Struct Strings

Source

pub struct Strings { /* private fields */ }

Expand description

The keyspace every Redis string command works on.

Cheap to clone, and every clone is the same keyspace. Keys are byte strings the way Redis’s are, so anything that is bytes will do: "hits", a String, a &[u8] or a Vec<u8>.

let db = yo::open(yo::MEMORY)?;
let keys = db.strings();

keys.set("greeting", "hello")?;
assert_eq!(keys.get("greeting")?.as_deref(), Some(&b"hello"[..]));

assert_eq!(keys.incr("hits")?, 1);
assert_eq!(keys.incr_by("hits", 9)?, 10);

Implementations§

Source §

impl Strings

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pub fn get(&self, key: impl AsRef<[u8]>) -> Result<Option<Vec<u8>>>

Read a value.

Owned, because most callers want the bytes to outlive the call. Strings::with is the same read without the copy.

§Errors

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

Source

pub fn with<R>( &self, key: impl AsRef<[u8]>, f: impl FnOnce(Str<'_>) -> R, ) -> Result<Option<R>>

Read a value without copying it, by handing what is in the record to f.

The view is Str, which is either the bytes where they lie or the integer an int encoded value holds. This is the read the G6 budget is about, and it allocates nothing at all.

let db = yo::open(yo::MEMORY)?;
let keys = db.strings();
keys.set("greeting", "hello")?;

assert_eq!(keys.with("greeting", |v| v.len())?, Some(5));

§Errors

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

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pub fn exists(&self, key: impl AsRef<[u8]>) -> Result<bool>

Whether a key is there and has not expired.

§Errors

As Strings::get.

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pub fn len_of(&self, key: impl AsRef<[u8]>) -> Result<usize>

The length of a value in bytes, which is zero for a key that is not there. STRLEN.

§Errors

As Strings::get.

Source

pub fn set(&self, key: impl AsRef<[u8]>, value: impl AsRef<[u8]>) -> Result<()>

Store a value, clearing any deadline the key had. Plain SET.

§Errors

Code::Full for a value past yo_kv::STRING_MAX.

Source

pub fn set_if_missing( &self, key: impl AsRef<[u8]>, value: impl AsRef<[u8]>, ) -> Result<bool>

Store a value only if the key is missing, and say whether it was. SET NX.

§Errors

As Strings::set.

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pub fn set_for( &self, key: impl AsRef<[u8]>, value: impl AsRef<[u8]>, ttl: Duration, ) -> Result<()>

Store a value that expires after ttl. SET PX.

This is the call that turns the clock on for this database, because it is the first moment a deadline can be observed.

§Errors

As Strings::set, and Code::Invalid for a ttl past what fits in a millisecond deadline.

Source

pub fn ttl(&self, key: impl AsRef<[u8]>) -> Result<Option<Duration>>

How long a key has left, or None if it has no deadline or is not there. PTTL.

Keys::ttl is the one that tells those two apart, and it works on a key of any type rather than only on a string.

§Errors

As Strings::get.

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pub fn replace( &self, key: impl AsRef<[u8]>, value: impl AsRef<[u8]>, ) -> Result<Option<Vec<u8>>>

Store a value and hand back what was there. GETSET.

§Errors

As Strings::set.

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pub fn take(&self, key: impl AsRef<[u8]>) -> Result<Option<Vec<u8>>>

Remove a key and hand back what it held. GETDEL.

§Errors

As Strings::get.

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pub fn del(&self, key: impl AsRef<[u8]>) -> Result<bool>

Remove a key, and say whether it was there. DEL.

§Errors

As Strings::get.

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pub fn set_many<K: AsRef<[u8]>, V: AsRef<[u8]>>( &self, pairs: &[(K, V)], ) -> Result<()>

Store several values, all of them or none. MSET.

The pairs reach the store as an iterator rather than a Vec, which is the same thing the wire layer does and for the same reason: MSET is on the gate list and an API that forces an allocation to call it is the wrong API.

let db = yo::open(yo::MEMORY)?;
let keys = db.strings();

keys.set_many(&[("a", "1"), ("b", "2")])?;
assert_eq!(keys.get("b")?.as_deref(), Some(&b"2"[..]));