Review fixes, make constructor private

Author: JonasKunz

libs/exponential-histogram/src/main/java/org/elasticsearch/exponentialhistogram/ExponentialHistogram.java

@@ -206,8 +206,14 @@ static ExponentialHistogram empty() {
         return EmptyExponentialHistogram.INSTANCE;
     }
 
-    static ExponentialHistogramBuilder builder(ExponentialHistogramCircuitBreaker breaker) {
-        return new ExponentialHistogramBuilder(breaker);
+    /**
+     * Create a builder for an exponential histogram with the given scale.
+     * @param scale the scale of the histogram to build
+     * @param breaker the circuit breaker to use
+     * @return a new builder
+     */
+    static ExponentialHistogramBuilder builder(int scale, ExponentialHistogramCircuitBreaker breaker) {
+        return new ExponentialHistogramBuilder(scale, breaker);
     }
 
     /**

libs/exponential-histogram/src/main/java/org/elasticsearch/exponentialhistogram/ExponentialHistogramBuilder.java

@@ -33,7 +33,7 @@ public class ExponentialHistogramBuilder {
 
     private final ExponentialHistogramCircuitBreaker breaker;
 
-    private int scale;
+    private final int scale;
     private ZeroBucket zeroBucket = ZeroBucket.minimalEmpty();
     private Double sum;
     private Double min;
@@ -42,18 +42,9 @@ public class ExponentialHistogramBuilder {
     private final TreeMap<Long, Long> negativeBuckets = new TreeMap<>();
     private final TreeMap<Long, Long> positiveBuckets = new TreeMap<>();
 
-    public ExponentialHistogramBuilder(ExponentialHistogramCircuitBreaker breaker) {
+    ExponentialHistogramBuilder(int scale, ExponentialHistogramCircuitBreaker breaker) {
         this.breaker = breaker;
-    }
-
-    /**
-     * Sets the scale of the histogram.
-     * @param scale the scale to set
-     * @return the builder
-     */
-    public ExponentialHistogramBuilder scale(int scale) {
         this.scale = scale;
-        return this;
     }
 
     public ExponentialHistogramBuilder zeroBucket(ZeroBucket zeroBucket) {

libs/exponential-histogram/src/test/java/org/elasticsearch/exponentialhistogram/ExponentialHistogramBuilderTests.java

@@ -29,8 +29,7 @@ public class ExponentialHistogramBuilderTests extends ExponentialHistogramTestCa
 
     public void testBuildWithAllFieldsSet() {
         ZeroBucket zeroBucket = ZeroBucket.create(1, 2);
-        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(breaker())
-            .scale(3)
+        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(3, breaker())
             .zeroBucket(zeroBucket)
             .sum(100.0)
             .min(1.0)
@@ -53,8 +52,7 @@ public void testBuildWithAllFieldsSet() {
     }
 
     public void testBuildWithEstimation() {
-        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(breaker())
-            .scale(0)
+        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(0, breaker())
             .addPositiveBucket(0, 1)
             .addPositiveBucket(1, 1)
             .addNegativeBucket(0, 4);
@@ -71,13 +69,13 @@ public void testBuildWithEstimation() {
     }
 
     public void testAddDuplicatePositiveBucketThrows() {
-        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(breaker());
+        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(0, breaker());
         builder.addPositiveBucket(1, 10);
         expectThrows(IllegalArgumentException.class, () -> builder.addPositiveBucket(1, 5));
     }
 
     public void testAddDuplicateNegativeBucketThrows() {
-        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(breaker());
+        ExponentialHistogramBuilder builder = ExponentialHistogram.builder(0, breaker());
         builder.addNegativeBucket(-1, 10);
         expectThrows(IllegalArgumentException.class, () -> builder.addNegativeBucket(-1, 5));
     }