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- // Copyright 2019 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_SIMPLE_KEYED_SERVICE_FACTORY_H_
- #define COMPONENTS_KEYED_SERVICE_CORE_SIMPLE_KEYED_SERVICE_FACTORY_H_
- #include <memory>
- #include "base/compiler_specific.h"
- #include "components/keyed_service/core/keyed_service_export.h"
- #include "components/keyed_service/core/keyed_service_factory.h"
- class KeyedService;
- class SimpleDependencyManager;
- class SimpleFactoryKey;
- // Base class for Factories that take a SimpleFactoryKey object and return some
- // service on a one-to-one mapping. Each factory that derives from this class
- // *must* be a Singleton (only unit tests don't do that).
- //
- // We do this because services depend on each other and we need to control
- // shutdown/destruction order. In each derived classes' constructors, the
- // implementors must explicitly state on which services they depend.
- //
- // Note:
- // The SimpleKeyedServiceFactory (SKSF) provides a way to create or get a
- // SimpleKeyedService before BrowserContext is created.
- // BrowserContextKeyedServiceFactories (BCKSFs) can only be converted to
- // SKSFs as long as they access only part of Profile properties:
- // path, PrefService, and is_off_the_record flag.
- //
- // An SKSF shouldn't declare DependsOn() of any BCKSF on creation (constructor).
- // It is because an SKSF can't depend on any BCKSF when it is created. However,
- // dependencies from SKSFs to BCKSFs may exist after full browser launches,
- // since some SimpleKeyedServices move from "reduced mode" to "full browser
- // mode" when the full browser starts up, which involves injection of
- // BrowserContextKeyedService dependencies into the SimpleKeyedService.
- //
- // If such dependencies exist in a SimpleKeyedService, the service **MUST**
- // explicitly reset/clean up the dependencies in KeyedService::Shutdown().
- //
- // Once the dependencies are reset, the dependencies from the BCKSF dependency
- // graph to the SKSF dependency graph are removed. Therefore, we adopt a
- // two-phase shutdown:
- // - Shutdown of all BCKSFactories
- // - Shutdown of all SKSFactories
- // - Destruction of all BCKSFactories
- // - Destruction of all SKSFactories
- // A SimpleKeyedService should *AVOID* full browser inflation whenever it is
- // possible. A solution might be splitting the part of the service that
- // depends on BrowserContextKeyedService or BrowserContext into a separate
- // BrowserContextKeyedService.
- //
- // See
- // https://docs.google.com/document/d/1caWonaPnBhMb6sk4syNe0BbdsQih13S6QmDW237Mcrg/edit?usp=sharing
- // for more details.
- class KEYED_SERVICE_EXPORT SimpleKeyedServiceFactory
- : public KeyedServiceFactory {
- public:
- // A callback that supplies the instance of a KeyedService for a given
- // SimpleFactoryKey. This is used primarily for testing, where we want to feed
- // a specific test double into the SKSF system.
- using TestingFactory = base::RepeatingCallback<std::unique_ptr<KeyedService>(
- SimpleFactoryKey* key)>;
- SimpleKeyedServiceFactory(const SimpleKeyedServiceFactory&) = delete;
- SimpleKeyedServiceFactory& operator=(const SimpleKeyedServiceFactory&) =
- delete;
- // Associates |testing_factory| with |key| so that |testing_factory| is
- // used to create the KeyedService when requested. |testing_factory| can be
- // empty to signal that KeyedService should be null. Multiple calls to
- // SetTestingFactory() are allowed; previous services will be shut down.
- void SetTestingFactory(SimpleFactoryKey* key, TestingFactory testing_factory);
- // Associates |testing_factory| with |key| and immediately returns the
- // created KeyedService. Since the factory will be used immediately, it may
- // not be empty.
- KeyedService* SetTestingFactoryAndUse(SimpleFactoryKey* key,
- TestingFactory testing_factory);
- protected:
- SimpleKeyedServiceFactory(const char* name, SimpleDependencyManager* manager);
- ~SimpleKeyedServiceFactory() override;
- // Common implementation that maps |key| to some service object. Deals
- // with incognito contexts per subclass instructions with
- // GetBrowserContextRedirectedInIncognito() and
- // GetBrowserContextOwnInstanceInIncognito() through the
- // GetBrowserContextToUse() method on the base. If |create| is true, the
- // service will be created using BuildServiceInstanceFor() if it doesn't
- // already exist.
- KeyedService* GetServiceForKey(SimpleFactoryKey* key,
- bool create);
- // Interface for people building a concrete FooServiceFactory: --------------
- // Finds which SimpleFactoryKey (if any) to use.
- virtual SimpleFactoryKey* GetKeyToUse(SimpleFactoryKey* key) const;
- // Interface for people building a type of SimpleKeyedFactory: -------
- // All subclasses of SimpleKeyedServiceFactory must return a
- // KeyedService.
- virtual std::unique_ptr<KeyedService> BuildServiceInstanceFor(
- SimpleFactoryKey* key) const = 0;
- // A helper object actually listens for notifications about BrowserContext
- // destruction, calculates the order in which things are destroyed and then
- // does a two pass shutdown.
- //
- // First, SimpleContextShutdown() is called on every ServiceFactory and will
- // usually call KeyedService::Shutdown(), which gives each
- // KeyedService a chance to remove dependencies on other
- // services that it may be holding.
- //
- // Secondly, SimpleContextDestroyed() is called on every ServiceFactory
- // and the default implementation removes it from |mapping_| and deletes
- // the pointer.
- virtual void SimpleContextShutdown(SimpleFactoryKey* key);
- virtual void SimpleContextDestroyed(SimpleFactoryKey* key);
- private:
- // Registers any user preferences on this service. This is called by
- // RegisterPrefsIfNecessaryForContext() and should be overriden by any service
- // that wants to register profile-specific preferences.
- virtual void RegisterProfilePrefs(
- user_prefs::PrefRegistrySyncable* registry) {}
- // KeyedServiceFactory:
- std::unique_ptr<KeyedService> BuildServiceInstanceFor(
- void* context) const final;
- bool IsOffTheRecord(void* context) const final;
- // KeyedServiceBaseFactory:
- void* GetContextToUse(void* context) const final;
- bool ServiceIsCreatedWithContext() const final;
- void ContextShutdown(void* context) final;
- void ContextDestroyed(void* context) final;
- void RegisterPrefs(user_prefs::PrefRegistrySyncable* registry) final;
- void SetEmptyTestingFactory(void* context) final;
- bool HasTestingFactory(void* context) final;
- void CreateServiceNow(void* context) final;
- };
- #endif // COMPONENTS_KEYED_SERVICE_CORE_SIMPLE_KEYED_SERVICE_FACTORY_H_
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