1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
|
// Copyright 2014 The Chromium Authors
// 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 <memory>
#include <string>
#include <vector>
#include "base/memory/raw_ptr.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:
// Different reasons that Observer::OnDailyEvent() is called.
// This enum is used for histograms and must not be renumbered.
enum class IntervalType {
FIRST_RUN,
DAY_ELAPSED,
CLOCK_CHANGED,
kMaxValue = CLOCK_CHANGED,
};
// 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();
Observer(const Observer&) = delete;
Observer& operator=(const Observer&) = delete;
virtual ~Observer();
// Called when the daily event is fired.
virtual void OnDailyEvent(IntervalType type) = 0;
};
// 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. If
// |histogram_name| is empty - interval fires are not recorded.
DailyEvent(PrefService* pref_service,
const char* pref_name,
const std::string& histogram_name);
DailyEvent(const DailyEvent&) = delete;
DailyEvent& operator=(const DailyEvent&) = delete;
~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(std::unique_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 std::string& pref_name);
private:
// Handles an interval elapsing because of |type|.
void OnInterval(base::Time now, IntervalType type);
// 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.
raw_ptr<PrefService, LeakedDanglingUntriaged> 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.
std::vector<std::unique_ptr<Observer>> observers_;
// The time that the daily event was last fired.
base::Time last_fired_;
};
} // namespace metrics
#endif // COMPONENTS_METRICS_DAILY_EVENT_H_
|
