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Diffstat (limited to 'chromium/components/metrics/daily_event.h')
-rw-r--r-- | chromium/components/metrics/daily_event.h | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/chromium/components/metrics/daily_event.h b/chromium/components/metrics/daily_event.h new file mode 100644 index 00000000000..24b31dc58ea --- /dev/null +++ b/chromium/components/metrics/daily_event.h @@ -0,0 +1,92 @@ +// Copyright 2014 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 COMPONENTS_METRICS_DAILY_EVENT_H_ +#define COMPONENTS_METRICS_DAILY_EVENT_H_ + +#include "base/macros.h" +#include "base/memory/scoped_ptr.h" +#include "base/memory/scoped_vector.h" +#include "base/time/time.h" + +class PrefRegistrySimple; +class PrefService; + +namespace metrics { + +// DailyEvent is used for throttling an event to about once per day, even if +// the program is restarted more frequently. It is based on local machine +// time, so it could be fired more often if the clock is changed. +// +// The service using the DailyEvent should first provide all of the Observers +// for the interval, and then arrange for CheckInterval() to be called +// periodically to test if the event should be fired. +class DailyEvent { + public: + // Observer receives notifications from a DailyEvent. + // Observers must be added before the DailyEvent begins checking time, + // and will be owned by the DailyEvent. + class Observer { + public: + Observer(); + virtual ~Observer(); + + // Called when the daily event is fired. + virtual void OnDailyEvent() = 0; + + private: + DISALLOW_COPY_AND_ASSIGN(Observer); + }; + + // Constructs DailyEvent monitor which stores the time it last fired in the + // preference |pref_name|. |pref_name| should be registered by calling + // RegisterPref before using this object. + // Caller is responsible for ensuring that |pref_service| and |pref_name| + // outlive the DailyEvent. + // |histogram_name| is the name of the UMA metric which record when this + // interval fires, and should be registered in histograms.xml + DailyEvent(PrefService* pref_service, + const char* pref_name, + const std::string& histogram_name); + ~DailyEvent(); + + // Adds a observer to be notified when a day elapses. All observers should + // be registered before the the DailyEvent starts checking time. + void AddObserver(scoped_ptr<Observer> observer); + + // Checks if a day has elapsed. If it has, OnDailyEvent will be called on + // all observers. + void CheckInterval(); + + // Registers the preference used by this interval. + static void RegisterPref(PrefRegistrySimple* registry, const char* pref_name); + + private: + // Handles an interval elapsing. + void OnInterval(base::Time now); + + // A weak pointer to the PrefService object to read and write preferences + // from. Calling code should ensure this object continues to exist for the + // lifetime of the DailyEvent object. + PrefService* pref_service_; + + // The name of the preference to store the last fired time in. + // Calling code should ensure this outlives the DailyEvent. + const char* pref_name_; + + // The name of the histogram to record intervals. + std::string histogram_name_; + + // A list of observers. + ScopedVector<Observer> observers_; + + // The time that the daily event was last fired. + base::Time last_fired_; + + DISALLOW_COPY_AND_ASSIGN(DailyEvent); +}; + +} // namespace metrics + +#endif // COMPONENTS_METRICS_DAILY_EVENT_H_ |