chrome/browser/chromeos/policy/server_backed_state_keys_broker.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 CHROME_BROWSER_CHROMEOS_POLICY_SERVER_BACKED_STATE_KEYS_BROKER_H_
   6 #define CHROME_BROWSER_CHROMEOS_POLICY_SERVER_BACKED_STATE_KEYS_BROKER_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/callback.h"
  12 #include "base/callback_list.h"
  13 #include "base/macros.h"
  14 #include "base/memory/ref_counted.h"
  15 #include "base/memory/weak_ptr.h"
  16
  17 namespace base {
  18 class TaskRunner;
  19 }
  20
  21 namespace chromeos {
  22 class SessionManagerClient;
  23 }
  24
  25 namespace policy {
  26
  27 // Brokers server-backed FRE state keys for the device. Retrieves them from
  28 // session manager via DBus and refreshes them periodically. Consumers can
  29 // register callbacks to invoke when the state keys change.
  30 class ServerBackedStateKeysBroker {
  31  public:
  32   typedef scoped_ptr<base::CallbackList<void()>::Subscription> Subscription;
  33   typedef base::Callback<void(const std::vector<std::string>&)>
  34       StateKeysCallback;
  35
  36   ServerBackedStateKeysBroker(
  37       chromeos::SessionManagerClient* session_manager_client,
  38       scoped_refptr<base::TaskRunner> delayed_task_runner);
  39   ~ServerBackedStateKeysBroker();
  40
  41   // Registers a callback to be invoked whenever the state keys get updated.
  42   // Note that consuming code needs to hold on to the returned Subscription as
  43   // long as it wants to receive the callback. If the state keys haven't been
  44   // requested yet, calling this will also trigger their initial fetch.
  45   Subscription RegisterUpdateCallback(const base::Closure& callback);
  46
  47   // Requests state keys asynchronously. Invokes the passed callback exactly
  48   // once (unless |this| gets destroyed before the callback happens), with the
  49   // current state keys passed as a parameter to the callback. If there's a
  50   // problem determining the state keys, the passed vector will be empty.
  51   void RequestStateKeys(const StateKeysCallback& callback);
  52
  53   // Get the set of current state keys. Empty if state keys are unavailable
  54   // or pending retrieval.
  55   const std::vector<std::string>& state_keys() const { return state_keys_; }
  56
  57   // Returns the state key for the current point in time. Returns an empty
  58   // string if state keys are unavailable or pending retrieval.
  59   std::string current_state_key() const {
  60     return state_keys_.empty() ? std::string() : state_keys_.front();
  61   }
  62
  63   // Whether state key retrieval is pending.
  64   bool pending() const { return !initial_retrieval_completed_; }
  65
  66   // Whether state keys are available.
  67   bool available() const { return !state_keys_.empty(); }
  68
  69  private:
  70   // Asks |session_manager_client_| to provide current state keys..
  71   void FetchStateKeys();
  72
  73   // Stores newly-received state keys and notifies consumers.
  74   void StoreStateKeys(const std::vector<std::string>& state_keys);
  75
  76   chromeos::SessionManagerClient* session_manager_client_;
  77
  78   scoped_refptr<base::TaskRunner> delayed_task_runner_;
  79
  80   // The current set of state keys.
  81   std::vector<std::string> state_keys_;
  82
  83   // Whether a request for state keys is pending.
  84   bool requested_;
  85
  86   // Whether the initial retrieval operation completed.
  87   bool initial_retrieval_completed_;
  88
  89   // List of callbacks to receive update notifications.
  90   base::CallbackList<void()> update_callbacks_;
  91
  92   // List of pending one-shot state key request callbacks.
  93   std::vector<StateKeysCallback> request_callbacks_;
  94
  95   base::WeakPtrFactory<ServerBackedStateKeysBroker> weak_factory_;
  96
  97   DISALLOW_COPY_AND_ASSIGN(ServerBackedStateKeysBroker);
  98 };
  99
 100 }  // namespace policy
 101
 102 #endif  // CHROME_BROWSER_CHROMEOS_POLICY_SERVER_BACKED_STATE_KEYS_BROKER_H_