Add optional structured logging via the tracing crate:
- info-level spans on all optimize* methods (direction, n_trials/duration)
- info events for trial completed, new best value, trial pruned
- debug events for trial failed and parameter sampled
- Zero overhead when the feature is disabled
Adds a convenience method that combines optimize_with_callback + save
to automatically checkpoint every N trials. Also makes save() use
atomic writes (write to temp file, then rename) to prevent corrupt
files on crash.
Add Serialize/Deserialize derives to all public data types (ParamValue,
Distribution, Direction, TrialState, ParamId, AttrValue, CompletedTrial)
gated behind a `serde` feature flag. Introduce StudySnapshot struct and
Study::save()/Study::load() for persisting and restoring study state as
human-readable JSON.
Add a human-readable summary method and Display trait for Study<V>
where V: Display. The summary shows optimization direction, trial
counts (with complete/pruned breakdown), best value, and best
parameters with their labels.
Also derive PartialOrd + Ord on ParamId for deterministic parameter
ordering in summary output.
Add Study::enqueue() to push specific parameter configurations onto a
FIFO queue. The next call to ask()/create_trial() or the next iteration
in optimize() pops the front entry and injects it into the trial so
that suggest_param() returns the pre-filled value instead of sampling.
Parameters missing from an enqueued map fall back to normal sampling,
and once the queue is drained regular sampler-driven trials resume.
Add AttrValue enum (Float, Int, String, Bool) with From impls and
set_user_attr/user_attr/user_attrs methods on both Trial and
CompletedTrial. Attributes set during optimization are propagated
through complete_trial and prune_trial. AttrValue is re-exported
at crate root and in the prelude.
Add duration-based variants of all optimization methods that run trials
until a wall-clock deadline rather than for a fixed trial count:
- optimize_until(duration, objective)
- optimize_until_with_callback(duration, objective, callback)
- optimize_until_async(duration, objective)
- optimize_until_parallel(duration, concurrency, objective)
- Add `Pruned` variant to `TrialState`
- Add `Error::TrialPruned` variant and standalone `TrialPruned` struct
with `From<TrialPruned> for Error` for ergonomic `?` usage
- Add `state` field to `CompletedTrial` (defaults to `Complete`)
- Add `Study::prune_trial()` and `Study::n_pruned_trials()`
- `optimize()` and `optimize_with_callback()` detect `TrialPruned`
errors via Any downcasting and record pruned trials instead of
failing them
- `best_trial()` / `best_value()` now filter to only `Complete` trials
- Re-export `TrialPruned` from crate root and prelude
- Add report(step, value) and should_prune() methods to Trial
- Store intermediate_values in Trial, copied to CompletedTrial on completion
- Pass pruner through trial factory so trials can consult it
- Rebuild trial factory when pruner is changed via set_pruner()
Introduce the pruning extension point for the trial pruning system.
The Pruner trait allows deciding whether to stop a trial early based
on intermediate values. NopPruner (never prunes) is the default.
- Add `.name()` builder method on all 5 parameter types for custom labels
- Add `CompletedTrial::get(¶m)` for typed parameter access
- Add `Display` impl on `ParamValue`
- Add prelude module at `optimizer::prelude::*`
- Shadow `_with_sampler` methods on `Study<f64>` so `optimize()` auto-uses
the configured sampler; deprecate `_with_sampler` variants
- Use runtime `Any` downcasting with `trial_factory` to avoid E0592
- Update all examples and tests to use the new API
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Manuel Raimann