Struct mz_repr::explain_new::PlanTrace

pub struct PlanTrace<T> {
    find: Option<&'static str>,
    path: Mutex<String>,
    times: Mutex<Vec<Instant>>,
    entries: Mutex<Vec<TraceEntry<T>>>,
}

A tracing layer used to accumulate a sequence of explainable plans.

Fields

find: Option<&'static str>

A specific concrete path to find in this trace. If present, PlanTrace::push will only collect traces if the current path is a prefix of find.

path: Mutex<String>

A path of segments identifying the spans in the current ancestor-or-self chain. The current path is used when accumulating new entries.

times: Mutex<Vec<Instant>>

A path of times at which the spans in the current ancestor-or-self chain were started. The duration since the last time is used when accumulating new entries.

entries: Mutex<Vec<TraceEntry<T>>>

A sequence of entries associating for a specific plan type T.

Implementations

impl<T: Clone + 'static> PlanTrace<T>

pub fn new() -> Self

Create a new trace for plans of type T.

pub fn find(path: &'static str) -> Self

Create a new trace for plans of type T that will only accumulate TraceEntry instances along the prefix of the given path.

pub fn drain_as_vec(&self) -> Vec<TraceEntry<T>> where
    T: Debug,

Drain the trace data collected so far.

Note that this method will mutate the internal state of the enclosing PlanTrace even though its receiver is not &mut self. This quirk is required because the tracing Dispatch does not have downcast_mut method.

fn push(&self, plan: &T)

Push a trace entry for the given plan to the current trace.

This is a noop if (1) the call is within a context without an enclosing span, or if (2) PlanTrace::find is set and the current path is not a prefix of its value.

fn current_path(&self) -> Option<String>

Helper method: get a copy of the current path.

If PlanTrace::find is set, this will also check the current path against the find entry and return None if the former is not a prefix of the latter.

Trait Implementations

impl<S, T> Layer<S> for PlanTrace<T>where
    S: Subscriber + for<'span> LookupSpan<'span>,
    T: 'static,

A layer::Layer implementation for PlanTrace.

Populates the data wrapped by the PlanTrace instance with TraceEntry values, one for each span with attached plan in its extensions map.

fn on_new_span(&self, attrs: &Attributes<'_>, id: &Id, ctx: Context<'_, S>)

Notifies this layer that a new span was constructed with the given Attributes and Id.

fn on_enter(&self, _id: &Id, _ctx: Context<'_, S>)

Notifies this layer that a span with the given ID was entered.

fn on_exit(&self, _id: &Id, _ctx: Context<'_, S>)

Notifies this layer that the span with the given ID was exited.

fn on_register_dispatch(&self, collector: &Dispatch)

Performs late initialization when installing this layer as a Subscriber.

fn on_layer(&mut self, subscriber: &mut S)

Performs late initialization when attaching a Layer to a Subscriber.

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

Registers a new callsite with this layer, returning whether or not the layer is interested in being notified about the callsite, similarly to Subscriber::register_callsite.

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

Returns true if this layer is interested in a span or event with the given metadata in the current Context, similarly to Subscriber::enabled.

fn on_record(&self, _span: &Id, _values: &Record<'_>, _ctx: Context<'_, S>)

Notifies this layer that a span with the given Id recorded the given values.

fn on_follows_from(&self, _span: &Id, _follows: &Id, _ctx: Context<'_, S>)

Notifies this layer that a span with the ID span recorded that it follows from the span with the ID follows.

fn event_enabled(&self, _event: &Event<'_>, _ctx: Context<'_, S>) -> bool

Called before on_event, to determine if on_event should be called.

fn on_event(&self, _event: &Event<'_>, _ctx: Context<'_, S>)

Notifies this layer that an event has occurred.

fn on_close(&self, _id: Id, _ctx: Context<'_, S>)

Notifies this layer that the span with the given ID has been closed.

fn on_id_change(&self, _old: &Id, _new: &Id, _ctx: Context<'_, S>)

Notifies this layer that a span ID has been cloned, and that the subscriber returned a different ID.

fn and_then<L>(self, layer: L) -> Layered<L, Self, S>where
    L: Layer<S>,
    Self: Sized,

Composes this layer around the given Layer, returning a Layered struct implementing Layer.

fn with_subscriber(self, inner: S) -> Layered<Self, S, S>where
    Self: Sized,

Composes this Layer with the given Subscriber, returning a Layered struct that implements Subscriber.

fn with_filter<F>(self, filter: F) -> Filtered<Self, F, S>where
    Self: Sized,
    F: Filter<S>,

Combines self with a Filter, returning a Filtered layer.