components/policy/core/common/schema_registry.h

   1 // Copyright 2013 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_POLICY_CORE_COMMON_SCHEMA_REGISTRY_H_
   6 #define COMPONENTS_POLICY_CORE_COMMON_SCHEMA_REGISTRY_H_
   7
   8 #include <set>
   9
  10 #include "base/basictypes.h"
  11 #include "base/compiler_specific.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/observer_list.h"
  14 #include "base/threading/non_thread_safe.h"
  15 #include "components/policy/core/common/policy_namespace.h"
  16 #include "components/policy/core/common/schema.h"
  17 #include "components/policy/core/common/schema_map.h"
  18 #include "components/policy/policy_export.h"
  19
  20 namespace policy {
  21
  22 class SchemaMap;
  23
  24 // Holds the main reference to the current SchemaMap, and allows a list of
  25 // observers to get notified whenever it is updated.
  26 // This object is not thread safe and must be used from the owner's thread,
  27 // usually UI.
  28 class POLICY_EXPORT SchemaRegistry : public base::NonThreadSafe {
  29  public:
  30   class POLICY_EXPORT Observer {
  31    public:
  32     // Invoked whenever schemas are registered or unregistered.
  33     // |has_new_schemas| is true if a new component has been registered since
  34     // the last update; this allows observers to ignore updates when
  35     // components are unregistered but still get a handle to the current map
  36     // (e.g. for periodic reloads).
  37     virtual void OnSchemaRegistryUpdated(bool has_new_schemas) = 0;
  38
  39     // Invoked when all policy domains become ready.
  40     virtual void OnSchemaRegistryReady() {}
  41
  42    protected:
  43     virtual ~Observer();
  44   };
  45
  46   // This observer is only meant to be used by subclasses.
  47   class POLICY_EXPORT InternalObserver {
  48    public:
  49     // Invoked when |registry| is about to be destroyed.
  50     virtual void OnSchemaRegistryShuttingDown(SchemaRegistry* registry) = 0;
  51
  52    protected:
  53     virtual ~InternalObserver();
  54   };
  55
  56   SchemaRegistry();
  57   virtual ~SchemaRegistry();
  58
  59   const scoped_refptr<SchemaMap>& schema_map() const { return schema_map_; }
  60
  61   // Register a single component.
  62   void RegisterComponent(const PolicyNamespace& ns,
  63                          const Schema& schema);
  64
  65   // Register a list of components for a given domain.
  66   virtual void RegisterComponents(PolicyDomain domain,
  67                                   const ComponentMap& components);
  68
  69   virtual void UnregisterComponent(const PolicyNamespace& ns);
  70
  71   // Returns true if all domains have registered the initial components.
  72   bool IsReady() const;
  73
  74   // This indicates that the initial components for |domain| have all been
  75   // registered. It must be invoked at least once for each policy domain;
  76   // subsequent calls for the same domain are ignored.
  77   void SetReady(PolicyDomain domain);
  78
  79   void AddObserver(Observer* observer);
  80   void RemoveObserver(Observer* observer);
  81
  82   void AddInternalObserver(InternalObserver* observer);
  83   void RemoveInternalObserver(InternalObserver* observer);
  84
  85  protected:
  86   void Notify(bool has_new_schemas);
  87
  88   scoped_refptr<SchemaMap> schema_map_;
  89
  90  private:
  91   base::ObserverList<Observer, true> observers_;
  92   base::ObserverList<InternalObserver, true> internal_observers_;
  93   bool domains_ready_[POLICY_DOMAIN_SIZE];
  94
  95   DISALLOW_COPY_AND_ASSIGN(SchemaRegistry);
  96 };
  97
  98 // A registry that combines the maps of other registries.
  99 class POLICY_EXPORT CombinedSchemaRegistry
 100     : public SchemaRegistry,
 101       public SchemaRegistry::Observer,
 102       public SchemaRegistry::InternalObserver {
 103  public:
 104   CombinedSchemaRegistry();
 105   ~CombinedSchemaRegistry() override;
 106
 107   void Track(SchemaRegistry* registry);
 108
 109   // SchemaRegistry:
 110   void RegisterComponents(PolicyDomain domain,
 111                           const ComponentMap& components) override;
 112   void UnregisterComponent(const PolicyNamespace& ns) override;
 113
 114   // SchemaRegistry::Observer:
 115   void OnSchemaRegistryUpdated(bool has_new_schemas) override;
 116
 117   // SchemaRegistry::InternalObserver:
 118   void OnSchemaRegistryShuttingDown(SchemaRegistry* registry) override;
 119
 120  private:
 121   void Combine(bool has_new_schemas);
 122
 123   std::set<SchemaRegistry*> registries_;
 124   scoped_refptr<SchemaMap> own_schema_map_;
 125
 126   DISALLOW_COPY_AND_ASSIGN(CombinedSchemaRegistry);
 127 };
 128
 129 // A registry that wraps another schema registry.
 130 class POLICY_EXPORT ForwardingSchemaRegistry
 131     : public SchemaRegistry,
 132       public SchemaRegistry::Observer,
 133       public SchemaRegistry::InternalObserver {
 134  public:
 135   // This registry will stop updating its SchemaMap when |wrapped| is
 136   // destroyed.
 137   explicit ForwardingSchemaRegistry(SchemaRegistry* wrapped);
 138   ~ForwardingSchemaRegistry() override;
 139
 140   // SchemaRegistry:
 141   void RegisterComponents(PolicyDomain domain,
 142                           const ComponentMap& components) override;
 143   void UnregisterComponent(const PolicyNamespace& ns) override;
 144
 145   // SchemaRegistry::Observer:
 146   void OnSchemaRegistryUpdated(bool has_new_schemas) override;
 147
 148   // SchemaRegistry::InternalObserver:
 149   void OnSchemaRegistryShuttingDown(SchemaRegistry* registry) override;
 150
 151  private:
 152   SchemaRegistry* wrapped_;
 153
 154   DISALLOW_COPY_AND_ASSIGN(ForwardingSchemaRegistry);
 155 };
 156
 157 }  // namespace policy
 158
 159 #endif  // COMPONENTS_POLICY_CORE_COMMON_SCHEMA_REGISTRY_H_