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| </pre><pre class="rust"><code><span class="doccomment">//! Events represent single points in time during the execution of a program. |
| </span><span class="kw">use </span><span class="kw">crate</span>::parent::Parent; |
| <span class="kw">use </span><span class="kw">crate</span>::span::Id; |
| <span class="kw">use crate</span>::{field, Metadata}; |
| |
| <span class="doccomment">/// `Event`s represent single points in time where something occurred during the |
| /// execution of a program. |
| /// |
| /// An `Event` can be compared to a log record in unstructured logging, but with |
| /// two key differences: |
| /// - `Event`s exist _within the context of a [span]_. Unlike log lines, they |
| /// may be located within the trace tree, allowing visibility into the |
| /// _temporal_ context in which the event occurred, as well as the source |
| /// code location. |
| /// - Like spans, `Event`s have structured key-value data known as _[fields]_, |
| /// which may include textual message. In general, a majority of the data |
| /// associated with an event should be in the event's fields rather than in |
| /// the textual message, as the fields are more structured. |
| /// |
| /// [span]: super::span |
| /// [fields]: super::field |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>Event<<span class="lifetime">'a</span>> { |
| fields: <span class="kw-2">&</span><span class="lifetime">'a </span>field::ValueSet<<span class="lifetime">'a</span>>, |
| metadata: <span class="kw-2">&</span><span class="lifetime">'static </span>Metadata<<span class="lifetime">'static</span>>, |
| parent: Parent, |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>> Event<<span class="lifetime">'a</span>> { |
| <span class="doccomment">/// Constructs a new `Event` with the specified metadata and set of values, |
| /// and observes it with the current subscriber. |
| </span><span class="kw">pub fn </span>dispatch(metadata: <span class="kw-2">&</span><span class="lifetime">'static </span>Metadata<<span class="lifetime">'static</span>>, fields: <span class="kw-2">&</span><span class="lifetime">'a </span>field::ValueSet<<span class="lifetime">'_</span>>) { |
| <span class="kw">let </span>event = Event::new(metadata, fields); |
| <span class="kw">crate</span>::dispatcher::get_default(|current| { |
| current.event(<span class="kw-2">&</span>event); |
| }); |
| } |
| |
| <span class="doccomment">/// Returns a new `Event` in the current span, with the specified metadata |
| /// and set of values. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>new(metadata: <span class="kw-2">&</span><span class="lifetime">'static </span>Metadata<<span class="lifetime">'static</span>>, fields: <span class="kw-2">&</span><span class="lifetime">'a </span>field::ValueSet<<span class="lifetime">'a</span>>) -> <span class="self">Self </span>{ |
| Event { |
| fields, |
| metadata, |
| parent: Parent::Current, |
| } |
| } |
| |
| <span class="doccomment">/// Returns a new `Event` as a child of the specified span, with the |
| /// provided metadata and set of values. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>new_child_of( |
| parent: <span class="kw">impl </span>Into<<span class="prelude-ty">Option</span><Id>>, |
| metadata: <span class="kw-2">&</span><span class="lifetime">'static </span>Metadata<<span class="lifetime">'static</span>>, |
| fields: <span class="kw-2">&</span><span class="lifetime">'a </span>field::ValueSet<<span class="lifetime">'a</span>>, |
| ) -> <span class="self">Self </span>{ |
| <span class="kw">let </span>parent = <span class="kw">match </span>parent.into() { |
| <span class="prelude-val">Some</span>(p) => Parent::Explicit(p), |
| <span class="prelude-val">None </span>=> Parent::Root, |
| }; |
| Event { |
| fields, |
| metadata, |
| parent, |
| } |
| } |
| |
| <span class="doccomment">/// Constructs a new `Event` with the specified metadata and set of values, |
| /// and observes it with the current subscriber and an explicit parent. |
| </span><span class="kw">pub fn </span>child_of( |
| parent: <span class="kw">impl </span>Into<<span class="prelude-ty">Option</span><Id>>, |
| metadata: <span class="kw-2">&</span><span class="lifetime">'static </span>Metadata<<span class="lifetime">'static</span>>, |
| fields: <span class="kw-2">&</span><span class="lifetime">'a </span>field::ValueSet<<span class="lifetime">'_</span>>, |
| ) { |
| <span class="kw">let </span>event = <span class="self">Self</span>::new_child_of(parent, metadata, fields); |
| <span class="kw">crate</span>::dispatcher::get_default(|current| { |
| current.event(<span class="kw-2">&</span>event); |
| }); |
| } |
| |
| <span class="doccomment">/// Visits all the fields on this `Event` with the specified [visitor]. |
| /// |
| /// [visitor]: super::field::Visit |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>record(<span class="kw-2">&</span><span class="self">self</span>, visitor: <span class="kw-2">&mut </span><span class="kw">dyn </span>field::Visit) { |
| <span class="self">self</span>.fields.record(visitor); |
| } |
| |
| <span class="doccomment">/// Returns an iterator over the set of values on this `Event`. |
| </span><span class="kw">pub fn </span>fields(<span class="kw-2">&</span><span class="self">self</span>) -> field::Iter { |
| <span class="self">self</span>.fields.field_set().iter() |
| } |
| |
| <span class="doccomment">/// Returns [metadata] describing this `Event`. |
| /// |
| /// [metadata]: super::Metadata |
| </span><span class="kw">pub fn </span>metadata(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'static </span>Metadata<<span class="lifetime">'static</span>> { |
| <span class="self">self</span>.metadata |
| } |
| |
| <span class="doccomment">/// Returns true if the new event should be a root. |
| </span><span class="kw">pub fn </span>is_root(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="macro">matches!</span>(<span class="self">self</span>.parent, Parent::Root) |
| } |
| |
| <span class="doccomment">/// Returns true if the new event's parent should be determined based on the |
| /// current context. |
| /// |
| /// If this is true and the current thread is currently inside a span, then |
| /// that span should be the new event's parent. Otherwise, if the current |
| /// thread is _not_ inside a span, then the new event will be the root of its |
| /// own trace tree. |
| </span><span class="kw">pub fn </span>is_contextual(<span class="kw-2">&</span><span class="self">self</span>) -> bool { |
| <span class="macro">matches!</span>(<span class="self">self</span>.parent, Parent::Current) |
| } |
| |
| <span class="doccomment">/// Returns the new event's explicitly-specified parent, if there is one. |
| /// |
| /// Otherwise (if the new event is a root or is a child of the current span), |
| /// returns `None`. |
| </span><span class="kw">pub fn </span>parent(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><<span class="kw-2">&</span>Id> { |
| <span class="kw">match </span><span class="self">self</span>.parent { |
| Parent::Explicit(<span class="kw-2">ref </span>p) => <span class="prelude-val">Some</span>(p), |
| <span class="kw">_ </span>=> <span class="prelude-val">None</span>, |
| } |
| } |
| } |
| </code></pre></div> |
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