Refactor chrome.alarms interface to support absolute alarm deadlines.

chrome/browser/extensions/api/alarms/alarm_manager.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CHROME_BROWSER_EXTENSIONS_API_ALARMS_ALARM_MANAGER_H__
 #define CHROME_BROWSER_EXTENSIONS_API_ALARMS_ALARM_MANAGER_H__
 #pragma once
 
 #include <string>
 #include <map>
 #include <vector>
 
 #include "base/memory/weak_ptr.h"
 #include "base/timer.h"
 #include "chrome/browser/extensions/extension_function.h"
 #include "chrome/common/extensions/api/alarms.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_registrar.h"
 
 class Profile;
 
 namespace extensions {
 
 class ExtensionAlarmsSchedulingTest;
 
+struct Alarm {
+  typedef base::Time (*TimeProvider)();
+
+  Alarm();
+  Alarm(const std::string& name,
+        const api::alarms::AlarmCreateInfo& create_info,
+        base::TimeDelta min_granularity,
+        TimeProvider now);
+  ~Alarm();
+
+  linked_ptr<api::alarms::Alarm> js_alarm;
+  // The granularity isn't exposed to the extension's javascript, but we poll at
+  // least as often as the shortest alarm's granularity.  It's initialized as
+  // the relative delay requested in creation, even if creation uses an absolute
+  // time.  This will always be at least as large as the min_granularity
+  // constructor argument.
+  base::TimeDelta granularity;
+};
+
 // Manages the currently pending alarms for every extension in a profile.
 // There is one manager per virtual Profile.
 class AlarmManager
     : public content::NotificationObserver,
       public base::SupportsWeakPtr<AlarmManager> {
  public:
-  typedef extensions::api::alarms::Alarm Alarm;
-  typedef std::vector<linked_ptr<Alarm> > AlarmList;
+  typedef base::Time (*TimeProvider)();
+  typedef std::vector<Alarm> AlarmList;
 
   class Delegate {
    public:
     virtual ~Delegate() {}
     // Called when an alarm fires.
     virtual void OnAlarm(const std::string& extension_id,
                          const Alarm& alarm) = 0;
   };
 
-  explicit AlarmManager(Profile* profile);
+  // 'now' is usually &base::Time::Now.
+  explicit AlarmManager(Profile* profile, TimeProvider now);
   virtual ~AlarmManager();
 
   // Override the default delegate. Callee assumes onwership. Used for testing.
   void set_delegate(Delegate* delegate) { delegate_.reset(delegate); }
 
   // Adds |alarm| for the given extension, and starts the timer.
   void AddAlarm(const std::string& extension_id,
-                const linked_ptr<Alarm>& alarm);
+                const Alarm& alarm);
 
   // Returns the alarm with the given name, or NULL if none exists.
   const Alarm* GetAlarm(const std::string& extension_id,
                         const std::string& name);
 
   // Returns the list of pending alarms for the given extension, or NULL
   // if none exist.
   const AlarmList* GetAllAlarms(const std::string& extension_id);
 
   // Cancels and removes the alarm with the given name.
   bool RemoveAlarm(const std::string& extension_id,
                    const std::string& name);
 
   // Cancels and removes all alarms for the given extension.
   void RemoveAllAlarms(const std::string& extension_id);
 
  private:
   FRIEND_TEST_ALL_PREFIXES(ExtensionAlarmsTest, CreateRepeating);
   FRIEND_TEST_ALL_PREFIXES(ExtensionAlarmsTest, Clear);
   friend class ExtensionAlarmsSchedulingTest;
   FRIEND_TEST_ALL_PREFIXES(ExtensionAlarmsSchedulingTest, PollScheduling);
+  FRIEND_TEST_ALL_PREFIXES(ExtensionAlarmsSchedulingTest,
+                           ReleasedExtensionPollsInfrequently);
   FRIEND_TEST_ALL_PREFIXES(ExtensionAlarmsSchedulingTest, TimerRunning);
 
   typedef std::string ExtensionId;
   typedef std::map<ExtensionId, AlarmList> AlarmMap;
 
   // Iterator used to identify a particular alarm within the Map/List pair.
   // "Not found" is represented by <alarms_.end(), invalid_iterator>.
   typedef std::pair<AlarmMap::iterator, AlarmList::iterator> AlarmIterator;
 
-  struct AlarmRuntimeInfo {
-    std::string extension_id;
-    base::Time time;
-  };
-  typedef std::map<const Alarm*, AlarmRuntimeInfo> AlarmRuntimeInfoMap;
-
   // Helper to return the iterators within the AlarmMap and AlarmList for the
   // matching alarm, or an iterator to the end of the AlarmMap if none were
   // found.
   AlarmIterator GetAlarmIterator(const std::string& extension_id,
                                  const std::string& name);
 
   // Helper to cancel and remove the alarm at the given iterator. The iterator
   // must be valid.
   void RemoveAlarmIterator(const AlarmIterator& iter);
 
   // Callback for when an alarm fires.
-  void OnAlarm(const std::string& extension_id, const std::string& name);
+  void OnAlarm(AlarmIterator iter);
 
   // Internal helper to add an alarm and start the timer with the given delay.
   void AddAlarmImpl(const std::string& extension_id,
-                    const linked_ptr<Alarm>& alarm,
-                    base::TimeDelta time_delay);
+                    const Alarm& alarm);
 
   // Syncs our alarm data for the given extension to/from the state storage.
   void WriteToStorage(const std::string& extension_id);
   void ReadFromStorage(const std::string& extension_id,
                        scoped_ptr<base::Value> value);
 
   // Schedules the next poll of alarms for when the next soonest alarm runs,
   // but do not more often than min_period.
   void ScheduleNextPoll(base::TimeDelta min_period);
 
   // Polls the alarms, running any that have elapsed. After running them and
   // rescheduling repeating alarms, schedule the next poll.
   void PollAlarms();
 
   // NotificationObserver:
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   Profile* profile_;
+  const TimeProvider now_;
   content::NotificationRegistrar registrar_;
   scoped_ptr<Delegate> delegate_;
 
   // The timer for this alarm manager.
   base::OneShotTimer<AlarmManager> timer_;
 
   // A map of our pending alarms, per extension.
+  // Invariant: None of the AlarmLists are empty.
   AlarmMap alarms_;
 
-  // A map of the next scheduled times associated with each alarm.
-  AlarmRuntimeInfoMap scheduled_times_;
-
   // The previous and next time that alarms were and will be run.
   base::Time last_poll_time_;
   base::Time next_poll_time_;
 };
 
 } //  namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_ALARMS_ALARM_MANAGER_H__