htrace-core/src/main/java/org/apache/htrace/core/NullScope.java

/*
 * 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 org.apache.htrace.core;

/**
 * Singleton instance representing an empty {@link TraceScope}.
 */
public final class NullScope extends TraceScope {

  public static final TraceScope INSTANCE = new NullScope();

  private NullScope() {
    super(null, null);
  }

  @Override
  public Span detach() {
    return null;
  }

  @Override
  public void close() {
    return;
  }

  @Override
  public String toString() {
    return "NullScope";
  }
}