Struct std::time::SystemTime
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pub struct SystemTime(_);1.8.0
A measurement of the system clock, useful for talking to external entities like the file system or other processes.
Distinct from the Instant type, this time measurement is not
monotonic. This means that you can save a file to the file system, then
save another file to the file system, and the second file has a
SystemTime measurement earlier than the second. In other words, an
operation that happens after another operation in real time may have an
earlier SystemTime!
Consequently, comparing two SystemTime instances to learn about the
duration between them returns a Result instead of an infallible Duration
to indicate that this sort of time drift may happen and needs to be handled.
Although a SystemTime cannot be directly inspected, the UNIX_EPOCH
constant is provided in this module as an anchor in time to learn
information about a SystemTime. By calculating the duration from this
fixed point in time, a SystemTime can be converted to a human-readable time,
or perhaps some other string representation.
Example:
use std::time::{Duration, SystemTime}; use std::thread::sleep; fn main() { let now = SystemTime::now(); // we sleep for 2 seconds sleep(Duration::new(2, 0)); match now.elapsed() { Ok(elapsed) => { // it prints '2' println!("{}", elapsed.as_secs()); } Err(e) => { // an error occured! println!("Error: {:?}", e); } } }use std::time::{Duration, SystemTime}; use std::thread::sleep; fn main() { let now = SystemTime::now(); // we sleep for 2 seconds sleep(Duration::new(2, 0)); match now.elapsed() { Ok(elapsed) => { // it prints '2' println!("{}", elapsed.as_secs()); } Err(e) => { // an error occured! println!("Error: {:?}", e); } } }
Methods
impl SystemTime
fn now() -> SystemTime
Returns the system time corresponding to "now".
fn duration_since(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError>
Returns the amount of time elapsed from an earlier point in time.
This function may fail because measurements taken earlier are not guaranteed to always be before later measurements (due to anomalies such as the system clock being adjusted either forwards or backwards).
If successful, Ok(Duration) is returned where the duration represents
the amount of time elapsed from the specified measurement to this one.
Returns an Err if earlier is later than self, and the error
contains how far from self the time is.
fn duration_from_earlier(&self, earlier: SystemTime) -> Result<Duration, SystemTimeError>
: renamed to duration_since
Deprecated, renamed to duration_since
fn elapsed(&self) -> Result<Duration, SystemTimeError>
Returns the amount of time elapsed since this system time was created.
This function may fail as the underlying system clock is susceptible to
drift and updates (e.g. the system clock could go backwards), so this
function may not always succeed. If successful, Ok(duration) is
returned where the duration represents the amount of time elapsed from
this time measurement to the current time.
Returns an Err if self is later than the current system time, and
the error contains how far from the current system time self is.