Provide optimized writers for OpenTelemetry's "trace.proto" wire protocol

Author: mcculls

dd-trace-core/src/main/java/datadog/trace/core/DDSpan.java

@@ -884,7 +884,7 @@ public TraceConfig traceConfig() {
     return context.getTraceCollector().getTraceConfig();
   }
 
-  List<? extends AgentSpanLink> getLinks() {
+  public List<? extends AgentSpanLink> getLinks() {
     return this.links;
   }
 

dd-trace-core/src/main/java/datadog/trace/core/otlp/common/OtlpCommonProto.java

@@ -15,6 +15,7 @@
 import datadog.communication.serialization.SimpleUtf8Cache;
 import datadog.communication.serialization.StreamingBuffer;
 import datadog.trace.api.Config;
+import datadog.trace.bootstrap.instrumentation.api.UTF8BytesString;
 import datadog.trace.bootstrap.otel.common.OtelInstrumentationScope;
 import java.nio.ByteBuffer;
 import java.util.List;
@@ -45,6 +46,10 @@ private OtlpCommonProto() {}
           ? new GenerationalUtf8Cache(Config.get().getTagValueUtf8CacheSize())
           : null;
 
+  public static void recalibrateCaches() {
+    VALUE_CACHE.recalibrate();
+  }
+
   public static int sizeVarInt(int value) {
     return 1 + (31 - Integer.numberOfLeadingZeros(value)) / 7;
   }
@@ -153,8 +158,13 @@ public static void writeInstrumentationScope(
   }
 
   @SuppressWarnings("unchecked")
-  public static void writeAttribute(StreamingBuffer buf, int type, String key, Object value) {
-    byte[] keyUtf8 = keyUtf8(key);
+  public static void writeAttribute(StreamingBuffer buf, int type, CharSequence key, Object value) {
+    byte[] keyUtf8;
+    if (key instanceof UTF8BytesString) {
+      keyUtf8 = ((UTF8BytesString) key).getUtf8Bytes();
+    } else {
+      keyUtf8 = keyUtf8(key.toString());
+    }
     switch (type) {
       case STRING:
         writeStringAttribute(buf, keyUtf8, valueUtf8((String) value));
@@ -185,6 +195,19 @@ public static void writeAttribute(StreamingBuffer buf, int type, String key, Obj
     }
   }
 
+  public static void writeAttribute(
+      StreamingBuffer buf, UTF8BytesString key, UTF8BytesString value) {
+    writeStringAttribute(buf, key.getUtf8Bytes(), value.getUtf8Bytes());
+  }
+
+  public static void writeAttribute(StreamingBuffer buf, UTF8BytesString key, String value) {
+    writeStringAttribute(buf, key.getUtf8Bytes(), valueUtf8(value));
+  }
+
+  public static void writeAttribute(StreamingBuffer buf, UTF8BytesString key, long value) {
+    writeLongAttribute(buf, key.getUtf8Bytes(), value);
+  }
+
   private static byte[] keyUtf8(String key) {
     return KEY_CACHE != null ? KEY_CACHE.getUtf8(key) : key.getBytes(UTF_8);
   }

dd-trace-core/src/main/java/datadog/trace/core/otlp/metrics/OtlpMetricsProtoCollector.java

@@ -25,6 +25,7 @@
 import datadog.trace.bootstrap.otlp.metrics.OtlpMetricVisitor;
 import datadog.trace.bootstrap.otlp.metrics.OtlpMetricsVisitor;
 import datadog.trace.bootstrap.otlp.metrics.OtlpScopedMetricsVisitor;
+import datadog.trace.core.otlp.common.OtlpCommonProto;
 import datadog.trace.core.otlp.common.OtlpPayload;
 import java.util.ArrayDeque;
 import java.util.ArrayList;
@@ -93,6 +94,7 @@ public OtlpPayload collectMetrics() {
   }
 
   OtlpPayload collectMetrics(Consumer<OtlpMetricsVisitor> registry) {
+    OtlpCommonProto.recalibrateCaches();
     start();
     try {
       registry.accept(this);
@@ -108,15 +110,15 @@ private void start() {
     startNanos = endNanos;
     endNanos = timeSource.getCurrentTimeNanos();
 
-    // clear payloadChunks in case it wasn't fully consumed via OtlpMetricsPayload
+    // clear payloadChunks in case it wasn't fully consumed via OtlpPayload
     payloadChunks.clear();
   }
 
   /** Cleanup elements used to collect metrics data. */
   private void stop() {
     buf.reset();
 
-    // leave payloadChunks in place so it can be consumed via OtlpMetricsPayload
+    // leave payloadChunks in place so it can be consumed via OtlpPayload
     scopedChunks.clear();
     metricChunks.clear();
 

dd-trace-core/src/main/java/datadog/trace/core/otlp/trace/OtlpTraceCollector.java

@@ -0,0 +1,12 @@
+package datadog.trace.core.otlp.trace;
+
+import datadog.trace.core.DDSpan;
+import datadog.trace.core.otlp.common.OtlpPayload;
+import java.util.List;
+
+/** Collects trace spans ready for export. */
+public interface OtlpTraceCollector {
+  OtlpTraceCollector NOOP_COLLECTOR = spans -> OtlpPayload.EMPTY;
+
+  OtlpPayload collectSpans(List<DDSpan> spans);
+}