fix: include counter names in negative value errors

Author: zeitlinger

prometheus-metrics-core/src/main/java/io/prometheus/metrics/core/metrics/Counter.java

@@ -213,8 +213,13 @@ private CounterSnapshot.CounterDataPointSnapshot collect(Labels labels, String m
           }
         }
       }
-      return new CounterSnapshot.CounterDataPointSnapshot(
-          get(), labels, latestExemplar, createdTimeMillis, metricName);
+      return CounterSnapshot.CounterDataPointSnapshot.builder()
+          .value(get())
+          .labels(labels)
+          .exemplar(latestExemplar)
+          .createdTimestampMillis(createdTimeMillis)
+          .metricName(metricName)
+          .build();
     }
   }
 

prometheus-metrics-core/src/main/java/io/prometheus/metrics/core/metrics/CounterWithCallback.java

@@ -47,8 +47,11 @@ public CounterSnapshot collect() {
     callback.accept(
         (value, labelValues) -> {
           dataPoints.add(
-              new CounterSnapshot.CounterDataPointSnapshot(
-                  value, makeLabels(labelValues), null, 0L, metadata.getName()));
+              CounterSnapshot.CounterDataPointSnapshot.builder()
+                  .value(value)
+                  .labels(makeLabels(labelValues))
+                  .metricName(metadata.getName())
+                  .build());
         });
     return new CounterSnapshot(metadata, dataPoints);
   }

prometheus-metrics-core/src/test/java/io/prometheus/metrics/core/metrics/CounterWithCallbackTest.java

@@ -43,4 +43,17 @@ void testCounterNoCallback() {
         .isThrownBy(
             () -> CounterWithCallback.builder().name("counter").labelNames("l1", "l2").build());
   }
+
+  @Test
+  void testNegativeValueIncludesMetricName() {
+    CounterWithCallback counter =
+        CounterWithCallback.builder()
+            .name("negative_counter")
+            .callback(callback -> callback.call(-1.0))
+            .build();
+
+    assertThatExceptionOfType(IllegalArgumentException.class)
+        .isThrownBy(counter::collect)
+        .withMessage("negative_counter=-1.0: counters cannot have a negative value");
+  }
 }

prometheus-metrics-model/src/main/java/io/prometheus/metrics/model/snapshots/CounterSnapshot.java

@@ -48,6 +48,7 @@ public static class CounterDataPointSnapshot extends DataPointSnapshot {
 
     private final double value;
     @Nullable private final Exemplar exemplar;
+
     /** Optional metric name used only in validation error messages. */
     @Nullable private final String metricName;
 
@@ -64,20 +65,7 @@ public static class CounterDataPointSnapshot extends DataPointSnapshot {
      */
     public CounterDataPointSnapshot(
         double value, Labels labels, @Nullable Exemplar exemplar, long createdTimestampMillis) {
-      this(value, labels, exemplar, createdTimestampMillis, 0, null);
-    }
-
-    /**
-     * Same as {@link #CounterDataPointSnapshot(double, Labels, Exemplar, long)} with an optional
-     * metric name included in validation error messages when the value is negative.
-     */
-    public CounterDataPointSnapshot(
-        double value,
-        Labels labels,
-        @Nullable Exemplar exemplar,
-        long createdTimestampMillis,
-        @Nullable String metricName) {
-      this(value, labels, exemplar, createdTimestampMillis, 0, metricName);
+      this(value, labels, exemplar, createdTimestampMillis, 0, false, null);
     }
 
     /**
@@ -95,29 +83,6 @@ public CounterDataPointSnapshot(
       this(value, labels, exemplar, createdTimestampMillis, scrapeTimestampMillis, false, null);
     }
 
-    /**
-     * Constructor with scrape timestamp and optional metric name for validation messages.
-     *
-     * @see #CounterDataPointSnapshot(double, Labels, Exemplar, long, long)
-     */
-    @SuppressWarnings("this-escape")
-    public CounterDataPointSnapshot(
-        double value,
-        Labels labels,
-        @Nullable Exemplar exemplar,
-        long createdTimestampMillis,
-        long scrapeTimestampMillis,
-        @Nullable String metricName) {
-      this(
-          value,
-          labels,
-          exemplar,
-          createdTimestampMillis,
-          scrapeTimestampMillis,
-          false,
-          metricName);
-    }
-
     @SuppressWarnings("this-escape")
     public CounterDataPointSnapshot(
         double value,
@@ -231,6 +196,7 @@ public CounterDataPointSnapshot build() {
             exemplar,
             createdTimestampMillis,
             scrapeTimestampMillis,
+            false,
             metricName);
       }
 

prometheus-metrics-model/src/test/java/io/prometheus/metrics/model/snapshots/CounterSnapshotTest.java

@@ -136,10 +136,7 @@ void testNegativeValueIncludesMetricNameInMessage() {
     assertThatExceptionOfType(IllegalArgumentException.class)
         .isThrownBy(
             () ->
-                CounterDataPointSnapshot.builder()
-                    .metricName("http_requests")
-                    .value(-2.0)
-                    .build())
+                CounterDataPointSnapshot.builder().metricName("http_requests").value(-2.0).build())
         .withMessageContaining("http_requests")
         .withMessageContaining("-2.0")
         .withMessageContaining("counters cannot have a negative value");