chore(css): Add peer tags, span kind and trace root flag to MetricKey bucket

Author: bric3

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

@@ -24,6 +24,8 @@
 import datadog.trace.core.CoreSpan;
 import datadog.trace.core.DDTraceCoreInfo;
 import datadog.trace.util.AgentTaskScheduler;
+import datadog.trace.util.TraceUtils;
+import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Map;
@@ -249,7 +251,10 @@ private boolean publish(CoreSpan<?> span, boolean isTopLevel) {
             span.getOperationName(),
             span.getType(),
             span.getHttpStatusCode(),
-            isSynthetic(span));
+            isSynthetic(span),
+            span.isTopLevel(),
+            span.getTag(SPAN_KIND, ""),
+            getPeerTags(span));
     boolean isNewKey = false;
     MetricKey key = keys.putIfAbsent(newKey, newKey);
     if (null == key) {
@@ -284,6 +289,17 @@ private boolean publish(CoreSpan<?> span, boolean isTopLevel) {
     return isNewKey || span.getError() > 0;
   }
 
+  private List<CharSequence> getPeerTags(CoreSpan<?> span) {
+    List<CharSequence> peerTags = new ArrayList<>();
+    for (String peerTag : features.peerTags()) {
+      Object value = span.getTag(peerTag);
+      if (value != null) {
+        peerTags.add(peerTag + ":" + TraceUtils.normalizeTag(value.toString()));
+      }
+    }
+    return peerTags;
+  }
+
   private static boolean isSynthetic(CoreSpan<?> span) {
     return span.getOrigin() != null && SYNTHETICS_ORIGIN.equals(span.getOrigin().toString());
   }

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

@@ -3,6 +3,8 @@
 import static datadog.trace.bootstrap.instrumentation.api.UTF8BytesString.EMPTY;
 
 import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString;
+import java.util.Arrays;
+import java.util.List;
 
 /** The aggregation key for tracked metrics. */
 public final class MetricKey {
@@ -13,25 +15,45 @@ public final class MetricKey {
   private final int httpStatusCode;
   private final boolean synthetics;
   private final int hash;
+  private final boolean isTraceRoot;
+  private final UTF8BytesString spanKind;
+  private final UTF8BytesString[] peerTags;
 
   public MetricKey(
       CharSequence resource,
       CharSequence service,
       CharSequence operationName,
       CharSequence type,
       int httpStatusCode,
-      boolean synthetics) {
+      boolean synthetics,
+      boolean isTraceRoot,
+      CharSequence spanKind,
+      List<CharSequence> peerTags) {
     this.resource = null == resource ? EMPTY : UTF8BytesString.create(resource);
     this.service = null == service ? EMPTY : UTF8BytesString.create(service);
     this.operationName = null == operationName ? EMPTY : UTF8BytesString.create(operationName);
     this.type = null == type ? EMPTY : UTF8BytesString.create(type);
     this.httpStatusCode = httpStatusCode;
     this.synthetics = synthetics;
-    // unrolled polynomial hashcode which avoids allocating varargs
-    // the constants are 31^5, 31^4, 31^3, 31^2, 31^1, 31^0
+    this.isTraceRoot = isTraceRoot;
+    this.spanKind = null == spanKind ? EMPTY : UTF8BytesString.create(spanKind);
+    this.peerTags = new UTF8BytesString[peerTags.size()];
+    for (int i = 0; i < peerTags.size(); i++) {
+      this.peerTags[i] = UTF8BytesString.create(peerTags.get(i));
+    }
+    
+    // Unrolled polynomial hashcode to avoid varargs allocation
+    // and eliminate data dependency between iterations as in Arrays.hashCode.
+    // Coefficient constants are powers of 31, with integer overflow (hence negative numbers).
+    // See
+    // * https://richardstartin.github.io/posts/collecting-rocks-and-benchmarks
+    // * https://richardstartin.github.io/posts/still-true-in-java-9-handwritten-hash-codes-are-faster
     this.hash =
-        28629151 * this.resource.hashCode()
-            + 923521 * this.service.hashCode()
+        -196513505 * Boolean.hashCode(this.isTraceRoot)
+            + -1807454463 * this.spanKind.hashCode()
+            + 887_503_681 * Arrays.hashCode(this.peerTags)
+            + 28_629_151 * this.resource.hashCode()
+            + 923_521 * this.service.hashCode()
             + 29791 * this.operationName.hashCode()
             + 961 * this.type.hashCode()
             + 31 * httpStatusCode
@@ -62,6 +84,18 @@ public boolean isSynthetics() {
     return synthetics;
   }
 
