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.arrow.util;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Iterator;
  import java.util.List;
  import java.util.stream.StreamSupport;
  
  /** Utilities for AutoCloseable classes. */
  public final class AutoCloseables {
    // Utility class. Should not be instantiated
    private AutoCloseables() {}
  
    /**
     * Returns a new {@link AutoCloseable} that calls {@link #close(Iterable)} on <code>autoCloseables
     * </code> when close is called.
     */
    public static AutoCloseable all(final Collection<? extends AutoCloseable> autoCloseables) {
      return new AutoCloseable() {
        @Override
        public void close() throws Exception {
          AutoCloseables.close(autoCloseables);
        }
      };
    }
  
    /**
     * Closes all autoCloseables if not null and suppresses exceptions by adding them to t.
     *
     * @param t the throwable to add suppressed exception to
     * @param autoCloseables the closeables to close
     */
    public static void close(Throwable t, AutoCloseable... autoCloseables) {
      close(t, Arrays.asList(autoCloseables));
    }
  
    /**
     * Closes all autoCloseables if not null and suppresses exceptions by adding them to t.
     *
     * @param t the throwable to add suppressed exception to
     * @param autoCloseables the closeables to close
     */
    public static void close(Throwable t, Iterable<? extends AutoCloseable> autoCloseables) {
      try {
        close(autoCloseables);
      } catch (Exception e) {
        t.addSuppressed(e);
      }
    }
  
    /**
     * Closes all autoCloseables if not null and suppresses subsequent exceptions if more than one.
     *
     * @param autoCloseables the closeables to close
     */
    public static void close(AutoCloseable... autoCloseables) throws Exception {
      close(Arrays.asList(autoCloseables));
    }
  
    /**
     * Closes all autoCloseables if not null and suppresses subsequent exceptions if more than one.
     *
     * @param ac the closeables to close
     */
    public static void close(Iterable<? extends AutoCloseable> ac) throws Exception {
      // this method can be called on a single object if it implements Iterable<AutoCloseable>
      // like for example VectorContainer make sure we handle that properly
      if (ac == null) {
        return;
      } else if (ac instanceof AutoCloseable) {
        ((AutoCloseable) ac).close();
        return;
      }
  
      Exception topLevelException = null;
      for (AutoCloseable closeable : ac) {
        try {
          if (closeable != null) {
            closeable.close();
          }
        } catch (Exception e) {
          if (topLevelException == null) {
            topLevelException = e;
          } else if (e != topLevelException) {
            topLevelException.addSuppressed(e);
          }
        }
      }
      if (topLevelException != null) {
        throw topLevelException;
      }
    }
  
    /** Calls {@link #close(Iterable)} on the flattened list of closeables. */
    @SafeVarargs
    public static void close(Iterable<? extends AutoCloseable>... closeables) throws Exception {
      close(flatten(closeables));
    }
  
    @SafeVarargs
    private static Iterable<AutoCloseable> flatten(Iterable<? extends AutoCloseable>... closeables) {
      return new Iterable<AutoCloseable>() {
        // Cast from Iterable<? extends AutoCloseable> to Iterable<AutoCloseable> is safe in this
        // context
        // since there's no modification of the original collection
        @SuppressWarnings("unchecked")
        @Override
        public Iterator<AutoCloseable> iterator() {
          return Arrays.stream(closeables)
              .flatMap(
                  (Iterable<? extends AutoCloseable> i) ->
                      StreamSupport.stream(
                          ((Iterable<AutoCloseable>) i).spliterator(), /* parallel= */ false))
              .iterator();
        }
      };
    }
  
    /** Converts <code>ac</code> to a {@link Iterable} filtering out any null values. */
    public static Iterable<AutoCloseable> iter(AutoCloseable... ac) {
      if (ac.length == 0) {
        return Collections.emptyList();
      } else {
        final List<AutoCloseable> nonNullAc = new ArrayList<>();
        for (AutoCloseable autoCloseable : ac) {
          if (autoCloseable != null) {
            nonNullAc.add(autoCloseable);
          }
        }
        return nonNullAc;
      }
    }
  
    /** A closeable wrapper that will close the underlying closeables if a commit does not occur. */
    public static class RollbackCloseable implements AutoCloseable {
  
      private boolean commit = false;
      private List<AutoCloseable> closeables;
  
      public RollbackCloseable(AutoCloseable... closeables) {
        this.closeables = new ArrayList<>(Arrays.asList(closeables));
      }
  
      public <T extends AutoCloseable> T add(T t) {
        closeables.add(t);
        return t;
      }
  
      /** Add all of <code>list</code> to the rollback list. */
      public void addAll(AutoCloseable... list) {
        closeables.addAll(Arrays.asList(list));
      }
  
      /** Add all of <code>list</code> to the rollback list. */
      public void addAll(Iterable<? extends AutoCloseable> list) {
        for (AutoCloseable ac : list) {
          closeables.add(ac);
        }
      }
  
      public void commit() {
        commit = true;
      }
  
      @Override
      public void close() throws Exception {
        if (!commit) {
          AutoCloseables.close(closeables);
        }
      }
    }
  
    /** Creates an {@link RollbackCloseable} from the given closeables. */
    public static RollbackCloseable rollbackable(AutoCloseable... closeables) {
      return new RollbackCloseable(closeables);
    }
  
    /**
     * close() an {@link java.lang.AutoCloseable} without throwing a (checked) {@link
     * java.lang.Exception}. This wraps the close() call with a try-catch that will rethrow an
     * Exception wrapped with a {@link java.lang.RuntimeException}, providing a way to call close()
     * without having to do the try-catch everywhere or propagate the Exception.
     *
     * @param autoCloseable the AutoCloseable to close; may be null
     * @throws RuntimeException if an Exception occurs; the Exception is wrapped by the
     *     RuntimeException
     */
    public static void closeNoChecked(final AutoCloseable autoCloseable) {
      if (autoCloseable != null) {
        try {
          autoCloseable.close();
        } catch (final Exception e) {
          throw new RuntimeException("Exception while closing: " + e.getMessage(), e);
        }
      }
    }
  
    private static final AutoCloseable noOpAutocloseable =
        new AutoCloseable() {
          @Override
          public void close() {}
        };
  
    /**
     * Get an AutoCloseable that does nothing.
     *
     * @return A do-nothing autocloseable
     */
    public static AutoCloseable noop() {
      return noOpAutocloseable;
    }
  }
  