components/keyed_service/core/keyed_service_factory.h

   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_CORE_KEYED_SERVICE_FACTORY_H_
   6 #define COMPONENTS_KEYED_SERVICE_CORE_KEYED_SERVICE_FACTORY_H_
   7
   8 #include <map>
   9
  10 #include "base/basictypes.h"
  11 #include "base/callback_forward.h"
  12 #include "base/compiler_specific.h"
  13 #include "components/keyed_service/core/keyed_service_base_factory.h"
  14 #include "components/keyed_service/core/keyed_service_export.h"
  15
  16 class DependencyManager;
  17 class KeyedService;
  18
  19 // Base class for Factories that take a base::SupportsUserData object and return
  20 // some service on a one-to-one mapping. Each concrete factory that derives from
  21 // this class *must* be a Singleton (only unit tests don't do that).
  22 //
  23 // We do this because services depend on each other and we need to control
  24 // shutdown/destruction order. In each derived classes' constructors, the
  25 // implementors must explicitly state which services are depended on.
  26 class KEYED_SERVICE_EXPORT KeyedServiceFactory
  27     : public KeyedServiceBaseFactory {
  28  protected:
  29   KeyedServiceFactory(const char* name, DependencyManager* manager);
  30   ~KeyedServiceFactory() override;
  31
  32   // A function that supplies the instance of a KeyedService for a given
  33   // |context|. This is used primarily for testing, where we want to feed
  34   // a specific mock into the KeyedServiceFactory system.
  35   typedef KeyedService* (*TestingFactoryFunction)(
  36       base::SupportsUserData* context);
  37
  38   // Associates |factory| with |context| so that |factory| is used to create
  39   // the KeyedService when requested.  |factory| can be NULL to signal that
  40   // KeyedService should be NULL. Multiple calls to SetTestingFactory() are
  41   // allowed; previous services will be shut down.
  42   void SetTestingFactory(base::SupportsUserData* context,
  43                          TestingFactoryFunction factory);
  44
  45   // Associates |factory| with |context| and immediately returns the created
  46   // KeyedService. Since the factory will be used immediately, it may not be
  47   // NULL.
  48   KeyedService* SetTestingFactoryAndUse(base::SupportsUserData* context,
  49                                         TestingFactoryFunction factory);
  50
  51   // Common implementation that maps |context| to some service object. Deals
  52   // with incognito contexts per subclass instructions with GetContextToUse()
  53   // method on the base.  If |create| is true, the service will be created
  54   // using BuildServiceInstanceFor() if it doesn't already exist.
  55   KeyedService* GetServiceForContext(base::SupportsUserData* context,
  56                                      bool create);
  57
  58   // Maps |context| to |service| with debug checks to prevent duplication.
  59   void Associate(base::SupportsUserData* context, KeyedService* service);
  60
  61   // Removes the mapping from |context| to a service.
  62   void Disassociate(base::SupportsUserData* context);
  63
  64   // Returns a new KeyedService that will be associated with |context|.
  65   virtual KeyedService* BuildServiceInstanceFor(
  66       base::SupportsUserData* context) const = 0;
  67
  68   // Returns whether the |context| is off-the-record or not.
  69   virtual bool IsOffTheRecord(base::SupportsUserData* context) const = 0;
  70
  71   // KeyedServiceBaseFactory:
  72   void ContextShutdown(base::SupportsUserData* context) override;
  73   void ContextDestroyed(base::SupportsUserData* context) override;
  74
  75   void SetEmptyTestingFactory(base::SupportsUserData* context) override;
  76   bool HasTestingFactory(base::SupportsUserData* context) override;
  77   void CreateServiceNow(base::SupportsUserData* context) override;
  78
  79  private:
  80   friend class DependencyManager;
  81   friend class DependencyManagerUnittests;
  82
  83   typedef std::map<base::SupportsUserData*, KeyedService*> KeyedServices;
  84   typedef std::map<base::SupportsUserData*, TestingFactoryFunction>
  85       OverriddenTestingFunctions;
  86
  87   // The mapping between a context and its service.
  88   KeyedServices mapping_;
  89
  90   // The mapping between a context and its overridden
  91   // TestingFactoryFunction.
  92   OverriddenTestingFunctions testing_factories_;
  93
  94   DISALLOW_COPY_AND_ASSIGN(KeyedServiceFactory);
  95 };
  96
  97 #endif  // COMPONENTS_KEYED_SERVICE_CORE_KEYED_SERVICE_FACTORY_H_