Struct NixExecutor 

pub struct NixExecutor { /* private fields */ }

Executor that runs synthesized stages through Nix-managed language runtimes.

When nix is available, each stage is executed as a subprocess with a Nix-pinned runtime (e.g. nix run nixpkgs#python3 -- stage.py). The Nix binary cache ensures the runtime is downloaded once and then reused from the store. This gives reproducibility, not isolation: the subprocess inherits the host user’s privileges, filesystem, and network. See module docs and SECURITY.md for the full trust model.

Resource limits

• Timeout: configured via NixConfig::timeout_secs (default 30 s). The child is sent SIGKILL when the limit is exceeded.
• Output cap: configured via NixConfig::max_output_bytes (default 10 MiB).

Implementations

impl NixExecutor

pub fn find_nix() -> Option<PathBuf>

Probe the system for a usable nix binary. Returns the path if found, or None if Nix is not installed.

pub fn from_store(store: &dyn StageStore) -> Option<Self>

Build an executor that can run synthesized stages found in store.

Returns None when nix is not available — callers should fall back to InlineExecutor exclusively in that case.

pub fn from_store_with_config( store: &dyn StageStore, config: NixConfig, ) -> Option<Self>

Like [from_store] but with a custom NixConfig.

pub fn config_snapshot(&self) -> NixConfig

Clone the current config (minus the implementations map) for callers that want to rebuild with different knobs.

pub fn rebuild_with_config(self, config: NixConfig) -> Option<Self>

Rebuild a NixExecutor with a replacement config, preserving its registered implementations. Returns Some(..) or None when reconstruction fails — today it can’t fail, but the Option keeps the API forward-compatible.

pub fn register_with_effects( &mut self, stage_id: &StageId, code: &str, language: &str, effects: EffectSet, )

Register a stage with explicit declared effects. Used by tests and by callers that want to drive the isolation policy without going through the full StageStore.

pub fn has_implementation(&self, stage_id: &StageId) -> bool

True when we have a real implementation for this stage.

pub fn warmup(&self) -> JoinHandle<()>

Pre-fetch the Python 3 runtime into the Nix store in a background thread.

The first time any Python stage runs, Nix may take several seconds to download and verify the runtime closure. Calling warmup() at startup overlaps that latency with application boot time.

The returned JoinHandle can be ignored — any error is logged to stderr but does not affect correctness; the runtime will still be fetched on first actual use.

Trait Implementations

impl StageExecutor for NixExecutor

fn execute( &self, stage_id: &StageId, input: &Value, ) -> Result<Value, ExecutionError>