| // 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_CORE_REFCOUNTED_KEYED_SERVICE_H_ |
| #define COMPONENTS_KEYED_SERVICE_CORE_REFCOUNTED_KEYED_SERVICE_H_ |
| |
| #include "base/memory/ref_counted.h" |
| #include "base/sequenced_task_runner.h" |
| #include "base/sequenced_task_runner_helpers.h" |
| #include "components/keyed_service/core/keyed_service_export.h" |
| |
| class RefcountedKeyedService; |
| |
| namespace impl { |
| |
| struct KEYED_SERVICE_EXPORT RefcountedKeyedServiceTraits { |
| static void Destruct(const RefcountedKeyedService* 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 |
| // SequencedTaskRunner, your service will be deleted on that sequence. We |
| // can't use content::DeleteOnThread<> directly because RefcountedKeyedService |
| // must not depend on //content. |
| class KEYED_SERVICE_EXPORT RefcountedKeyedService |
| : public base::RefCountedThreadSafe<RefcountedKeyedService, |
| impl::RefcountedKeyedServiceTraits> { |
| 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 sequence, use the |
| // default constructor. |
| RefcountedKeyedService(); |
| |
| // If you need your service to be deleted on a specific sequence (for example, |
| // you're converting a service that used content::DeleteOnThread<IO>), then |
| // use this constructor with a reference to the SequencedTaskRunner (e.g., you |
| // can get it from base::CreateSequencedTaskRunnerWithTraits). |
| explicit RefcountedKeyedService( |
| scoped_refptr<base::SequencedTaskRunner> task_runner); |
| |
| // The second pass destruction can happen anywhere unless you specify which |
| // sequence this service must be destroyed on by using the second constructor. |
| virtual ~RefcountedKeyedService(); |
| |
| private: |
| friend struct impl::RefcountedKeyedServiceTraits; |
| friend class base::DeleteHelper<RefcountedKeyedService>; |
| friend class base::RefCountedThreadSafe<RefcountedKeyedService, |
| impl::RefcountedKeyedServiceTraits>; |
| |
| // Do we have to delete this object on a specific sequence? |
| scoped_refptr<base::SequencedTaskRunner> task_runner_; |
| }; |
| |
| #endif // COMPONENTS_KEYED_SERVICE_CORE_REFCOUNTED_KEYED_SERVICE_H_ |