// Path: api/src/main/java/io/opencensus/trace/ContextHandle.java
// public interface ContextHandle {
// 
//   ContextHandle attach();
// 
//   void detach(ContextHandle contextHandle);
// }
// 
// Path: api/src/main/java/io/opencensus/trace/unsafe/ContextHandleUtils.java
// public class ContextHandleUtils {
// 
//   // No instance of this class.
//   private ContextHandleUtils() {}
// 
//   private static final Logger LOGGER = Logger.getLogger(ContextHandleUtils.class.getName());
//   private static final ContextManager CONTEXT_MANAGER =
//       loadContextManager(ContextManager.class.getClassLoader());
// 
//   private static ContextManager loadContextManager(@Nullable ClassLoader classLoader) {
//     try {
//       return Provider.createInstance(
//           Class.forName(
//               "io.opentelemetry.opencensusshim.OpenTelemetryContextManager",
//               /*initialize=*/ true,
//               classLoader),
//           ContextManager.class);
//     } catch (ClassNotFoundException e) {
//       LOGGER.log(
//           Level.FINE,
//           "Couldn't load full implementation for OpenTelemetry context manager, now loading "
//               + "original implementation.",
//           e);
//     }
//     return new ContextManagerImpl();
//   }
// 
//   public static ContextHandle currentContext() {
//     return CONTEXT_MANAGER.currentContext();
//   }
// 
//   /**
//    * Creates a new {@code ContextHandle} with the given value set.
//    *
//    * @param context the parent {@code ContextHandle}.
//    * @param span the value to be set.
//    * @return a new context with the given value set.
//    */
//   public static ContextHandle withValue(
//       ContextHandle context, @javax.annotation.Nullable Span span) {
//     return CONTEXT_MANAGER.withValue(context, span);
//   }
// 
//   /**
//    * Returns the value from the specified {@code ContextHandle}.
//    *
//    * @param context the specified {@code ContextHandle}.
//    * @return the value from the specified {@code ContextHandle}.
//    */
//   public static Span getValue(ContextHandle context) {
//     return CONTEXT_MANAGER.getValue(context);
//   }
// 
//   /**
//    * Attempts to pull the {@link io.grpc.Context} out of an OpenCensus {@code ContextHandle}.
//    *
//    * @return The context, or null if not a GRPC backed context handle.
//    */
//   @Nullable
//   public static Context tryExtractGrpcContext(ContextHandle handle) {
//     if (handle instanceof ContextHandleImpl) {
//       return ((ContextHandleImpl) handle).getContext();
//     }
//     // TODO: see if we can do something for the OpenTelemetry shim.
//     return null;
//   }
// }


import io.grpc.Context;
import io.opencensus.common.ExperimentalApi;
import io.opencensus.trace.ContextHandle;
import io.opencensus.trace.unsafe.ContextHandleUtils;
import org.apache.commons.logging.Log;
import org.springframework.cloud.sleuth.Span;
import org.springframework.core.NamedThreadLocal;

  interface SpanFunction {
    void apply(Span span);
  }

  private static final SpanFunction NO_OP_FUNCTION =
      new SpanFunction() {
        @Override
        public void apply(Span span) {}
      };

  @SuppressWarnings("CheckReturnValue")
  private static void setSpanContextInternal(SpanContext spanContext) {
    CURRENT_SPAN.set(spanContext);
    spanContext.ocCurrentContext.attach();
  }

  private static boolean isCurrent(Span span) {
    if (span == null) {
      return false;
    }
    SpanContext currentSpanContext = CURRENT_SPAN.get();
    return currentSpanContext != null && span.equals(currentSpanContext.span);
  }

