tracing_subscriber/fmt/time/
mod.rs

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#[cfg(feature = "time")]
20#[cfg_attr(docsrs, doc(cfg(feature = "time")))]
21pub use time_crate::OffsetTime;
22
23/// [`chrono`]-based implementation for [`FormatTime`].
24#[cfg(feature = "chrono")]
25mod chrono_crate;
26
27#[cfg(feature = "chrono")]
28#[cfg_attr(docsrs, doc(cfg(feature = "chrono")))]
29pub use chrono_crate::ChronoLocal;
30
31#[cfg(feature = "chrono")]
32#[cfg_attr(docsrs, doc(cfg(feature = "chrono")))]
33pub use chrono_crate::ChronoUtc;
34
35/// A type that can measure and format the current time.
36///
37/// This trait is used by `Format` to include a timestamp with each `Event` when it is logged.
38///
39/// Notable default implementations of this trait are `SystemTime` and `()`. The former prints the
40/// current time as reported by `std::time::SystemTime`, and the latter does not print the current
41/// time at all. `FormatTime` is also automatically implemented for any function pointer with the
42/// appropriate signature.
43///
44/// The full list of provided implementations can be found in [`time`].
45///
46/// [`time`]: self
47pub trait FormatTime {
48    /// Measure and write out the current time.
49    ///
50    /// When `format_time` is called, implementors should get the current time using their desired
51    /// mechanism, and write it out to the given `fmt::Write`. Implementors must insert a trailing
52    /// space themselves if they wish to separate the time from subsequent log message text.
53    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result;
54}
55
56/// Returns a new `SystemTime` timestamp provider.
57///
58/// This can then be configured further to determine how timestamps should be
59/// configured.
60///
61/// This is equivalent to calling
62/// ```rust
63/// # fn timer() -> tracing_subscriber::fmt::time::SystemTime {
64/// tracing_subscriber::fmt::time::SystemTime::default()
65/// # }
66/// ```
67pub fn time() -> SystemTime {
68    SystemTime
69}
70
71/// Returns a new `Uptime` timestamp provider.
72///
73/// With this timer, timestamps will be formatted with the amount of time
74/// elapsed since the timestamp provider was constructed.
75///
76/// This can then be configured further to determine how timestamps should be
77/// configured.
78///
79/// This is equivalent to calling
80/// ```rust
81/// # fn timer() -> tracing_subscriber::fmt::time::Uptime {
82/// tracing_subscriber::fmt::time::Uptime::default()
83/// # }
84/// ```
85pub fn uptime() -> Uptime {
86    Uptime::default()
87}
88
89impl<F> FormatTime for &F
90where
91    F: FormatTime,
92{
93    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
94        (*self).format_time(w)
95    }
96}
97
98impl FormatTime for () {
99    fn format_time(&self, _: &mut Writer<'_>) -> fmt::Result {
100        Ok(())
101    }
102}
103
104impl FormatTime for fn(&mut Writer<'_>) -> fmt::Result {
105    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
106        (*self)(w)
107    }
108}
109
110/// Retrieve and print the current wall-clock time.
111#[derive(Debug, Clone, Copy, Eq, PartialEq, Default)]
112pub struct SystemTime;
113
114/// Retrieve and print the relative elapsed wall-clock time since an epoch.
115///
116/// The `Default` implementation for `Uptime` makes the epoch the current time.
117#[derive(Debug, Clone, Copy, Eq, PartialEq)]
118pub struct Uptime {
119    epoch: Instant,
120}
121
122impl Default for Uptime {
123    fn default() -> Self {
124        Uptime {
125            epoch: Instant::now(),
126        }
127    }
128}
129
130impl From<Instant> for Uptime {
131    fn from(epoch: Instant) -> Self {
132        Uptime { epoch }
133    }
134}
135
136impl FormatTime for SystemTime {
137    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
138        write!(
139            w,
140            "{}",
141            datetime::DateTime::from(std::time::SystemTime::now())
142        )
143    }
144}
145
146impl FormatTime for Uptime {
147    fn format_time(&self, w: &mut Writer<'_>) -> fmt::Result {
148        let e = self.epoch.elapsed();
149        write!(w, "{:4}.{:09}s", e.as_secs(), e.subsec_nanos())
150    }
151}
tracing_subscriber/fmt/time/mod.rs

tracing_subscriber/fmt/time/
mod.rs
