Struct Dispatch

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pub struct Dispatch { /* private fields */ }

Expand description

Dispatch trace data to a Collect.

Implementations§

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impl Dispatch

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pub fn none() -> Dispatch

Returns a new Dispatch that discards events and spans.

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pub fn from_static(collector: &'static (dyn Collect + Sync + Send)) -> Dispatch

Returns a Dispatch that forwards to the given static collector.

Unlike [Dispatch::new], this function is always available on all platforms, even when the std or alloc features are disabled.

In order to use from_static, the Collector itself must be stored in a static. For example:

struct MyCollector {
   // ...
}

impl tracing_core::Collect for MyCollector {
    // ...
}

static COLLECTOR: MyCollector = MyCollector {
    // ...
};

fn main() {
    use tracing_core::dispatch::{self, Dispatch};

    let dispatch = Dispatch::from_static(&COLLECTOR);

    dispatch::set_global_default(dispatch)
        .expect("no global default collector should have been set previously!");
}

Constructing the collector in a static initializer may make some forms of runtime configuration more challenging. If this is the case, users with access to liballoc or the Rust standard library are encouraged to use [Dispatch::new] rather than from_static. no_std users who cannot allocate or do not have access to liballoc may want to consider the once_cell crate, or another library which allows lazy initialization of statics.

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pub fn register_callsite( &self, metadata: &'static Metadata<'static>, ) -> Interest

Registers a new callsite with this collector, returning whether or not the collector is interested in being notified about the callsite.

This calls the register_callsite function on the Collect that this Dispatch forwards to.

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pub fn new_span(&self, span: &Attributes<'_>) -> Id

Record the construction of a new span, returning a new ID for the span being constructed.

This calls the new_span function on the Collect that this Dispatch forwards to.

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pub fn record(&self, span: &Id, values: &Record<'_>)

Record a set of values on a span.

This calls the record function on the Collect that this Dispatch forwards to.

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pub fn record_follows_from(&self, span: &Id, follows: &Id)

Adds an indication that span follows from the span with the id follows.

This calls the record_follows_from function on the Collect that this Dispatch forwards to.

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pub fn enabled(&self, metadata: &Metadata<'_>) -> bool

Returns true if a span with the specified metadata would be recorded.

This calls the enabled function on the Collect that this Dispatch forwards to.

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pub fn event(&self, event: &Event<'_>)

Records that an Event has occurred.

This calls the event function on the Collect that this Dispatch forwards to.

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pub fn enter(&self, span: &Id)

Records that a span has been can_enter.

This calls the enter function on the Collect that this Dispatch forwards to.

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pub fn exit(&self, span: &Id)

Records that a span has been exited.

This calls the exit function on the Collect that this Dispatch forwards to.

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pub fn clone_span(&self, id: &Id) -> Id

Notifies the collector that a span ID has been cloned.

This function must only be called with span IDs that were returned by this Dispatch’s new_span function. The tracing crate upholds this guarantee and any other libraries implementing instrumentation APIs must as well.

This calls the clone_span function on the Collect that this Dispatch forwards to.

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pub fn drop_span(&self, id: Id)

👎Deprecated since 0.1.2: use Dispatch::try_close instead

Notifies the collector that a span ID has been dropped.

This function must only be called with span IDs that were returned by this Dispatch’s new_span function. The tracing crate upholds this guarantee and any other libraries implementing instrumentation APIs must as well.

This calls the drop_span function on the Collect that this Dispatch forwards to.

Deprecated: The try_close method is functionally identical, but returns true if the span is now closed. It should be used instead of this method.

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pub fn try_close(&self, id: Id) -> bool

Notifies the collector that a span ID has been dropped, and returns true if there are now 0 IDs referring to that span.

This function must only be called with span IDs that were returned by this Dispatch’s new_span function. The tracing crate upholds this guarantee and any other libraries implementing instrumentation APIs must as well.

This calls the try_close function on the Collect trait that this Dispatch forwards to.

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