Enum Decision 

#[non_exhaustive]
pub enum Decision {
    Continue,
    Prune,
    Pause,
    Fork {
        parent: TrialId,
        mutation: Assignment,
    },
    Restart {
        parent: TrialId,
        mutation: Assignment,
        mode: RestartMode,
    },
}

What should happen to a trial that just reported.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Continue

Keep going.

Prune

Stop now. The trial’s last intermediate value becomes its objective value (FrozenTrial::objective_value).

Pause

Suspend, keeping the checkpoint. The trial may be resumed later via Command::ResumeTrial.

Executed by the study loop, which transitions the trial to crate::trial::TrialState::Paused — a resumable, non-terminal state that keeps the trial’s checkpoint reference — instead of completing, pruning or failing it.

Fork

Start a child of parent with mutated parameters — PBT’s exploit-and-explore step.

Executed by the study loop. A fork does not stop the trial that reported it (see stops_the_trial): the study loop materializes a new trial whose TrialTemplate carries the parent reference and whose parameters are the parent’s with mutation applied, and the child starts from the parent’s checkpoint reference. Only scalar perturbations are allowed in mutation — a shape/categorical parameter is resume-blocked because the parent checkpoint would not load — and one that is not is refused loudly.

Fields

parent: TrialId

The trial to copy the checkpoint from.

mutation: Assignment

Parameters that differ from the parent’s.

Restart

Start a child of parent that restarts rather than continues — the fresh or shrink-and-perturb variant of Fork.

Executed by the study loop exactly like a fork, and like a fork it does not stop the reporting trial. The child’s parameters are the parent’s with mutation applied, and its TrialCtx::restart carries mode and a restart seed derived from the study seed and the child’s number. A RestartMode::Fresh child gets no parent checkpoint and records the donor only in its lineage, so mutation may change any parameter; a RestartMode::ShrinkPerturb child starts from the donor’s checkpoint like a fork, so only scalar perturbations are allowed.

Fields

parent: TrialId

The donor trial whose configuration (and, for RestartMode::ShrinkPerturb, checkpoint) the child starts from.

mutation: Assignment

Parameters that differ from the donor’s.

mode: RestartMode

How the child restarts.

Implementations

impl Decision

pub const fn stops_the_trial(&self) -> bool

true if the trial should stop making progress right now.

Trait Implementations

impl Clone for Decision

fn clone(&self) -> Decision

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Decision

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Decision

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl PartialEq for Decision

fn eq(&self, other: &Decision) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl Serialize for Decision

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.

impl StructuralPartialEq for Decision