Support histogram precision (#407)

* update proto version

* support parsing precision in incoming messages

* record precision to kairosdb

* checkstyle and weird spacing

Author: BrandonArp

pom.xml

@@ -136,7 +136,7 @@
     <metrics.client.incubator.version>0.13.0</metrics.client.incubator.version>
     <metrics.jvm.extra.version>0.13.1</metrics.jvm.extra.version>
     <metrics.http.extra.version>0.13.1</metrics.http.extra.version>
-    <metrics.aggregator.protocol.version>1.1.0</metrics.aggregator.protocol.version>
+    <metrics.aggregator.protocol.version>1.2.1</metrics.aggregator.protocol.version>
     <mockito.version>5.13.0</mockito.version>
     <netty.version>4.0.56.Final</netty.version>
     <netty.all.version>4.0.21.Final</netty.all.version>

src/main/java/com/arpnetworking/clusteraggregator/models/CombinedMetricData.java

@@ -303,7 +303,13 @@ public static Builder fromStatisticSetRecord(final Messages.StatisticSetRecord r
                 if (statistic instanceof HistogramStatistic) {
                     final Messages.SparseHistogramSupportingData supportingData = deserialzeSupportingData(statisticRecord);
 
-                    final HistogramStatistic.Histogram histogram = new HistogramStatistic.Histogram();
+                    final HistogramStatistic.Histogram histogram;
+                    if (supportingData.getPrecision() == 0) {
+                        histogram = new HistogramStatistic.Histogram();
+                    } else {
+                        // Subtract 1 from the precision to get the actual precision since 0 means default precision
+                        histogram = new HistogramStatistic.Histogram(supportingData.getPrecision() - 1);
+                    }
                     for (final Messages.SparseHistogramEntry entry : supportingData.getEntriesList()) {
                         final double bucket = entry.getBucket();
                         final long count = entry.getCount();

src/main/java/com/arpnetworking/tsdcore/sinks/KairosDbSink.java

@@ -314,16 +314,17 @@ public void serializeDatum(
             }
         }
 
-       public void serializeHistogram(
-               final List<SerializedDatum> completeChunks,
-               final ByteBuffer currentChunk,
-               final ByteArrayOutputStream chunkStream,
-               final AggregatedData data,
-               final KairosHistogramAdditionalData additionalData,
-               final LongAdder currentChunkPopulationSize) {
-           final FQDSN fqdsn = data.getFQDSN();
-
-           try {
+        // CHECKSTYLE.OFF: ExecutableStatementCount - There are a lot of fields, we just need to serialize them
+        public void serializeHistogram(
+                final List<SerializedDatum> completeChunks,
+                final ByteBuffer currentChunk,
+                final ByteArrayOutputStream chunkStream,
+                final AggregatedData data,
+                final KairosHistogramAdditionalData additionalData,
+                final LongAdder currentChunkPopulationSize) {
+            final FQDSN fqdsn = data.getFQDSN();
+
+            try {
                 final HistogramStatistic.HistogramSnapshot bins = ((HistogramStatistic.HistogramSupportingData) data.getSupportingData())
                         .getHistogramSnapshot();
                 final JsonGenerator chunkGenerator = OBJECT_MAPPER.getFactory().createGenerator(chunkStream, JsonEncoding.UTF8);
@@ -338,6 +339,7 @@ public void serializeHistogram(
                 chunkGenerator.writeNumberField("max", additionalData.getMax());
                 chunkGenerator.writeNumberField("mean", additionalData.getMean());
                 chunkGenerator.writeNumberField("sum", additionalData.getSum());
+                chunkGenerator.writeNumberField("precision", bins.getPrecision());
                 chunkGenerator.writeObjectFieldStart("bins");
                 for (Double2LongMap.Entry bin : bins.getValues()) {
                     chunkGenerator.writeNumberField(String.valueOf(bin.getDoubleKey()), bin.getLongValue());
@@ -373,6 +375,7 @@ public void serializeHistogram(
                         .log();
             }
         }
+        // CHECKSTYLE.ON: ExecutableStatementCount
 
         public void serializeCondition(
                 final List<SerializedDatum> completeChunks,