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| 1 | +use std::any::TypeId; |
| 2 | + |
| 3 | +use opentelemetry::{trace::TraceContextExt as _, Key, KeyValue, Value}; |
| 4 | +use tracing::{span, Event, Subscriber}; |
| 5 | +use tracing_subscriber::{ |
| 6 | + layer::{Context, Filter}, |
| 7 | + registry::LookupSpan, |
| 8 | + Layer, |
| 9 | +}; |
| 10 | + |
| 11 | +use crate::{OtelData, OtelDataState}; |
| 12 | + |
| 13 | +use super::{OpenTelemetryLayer, SPAN_EVENT_COUNT_FIELD}; |
| 14 | + |
| 15 | +/// A layer wrapping a [`OpenTelemetryLayer`], discarding all events filtered out by a given |
| 16 | +/// [`Filter`]. This can be built by calling [`OpenTelemetryLayer::with_counting_event_filter`]. |
| 17 | +/// |
| 18 | +/// Only events that are not filtered out will be saved as events on the span. All events, including |
| 19 | +/// those filtered out, will be counted and the total will be provided in the |
| 20 | +/// `otel.tracing_event_count` field of the exported span. |
| 21 | +/// |
| 22 | +/// This is useful when there is large volume of logs outputted by the application and it would be |
| 23 | +/// too expensive to export all of them as span events, but it is still desirable to have |
| 24 | +/// information whether there is more information in logs for the given span. |
| 25 | +pub struct FilteredOpenTelemetryLayer<S, T, F> { |
| 26 | + inner: OpenTelemetryLayer<S, T>, |
| 27 | + filter: F, |
| 28 | +} |
| 29 | + |
| 30 | +impl<S, T, F> FilteredOpenTelemetryLayer<S, T, F> { |
| 31 | + pub fn map_inner<Mapper, S2, T2>(self, mapper: Mapper) -> FilteredOpenTelemetryLayer<S2, T2, F> |
| 32 | + where |
| 33 | + Mapper: FnOnce(OpenTelemetryLayer<S, T>) -> OpenTelemetryLayer<S2, T2>, |
| 34 | + F: Filter<S>, |
| 35 | + { |
| 36 | + FilteredOpenTelemetryLayer { |
| 37 | + inner: mapper(self.inner), |
| 38 | + filter: self.filter, |
| 39 | + } |
| 40 | + } |
| 41 | + |
| 42 | + pub fn with_counting_event_filter<F2>(self, filter: F2) -> FilteredOpenTelemetryLayer<S, T, F2> |
| 43 | + where |
| 44 | + F2: Filter<S>, |
| 45 | + { |
| 46 | + FilteredOpenTelemetryLayer { |
| 47 | + inner: self.inner, |
| 48 | + filter, |
| 49 | + } |
| 50 | + } |
| 51 | + |
| 52 | + pub(crate) fn new(inner: OpenTelemetryLayer<S, T>, filter: F) -> Self |
| 53 | + where |
| 54 | + S: Subscriber + for<'span> LookupSpan<'span>, |
| 55 | + F: Filter<S>, |
| 56 | + { |
| 57 | + Self { inner, filter } |
| 58 | + } |
| 59 | +} |
| 60 | + |
| 61 | +struct EventCount(u32); |
| 62 | + |
| 63 | +impl<S, T, F> Layer<S> for FilteredOpenTelemetryLayer<S, T, F> |
| 64 | +where |
| 65 | + S: Subscriber + for<'lookup> LookupSpan<'lookup>, |
| 66 | + OpenTelemetryLayer<S, T>: Layer<S>, |
| 67 | + F: Filter<S> + 'static, |
| 68 | +{ |
| 69 | + fn on_layer(&mut self, subscriber: &mut S) { |
| 70 | + self.inner.on_layer(subscriber); |
| 71 | + } |
| 72 | + |
| 73 | + fn register_callsite( |
| 74 | + &self, |
| 75 | + metadata: &'static tracing::Metadata<'static>, |
| 76 | + ) -> tracing_core::Interest { |
| 77 | + self.inner.register_callsite(metadata) |
| 78 | + } |
| 79 | + |
| 80 | + fn enabled(&self, metadata: &tracing::Metadata<'_>, ctx: Context<'_, S>) -> bool { |
| 81 | + self.inner.enabled(metadata, ctx) |
| 82 | + } |
| 83 | + |
| 84 | + fn on_new_span(&self, attrs: &span::Attributes<'_>, id: &span::Id, ctx: Context<'_, S>) { |
| 85 | + self.inner.on_new_span(attrs, id, ctx); |
| 86 | + } |
| 87 | + |
