From 451abd56e7a33af1016cb13e2f3d0c828c70fcb2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Ml=C3=A1dek?= <david.mladek.cz@gmail.com>
Date: Fri, 16 Feb 2024 00:31:48 +0100
Subject: [PATCH] enhancement: honor span limits when collecting events

---
 src/layer.rs  | 14 ++++++++++++++
 src/tracer.rs | 10 ++++++++++
 2 files changed, 24 insertions(+)

diff --git a/src/layer.rs b/src/layer.rs
index 2a16d47..376dc58 100644
--- a/src/layer.rs
+++ b/src/layer.rs
@@ -1022,6 +1022,20 @@ where
             let mut otel_data = span.extensions_mut().remove::<OtelData>();
             let span_builder = otel_data.as_mut().map(|data| &mut data.builder);
 
+            let limits = self.tracer.span_limits();
+
+            if span_builder
+                .as_ref()
+                .and_then(|span_builder| span_builder.events.as_ref().map(|events| events.len()))
+                .zip(limits)
+                .map_or(false, |(current_length, limits)| {
+                    current_length >= limits.max_events_per_span as usize
+                })
+            {
+                // We have reached the configured limit for events so there is no point in storing any more.
+                return;
+            }
+
             let mut otel_event = otel::Event::new(
                 String::new(),
                 crate::time::now(),
diff --git a/src/tracer.rs b/src/tracer.rs
index c37966b..b45ec58 100644
--- a/src/tracer.rs
+++ b/src/tracer.rs
@@ -47,6 +47,11 @@ pub trait PreSampledTracer {
 
     /// Generate a new span id.
     fn new_span_id(&self) -> otel::SpanId;
+
+    /// Gets the current span limits.
+    fn span_limits(&self) -> Option<opentelemetry_sdk::trace::SpanLimits> {
+        None
+    }
 }
 
 impl PreSampledTracer for noop::NoopTracer {
@@ -111,6 +116,11 @@ impl PreSampledTracer for SdkTracer {
             .map(|provider| provider.config().id_generator.new_span_id())
             .unwrap_or(otel::SpanId::INVALID)
     }
+
+    fn span_limits(&self) -> Option<opentelemetry_sdk::trace::SpanLimits> {
+        self.provider()
+            .map(|provider| provider.config().span_limits)
+    }
 }
 
 fn current_trace_state(