Struct Trial 

pub struct Trial {
    pub id: String,
    pub params: HashMap<String, Value>,
    pub state: TrialState,
    pub metrics: Vec<MetricRecord>,
    pub duration_ms: Option<u64>,
    pub started_at: Option<DateTime<Utc>>,
    pub finished_at: Option<DateTime<Utc>>,
}

A single hyperparameter evaluation.

Fields

id: String

Identifier unique within the study (the runner uses trial_NNNN).

params: HashMap<String, Value>

The full configuration this trial ran with: sampled dimension values (prefixed names like "SVM.C"), plus the study’s frozen params and a "seed" entry when Study::seeds is non-empty.

state: TrialState

Lifecycle state; see TrialState.

metrics: Vec<MetricRecord>

Every metric recorded during the trial, in recording order — multiple values per name across steps are expected.

duration_ms: Option<u64>

Wall-clock duration, set when the trial reaches a terminal state.

started_at: Option<DateTime<Utc>>

When execution started. serde(default): absent in trials serialized before timestamps existed.

finished_at: Option<DateTime<Utc>>

When the trial reached a terminal state. serde(default) for the same pre-timestamp JSON.

Implementations

impl Trial

pub fn new(id: impl Into<String>, params: HashMap<String, Value>) -> Self

A fresh TrialState::Pending trial for a sampled configuration: no metrics, no timestamps. The runner flips it to Running and stamps started_at when execution begins.

pub fn last_metric(&self, name: &str) -> Option<f64>

Last recorded value for a metric (its final value).

pub fn best_metric(&self, name: &str, direction: Direction) -> Option<f64>

Get the best recorded value for a specific metric.

pub fn is_complete(&self) -> bool

true only for TrialState::Completed — pruned and failed trials are finished but not complete. This is the filter Study::completed_trials and pruner histories use.

pub fn is_terminal(&self) -> bool

true once the trial can no longer change state: Completed, Pruned, or Failed. This is what Study::progress counts, so pruned and failed trials still advance the progress bar.

Trait Implementations

impl Clone for Trial

fn clone(&self) -> Trial

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Trial

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

Formats the value using the given formatter.

impl<'de> Deserialize<'de> for Trial

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

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for Trial

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

where __S: Serializer,

Serialize this value into the given Serde serializer.