gecko-dev/dom/localstorage/LSObserver.h

69 lines
2.1 KiB
C++

/* -*- 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_localstorage_LSObserver_h
#define mozilla_dom_localstorage_LSObserver_h
#include "mozilla/Assertions.h"
#include "nsISupports.h"
#include "nsString.h"
namespace mozilla::dom {
class LSObserverChild;
/**
* Effectively just a refcounted life-cycle management wrapper around
* LSObserverChild which exists to receive "storage" event information from
* other processes. (Same-process events are handled within the process, see
* `LSObject::OnChange`.)
*
* ## Lifecycle ##
* - Created by LSObject::EnsureObserver via synchronous LSRequest idiom
* whenever the first window's origin adds a "storage" event. Placed in the
* gLSObservers LSObserverHashtable for subsequent LSObject's via
* LSObserver::Get lookup.
* - The LSObserverChild directly handles "Observe" messages, shunting them
* directly to Storage::NotifyChange which does all the legwork of notifying
* windows about "storage" events.
* - Destroyed when refcount goes to zero due to all owning LSObjects being
* destroyed or having their `LSObject::DropObserver` methods invoked due to
* the last "storage" event listener being removed from the owning window.
*/
class LSObserver final {
friend class LSObject;
LSObserverChild* mActor;
const nsCString mOrigin;
public:
static LSObserver* Get(const nsACString& aOrigin);
NS_INLINE_DECL_REFCOUNTING(LSObserver)
void AssertIsOnOwningThread() const { NS_ASSERT_OWNINGTHREAD(LSObserver); }
void SetActor(LSObserverChild* aActor);
void ClearActor() {
AssertIsOnOwningThread();
MOZ_ASSERT(mActor);
mActor = nullptr;
}
private:
// Only created by LSObject.
explicit LSObserver(const nsACString& aOrigin);
~LSObserver();
};
} // namespace mozilla::dom
#endif // mozilla_dom_localstorage_LSObserver_h