Disallow histogram.set, counter.observe, gauge.observe

src/metric.cc

@@ -358,13 +358,36 @@ Metric::Increment(const double& value)
 void
 Metric::SetValue(const double& value)
 {
+  // SetValue and Observe share the same C API TRITONSERVER_MetricSet.
+  // Throws if SetValue is called by a histogram metric.
+  TRITONSERVER_MetricKind kind;
+  THROW_IF_TRITON_ERROR(TRITONSERVER_GetMetricKind(
+      reinterpret_cast<TRITONSERVER_Metric*>(metric_address_), &kind));
+  if (kind == TRITONSERVER_METRIC_KIND_HISTOGRAM) {
+    throw PythonBackendException(
+        "TRITONSERVER_METRIC_KIND_HISTOGRAM does not support SetValue");
+  }
+
   auto triton_metric = reinterpret_cast<TRITONSERVER_Metric*>(metric_address_);
   THROW_IF_TRITON_ERROR(TRITONSERVER_MetricSet(triton_metric, value));
 }
 
 void
 Metric::Observe(const double& value)
 {
+  // SetValue and Observe share the same C API TRITONSERVER_MetricSet.
+  // Throws if Observe is called by a non-histogram metric.
+  TRITONSERVER_MetricKind kind;
+  THROW_IF_TRITON_ERROR(TRITONSERVER_GetMetricKind(
+      reinterpret_cast<TRITONSERVER_Metric*>(metric_address_), &kind));
+  if (kind == TRITONSERVER_METRIC_KIND_COUNTER) {
+    throw PythonBackendException(
+        "TRITONSERVER_METRIC_KIND_COUNTER does not support Observe");
+  } else if (kind == TRITONSERVER_METRIC_KIND_GAUGE) {
+    throw PythonBackendException(
+        "TRITONSERVER_METRIC_KIND_GAUGE does not support Observe");
+  }
+
   auto triton_metric = reinterpret_cast<TRITONSERVER_Metric*>(metric_address_);
   THROW_IF_TRITON_ERROR(TRITONSERVER_MetricSet(triton_metric, value));
 }

src/metric.h

@@ -166,8 +166,8 @@ class Metric {
 
   // The labels of the metric, which is the identifier of the metric.
   std::string labels_;
-  // Monotonically increasing values representing the
-  // bucket boundaries. For histogram only.
+  // Monotonically increasing values representing bucket boundaries for creating
+  // histogram metric.
   std::optional<std::vector<double>> buckets_;
   // The value used for incrementing or setting the metric.
   double operation_value_;

src/metric_family.h

@@ -97,8 +97,8 @@ class MetricFamily {
 
   /// Create a metric from the metric family and store it in the metric map.
   /// \param labels The labels of the metric.
-  /// \param buckets Monotonically increasing values representing the
-  /// bucket boundaries. For histogram only.
+  /// \param buckets Monotonically increasing values representing bucket
+  /// boundaries for creating histogram metric.
   /// \return Returns the shared pointer to the created metric.
   std::shared_ptr<Metric> CreateMetric(
       const py::object& labels, const py::object& buckets);