chrome/browser/chromeos/policy/user_cloud_external_data_manager.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 CHROME_BROWSER_CHROMEOS_POLICY_USER_CLOUD_EXTERNAL_DATA_MANAGER_H_
   6 #define CHROME_BROWSER_CHROMEOS_POLICY_USER_CLOUD_EXTERNAL_DATA_MANAGER_H_
   7
   8 #include "base/basictypes.h"
   9 #include "base/files/file_path.h"
  10 #include "base/memory/ref_counted.h"
  11 #include "chrome/browser/chromeos/policy/cloud_external_data_manager_base.h"
  12 #include "components/policy/core/common/policy_details.h"
  13
  14 namespace base {
  15 class SequencedTaskRunner;
  16 }
  17
  18 namespace policy {
  19
  20 class CloudPolicyStore;
  21 class ResourceCache;
  22
  23 // Downloads, verifies, caches and retrieves external data referenced by
  24 // policies.
  25 // This is the implementation for regular users on Chrome OS. The code would
  26 // work on desktop platforms as well but for now, is used on Chrome OS only
  27 // because no other platform has policies referencing external data.
  28 class UserCloudExternalDataManager : public CloudExternalDataManagerBase {
  29  public:
  30   // |get_policy_details| is used to determine the maximum size that the
  31   // data referenced by each policy can have. Download scheduling, verification,
  32   // caching and retrieval tasks are done via the |backend_task_runner|, which
  33   // must support file I/O. Network I/O is done via the |io_task_runner|. The
  34   // manager is responsible for external data references by policies in
  35   // |policy_store|.
  36   UserCloudExternalDataManager(
  37       const GetChromePolicyDetailsCallback& get_policy_details,
  38       scoped_refptr<base::SequencedTaskRunner> backend_task_runner,
  39       scoped_refptr<base::SequencedTaskRunner> io_task_runner,
  40       const base::FilePath& cache_path,
  41       CloudPolicyStore* policy_store);
  42   ~UserCloudExternalDataManager() override;
  43
  44  private:
  45   // Cache used to store downloaded external data. The |resource_cache_| is
  46   // owned by the manager but its destruction must be handled with care:
  47   // * The manager owns a |backend_| which owns an |external_data_store_| which
  48   //   uses the |resource_cache_|. The |external_data_store_| must be destroyed
  49   //   before the |resource_cache_|.
  50   // * After construction, |backend_|, |external_data_store_| and
  51   //   |resource_cache_| can only be accessed through the
  52   //   |backend_task_runner_|.
  53   //
  54   // It follows that in order to destroy |resource_cache_|, the manager must
  55   // take the following steps:
  56   // * Post a task to the |backend_task_runner_| that will tell the |backend_|
  57   //   to destroy the |external_data_store_|.
  58   // * Post a task to the |backend_task_runner_| that will destroy the
  59   //   |resource_cache_|.
  60   // Because of this destruction sequence, a scoped_ptr cannot be used.
  61   ResourceCache* resource_cache_;
  62
  63   DISALLOW_COPY_AND_ASSIGN(UserCloudExternalDataManager);
  64 };
  65
  66 }  // namespace policy
  67
  68 #endif  // CHROME_BROWSER_CHROMEOS_POLICY_USER_CLOUD_EXTERNAL_DATA_MANAGER_H_