Struct zng_app_context::LocalContext

pub struct LocalContext { /* private fields */ }

Tracks the current execution context.

The context tracks the current app, all or some context_local! and TracingDispatcherContext.

Implementations

impl LocalContext

pub const fn new() -> Self

New empty context.

pub fn start_app(id: AppId) -> AppScope

Start an app scope in the current thread.

pub fn current_app() -> Option<AppId>

Get the ID of the app that owns the current context.

pub fn register_cleanup(cleanup: impl FnOnce(AppId) + Send + 'static)

Register to run when the app deinits and all clones of the app context are dropped.

pub fn capture() -> Self

Capture a snapshot of the current context that can be restored in another thread to recreate the current context.

Context locals modified after this capture are not included in the capture.

This is equivalent to ``CaptureFilter::All`.

pub fn capture_filtered(filter: CaptureFilter) -> Self

Capture a snapshot of the current context that only includes filter.

pub fn value_set(&self) -> ContextValueSet

Collects a set of all the values in the context.

pub fn with_context<R>(&mut self, f: impl FnOnce() -> R) -> R

Calls f in the captured context.

Note that this fully replaces the parent context for the duration of the f call, see with_context_blend for a blending alternative.

pub fn with_context_blend<R>(&mut self, over: bool, f: impl FnOnce() -> R) -> R

Calls f while all contextual values of self are set on the parent context.

Unlike with_context this does not remove values that are only set in the parent context, the downside is that this call is more expensive.

If over is true all the values of self are set over the parent values, if false only the values not already set in the parent are set.

pub fn extend(&mut self, ctx: Self)

Blend ctx over self.

Trait Implementations

impl Clone for LocalContext

fn clone(&self) -> LocalContext

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for LocalContext

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

Formats the value using the given formatter.

impl Default for LocalContext

fn default() -> Self

Returns the “default value” for a type.