flink-formats/flink-parquet/src/main/java/org/apache/flink/formats/parquet/StreamOutputFile.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.flink.formats.parquet;

import org.apache.flink.annotation.Internal;
import org.apache.flink.core.fs.FSDataOutputStream;

import org.apache.parquet.io.OutputFile;
import org.apache.parquet.io.PositionOutputStream;

import java.util.concurrent.atomic.AtomicBoolean;

import static org.apache.flink.util.Preconditions.checkNotNull;

/**
 * An implementation of Parquet's {@link OutputFile} interface that goes against
 * a Flink {@link FSDataOutputStream}.
 *
 * <p>Because the implementation goes against an open stream, rather than open its
 * own streams against a file, instances can create one stream only.
 */
@Internal
class StreamOutputFile implements OutputFile {

	private static final long DEFAULT_BLOCK_SIZE = 64L * 1024L * 1024L;

	private final FSDataOutputStream stream;

	private final AtomicBoolean used;

	/**
	 * Creates a new StreamOutputFile. The first call to {@link #create(long)}
	 * or {@link #createOrOverwrite(long)} returns a stream that writes to the given stream.
	 *
	 * @param stream The stream to write to.
	 */
	StreamOutputFile(FSDataOutputStream stream) {
		this.stream = checkNotNull(stream);
		this.used = new AtomicBoolean(false);
	}

	@Override
	public PositionOutputStream create(long blockSizeHint) {
		if (used.compareAndSet(false, true)) {
			return new PositionOutputStreamAdapter(stream);
		}
		else {
			throw new IllegalStateException("A stream against this file was already created.");
		}
	}

	@Override
	public PositionOutputStream createOrOverwrite(long blockSizeHint) {
		return create(blockSizeHint);
	}

	@Override
	public boolean supportsBlockSize() {
		return false;
	}

	@Override
	public long defaultBlockSize() {
		return DEFAULT_BLOCK_SIZE;
	}
}