# Struct std::time::Instant [−] [src]

    pub struct Instant(_);

Unstable (`time2` #29866)

: recently added

A measurement of a monotonically increasing clock. Opaque and useful only with `Duration`.

Instants are always guaranteed to be greater than any previously measured instant when created, and are often useful for tasks such as measuring benchmarks or timing how long an operation takes.

Note, however, that instants are not guaranteed to be steady. In other words, each tick of the underlying clock may not be the same length (e.g. some seconds may be longer than others). An instant may jump forwards or experience time dilation (slow down or speed up), but it will never go backwards.

Instants are opaque types that can only be compared to one another. There is no method to get "the number of seconds" from an instant. Instead, it only allows measuring the duration between two instants (or comparing two instants).

## Methods

### `impl Instant`

#### `fn now() -> Instant`

Unstable (`time2` #29866)

: recently added

Returns an instant corresponding to "now".

#### `fn duration_from_earlier(&self, earlier: Instant) -> Duration`

Unstable (`time2` #29866)

: recently added

Returns the amount of time elapsed from another instant to this one.

# Panics

This function will panic if `earlier` is later than `self`, which should only be possible if `earlier` was created after `self`. Because `Instant` is monotonic, the only time that this should happen should be a bug.

#### `fn elapsed(&self) -> Duration`

Unstable (`time2` #29866)

: recently added

Returns the amount of time elapsed since this instant was created.

# Panics

This function may panic if the current time is earlier than this instant, which is something that can happen if an `Instant` is produced synthetically.

## Trait Implementations

### `impl Add<Duration> for Instant`

#### `type Output = Instant`

#### `fn add(self, other: Duration) -> Instant`

### `impl Sub<Duration> for Instant`

#### `type Output = Instant`

#### `fn sub(self, other: Duration) -> Instant`

### `impl Debug for Instant`

#### `fn fmt(&self, f: &mut Formatter) -> Result`

### Derived Implementations

### `impl Ord for Instant`

#### `fn cmp(&self, __arg_0: &Instant) -> Ordering`

### `impl PartialOrd for Instant`

#### `fn partial_cmp(&self, __arg_0: &Instant) -> Option<Ordering>`

#### `fn lt(&self, __arg_0: &Instant) -> bool`

#### `fn le(&self, __arg_0: &Instant) -> bool`

#### `fn gt(&self, __arg_0: &Instant) -> bool`

#### `fn ge(&self, __arg_0: &Instant) -> bool`

### `impl Eq for Instant`

### `impl PartialEq for Instant`

#### `fn eq(&self, __arg_0: &Instant) -> bool`

#### `fn ne(&self, __arg_0: &Instant) -> bool`

### `impl Clone for Instant`

#### `fn clone(&self) -> Instant`

#### `fn clone_from(&mut self, source: &Self)`

### `impl Copy for Instant`

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