Implement cardinality limits for metrics streams open-telemetry#1065

Signed-off-by: Benjamin Coenen <5719034+bnjjj@users.noreply.github.com>

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

@@ -1,30 +1,35 @@
-use std::{marker, sync::Arc};
+use std::marker;
+use std::sync::atomic::AtomicU64;
+use std::sync::Arc;
 
 use once_cell::sync::Lazy;
 use opentelemetry::KeyValue;
 
-use crate::{
-    metrics::data::{Aggregation, Gauge, Temporality},
-    metrics::AttributeSet,
-};
-
-use super::{
-    exponential_histogram::ExpoHistogram,
-    histogram::Histogram,
-    last_value::LastValue,
-    sum::{PrecomputedSum, Sum},
-    Number,
-};
-
-const STREAM_CARDINALITY_LIMIT: u32 = 2000;
+use super::exponential_histogram::ExpoHistogram;
+use super::histogram::Histogram;
+use super::last_value::LastValue;
+use super::sum::PrecomputedSum;
+use super::sum::Sum;
+use super::Number;
+use crate::metrics::data::Aggregation;
+use crate::metrics::data::Gauge;
+use crate::metrics::data::Temporality;
+use crate::metrics::AttributeSet;
+
+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.
@@ -213,13 +218,17 @@ impl<T: Number<T>> AggregateBuilder<T> {
 
 #[cfg(test)]
 mod tests {
-    use crate::metrics::data::{
-        DataPoint, ExponentialBucket, ExponentialHistogram, ExponentialHistogramDataPoint,
-        Histogram, HistogramDataPoint, Sum,
-    };
-    use std::{time::SystemTime, vec};
+    use std::time::SystemTime;
+    use std::vec;
 
     use super::*;
+    use crate::metrics::data::DataPoint;
+    use crate::metrics::data::ExponentialBucket;
+    use crate::metrics::data::ExponentialHistogram;
+    use crate::metrics::data::ExponentialHistogramDataPoint;
+    use crate::metrics::data::Histogram;
+    use crate::metrics::data::HistogramDataPoint;
+    use crate::metrics::data::Sum;
 
     #[test]
     fn last_value_aggregation() {

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

@@ -5,12 +5,20 @@ mod last_value;
 mod sum;
 
 use core::fmt;
-use std::ops::{Add, AddAssign, Sub};
-use std::sync::atomic::{AtomicI64, AtomicU64, Ordering};
+use std::ops::Add;
+use std::ops::AddAssign;
+use std::ops::Sub;
+use std::sync::atomic::AtomicI64;
+use std::sync::atomic::AtomicU64;
+use std::sync::atomic::Ordering;
 use std::sync::Mutex;
 
-pub(crate) use aggregate::{AggregateBuilder, ComputeAggregation, Measure};
-pub(crate) use exponential_histogram::{EXPO_MAX_SCALE, EXPO_MIN_SCALE};
+pub use aggregate::set_stream_cardinality_limit;
+pub(crate) use aggregate::AggregateBuilder;
+pub(crate) use aggregate::ComputeAggregation;
+pub(crate) use aggregate::Measure;
+pub(crate) use exponential_histogram::EXPO_MAX_SCALE;
+pub(crate) use exponential_histogram::EXPO_MIN_SCALE;
 
 /// Marks a type that can have a value added and retrieved atomically. Required since
 /// different types have different backing atomic mechanisms

opentelemetry-sdk/src/metrics/mod.rs

@@ -52,21 +52,24 @@ pub(crate) mod pipeline;
 pub mod reader;
 pub(crate) mod view;
 
+use std::collections::hash_map::DefaultHasher;
+use std::collections::HashSet;
+use std::hash::Hash;
+use std::hash::Hasher;
+
 pub use aggregation::*;
 pub use instrument::*;
+pub use internal::set_stream_cardinality_limit;
 pub use manual_reader::*;
 pub use meter::*;
 pub use meter_provider::*;
+use opentelemetry::Key;
+use opentelemetry::KeyValue;
+use opentelemetry::Value;
 pub use periodic_reader::*;
 pub use pipeline::Pipeline;
 pub use view::*;
 
-use std::collections::hash_map::DefaultHasher;
-use std::collections::HashSet;
-use std::hash::{Hash, Hasher};
-
-use opentelemetry::{Key, KeyValue, Value};
-
 /// A unique set of attributes that can be used as instrument identifiers.
 ///
 /// This must implement [Hash], [PartialEq], and [Eq] so it may be used as
@@ -139,20 +142,32 @@ impl Hash for AttributeSet {
 
 #[cfg(all(test, feature = "testing"))]
 mod tests {
-    use self::data::{DataPoint, HistogramDataPoint, ScopeMetrics};
-    use super::*;
-    use crate::metrics::data::{ResourceMetrics, Temporality};
-    use crate::metrics::reader::TemporalitySelector;
-    use crate::testing::metrics::InMemoryMetricsExporterBuilder;
-    use crate::{runtime, testing::metrics::InMemoryMetricsExporter};
-    use opentelemetry::metrics::{Counter, Meter, UpDownCounter};
-    use opentelemetry::{metrics::MeterProvider as _, KeyValue};
-    use rand::{rngs, Rng, SeedableRng};
     use std::borrow::Cow;
-    use std::sync::{Arc, Mutex};
+    use std::sync::Arc;
+    use std::sync::Mutex;
     use std::thread;
     use std::time::Duration;
 
+    use opentelemetry::metrics::Counter;
+    use opentelemetry::metrics::Meter;
+    use opentelemetry::metrics::MeterProvider as _;
+    use opentelemetry::metrics::UpDownCounter;
+    use opentelemetry::KeyValue;
+    use rand::rngs;
+    use rand::Rng;
+    use rand::SeedableRng;
+
+    use self::data::DataPoint;
+    use self::data::HistogramDataPoint;
+    use self::data::ScopeMetrics;
+    use super::*;
+    use crate::metrics::data::ResourceMetrics;
+    use crate::metrics::data::Temporality;
+    use crate::metrics::reader::TemporalitySelector;
+    use crate::runtime;
+    use crate::testing::metrics::InMemoryMetricsExporter;
+    use crate::testing::metrics::InMemoryMetricsExporterBuilder;
+
     // Run all tests in this mod
     // cargo test metrics::tests --features=testing
     // Note for all tests from this point onwards in this mod: