Remove cardinality capping in Metrics (open-telemetry#2528)

Author: cijothomas

opentelemetry-sdk/CHANGELOG.md

@@ -257,6 +257,12 @@ metadata, a feature introduced in version 0.1.40. [#2418](https://github.com/ope
   - If you're implementing a custom runtime, you must explicitly enable the   experimental_async_runtime` feature in your 
   Cargo.toml and implement the required `Runtime` traits.
 
+- Removed Metrics Cardinality Limit feature. This was originally introduced in
+[#1066](https://github.com/open-telemetry/opentelemetry-rust/pull/1066) with a
+hardcoded limit of 2000 and no ability to change it. This feature will be
+re-introduced in a future date, along with the ability to change the cardinality
+limit.
+
 ## 0.27.1
 
 Released 2024-Nov-27

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

@@ -18,8 +18,11 @@ use super::{
 pub(crate) const STREAM_CARDINALITY_LIMIT: usize = 2000;
 
 /// Checks whether aggregator has hit cardinality limit for metric streams
-pub(crate) fn is_under_cardinality_limit(size: usize) -> bool {
-    size < STREAM_CARDINALITY_LIMIT
+pub(crate) fn is_under_cardinality_limit(_size: usize) -> bool {
+    true
+
+    // TODO: Implement this feature, after allowing the ability to customize the cardinality limit.
+    // size < STREAM_CARDINALITY_LIMIT
 }
 
 /// Receives measurements to be aggregated.

opentelemetry-sdk/src/metrics/mod.rs

@@ -259,11 +259,13 @@ mod tests {
         assert_eq!(data_point.value, 50, "Unexpected data point value");
     }
 
+    #[ignore = "https://github.com/open-telemetry/opentelemetry-rust/issues/1065"]
     #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
     async fn counter_aggregation_overflow_delta() {
         counter_aggregation_overflow_helper(Temporality::Delta);
     }
 
+    #[ignore = "https://github.com/open-telemetry/opentelemetry-rust/issues/1065"]
     #[tokio::test(flavor = "multi_thread", worker_threads = 1)]
     async fn counter_aggregation_overflow_cumulative() {
         counter_aggregation_overflow_helper(Temporality::Cumulative);