+  public boolean isTraceRoot() {
+    return isTraceRoot;
+  }
+
+  public UTF8BytesString getSpanKind() {
+    return spanKind;
+  }
+
+  public UTF8BytesString[] getPeerTags() {
+    return peerTags;
+  }
+
   @Override
   public boolean equals(Object o) {
     if (this == o) {
@@ -75,7 +109,10 @@ public boolean equals(Object o) {
           && resource.equals(metricKey.resource)
           && service.equals(metricKey.service)
           && operationName.equals(metricKey.operationName)
-          && type.equals(metricKey.type);
+          && type.equals(metricKey.type)
+          && isTraceRoot == metricKey.isTraceRoot
+          && spanKind.equals(metricKey.spanKind)
+          && Arrays.equals(peerTags, metricKey.peerTags);
     }
     return false;
   }

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

@@ -31,6 +31,9 @@ public final class SerializingMetricWriter implements MetricWriter {
   private static final byte[] OK_SUMMARY = "OkSummary".getBytes(ISO_8859_1);
   private static final byte[] ERROR_SUMMARY = "ErrorSummary".getBytes(ISO_8859_1);
   private static final byte[] PROCESS_TAGS = "ProcessTags".getBytes(ISO_8859_1);
+  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);
 
   private final WellKnownTags wellKnownTags;
   private final WritableFormatter writer;
@@ -93,8 +96,7 @@ public void startBucket(int metricCount, long start, long duration) {
 
   @Override
   public void add(MetricKey key, AggregateMetric aggregate) {
-
-    writer.startMap(12);
+    writer.startMap(15);
 
     writer.writeUTF8(NAME);
     writer.writeUTF8(key.getOperationName());
@@ -114,6 +116,19 @@ public void add(MetricKey key, AggregateMetric aggregate) {
     writer.writeUTF8(SYNTHETICS);
     writer.writeBoolean(key.isSynthetics());
 
+    writer.writeUTF8(IS_TRACE_ROOT);
+    writer.writeBoolean(key.isTraceRoot());
+
+    writer.writeUTF8(SPAN_KIND);
+    writer.writeUTF8(key.getSpanKind());
+
+    writer.writeUTF8(PEER_TAGS);
+    UTF8BytesString[] peerTags = key.getPeerTags();
+    writer.startArray(peerTags.length);
+    for (UTF8BytesString peerTag : peerTags) {
+      writer.writeUTF8(peerTag);
+    }
+
     writer.writeUTF8(HITS);
     writer.writeInt(aggregate.getHitCount());
 

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

@@ -51,7 +51,7 @@ class AggregateMetricTest extends DDSpecification {
     given:
     AggregateMetric aggregate = new AggregateMetric().recordDurations(3, new AtomicLongArray(0L, 0L, 0L | ERROR_TAG | TOP_LEVEL_TAG))
 
-    Batch batch = new Batch().reset(new MetricKey("foo", "bar", "qux", "type", 0, false))
+    Batch batch = new Batch().reset(new MetricKey("foo", "bar", "qux", "type", 0, false, true, "corge", ["grault"]))
     batch.add(0L, 10)
     batch.add(0L, 10)
     batch.add(0L, 10)
@@ -126,7 +126,7 @@ class AggregateMetricTest extends DDSpecification {
   def "consistent under concurrent attempts to read and write"() {
     given:
     AggregateMetric aggregate = new AggregateMetric()
-    MetricKey key = new MetricKey("foo", "bar", "qux", "type", 0, false)
+    MetricKey key = new MetricKey("foo", "bar", "qux", "type", 0, false, true, "corge", ["grault"])
     BlockingDeque<Batch> queue = new LinkedBlockingDeque<>(1000)
     ExecutorService reader = Executors.newSingleThreadExecutor()
     int writerCount = 10