gecko-dev/netwerk/base/OfflineObserver.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set sw=2 ts=8 et 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 nsOfflineObserver_h__
#define nsOfflineObserver_h__
#include "nsIObserver.h"
namespace mozilla {
namespace net {
/**
* Parents should extend this class and have a RefPtr<OfflineObserver> member.
* The constructor should initialize the member to new OfflineObserver(this)
* and the destructor should call RemoveObserver on the member.
*
* GetAppId and OfflineDisconnect are called from the default implementation
* of OfflineNotification. These should be overridden by classes that don't
* provide an implementation of OfflineNotification.
*/
class DisconnectableParent
{
public:
// This is called on the main thread, by the OfflineObserver.
// aSubject is of type nsAppOfflineInfo and contains appId and offline mode.
virtual nsresult OfflineNotification(nsISupports *aSubject);
// GetAppId returns the appId for the app associated with the parent
virtual uint32_t GetAppId() = 0;
// OfflineDisconnect cancels all existing connections in the parent when
// the app becomes offline.
// Since the offline observer holds a mutex while calling this,
// the implementation must make sure it doesn't call back into OfflineObserver
// or issue a notification for the "network:app-offline-status-changed" topic
virtual void OfflineDisconnect() { }
};
/**
* This class observes the "network:app-offline-status-changed" topic and calls
* OfflineNotification on the DisconnectableParent with the subject.
*/
class OfflineObserver
: public nsIObserver
{
NS_DECL_THREADSAFE_ISUPPORTS
NS_DECL_NSIOBSERVER
public:
// A nsRefPtr to this object should be kept by the disconnectable parent.
explicit OfflineObserver(DisconnectableParent * parent);
// This method needs to be called in the destructor of the parent
// It removes the observer from the nsObserverService list, and it clears
// the pointer it holds to the disconnectable parent.
void RemoveObserver();
private:
// These methods are called to register and unregister the observer.
// If they are called on the main thread they register the observer right
// away, otherwise they dispatch and event to the main thread
void RegisterOfflineObserver();
void RemoveOfflineObserver();
void RegisterOfflineObserverMainThread();
void RemoveOfflineObserverMainThread();
private:
virtual ~OfflineObserver() { }
// This needs to be a raw pointer, or else the parent's destructor
// will not get called
DisconnectableParent * mParent;
// We need to lock this mutex when accessing the value of mParent
mozilla::Mutex mLock;
};
} // namespace net
} // namespace mozilla
#endif // nsOfflineObserver_h__