  private static class SpanContext {
    final Span span;
    final boolean autoClose;
    @javax.annotation.Nullable final SpanContext parent;
    final OpenCensusSleuthSpan ocSpan;
// Path: api/src/main/java/io/opencensus/trace/ContextHandle.java
// public interface ContextHandle {
// 
//   ContextHandle attach();
// 
//   void detach(ContextHandle contextHandle);
// }
// 
// Path: api/src/main/java/io/opencensus/trace/unsafe/ContextHandleUtils.java
// public class ContextHandleUtils {
// 
//   // No instance of this class.
//   private ContextHandleUtils() {}
// 
//   private static final Logger LOGGER = Logger.getLogger(ContextHandleUtils.class.getName());
//   private static final ContextManager CONTEXT_MANAGER =
//       loadContextManager(ContextManager.class.getClassLoader());
// 
//   private static ContextManager loadContextManager(@Nullable ClassLoader classLoader) {
//     try {
//       return Provider.createInstance(
//           Class.forName(
//               "io.opentelemetry.opencensusshim.OpenTelemetryContextManager",
//               /*initialize=*/ true,
//               classLoader),
//           ContextManager.class);
//     } catch (ClassNotFoundException e) {
//       LOGGER.log(
//           Level.FINE,
//           "Couldn't load full implementation for OpenTelemetry context manager, now loading "
//               + "original implementation.",
//           e);
//     }
//     return new ContextManagerImpl();
//   }
// 
//   public static ContextHandle currentContext() {
//     return CONTEXT_MANAGER.currentContext();
//   }
// 
//   /**
//    * Creates a new {@code ContextHandle} with the given value set.
//    *
//    * @param context the parent {@code ContextHandle}.
//    * @param span the value to be set.
//    * @return a new context with the given value set.
//    */
//   public static ContextHandle withValue(
//       ContextHandle context, @javax.annotation.Nullable Span span) {
//     return CONTEXT_MANAGER.withValue(context, span);
//   }
// 
//   /**
//    * Returns the value from the specified {@code ContextHandle}.
//    *
//    * @param context the specified {@code ContextHandle}.
//    * @return the value from the specified {@code ContextHandle}.
//    */
//   public static Span getValue(ContextHandle context) {
//     return CONTEXT_MANAGER.getValue(context);
//   }
// 
//   /**
//    * Attempts to pull the {@link io.grpc.Context} out of an OpenCensus {@code ContextHandle}.
//    *
//    * @return The context, or null if not a GRPC backed context handle.
//    */
//   @Nullable
//   public static Context tryExtractGrpcContext(ContextHandle handle) {
//     if (handle instanceof ContextHandleImpl) {
//       return ((ContextHandleImpl) handle).getContext();
//     }
//     // TODO: see if we can do something for the OpenTelemetry shim.
//     return null;
//   }
// }


// Path: contrib/spring_sleuth_v1x/src/main/java/io/opencensus/contrib/spring/sleuth/v1x/OpenCensusSleuthSpanContextHolder.java
import io.grpc.Context;
import io.opencensus.common.ExperimentalApi;
import io.opencensus.trace.ContextHandle;
import io.opencensus.trace.unsafe.ContextHandleUtils;
import org.apache.commons.logging.Log;
import org.springframework.cloud.sleuth.Span;
import org.springframework.core.NamedThreadLocal;


  interface SpanFunction {
    void apply(Span span);
  }

  private static final SpanFunction NO_OP_FUNCTION =
      new SpanFunction() {
        @Override
        public void apply(Span span) {}
      };

  @SuppressWarnings("CheckReturnValue")
  private static void setSpanContextInternal(SpanContext spanContext) {
    CURRENT_SPAN.set(spanContext);
    spanContext.ocCurrentContext.attach();
  }

  private static boolean isCurrent(Span span) {
    if (span == null) {
      return false;
    }
    SpanContext currentSpanContext = CURRENT_SPAN.get();
    return currentSpanContext != null && span.equals(currentSpanContext.span);
  }

  private static class SpanContext {
    final Span span;
    final boolean autoClose;
    @javax.annotation.Nullable final SpanContext parent;
    final OpenCensusSleuthSpan ocSpan;
    final ContextHandle ocCurrentContext;