Struct KvReadHandle 

pub struct KvReadHandle { /* private fields */ }

Read access to Taquba’s caller KV namespace during a step.

Obtained through Delivery::kv. get reads from committed state: a value written by an earlier settlement (a previous step’s EffectsHandle writes, a RunSpec::effects write, a direct taquba::Queue::kv_put) is visible, and an effect staged by the current step becomes visible only once this step’s settlement commits it. The read is also not transactional with that settlement: a value read here can change before the step’s outcome commits. Delivery is at-least-once, so a read that misses (for example a marker a crashed settlement never committed) re-executes work that must be idempotent downstream.

The handle is cheap to clone and exposes no write or settlement operation. Use KvReadHandle::detached when constructing a Step in tests.

Implementations

impl KvReadHandle

pub fn detached() -> Self

Build a handle bound to no queue, for constructing a Step in tests. get on a detached handle returns Ok(None) for every key.

pub async fn get(&self, key: &[u8]) -> Result<Option<Bytes>>

Read the committed value under key from the caller KV namespace, None when no value exists.

Errors

Error::Queue when the underlying read fails.

Trait Implementations

impl Clone for KvReadHandle

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for KvReadHandle

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

Formats the value using the given formatter.