// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef COMPONENTS_KEYED_SERVICE_CONTENT_REFCOUNTED_BROWSER_CONTEXT_KEYED_SERVICE_H_
#define COMPONENTS_KEYED_SERVICE_CONTENT_REFCOUNTED_BROWSER_CONTEXT_KEYED_SERVICE_H_
#include "base/memory/ref_counted.h"
#include "base/sequenced_task_runner_helpers.h"
#include "components/keyed_service/core/keyed_service_export.h"
#include "content/public/browser/browser_thread.h"
class RefcountedBrowserContextKeyedService;
namespace impl {
struct KEYED_SERVICE_EXPORT RefcountedBrowserContextKeyedServiceTraits {
static void Destruct(const RefcountedBrowserContextKeyedService* obj);
};
} // namespace impl
// Base class for refcounted objects that hang off the BrowserContext.
//
// The two pass shutdown described in KeyedService works a bit differently
// because there could be outstanding references on other threads.
// ShutdownOnUIThread() will be called on the UI thread, and then the
// destructor will run when the last reference is dropped, which may or may not
// be after the corresponding BrowserContext has been destroyed.
//
// Optionally, if you initialize your service with the constructor that takes a
// thread ID, your service will be deleted on that thread. We can't use
// content::DeleteOnThread<> directly because
// RefcountedBrowserContextKeyedService must be one type that
// RefcountedBrowserContextKeyedServiceFactory can use.
class KEYED_SERVICE_EXPORT RefcountedBrowserContextKeyedService
: public base::RefCountedThreadSafe<
RefcountedBrowserContextKeyedService,
impl::RefcountedBrowserContextKeyedServiceTraits> {
public:
// Unlike KeyedService, ShutdownOnUI is not optional. You must do something
// to drop references during the first pass Shutdown() because this is the
// only point where you are guaranteed that something is running on the UI
// thread. The PKSF framework will ensure that this is only called on the UI
// thread; you do not need to check for that yourself.
virtual void ShutdownOnUIThread() = 0;
protected:
// If your service does not need to be deleted on a specific thread, use the
// default constructor.
RefcountedBrowserContextKeyedService();
// If you need your service to be deleted on a specific thread (for example,
// you're converting a service that used content::DeleteOnThread<IO>), then
// use this constructor with the ID of the thread.
explicit RefcountedBrowserContextKeyedService(
const content::BrowserThread::ID thread_id);
// The second pass destruction can happen anywhere unless you specify which
// thread this service must be destroyed on by using the second constructor.
virtual ~RefcountedBrowserContextKeyedService();
private:
friend struct impl::RefcountedBrowserContextKeyedServiceTraits;
friend class base::DeleteHelper<RefcountedBrowserContextKeyedService>;
friend class base::RefCountedThreadSafe<
RefcountedBrowserContextKeyedService,
impl::RefcountedBrowserContextKeyedServiceTraits>;
// Do we have to delete this object on a specific thread?
bool requires_destruction_on_thread_;
content::BrowserThread::ID thread_id_;
};
#endif // COMPONENTS_KEYED_SERVICE_CONTENT_REFCOUNTED_BROWSER_CONTEXT_KEYED_SERVICE_H_