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 org.apache.cassandra.service;
  
  import java.util.concurrent.CopyOnWriteArrayList;
  import java.util.List;
  
  import org.apache.cassandra.concurrent.ExecutorLocals;
  import org.apache.cassandra.utils.FBUtilities;
  
  public class ClientWarn extends ExecutorLocals.Impl
  {
      private static final String TRUNCATED = " [truncated]";
      public static ClientWarn instance = new ClientWarn();
  
      private ClientWarn()
      {
      }
  
      public State get()
      {
          return ExecutorLocals.current().clientWarnState;
      }
  
      public void set(State value)
      {
          ExecutorLocals current = ExecutorLocals.current();
          ExecutorLocals.Impl.set(current.traceState, value);
      }
  
      public void warn(String text)
      {
          State state = get();
          if (state != null)
              state.add(text);
      }
  
      public void captureWarnings()
      {
          set(new State());
      }
  
      /**
       * Provides an additional control on capturing warnings. When executing SchemaTransformations in the
       * metadata log follower or when committing on a CMS member, we don't want these to be triggered.
       * @see org.apache.cassandra.schema.SchemaTransformation#enterExecution()
       **/
      public void pauseCapture()
      {
          State state = get();
          if (state != null)
              state.collecting = false;
      }
  
      public void resumeCapture()
      {
          State state = get();
          if (state != null)
              state.collecting = true;
      }
  
      public List<String> getWarnings()
      {
          State state = get();
          if (state == null || state.warnings == null || state.warnings.isEmpty())
              return null;
          return state.warnings;
      }
  
      public void resetWarnings()
      {
          set(null);
      }
  
      public static class State
      {
          private boolean collecting = true;
          // This must be a thread-safe list. Even though it's wrapped in a ThreadLocal, it's propagated to each thread
          // from shared state, so multiple threads can reference the same State.
          private volatile List<String> warnings;
  
          private void add(String warning)
          {
              if (warnings == null)
                  synchronized (this) {
                      if (warnings == null) {
                          warnings = new CopyOnWriteArrayList<>();
                      }
                  }
              if (collecting && warnings.size() < FBUtilities.MAX_UNSIGNED_SHORT)
                  warnings.add(maybeTruncate(warning));
          }
  
          private static String maybeTruncate(String warning)
          {
              return warning.length() > FBUtilities.MAX_UNSIGNED_SHORT
                     ? warning.substring(0, FBUtilities.MAX_UNSIGNED_SHORT - TRUNCATED.length()) + TRUNCATED
                     : warning;
          }
      }
  }
  