| 88 | + fn on_record(&self, span: &span::Id, values: &span::Record<'_>, ctx: Context<'_, S>) { |
| 89 | + self.inner.on_record(span, values, ctx); |
| 90 | + } |
| 91 | + |
| 92 | + fn on_follows_from(&self, span: &span::Id, follows: &span::Id, ctx: Context<'_, S>) { |
| 93 | + self.inner.on_follows_from(span, follows, ctx); |
| 94 | + } |
| 95 | + |
| 96 | + fn on_event(&self, event: &Event<'_>, ctx: Context<'_, S>) { |
| 97 | + let Some(span) = event.parent().and_then(|id| ctx.span(id)).or_else(|| { |
| 98 | + event |
| 99 | + .is_contextual() |
| 100 | + .then(|| ctx.lookup_current()) |
| 101 | + .flatten() |
| 102 | + }) else { |
| 103 | + return; |
| 104 | + }; |
| 105 | + |
| 106 | + { |
| 107 | + let mut extensions = span.extensions_mut(); |
| 108 | + |
| 109 | + if let Some(count) = extensions.get_mut::<EventCount>() { |
| 110 | + count.0 += 1; |
| 111 | + } else { |
| 112 | + extensions.insert(EventCount(1)); |
| 113 | + } |
| 114 | + } |
| 115 | + |
| 116 | + drop(span); |
| 117 | + |
| 118 | + println!("evaluating event with level {}", event.metadata().level()); |
| 119 | + if self.filter.enabled(event.metadata(), &ctx) { |
| 120 | + println!("processing event with level {}", event.metadata().level()); |
| 121 | + self.inner.on_event(event, ctx); |
| 122 | + } |
| 123 | + } |
| 124 | + |
| 125 | + fn on_enter(&self, id: &span::Id, ctx: Context<'_, S>) { |
| 126 | + self.inner.on_enter(id, ctx); |
| 127 | + } |
| 128 | + |
| 129 | + fn on_exit(&self, id: &span::Id, ctx: Context<'_, S>) { |
| 130 | + self.inner.on_exit(id, ctx); |
| 131 | + } |
| 132 | + |
| 133 | + fn on_close(&self, id: span::Id, ctx: Context<'_, S>) { |
| 134 | + let span = ctx.span(&id).expect("Span not found, this is a bug"); |
| 135 | + let mut extensions = span.extensions_mut(); |
| 136 | + |
| 137 | + let count = extensions.remove::<EventCount>().map_or(0, |count| count.0); |
| 138 | + if let Some(OtelData { state, end_time: _ }) = extensions.get_mut::<OtelData>() { |
| 139 | + let key_value = KeyValue::new( |
| 140 | + Key::from_static_str(SPAN_EVENT_COUNT_FIELD), |
| 141 | + Value::I64(i64::from(count)), |
| 142 | + ); |
| 143 | + match state { |
| 144 | + OtelDataState::Builder { |
| 145 | + builder, |
| 146 | + parent_cx: _, |
| 147 | + } => { |
| 148 | + builder.attributes.get_or_insert(Vec::new()).push(key_value); |
| 149 | + } |
| 150 | + OtelDataState::Context { current_cx } => { |
| 151 | + let span = current_cx.span(); |
| 152 | + span.set_attribute(key_value); |
| 153 | + } |
| 154 | + } |
| 155 | + } |
| 156 | + |
| 157 | + drop(extensions); |
| 158 | + drop(span); |
| 159 | + |
| 160 | + self.inner.on_close(id, ctx); |
| 161 | + } |
| 162 | + |
| 163 | + fn on_id_change(&self, old: &span::Id, new: &span::Id, ctx: Context<'_, S>) { |
| 164 | + self.inner.on_id_change(old, new, ctx); |
| 165 | + } |
| 166 | + |
| 167 | + /// SAFETY: this is sound as long as the inner implementation is sound. |
| 168 | + unsafe fn downcast_raw(&self, id: TypeId) -> Option<*const ()> { |
| 169 | + if id == TypeId::of::<Self>() { |
| 170 | + Some(self as *const _ as *const ()) |
| 171 | + } else { |
| 172 | + unsafe { self.inner.downcast_raw(id) } |
| 173 | + } |
| 174 | + } |
| 175 | + |
| 176 | + // `and_then`, `with_subscriber`, and `with_filter` are not implemented on purpose. Other |
| 177 | + // methods should probably be implemented manually if there are new provided methods. |
| 178 | +} |
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