add NaN serialization/deserialization

Author: lalitb

opentelemetry-proto/src/proto.rs

@@ -200,6 +200,64 @@ pub(crate) mod serializers {
             .map(|s| s.parse::<u64>().map_err(de::Error::custom))
             .collect()
     }
+
+
+// Special serializer and deserializer for NaN, Infinity, and -Infinity
+pub fn serialize_f64_special<S>(value: &f64, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    if value.is_nan() {
+        serializer.serialize_str("NaN")
+    } else if value.is_infinite() {
+        if value.is_sign_positive() {
+            serializer.serialize_str("Infinity")
+        } else {
+            serializer.serialize_str("-Infinity")
+        }
+    } else {
+        serializer.serialize_f64(*value)
+    }
+}
+
+pub fn deserialize_f64_special<'de, D>(deserializer: D) -> Result<f64, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    struct F64Visitor;
+
+    impl<'de> de::Visitor<'de> for F64Visitor {
+        type Value = f64;
+
+        fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str("a float or a string representing NaN, Infinity, or -Infinity")
+        }
+
+        fn visit_f64<E>(self, value: f64) -> Result<f64, E>
+        where
+            E: de::Error,
+        {
+            Ok(value)
+        }
+
+        fn visit_str<E>(self, value: &str) -> Result<f64, E>
+        where
+            E: de::Error,
+        {
+            match value {
+                "NaN" => Ok(f64::NAN),
+                "Infinity" => Ok(f64::INFINITY),
+                "-Infinity" => Ok(f64::NEG_INFINITY),
+                _ => Err(E::custom(format!(
+                    "Invalid string for f64: expected NaN, Infinity, or -Infinity but got '{}'",
+                    value
+                ))),
+            }
+        }
+    }
+
+    deserializer.deserialize_any(F64Visitor)
+   }
 }
 
 #[cfg(feature = "gen-tonic-messages")]

opentelemetry-proto/src/proto/tonic/opentelemetry.proto.metrics.v1.rs

@@ -738,11 +738,25 @@ pub mod summary_data_point {
         /// The quantile of a distribution. Must be in the interval
         /// \[0.0, 1.0\].
         #[prost(double, tag = "1")]
+        #[cfg_attr(
+            feature = "with-serde",
+            serde(
+                serialize_with = "crate::proto::serializers::serialize_f64_special",
+                deserialize_with = "crate::proto::serializers::deserialize_f64_special"
+            )
+        )]
         pub quantile: f64,
         /// The value at the given quantile of a distribution.
         ///
         /// Quantile values must NOT be negative.
         #[prost(double, tag = "2")]
+        #[cfg_attr(
+            feature = "with-serde",
+            serde(
+                serialize_with = "crate::proto::serializers::serialize_f64_special",
+                deserialize_with = "crate::proto::serializers::deserialize_f64_special"
+            )
+        )]
         pub value: f64,
     }
 }

opentelemetry-proto/tests/grpc_build.rs

@@ -151,6 +151,19 @@ fn build_tonic() {
     );
     }
 
+    // Special handling for floating-point fields that might contain NaN, Infinity, or -Infinity
+    // TODO: More needs to be added here as we find more fields that need this special handling
+    for path in [
+        // metrics
+        "metrics.v1.SummaryDataPoint.ValueAtQuantile.value",
+        "metrics.v1.SummaryDataPoint.ValueAtQuantile.quantile",
+    ] {
+        builder = builder.field_attribute(
+        path,
+        "#[cfg_attr(feature = \"with-serde\", serde(serialize_with = \"crate::proto::serializers::serialize_f64_special\", deserialize_with = \"crate::proto::serializers::deserialize_f64_special\"))]",
+    );
+    }
+
     // special serializer and deserializer for value
     // The Value::value field must be hidden
     builder = builder