tracing_subscriber/fmt/time/
mod.rs

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1//! Formatters for event timestamps.
2use crate::fmt::format::Writer;
3use std::fmt;
4use std::time::Instant;
5
6mod datetime;
7
8#[cfg(feature = "time")]
9mod time_crate;
10
11#[cfg(feature = "time")]
12#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
13pub use time_crate::UtcTime;
14
15#[cfg(feature = "local-time")]
16#[cfg_attr(docsrs, doc(cfg(all(unsound_local_offset, feature = "local-time"))))]
17pub use time_crate::LocalTime;
18
19/// [`chrono`]-based implementation for [`FormatTime`].
20#[cfg(feature = "chrono")]
21mod chrono_crate;
22
23#[cfg(feature = "chrono")]
24#[cfg_attr(docsrs, doc(cfg(feature = "chrono")))]
25pub use chrono_crate::ChronoLocal;
26
27#[cfg(feature = "chrono")]
28#[cfg_attr(docsrs, doc(cfg(feature = "chrono")))]
29pub use chrono_crate::ChronoUtc;
30
31/// A type that can measure and format the current time.
32///
33/// This trait is used by `Format` to include a timestamp with each `Event` when it is logged.
34///
35/// Notable default implementations of this trait are `SystemTime` and `()`. The former prints the
36/// current time as reported by `std::time::SystemTime`, and the latter does not print the current
37/// time at all. `FormatTime` is also automatically implemented for any function pointer with the
38/// appropriate signature.
39///
40/// The full list of provided implementations can be found in [`time`].
41///
42/// [`time`]: self
43pub trait FormatTime {
44    /// Measure and write out the current time.
45    ///
46    /// When `format_time` is called, implementors should get the current time using their desired
47    /// mechanism, and write it out to the given `fmt::Write`. Implementors must insert a trailing
48    /// space themselves if they wish to separate the time from subsequent log message text.
49    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result;
50}
51
52/// Returns a new `SystemTime` timestamp provider.
53///
54/// This can then be configured further to determine how timestamps should be
55/// configured.
56///
57/// This is equivalent to calling
58/// ```rust
59/// # fn timer() -> tracing_subscriber::fmt::time::SystemTime {
60/// tracing_subscriber::fmt::time::SystemTime::default()
61/// # }
62/// ```
63pub fn time() -> SystemTime {
64    SystemTime
65}
66
67/// Returns a new `Uptime` timestamp provider.
68///
69/// With this timer, timestamps will be formatted with the amount of time
70/// elapsed since the timestamp provider was constructed.
71///
72/// This can then be configured further to determine how timestamps should be
73/// configured.
74///
75/// This is equivalent to calling
76/// ```rust
77/// # fn timer() -> tracing_subscriber::fmt::time::Uptime {
78/// tracing_subscriber::fmt::time::Uptime::default()
79/// # }
80/// ```
81pub fn uptime() -> Uptime {
82    Uptime::default()
83}
84
85impl<F> FormatTime for &F
86where
87    F: FormatTime,
88{
89    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
90        (*self).format_time(w)
91    }
92}
93
94impl FormatTime for () {
95    fn format_time(&self, _: &mut Writer<'_>) -> fmt::Result {
96        Ok(())
97    }
98}
99
100impl FormatTime for fn(&mut Writer<'_>) -> fmt::Result {
101    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
102        (*self)(w)
103    }
104}
105
106/// Retrieve and print the current wall-clock time.
107#[derive(Debug, Clone, Copy, Eq, PartialEq, Default)]
108pub struct SystemTime;
109
110/// Retrieve and print the relative elapsed wall-clock time since an epoch.
111///
112/// The `Default` implementation for `Uptime` makes the epoch the current time.
113#[derive(Debug, Clone, Copy, Eq, PartialEq)]
114pub struct Uptime {
115    epoch: Instant,
116}
117
118impl Default for Uptime {
119    fn default() -> Self {
120        Uptime {
121            epoch: Instant::now(),
122        }
123    }
124}
125
126impl From<Instant> for Uptime {
127    fn from(epoch: Instant) -> Self {
128        Uptime { epoch }
129    }
130}
131
132impl FormatTime for SystemTime {
133    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
134        write!(
135            w,
136            "{}",
137            datetime::DateTime::from(std::time::SystemTime::now())
138        )
139    }
140}
141
142impl FormatTime for Uptime {
143    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
144        let e = self.epoch.elapsed();
145        write!(w, "{:4}.{:09}s", e.as_secs(), e.subsec_nanos())
146    }
147}
tracing_subscriber/fmt/time/mod.rs

tracing_subscriber/fmt/time/
mod.rs
