add APIs for llm obs

Author: gary-huang

dd-trace-api/src/main/java/datadog/trace/api/llmobs/LLMObs.java

@@ -0,0 +1,56 @@
+package datadog.trace.api.llmobs;
+
+import datadog.trace.api.llmobs.noop.NoOpLLMObsSpanFactory;
+import javax.annotation.Nullable;
+
+public class LLMObs {
+  private static LLMObsSpanFactory SPAN_FACTORY = NoOpLLMObsSpanFactory.INSTANCE;
+
+  /**
+   * This a hook for injecting SpanFactory implementation. It should only be used internally by
+   * the tracer logic
+   *
+   * @param spanFactory span factory instance
+   */
+  public static void registerSpanFactory(LLMObsSpanFactory spanFactory) {
+    SPAN_FACTORY = spanFactory;
+  }
+
+  public static LLMObsSpan startLLMSpan(
+      String spanName,String modelName,  String modelProvider, @Nullable String mlApp, @Nullable String sessionID) {
+
+    return SPAN_FACTORY.startLLMSpan(spanName, modelName, modelProvider, sessionID, mlApp);
+  }
+
+  public static LLMObsSpan startAgentSpan(
+      String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+
+    return SPAN_FACTORY.startAgentSpan(spanName, sessionID, mlApp);
+  }
+
+  public static LLMObsSpan startToolSpan(
+      String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+
+    return SPAN_FACTORY.startToolSpan(spanName, sessionID, mlApp);
+  }
+
+  public static LLMObsSpan startTaskSpan(
+      String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+
+    return SPAN_FACTORY.startTaskSpan(spanName, sessionID, mlApp);
+  }
+
+  public static LLMObsSpan startWorkflowSpan(
+      String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+
+    return SPAN_FACTORY.startWorkflowSpan(spanName, sessionID, mlApp);
+  }
+
+  public interface LLMObsSpanFactory {
+    LLMObsSpan startLLMSpan(String spanName, String modelName, String modelProvider, @Nullable String mlApp, @Nullable String sessionID);
+    LLMObsSpan startAgentSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID);
+    LLMObsSpan startToolSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID);
+    LLMObsSpan startTaskSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID);
+    LLMObsSpan startWorkflowSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID);
+  }
+}

dd-trace-api/src/main/java/datadog/trace/api/llmobs/LLMObsSpan.java

@@ -0,0 +1,15 @@
+package datadog.trace.api.llmobs;
+
+/**
+ * This interface represent an individual LLM Obs span.
+ */
+public interface LLMObsSpan {
+
+  /**
+   * Annotate spans with inputs, outputs, and metadata.
+   *
+   * @param key The name of the tag
+   * @param value The value of the tag
+   */
+  void annotate(String key, Object value);
+}

dd-trace-api/src/main/java/datadog/trace/api/llmobs/noop/NoOpLLMObsSpan.java

@@ -0,0 +1,10 @@
+package datadog.trace.api.llmobs.noop;
+
+import datadog.trace.api.llmobs.LLMObsSpan;
+
+public class NoOpLLMObsSpan implements LLMObsSpan {
+  public static final LLMObsSpan INSTANCE = new NoOpLLMObsSpan();
+
+  @Override
+  public void annotate(String key, Object value) {}
+}

dd-trace-api/src/main/java/datadog/trace/api/llmobs/noop/NoOpLLMObsSpanFactory.java

@@ -0,0 +1,26 @@
+package datadog.trace.api.llmobs.noop;
+
+import datadog.trace.api.llmobs.LLMObs;
+import datadog.trace.api.llmobs.LLMObsSpan;
+import javax.annotation.Nullable;
+
+public class NoOpLLMObsSpanFactory implements LLMObs.LLMObsSpanFactory {
+  public static final NoOpLLMObsSpanFactory INSTANCE = new NoOpLLMObsSpanFactory();
+
+  public LLMObsSpan startLLMSpan(String spanName, String modelName, String modelProvider, @Nullable String mlApp, @Nullable String sessionID) {
+    return NoOpLLMObsSpan.INSTANCE;
+  }
+  public LLMObsSpan startAgentSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+    return NoOpLLMObsSpan.INSTANCE;
+  }
+  public LLMObsSpan startToolSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+    return NoOpLLMObsSpan.INSTANCE;
+  }
+  public LLMObsSpan startTaskSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID) {
+    return NoOpLLMObsSpan.INSTANCE;
+  }
+  public LLMObsSpan startWorkflowSpan(String spanName, @Nullable String mlApp, @Nullable String sessionID){
+    return NoOpLLMObsSpan.INSTANCE;
+  }
+}
+