Struct JsWorker 

pub struct JsWorker { /* private fields */ }

Available on crate features js and std only.

A JsRuntime owned by a dedicated OS thread: the compile-once, call-many execution model.

State (globals, function definitions, …) persists for the lifetime of the worker: execute a script once, then call into its functions per request. This is the model browsers and proxies use for long-lived configuration scripts; spawn a fresh worker instead when a script must not observe earlier executions.

The handle is cheap to clone; all handles share the same runtime and jobs run strictly in order. The thread exits once the last handle is dropped.

A job that exceeds the worker’s timeout cannot be interrupted — a thread running native engine code is not cancellable — so its caller is released with a JsErrorKind::Timeout while the job runs on. Until the worker finishes something again, it is abandoned: later jobs fail fast with JsErrorKind::Setup instead of queueing behind work that may never end. A merely slow job therefore costs nothing once it lands; a job that never returns retires the worker and leaks its thread, so spawn a replacement. Without a timeout configured, such a job blocks its caller and the queue indefinitely.

A panicking host function kills the worker: the pending and all later jobs fail fast with a JsErrorKind::Setup error (fail-loud, rather than continuing on a runtime in unknown state).

Implementations

impl JsWorker

pub const DEFAULT_QUEUE_CAPACITY: usize = 128

Default capacity of the worker’s job queue.

pub fn builder() -> JsWorkerBuilder

Create a JsWorkerBuilder to configure a new worker.

pub fn spawn(builder: JsRuntimeBuilder) -> Result<JsWorker, JsError>

Spawn a worker thread owning a fresh JsRuntime built from the given builder, with the default worker configuration.

pub fn is_abandoned(&self) -> bool

Whether the worker is stuck on a job that overran its timeout.

Abandoned workers refuse further jobs. The state clears by itself if the overrunning job does eventually finish; a job that never returns retires the worker for good, so spawn a replacement.

pub async fn run<T, F>(&self, f: F) -> Result<T, JsError>

where F: FnOnce(&mut JsRuntime) -> Result<T, JsError> + Send + 'static, T: Send + 'static,

Execute the given closure with exclusive access to the worker’s runtime.

pub async fn eval<S>(&self, src: S) -> Result<JsValue, JsError>

where S: AsRef<str> + Send + 'static,

Evaluate a script on the worker’s runtime, returning the value of its final expression.

pub async fn exec<S>(&self, src: S) -> Result<(), JsError>

where S: AsRef<str> + Send + 'static,

Execute a script on the worker’s runtime, discarding its final expression value.

pub async fn call<N, I, V>(&self, name: N, args: I) -> Result<JsValue, JsError>

where N: AsRef<str> + Send + 'static, I: IntoIterator<Item = V>, V: Into<JsValue>,

Call a global function (defined by a previously executed script, or registered as a host function) with the given arguments.

Trait Implementations

impl Clone for JsWorker

fn clone(&self) -> JsWorker

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for JsWorker

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

Formats the value using the given formatter.