chrome/browser/chromeos/policy/cloud_external_data_store.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_CLOUD_EXTERNAL_DATA_STORE_H_
   6 #define CHROME_BROWSER_CHROMEOS_POLICY_CLOUD_EXTERNAL_DATA_STORE_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/memory/ref_counted.h"
  12 #include "components/policy/core/common/cloud/cloud_external_data_manager.h"
  13
  14 namespace base {
  15 class SequencedTaskRunner;
  16 }
  17
  18 namespace policy {
  19
  20 class ResourceCache;
  21
  22 // Stores external data referenced by policies. Data is keyed by (policy, hash),
  23 // the name of the policy referencing it and its SHA1 hash. Outdated entries are
  24 // removed by calling Prune() with the list of (policy, hash) entries that are
  25 // to be kept. Instances of this class may be created on any thread and may
  26 // share the same cache, however:
  27 // * After creation, the cache and all stores using it must always be accessed
  28 //   via the same |task_runner| only.
  29 // * Stores sharing a cache must use different cache_keys to avoid namespace
  30 //   overlaps.
  31 // * The cache must outlive all stores using it.
  32 class CloudExternalDataStore {
  33  public:
  34   CloudExternalDataStore(const std::string& cache_key,
  35                          scoped_refptr<base::SequencedTaskRunner> task_runner,
  36                          ResourceCache* cache);
  37   ~CloudExternalDataStore();
  38
  39   // Removes all entries from the store whose (policy, hash) pair is not found
  40   // in |metadata|.
  41   void Prune(const CloudExternalDataManager::Metadata& metadata);
  42
  43   // Stores |data| under (policy, hash). Returns true if the store succeeded.
  44   bool Store(const std::string& policy,
  45              const std::string& hash,
  46              const std::string& data);
  47
  48   // Loads the entry at (policy, hash) into |data|, verifies that it does not
  49   // exceed |max_size| and matches the expected |hash|, then returns true.
  50   // Returns false if no entry is found at (policy, hash), there is a problem
  51   // during the load, the entry exceeds |max_size| or does not match |hash|.
  52   bool Load(const std::string& policy,
  53             const std::string& hash,
  54             size_t max_size,
  55             std::string* data);
  56
  57  private:
  58   std::string cache_key_;
  59
  60   // Task runner that |this| runs on.
  61   scoped_refptr<base::SequencedTaskRunner> task_runner_;
  62
  63   ResourceCache* cache_;  // Not owned.
  64
  65   DISALLOW_COPY_AND_ASSIGN(CloudExternalDataStore);
  66 };
  67
  68 }  // namespace policy
  69
  70 #endif  // CHROME_BROWSER_CHROMEOS_POLICY_CLOUD_EXTERNAL_DATA_STORE_H_