Implement cardinality limits for metrics streams

opentelemetry-sdk/CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## vNext
 
+- Implement function to set cardinality limits for metrics streams using `set_stream_cardinality_limit` function.
 - Add "metrics", "logs" to default features. With this, default feature list is
   "trace", "metrics" and "logs".
 - Add `with_resource` on Builder for LoggerProvider, replacing the `with_config`

opentelemetry-sdk/src/metrics/internal/aggregate.rs

@@ -1,4 +1,4 @@
-use std::{marker, sync::Arc};
+use std::{marker, sync::atomic::AtomicU64, sync::Arc};
 
 use once_cell::sync::Lazy;
 use opentelemetry::KeyValue;
@@ -16,15 +16,20 @@ use super::{
     Number,
 };
 
-const STREAM_CARDINALITY_LIMIT: u32 = 2000;
+static STREAM_CARDINALITY_LIMIT: AtomicU64 = AtomicU64::new(2000);
 pub(crate) static STREAM_OVERFLOW_ATTRIBUTE_SET: Lazy<AttributeSet> = Lazy::new(|| {
     let key_values: [KeyValue; 1] = [KeyValue::new("otel.metric.overflow", "true")];
     AttributeSet::from(&key_values[..])
 });
 
 /// Checks whether aggregator has hit cardinality limit for metric streams
 pub(crate) fn is_under_cardinality_limit(size: usize) -> bool {
-    size < STREAM_CARDINALITY_LIMIT as usize
+    size < STREAM_CARDINALITY_LIMIT.load(std::sync::atomic::Ordering::Relaxed) as usize
+}
+
+/// Set cardinality limit for metric streams
+pub fn set_stream_cardinality_limit(size: u64) {
+    STREAM_CARDINALITY_LIMIT.store(size, std::sync::atomic::Ordering::Relaxed)
 }
 
 /// Receives measurements to be aggregated.

opentelemetry-sdk/src/metrics/internal/mod.rs

@@ -9,6 +9,8 @@ use std::ops::{Add, AddAssign, Sub};
 use std::sync::atomic::{AtomicI64, AtomicU64, Ordering};
 use std::sync::Mutex;
 
+pub use aggregate::set_stream_cardinality_limit;
+
 pub(crate) use aggregate::{AggregateBuilder, ComputeAggregation, Measure};
 pub(crate) use exponential_histogram::{EXPO_MAX_SCALE, EXPO_MIN_SCALE};
 

opentelemetry-sdk/src/metrics/mod.rs

@@ -54,6 +54,7 @@ pub(crate) mod view;
 
 pub use aggregation::*;
 pub use instrument::*;
+pub use internal::set_stream_cardinality_limit;
 pub use manual_reader::*;
 pub use meter::*;
 pub use meter_provider::*;