Merge branch '1.9.x' into 1.10.x

Author: shakuzen

micrometer-core/src/main/java/io/micrometer/core/instrument/distribution/FixedBoundaryVictoriaMetricsHistogram.java

@@ -66,16 +66,16 @@ public class FixedBoundaryVictoriaMetricsHistogram implements Histogram {
     static {
         VMRANGES = new String[3 + BUCKETS_COUNT * BUCKET_SIZE];
         VMRANGES[0] = "0...0";
-        VMRANGES[1] = String.format("0...%.1fe%d", 1.0, E10MIN);
-        VMRANGES[2] = String.format("%.1fe%d...+Inf", 1.0, E10MAX);
+        VMRANGES[1] = String.format(Locale.US, "0...%.1fe%d", 1.0, E10MIN);
+        VMRANGES[2] = String.format(Locale.US, "%.1fe%d...+Inf", 1.0, E10MAX);
 
         UPPER_BOUNDS = new double[3 + BUCKETS_COUNT * BUCKET_SIZE];
         UPPER_BOUNDS[0] = 0.0;
         UPPER_BOUNDS[1] = BigDecimal.TEN.pow(E10MIN, MathContext.DECIMAL128).doubleValue();
         UPPER_BOUNDS[2] = Double.POSITIVE_INFINITY;
 
         int idx = 3;
-        String start = String.format("%.1fe%d", 1.0, E10MIN);
+        String start = String.format(Locale.US, "%.1fe%d", 1.0, E10MIN);
 
         for (int bucketIdx = 0; bucketIdx < BUCKETS_COUNT; bucketIdx++) {
             for (int offset = 0; offset < BUCKET_SIZE; offset++) {
@@ -85,7 +85,7 @@ public class FixedBoundaryVictoriaMetricsHistogram implements Histogram {
                     m = 1;
                     e10++;
                 }
-                String end = String.format("%.1fe%d", m, e10);
+                String end = String.format(Locale.US, "%.1fe%d", m, e10);
                 VMRANGES[idx] = start + "..." + end;
 
                 UPPER_BOUNDS[idx] = BigDecimal.valueOf(m)

micrometer-core/src/test/java/io/micrometer/core/instrument/distribution/FixedBoundaryVictoriaMetricsHistogramTest.java

@@ -15,8 +15,11 @@
  */
 package io.micrometer.core.instrument.distribution;
 
+import io.micrometer.core.Issue;
 import org.junit.jupiter.api.Test;
 
+import java.util.Locale;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 class FixedBoundaryVictoriaMetricsHistogramTest {
@@ -31,4 +34,23 @@ void checkUpperBoundLookup() {
         }
     }
 
+    @Test
+    @Issue("#3676")
+    void localeDoesNotChangeOutput() {
+        Locale defaultLocale = Locale.getDefault();
+        try {
+            // set a Locale that uses a comma for the decimal separator
+            Locale.setDefault(Locale.FRANCE);
+            try (FixedBoundaryVictoriaMetricsHistogram histogram = new FixedBoundaryVictoriaMetricsHistogram()) {
+                assertThat(histogram.getRangeTagValue(0.0d)).isEqualTo("0...0");
+                assertThat(histogram.getRangeTagValue(1e-9d)).isEqualTo("0...1.0e-9");
+                assertThat(histogram.getRangeTagValue(Double.POSITIVE_INFINITY)).isEqualTo("1.0e18...+Inf");
+                assertThat(histogram.getRangeTagValue(1e18d)).isEqualTo("9.5e17...1.0e18");
+            }
+        }
+        finally {
+            Locale.setDefault(defaultLocale);
+        }
+    }
+
 }