fix: PR Review

Author: bric3

dd-trace-core/src/main/java/datadog/trace/common/metrics/SerializingMetricWriter.java

@@ -1,16 +1,15 @@
 package datadog.trace.common.metrics;
 
+import static java.nio.charset.StandardCharsets.ISO_8859_1;
+
 import datadog.communication.serialization.GrowableBuffer;
 import datadog.communication.serialization.WritableFormatter;
 import datadog.communication.serialization.msgpack.MsgPackWriter;
 import datadog.trace.api.ProcessTags;
 import datadog.trace.api.WellKnownTags;
 import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString;
-
 import java.util.List;
 
-import static java.nio.charset.StandardCharsets.ISO_8859_1;
-
 public final class SerializingMetricWriter implements MetricWriter {
 
   private static final byte[] SEQUENCE = "Seq".getBytes(ISO_8859_1);
@@ -36,9 +35,10 @@ public final class SerializingMetricWriter implements MetricWriter {
   private static final byte[] IS_TRACE_ROOT = "IsTraceRoot".getBytes(ISO_8859_1);
   private static final byte[] SPAN_KIND = "SpanKind".getBytes(ISO_8859_1);
   private static final byte[] PEER_TAGS = "PeerTags".getBytes(ISO_8859_1);
-  // Is trace root is a tristate (0 unknown, 1 true, 2 false)
-  public static final int IS_TRACE_ROOT_TRUE = 1;
-  public static final int IS_TRACE_ROOT_FALSE = 2;
+  @SuppressWarnings("unused") // Kept for representing all possible states
+  public static final int TRISTATE_UNKNOWN = 0;
+  public static final int TRISTATE_TRUE = 1;
+  public static final int TRISTATE_FALSE = 2;
 
   private final WellKnownTags wellKnownTags;
   private final WritableFormatter writer;
@@ -122,7 +122,7 @@ public void add(MetricKey key, AggregateMetric aggregate) {
     writer.writeBoolean(key.isSynthetics());
 
     writer.writeUTF8(IS_TRACE_ROOT);
-    writer.writeInt(key.isTraceRoot() ? IS_TRACE_ROOT_TRUE : IS_TRACE_ROOT_FALSE);
+    writer.writeInt(key.isTraceRoot() ? TRISTATE_TRUE : TRISTATE_FALSE);
 
     writer.writeUTF8(SPAN_KIND);
     writer.writeUTF8(key.getSpanKind());

dd-trace-core/src/test/groovy/datadog/trace/common/metrics/SerializingMetricWriterTest.groovy

@@ -18,8 +18,8 @@ import static java.util.concurrent.TimeUnit.SECONDS
 
 class SerializingMetricWriterTest extends DDSpecification {
 
-  public static final int IS_TRACE_ROOT_TRUE = 1
-  public static final int IS_TRACE_ROOT_FALSE = 2
+  public static final int TRISTATE_TRUE = 1
+  public static final int TRISTATE_FALSE = 2
 
   def "should produce correct message #iterationIndex with process tags enabled #withProcessTags" () {
     setup:
@@ -180,7 +180,7 @@ class SerializingMetricWriterTest extends DDSpecification {
         assert unpacker.unpackBoolean() == key.isSynthetics()
         ++elementCount
         assert unpacker.unpackString() == "IsTraceRoot"
-        assert unpacker.unpackInt() == (key.isTraceRoot() ? IS_TRACE_ROOT_TRUE : IS_TRACE_ROOT_FALSE)
+        assert unpacker.unpackInt() == (key.isTraceRoot() ? TRISTATE_TRUE : TRISTATE_FALSE)
         ++elementCount
         assert unpacker.unpackString() == "SpanKind"
         assert unpacker.unpackString() == key.getSpanKind() as String