feat: add max_attributes_per_event and max_attributes_per_link.

opentelemetry/src/sdk/trace/config.rs

@@ -7,6 +7,12 @@ use std::env;
 use std::str::FromStr;
 use std::sync::Arc;
 
+pub(crate) const DEFAULT_MAX_EVENT_PER_SPAN: u32 = 128;
+pub(crate) const DEFAULT_MAX_ATTRIBUTES_PER_SPAN: u32 = 128;
+pub(crate) const DEFAULT_MAX_LINKS_PER_SPAN: u32 = 128;
+pub(crate) const DEFAULT_MAX_ATTRIBUTES_PER_EVENT: u32 = 128;
+pub(crate) const DEFAULT_MAX_ATTRIBUTES_PER_LINK: u32 = 128;
+
 /// Default trace configuration
 pub fn config() -> Config {
     Config::default()
@@ -25,6 +31,10 @@ pub struct Config {
     pub max_attributes_per_span: u32,
     /// The max links that can be added to a `Span`.
     pub max_links_per_span: u32,
+    /// The max attributes that can be added into an `Event`
+    pub max_attributes_per_event: u32,
+    /// The max attributes that can be added into a `Link`
+    pub max_attributes_per_link: u32,
     /// Contains attributes representing an entity that produces telemetry.
     pub resource: Option<Arc<sdk::Resource>>,
 }
@@ -60,6 +70,18 @@ impl Config {
         self
     }
 
+    /// Specify the number of attributes one event can have.
+    pub fn with_max_attributes_per_event(mut self, max_attributes: u32) -> Self {
+        self.max_attributes_per_event = max_attributes;
+        self
+    }
+
+    /// Specify the number of attributes one link can have.
+    pub fn with_max_attributes_per_link(mut self, max_attributes: u32) -> Self {
+        self.max_attributes_per_link = max_attributes;
+        self
+    }
+
     /// Specify the attributes representing the entity that produces telemetry
     pub fn with_resource(mut self, resource: sdk::Resource) -> Self {
         self.resource = Some(Arc::new(resource));
@@ -73,9 +95,11 @@ impl Default for Config {
         let mut config = Config {
             sampler: Box::new(Sampler::ParentBased(Box::new(Sampler::AlwaysOn))),
             id_generator: Box::new(sdk::trace::IdGenerator::default()),
-            max_events_per_span: 128,
-            max_attributes_per_span: 128,
-            max_links_per_span: 128,
+            max_events_per_span: DEFAULT_MAX_EVENT_PER_SPAN,
+            max_attributes_per_span: DEFAULT_MAX_ATTRIBUTES_PER_SPAN,
+            max_links_per_span: DEFAULT_MAX_LINKS_PER_SPAN,
+            max_attributes_per_link: DEFAULT_MAX_ATTRIBUTES_PER_LINK,
+            max_attributes_per_event: DEFAULT_MAX_ATTRIBUTES_PER_EVENT,
             resource: None,
         };
 

opentelemetry/src/sdk/trace/span.rs

@@ -8,6 +8,7 @@
 //! start time is set to the current time on span creation. After the `Span` is created, it
 //! is possible to change its name, set its `Attributes`, and add `Links` and `Events`.
 //! These cannot be changed after the `Span`'s end time has been set.
+use crate::sdk::trace::config::DEFAULT_MAX_ATTRIBUTES_PER_EVENT;
 use crate::trace::{Event, SpanContext, SpanId, SpanKind, StatusCode};
 use crate::{sdk, trace, KeyValue};
 use std::borrow::Cow;
@@ -78,9 +79,20 @@ impl crate::trace::Span for Span {
         &mut self,
         name: String,
         timestamp: SystemTime,
-        attributes: Vec<KeyValue>,
+        mut attributes: Vec<KeyValue>,
     ) {
+        let max_attributes_per_event =
+            self.tracer
+                .provider()
+                .map(|provider| provider.config().max_attributes_per_event)
+                .unwrap_or(DEFAULT_MAX_ATTRIBUTES_PER_EVENT) as usize;
         self.with_data(|data| {
+            if attributes.len() > max_attributes_per_event {
+                let _dropped: Vec<_> = attributes
+                    .drain((max_attributes_per_event + 1)..)
+                    .collect();
+            }
+
             data.message_events
                 .push_back(Event::new(name, timestamp, attributes))
         });

opentelemetry/src/sdk/trace/tracer.rs

@@ -259,6 +259,15 @@ impl crate::trace::Tracer for Tracer {
             }
             let mut links = EvictedQueue::new(config.max_links_per_span);
             if let Some(link_options) = &mut link_options {
+                for link in link_options.iter_mut() {
+                    // make sure the attributes is less than max_attribute_per_link
+                    let attributes = link.attributes_mut();
+                    if attributes.len() > config.max_attributes_per_link as usize {
+                        let _dropped: Vec<_> = attributes
+                            .drain((config.max_attributes_per_link as usize + 1)..)
+                            .collect();
+                    }
+                }
                 links.append_vec(link_options);
             }
             let start_time = start_time.unwrap_or_else(crate::time::now);

opentelemetry/src/trace/link.rs

@@ -30,4 +30,9 @@ impl Link {
     pub fn attributes(&self) -> &Vec<KeyValue> {
         &self.attributes
     }
+
+    /// Mutable attributes of the link
+    pub(crate) fn attributes_mut(&mut self) -> &mut Vec<KeyValue> {
+        self.attributes.as_mut()
+    }
 }