1// Copyright 2014 The Chromium Authors. All rights reserved. 2// Use of this source code is governed by a BSD-style license that can be 3// found in the LICENSE file. 4 5#ifndef COMPONENTS_KEYED_SERVICE_CONTENT_REFCOUNTED_BROWSER_CONTEXT_KEYED_SERVICE_H_ 6#define COMPONENTS_KEYED_SERVICE_CONTENT_REFCOUNTED_BROWSER_CONTEXT_KEYED_SERVICE_H_ 7 8#include "base/memory/ref_counted.h" 9#include "base/sequenced_task_runner_helpers.h" 10#include "components/keyed_service/core/keyed_service_export.h" 11#include "content/public/browser/browser_thread.h" 12 13class RefcountedBrowserContextKeyedService; 14 15namespace impl { 16 17struct KEYED_SERVICE_EXPORT RefcountedBrowserContextKeyedServiceTraits { 18 static void Destruct(const RefcountedBrowserContextKeyedService* obj); 19}; 20 21} // namespace impl 22 23// Base class for refcounted objects that hang off the BrowserContext. 24// 25// The two pass shutdown described in KeyedService works a bit differently 26// because there could be outstanding references on other threads. 27// ShutdownOnUIThread() will be called on the UI thread, and then the 28// destructor will run when the last reference is dropped, which may or may not 29// be after the corresponding BrowserContext has been destroyed. 30// 31// Optionally, if you initialize your service with the constructor that takes a 32// thread ID, your service will be deleted on that thread. We can't use 33// content::DeleteOnThread<> directly because 34// RefcountedBrowserContextKeyedService must be one type that 35// RefcountedBrowserContextKeyedServiceFactory can use. 36class KEYED_SERVICE_EXPORT RefcountedBrowserContextKeyedService 37 : public base::RefCountedThreadSafe< 38 RefcountedBrowserContextKeyedService, 39 impl::RefcountedBrowserContextKeyedServiceTraits> { 40 public: 41 // Unlike KeyedService, ShutdownOnUI is not optional. You must do something 42 // to drop references during the first pass Shutdown() because this is the 43 // only point where you are guaranteed that something is running on the UI 44 // thread. The PKSF framework will ensure that this is only called on the UI 45 // thread; you do not need to check for that yourself. 46 virtual void ShutdownOnUIThread() = 0; 47 48 protected: 49 // If your service does not need to be deleted on a specific thread, use the 50 // default constructor. 51 RefcountedBrowserContextKeyedService(); 52 53 // If you need your service to be deleted on a specific thread (for example, 54 // you're converting a service that used content::DeleteOnThread<IO>), then 55 // use this constructor with the ID of the thread. 56 explicit RefcountedBrowserContextKeyedService( 57 const content::BrowserThread::ID thread_id); 58 59 // The second pass destruction can happen anywhere unless you specify which 60 // thread this service must be destroyed on by using the second constructor. 61 virtual ~RefcountedBrowserContextKeyedService(); 62 63 private: 64 friend struct impl::RefcountedBrowserContextKeyedServiceTraits; 65 friend class base::DeleteHelper<RefcountedBrowserContextKeyedService>; 66 friend class base::RefCountedThreadSafe< 67 RefcountedBrowserContextKeyedService, 68 impl::RefcountedBrowserContextKeyedServiceTraits>; 69 70 // Do we have to delete this object on a specific thread? 71 bool requires_destruction_on_thread_; 72 content::BrowserThread::ID thread_id_; 73}; 74 75#endif // COMPONENTS_KEYED_SERVICE_CONTENT_REFCOUNTED_BROWSER_CONTEXT_KEYED_SERVICE_H_ 76