blob: 8e27ff2ebbcbcedc19430604237adff6e3c3a66d (
plain)
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
|
// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_TASK_COMMON_LAZY_NOW_H_
#define BASE_TASK_COMMON_LAZY_NOW_H_
#include "base/base_export.h"
#include "base/memory/raw_ptr_exclusion.h"
#include "base/time/time.h"
#include "third_party/abseil-cpp/absl/types/optional.h"
namespace base {
class TickClock;
// Now() is somewhat expensive so it makes sense not to call Now() unless we
// really need to and to avoid subsequent calls if already called once.
// LazyNow objects are expected to be short-living to represent accurate time.
class BASE_EXPORT LazyNow {
public:
explicit LazyNow(TimeTicks now);
explicit LazyNow(absl::optional<TimeTicks> now, const TickClock* tick_clock);
explicit LazyNow(const TickClock* tick_clock);
LazyNow(const LazyNow&) = delete;
LazyNow& operator=(const LazyNow&) = delete;
LazyNow(LazyNow&& move_from) noexcept;
// Result will not be updated on any subsesequent calls.
TimeTicks Now();
bool has_value() const { return !!now_; }
private:
absl::optional<TimeTicks> now_;
// `tick_clock_` is not a raw_ptr<TickClock> as a performance optimization:
// The pointee doesn't need UaF protection (it has the same lifetime as the
// theead/sequence).
RAW_PTR_EXCLUSION const TickClock* tick_clock_; // Not owned.
};
} // namespace base
#endif // BASE_TASK_COMMON_LAZY_NOW_H_
|
