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      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_ASYNC_POLICY_PROVIDER_H_
      6 #define COMPONENTS_POLICY_CORE_COMMON_ASYNC_POLICY_PROVIDER_H_
      7 
      8 #include "base/cancelable_callback.h"
      9 #include "base/memory/ref_counted.h"
     10 #include "base/memory/scoped_ptr.h"
     11 #include "base/memory/weak_ptr.h"
     12 #include "base/threading/non_thread_safe.h"
     13 #include "components/policy/core/common/configuration_policy_provider.h"
     14 #include "components/policy/policy_export.h"
     15 
     16 namespace base {
     17 class MessageLoopProxy;
     18 }
     19 
     20 namespace policy {
     21 
     22 class AsyncPolicyLoader;
     23 class PolicyBundle;
     24 class SchemaRegistry;
     25 
     26 // A policy provider that loads its policies asynchronously on a background
     27 // thread. Platform-specific providers are created by passing an implementation
     28 // of AsyncPolicyLoader to a new AsyncPolicyProvider.
     29 class POLICY_EXPORT AsyncPolicyProvider : public ConfigurationPolicyProvider,
     30                                           public base::NonThreadSafe {
     31  public:
     32   // The AsyncPolicyProvider does a synchronous load in its constructor, and
     33   // therefore it needs the |registry| at construction time. The same |registry|
     34   // should be passed later to Init().
     35   AsyncPolicyProvider(SchemaRegistry* registry,
     36                       scoped_ptr<AsyncPolicyLoader> loader);
     37   virtual ~AsyncPolicyProvider();
     38 
     39   // ConfigurationPolicyProvider implementation.
     40   virtual void Init(SchemaRegistry* registry) OVERRIDE;
     41   virtual void Shutdown() OVERRIDE;
     42   virtual void RefreshPolicies() OVERRIDE;
     43 
     44  private:
     45   // Helper for RefreshPolicies().
     46   void ReloadAfterRefreshSync();
     47 
     48   // Invoked with the latest bundle loaded by the |loader_|.
     49   void OnLoaderReloaded(scoped_ptr<PolicyBundle> bundle);
     50 
     51   // Callback passed to the loader that it uses to pass back the current policy
     52   // bundle to the provider. This is invoked on the background thread and
     53   // forwards to OnLoaderReloaded() on the loop that owns the provider,
     54   // if |weak_this| is still valid.
     55   static void LoaderUpdateCallback(scoped_refptr<base::MessageLoopProxy> loop,
     56                                    base::WeakPtr<AsyncPolicyProvider> weak_this,
     57                                    scoped_ptr<PolicyBundle> bundle);
     58 
     59   // The |loader_| that does the platform-specific policy loading. It lives
     60   // on the background thread but is owned by |this|.
     61   AsyncPolicyLoader* loader_;
     62 
     63   // Callback used to synchronize RefreshPolicies() calls with the background
     64   // thread. See the implementation for the details.
     65   base::CancelableClosure refresh_callback_;
     66 
     67   // Used to get a WeakPtr to |this| for the update callback given to the
     68   // loader.
     69   base::WeakPtrFactory<AsyncPolicyProvider> weak_factory_;
     70 
     71   DISALLOW_COPY_AND_ASSIGN(AsyncPolicyProvider);
     72 };
     73 
     74 }  // namespace policy
     75 
     76 #endif  // COMPONENTS_POLICY_CORE_COMMON_ASYNC_POLICY_PROVIDER_H_
     77