Struct EffectsHandle 

pub struct EffectsHandle { /* private fields */ }

Application KV effects staged during a step, applied in the same transaction as the settlement that commits the step’s outcome.

Obtained through Delivery::effects. Writes and deletes staged here are applied atomically with the acknowledgement of the StepOutcome the runner returns (Continue, Succeed, Fail and Cancel): either the settlement and every staged effect commit together or none of them do. Delivery is at-least-once, so a retried step stages its effects again and every staged value must be correct when applied more than once. No effects are applied when the runner returns a StepError or when an external WorkflowRuntime::cancel overrides the runner’s outcome.

Each operation is validated when it is staged: keys must not start with the reserved workflow/ prefix (RESERVED_KV_PREFIX), values are capped at taquba::MAX_KV_VALUE_SIZE each (an effects set has no aggregate cap) and a key cannot be staged for both a write and a delete within one step. The handle is sealed once run_step returns; staging through a clone retained past that point returns Error::EffectsSealed.

The handle is cheap to clone and clones share one accumulator. Use EffectsHandle::detached when constructing a Step in tests.

Implementations

impl EffectsHandle

pub fn detached() -> Self

Build a handle bound to no delivery, for constructing a Step in tests. A detached handle accepts and validates effects like a delivery-bound one, is never sealed and its staged effects are never applied.

pub fn put( &self, key: impl Into<Vec<u8>>, value: impl Into<Vec<u8>>, ) -> Result<()>

Stage a write of value under key in the caller KV namespace.

Errors

Error::ReservedKvKey when key starts with the reserved workflow/ prefix, Error::Queue with taquba::Error::KvValueTooLarge when value exceeds taquba::MAX_KV_VALUE_SIZE, Error::ConflictingKvEffect when key is already staged for a delete and Error::EffectsSealed when the step has returned.

pub fn delete(&self, key: impl Into<Vec<u8>>) -> Result<()>

Stage a delete of key from the caller KV namespace.

Errors

Error::ReservedKvKey when key starts with the reserved workflow/ prefix, Error::ConflictingKvEffect when key is already staged for a write and Error::EffectsSealed when the step has returned.

Trait Implementations

impl Clone for EffectsHandle

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 EffectsHandle

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

Formats the value using the given formatter.