such as ClientHandle,

// ClientSource, and ClientManager.  Currently it provides a common set

// of code for handling activation and shutdown of IPC actors.

template <typename ActorType>

class ClientThing

{

  ActorType* mActor;

  bool mShutdown;

protected:

  ClientThing()

    : mActor(nullptr)

    , mShutdown(false)

  {

  }

  ~ClientThing()

  {

    ShutdownThing();

  }

  // Return the current actor.

  ActorType*

  GetActor() const

  {

    return mActor;

  }

  // Returns true if ShutdownThing() has been called.

  bool

  IsShutdown() const

  {

    return mShutdown;

  }

  // Conditionally execute the given callable based on the current state.

  template<typename Callable>

  void

  MaybeExecute(const Callable& aCallable)

  {

    if (mShutdown) {

      return;

    }

    MOZ_DIAGNOSTIC_ASSERT(mActor);

    aCallable(mActor);

  }

  // Attach activate the thing by attaching its underlying IPC actor.  This

  // will make the thing register as the actor's owner as well.  The actor

  // must call RevokeActor() to clear this weak back reference before its

  // destroyed.

  void

  ActivateThing(ActorType* aActor)

  {

    MOZ_DIAGNOSTIC_ASSERT(aActor);

    MOZ_DIAGNOSTIC_ASSERT(!mActor);

    MOZ_DIAGNOSTIC_ASSERT(!mShutdown);

    mActor = aActor;

    mActor->SetOwner(this);

  }

  // Start destroying the underlying actor and disconnect the thing.

  void

  ShutdownThing()

  {

    if (mShutdown) {

      return;

    }

    mShutdown = true;

    // If we are shutdown before the actor, then clear the weak references

    // between the actor and the thing.

    if (mActor) {

      mActor->RevokeOwner(this);

      mActor->MaybeStartTeardown();

      mActor = nullptr;

    }

  }

public:

  // Clear the weak references between the thing and its IPC actor.

  void

  RevokeActor(ActorType* aActor)

  {

    MOZ_DIAGNOSTIC_ASSERT(mActor);

    MOZ_DIAGNOSTIC_ASSERT(mActor == aActor);

    mActor->RevokeOwner(this);

    mActor = nullptr;

  }

};

} // namespace dom

} // namespace mozilla

#endif // _mozilla_dom_ClientThing_h

  'ClientInfo.h',

  'ClientIPCUtils.h',

  'ClientState.h',

  'ClientThing.h',

]

UNIFIED_SOURCES += [