content: /*
   * Licensed to the Apache Software Foundation (ASF) under one or more
   * contributor license agreements.  See the NOTICE file distributed with
   * this work for additional information regarding copyright ownership.
   * The ASF licenses this file to You under the Apache License, Version 2.0
   * (the "License"); you may not use this file except in compliance with
   * the License.  You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package com.alibaba.compileflow.engine.core.observability.tracing;
  
  import com.alibaba.compileflow.engine.core.extension.ExtensionInvoker;
  import com.alibaba.compileflow.engine.core.runtime.context.EngineExecutionContext;
  import com.alibaba.compileflow.engine.core.runtime.context.EngineExecutionContextHolder;
  
  /**
   * Trace ID retrieval with ThreadLocal caching and safe fallback to extensions.
   *
   * @author yusu
   */
  public final class TracingHelper {
  
      private static final String NO_TRACE = "no-trace";
  
      private TracingHelper() {
          // Utility class
      }
  
      /**
       * Returns current trace ID (cached if available), never null.
       */
      public static String getCurrentTraceId() {
          // 1. Fast path: Check ThreadLocal cache first
          EngineExecutionContext context = EngineExecutionContextHolder.current();
          if (context != null) {
              String cachedTraceId = context.traceId();
              if (cachedTraceId != null) {
                  return cachedTraceId;
              }
          }
  
          // 2. Slow path: Get from extension system
          return getTraceIdFromExtension();
      }
  
      /**
       * Gets a fresh trace ID from extensions (bypasses cache).
       */
      public static String getFreshTraceId() {
          return getTraceIdFromExtension();
      }
  
      /**
       * Internal: fetch from TracingProvider extensions.
       */
      private static String getTraceIdFromExtension() {
          try {
              TracingProvider.TracingExtensionContext tracingContext = TracingProvider.TracingExtensionContext.getInstance();
              String traceId = ExtensionInvoker.getInstance().invokeFirst(
                      tracingContext,
                      TracingProvider.EXT_GET_TRACE_ID,
                      TracingProvider::getTraceId
              );
              return traceId != null ? traceId : NO_TRACE;
          } catch (Exception e) {
              // Silent handling - tracing failure should never break main business flow
              return NO_TRACE;
          }
      }
  }
  