components/browser_context_keyed_service/browser_context_keyed_service_factory.h

   1 // Copyright (c) 2012 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_BROWSER_CONTEXT_KEYED_SERVICE_BROWSER_CONTEXT_KEYED_SERVICE_FACTORY_H_
   6 #define COMPONENTS_BROWSER_CONTEXT_KEYED_SERVICE_BROWSER_CONTEXT_KEYED_SERVICE_FACTORY_H_
   7
   8 #include <map>
   9
  10 #include "base/basictypes.h"
  11 #include "base/compiler_specific.h"
  12 #include "components/browser_context_keyed_service/browser_context_keyed_base_factory.h"
  13 #include "components/browser_context_keyed_service/browser_context_keyed_service.h"
  14 #include "components/browser_context_keyed_service/browser_context_keyed_service_export.h"
  15
  16 class BrowserContextDependencyManager;
  17 class BrowserContextKeyedService;
  18
  19 // Base class for Factories that take a BrowserContext object and return some
  20 // service on a one-to-one mapping. Each factory that derives from this class
  21 // *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 BROWSER_CONTEXT_KEYED_SERVICE_EXPORT BrowserContextKeyedServiceFactory
  27     : public BrowserContextKeyedBaseFactory {
  28  public:
  29   // A function that supplies the instance of a BrowserContextKeyedService
  30   // for a given BrowserContext. This is used primarily for testing, where
  31   // we want to feed a specific mock into the BCKSF system.
  32   typedef BrowserContextKeyedService*
  33       (*FactoryFunction)(content::BrowserContext* context);
  34
  35   // Associates |factory| with |context| so that |factory| is used to create
  36   // the BrowserContextKeyedService when requested.  |factory| can be NULL
  37   // to signal that BrowserContextKeyedService should be NULL. Multiple calls to
  38   // SetTestingFactory() are allowed; previous services will be shut down.
  39   void SetTestingFactory(content::BrowserContext* context,
  40                          FactoryFunction factory);
  41
  42   // Associates |factory| with |context| and immediately returns the created
  43   // BrowserContextKeyedService. Since the factory will be used immediately,
  44   // it may not be NULL.
  45   BrowserContextKeyedService* SetTestingFactoryAndUse(
  46       content::BrowserContext* context,
  47       FactoryFunction factory);
  48
  49  protected:
  50   // BrowserContextKeyedServiceFactories must communicate with a
  51   // BrowserContextDependencyManager. For all non-test code, write your subclass
  52   // constructors like this:
  53   //
  54   //   MyServiceFactory::MyServiceFactory()
  55   //     : BrowserContextKeyedServiceFactory(
  56   //         "MyService",
  57   //         BrowserContextDependencyManager::GetInstance())
  58   //   {}
  59   BrowserContextKeyedServiceFactory(const char* name,
  60                                     BrowserContextDependencyManager* manager);
  61   virtual ~BrowserContextKeyedServiceFactory();
  62
  63   // Common implementation that maps |context| to some service object. Deals
  64   // with incognito contexts per subclass instructions with
  65   // GetBrowserContextRedirectedInIncognito() and
  66   // GetBrowserContextOwnInstanceInIncognito() through the
  67   // GetBrowserContextToUse() method on the base.  If |create| is true, the
  68   // service will be created using BuildServiceInstanceFor() if it doesn't
  69   // already exist.
  70   BrowserContextKeyedService* GetServiceForBrowserContext(
  71       content::BrowserContext* context,
  72       bool create);
  73
  74   // Maps |context| to |service| with debug checks to prevent duplication.
  75   void Associate(content::BrowserContext* context,
  76                  BrowserContextKeyedService* service);
  77
  78   // All subclasses of BrowserContextKeyedServiceFactory must return a
  79   // BrowserContextKeyedService instead of just a BrowserContextKeyedBase.
  80   virtual BrowserContextKeyedService* BuildServiceInstanceFor(
  81       content::BrowserContext* context) const = 0;
  82
  83   // A helper object actually listens for notifications about BrowserContext
  84   // destruction, calculates the order in which things are destroyed and then
  85   // does a two pass shutdown.
  86   //
  87   // First, BrowserContextShutdown() is called on every ServiceFactory and will
  88   // usually call BrowserContextKeyedService::Shutdown(), which gives each
  89   // BrowserContextKeyedService a chance to remove dependencies on other
  90   // services that it may be holding.
  91   //
  92   // Secondly, BrowserContextDestroyed() is called on every ServiceFactory
  93   // and the default implementation removes it from |mapping_| and deletes
  94   // the pointer.
  95   virtual void BrowserContextShutdown(
  96       content::BrowserContext* context) OVERRIDE;
  97   virtual void BrowserContextDestroyed(
  98       content::BrowserContext* context) OVERRIDE;
  99
 100   virtual void SetEmptyTestingFactory(
 101       content::BrowserContext* context) OVERRIDE;
 102   virtual void CreateServiceNow(content::BrowserContext* context) OVERRIDE;
 103
 104  private:
 105   friend class BrowserContextDependencyManager;
 106   friend class BrowserContextDependencyManagerUnittests;
 107
 108   typedef std::map<content::BrowserContext*, BrowserContextKeyedService*>
 109       BrowserContextKeyedServices;
 110   typedef std::map<content::BrowserContext*, FactoryFunction>
 111       BrowserContextOverriddenFunctions;
 112
 113   // The mapping between a BrowserContext and its service.
 114   std::map<content::BrowserContext*, BrowserContextKeyedService*> mapping_;
 115
 116   // The mapping between a BrowserContext and its overridden FactoryFunction.
 117   std::map<content::BrowserContext*, FactoryFunction> factories_;
 118
 119   DISALLOW_COPY_AND_ASSIGN(BrowserContextKeyedServiceFactory);
 120 };
 121
 122 #endif  // COMPONENTS_BROWSER_CONTEXT_KEYED_SERVICE_BROWSER_CONTEXT_KEYED_SERVICE_FACTORY_H_