Struct Counter 

pub struct Counter { /* private fields */ }

A counter at one key.

Sugar over crate::keyspace::Strings, and the kind of sugar that is worth having: counting is the commonest thing a string key is used for, and a handle that holds the key means the key is spelled once instead of at every call site, which is one fewer place for a typo to live.

A counter that has never been written reads as zero, the way Redis’s does, so there is no create step and nothing to check before the first incr.

let db = yo::open(yo::MEMORY)?;
let hits = db.counter("hits");

assert_eq!(hits.get()?, 0);
assert_eq!(hits.incr()?, 1);
assert_eq!(hits.add(41)?, 42);

Implementations

impl Counter

pub fn key(&self) -> &[u8]

The key this counter lives at.

pub fn get(&self) -> Result<i64>

What the counter reads, which is zero if nothing has written it yet.

Errors

Code::Invalid if the key holds something that is not an integer.

pub fn incr(&self) -> Result<i64>

Add one and hand back the result. INCR.

Errors

Code::Invalid if the key holds something that is not an integer, or if the result would leave the range of an i64.

pub fn decr(&self) -> Result<i64>

Subtract one and hand back the result. DECR.

Errors

As Counter::incr.

pub fn add(&self, by: i64) -> Result<i64>

Add by and hand back the result, which is DECRBY for a negative by. INCRBY.

Errors

As Counter::incr.

pub fn set(&self, value: i64) -> Result<()>

Put the counter at value, whatever it read before. SET.

Errors

Code::Invalid if called from inside a callback that is already holding this database.

pub fn reset(&self) -> Result<()>

Remove the key, so the counter reads zero again and stops taking up room. DEL.

Errors

Code::Invalid if called from inside a callback that is already holding this database.

Trait Implementations

impl Clone for Counter

fn clone(&self) -> Counter

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Counter

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.