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.datastax.oss.driver.internal.core.util.concurrent;
  
  import com.datastax.oss.driver.internal.core.util.Loggers;
  import io.netty.util.concurrent.Future;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * Utility methods to log unexpected exceptions in asynchronous tasks.
   *
   * <p>Use this whenever you execute a future callback to apply side effects, but throw away the
   * future itself:
   *
   * <pre>{@code
   * CompletionStage<Foo> futureFoo = FooFactory.build();
   *
   * futureFoo
   *   .whenComplete((f, error) -> { handler code with side effects })
   *   // futureFoo is not propagated, do this or any unexpected error in the handler will be
   *   // swallowed
   *   .exceptionally(UncaughtExceptions::log);
   *
   * // If you return the future, you don't need it (but it's up to the caller to handle a failed
   * // future)
   * return futureFoo.whenComplete(...)
   * }</pre>
   */
  public class UncaughtExceptions {
  
    private static final Logger LOG = LoggerFactory.getLogger(UncaughtExceptions.class);
  
    public static <T> void log(Future<T> future) {
      if (!future.isSuccess() && !future.isCancelled()) {
        Loggers.warnWithException(LOG, "Uncaught exception in scheduled task", future.cause());
      }
    }
  
    @SuppressWarnings("TypeParameterUnusedInFormals") // type parameter is only needed for chaining
    public static <T> T log(Throwable t) {
      Loggers.warnWithException(LOG, "Uncaught exception in scheduled task", t);
      return null;
    }
  }
  