components/keyed_service/core/dependency_manager.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_DEPENDENCY_MANAGER_H_
   6 #define COMPONENTS_KEYED_SERVICE_CORE_DEPENDENCY_MANAGER_H_
   7
   8 #include <string>
   9
  10 #include "components/keyed_service/core/dependency_graph.h"
  11 #include "components/keyed_service/core/keyed_service_export.h"
  12
  13 #ifndef NDEBUG
  14 #include <set>
  15 #endif
  16
  17 class KeyedServiceBaseFactory;
  18
  19 namespace base {
  20 class FilePath;
  21 class SupportsUserData;
  22 }
  23
  24 namespace user_prefs {
  25 class PrefRegistrySyncable;
  26 }
  27
  28 // DependencyManager manages dependency between KeyedServiceBaseFactory
  29 // broadcasting the context creation and destruction to each factory in
  30 // a safe order based on the stated dependencies.
  31 class KEYED_SERVICE_EXPORT DependencyManager {
  32  protected:
  33   DependencyManager();
  34   virtual ~DependencyManager();
  35
  36   // Adds/Removes a component from our list of live components. Removing will
  37   // also remove live dependency links.
  38   void AddComponent(KeyedServiceBaseFactory* component);
  39   void RemoveComponent(KeyedServiceBaseFactory* component);
  40
  41   // Adds a dependency between two factories.
  42   void AddEdge(KeyedServiceBaseFactory* depended,
  43                KeyedServiceBaseFactory* dependee);
  44
  45   // Registers preferences for all services via |registry| associated with
  46   // |context| (the association is managed by the embedder). The |context|
  47   // is used as a key to prevent multiple registration during tests.
  48   void RegisterPrefsForServices(const base::SupportsUserData* context,
  49                                 user_prefs::PrefRegistrySyncable* registry);
  50
  51   // Called upon creation of |context| to create services that want to be
  52   // started at the creation of a context and register service-related
  53   // preferences.
  54   //
  55   // To have a KeyedService started when a context is created the method
  56   // KeyedServiceBaseFactory::ServiceIsCreatedWithContext() must be overridden
  57   // to return true.
  58   //
  59   // If |is_testing_context| then the service will not be started unless the
  60   // method KeyedServiceBaseFactory::ServiceIsNULLWhileTesting() return false.
  61   void CreateContextServices(base::SupportsUserData* context,
  62                              bool is_testing_context);
  63
  64   // Called upon destruction of |context| to destroy all services associated
  65   // with it.
  66   void DestroyContextServices(base::SupportsUserData* context);
  67
  68 #ifndef NDEBUG
  69   // Debugging assertion called as part of GetServiceForContext() in debug
  70   // mode. This will NOTREACHED() whenever the |context| is considered stale.
  71   void AssertContextWasntDestroyed(const base::SupportsUserData* context);
  72
  73   // Marks |context| as live (i.e., not stale). This method can be called as a
  74   // safeguard against |AssertContextWasntDestroyed()| checks going off due to
  75   // |context| aliasing am instance from a prior test (i.e., 0xWhatever might
  76   // be created, be destroyed, and then a new object might be created at
  77   // 0xWhatever).
  78   void MarkContextLiveForTesting(const base::SupportsUserData* context);
  79
  80   // Dumps service dependency graph as a Graphviz dot file |dot_file| with a
  81   // title |top_level_name|. Helper for |DumpContextDependencies|.
  82   void DumpDependenciesAsGraphviz(const std::string& top_level_name,
  83                                   const base::FilePath& dot_file) const;
  84 #endif  // NDEBUG
  85
  86  private:
  87   friend class KeyedServiceBaseFactory;
  88
  89 #ifndef NDEBUG
  90   // Hook for subclass to dump the dependency graph of service for |context|.
  91   virtual void DumpContextDependencies(
  92       const base::SupportsUserData* context) const = 0;
  93 #endif  // NDEBUG
  94
  95   DependencyGraph dependency_graph_;
  96
  97 #ifndef NDEBUG
  98   // A list of context objects that have gone through the Shutdown() phase.
  99   // These pointers are most likely invalid, but we keep track of their
 100   // locations in memory so we can nicely assert if we're asked to do anything
 101   // with them.
 102   std::set<const base::SupportsUserData*> dead_context_pointers_;
 103 #endif  // NDEBUG
 104 };
 105
 106 #endif  // COMPONENTS_KEYED_SERVICE_CORE_DEPENDENCY_MANAGER_H_