# Tempus Fugit   [![Latest Version]][crates.io] [![Rustc Version 1.26+]][rustc]
[Latest Version]: https://img.shields.io/crates/v/tempus_fugit.svg
[crates.io]: https://crates.io/crates/tempus_fugit
[Rustc Version 1.26+]: https://img.shields.io/badge/rustc-1.26+-lightgray.svg
[rustc]: https://nothing.here
**This is a Rust crate that operates around the concept of measuring the time it
takes to take some action.**
Convenience is the name of the game here, specifically by empowering a dependent
crate to do 2 things:
1. Measuring the wall-clock time of any expression in nanosecond[1] resolution:
```toml
[dependencies]
tempus_fugit = "0.10"
```
``` rust
#[macro_use] extern crate tempus_fugit;
use std::fs::File;
use std::io::Read;
use tempus_fugit::Measurement;
fn main() {
let (contents, measurement) = measure! {{
let mut file = File::open("Cargo.lock")
.expect("failed to open Cargo.lock");
let mut contents = vec![];
file.read_to_end(&mut contents)
.expect("failed to read Cargo.lock");
String::from_utf8(contents)
.expect("failed to extract contents to String")
}};
println!("contents: {:?}", contents);
println!("opening and reading file took {}", measurement);
}
```
The `measure!` macro returns a tuple containing the result of executing
an expression (in this case a block), as well as a `Measurement` which
indicates how long the expression took to execute.
2. Displaying a `Measurement` in a human-readable fashion.
There is a `Display` impl for `Measurement`, so this is as easy as
formatting a value with e.g. `format!("{}", measurement)`.
The `Measurement` type also has impls for `Ord` and `Eq`, which makes
comparison and sorting easy.
In addition, there is opt-in support for de/serialization through Serde.
This is activated by using the follwing in your crate's `Cargo.toml`:
``` toml
[dependencies]
tempus_fugit = { version = "0.10", features = ["enable_serde"] }
```
[1] While the accounting is in nanosecond resolution, the actual resolution may
be limited to courser granularity by the operating system.
## Documentation
The API docs are located [here](https://docs.rs/tempus_fugit/).