org.apache.flink.runtime.state.gemini.engine.fs.GeminiLocalByteBufferableInputStream Maven / Gradle / Ivy

/*
 * 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.runtime.state.gemini.engine.fs;

import org.apache.flink.core.fs.FSDataInputStream;
import org.apache.flink.core.fs.Path;

import javax.annotation.Nonnull;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;

/**
 * GeminiLocalByteBufferableInputStream.
 */
public class GeminiLocalByteBufferableInputStream extends FSDataInputStream {
	/** The file input stream used to read data from. */
	private final FileInputStream fis;
	private final FileChannel fileChannel;

	public GeminiLocalByteBufferableInputStream(Path workDir, Path localFile) throws FileNotFoundException {
		File file = pathToFile(workDir, localFile);
		this.fis = new FileInputStream(file);
		this.fileChannel = fis.getChannel();
	}

	private File pathToFile(Path workDir, Path path) {
		if (!path.isAbsolute()) {
			path = new Path(workDir, path);
		}
		return new File(path.toUri().getPath());
	}

	@Override
	public void seek(long desired) throws IOException {
		if (desired != getPos()) {
			this.fileChannel.position(desired);
		}
	}

	@Override
	public long getPos() throws IOException {
		return this.fileChannel.position();
	}

	@Override
	public int read() throws IOException {
		return this.fis.read();
	}

	@Override
	public void close() throws IOException {
		// According to javadoc, this also closes the channel
		this.fis.close();
	}

	@Override
	public int available() throws IOException {
		return this.fis.available();
	}

	@Override
	public long skip(final long n) throws IOException {
		return this.fis.skip(n);
	}

	public int read(int position, @Nonnull ByteBuffer buffer) throws IOException {
		return this.fileChannel.read(buffer, position);
	}
}