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/*
 * 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.table.runtime.util;

import org.apache.flink.core.memory.MemorySegment;
import org.apache.flink.runtime.io.disk.iomanager.BlockChannelWriter;
import org.apache.flink.runtime.io.disk.iomanager.ChannelWriterOutputView;
import org.apache.flink.util.Preconditions;

import java.io.IOException;
import java.util.List;
import java.util.concurrent.LinkedBlockingQueue;

/**
 * Header less {@link ChannelWriterOutputView}. The caller saves the writePosition information.
 */
public final class HeaderlessChannelWriterOutputView extends AbstractChannelWriterOutputView {

	private final BlockChannelWriter writer; // the writer to the channel

	private int blockCount; // the number of blocks used

	public HeaderlessChannelWriterOutputView(BlockChannelWriter writer,
			List memory, int segmentSize) {
		super(writer, segmentSize, 0);

		if (writer == null) {
			throw new NullPointerException();
		}

		this.writer = writer;

		Preconditions.checkNotNull(memory);

		// load the segments into the queue
		final LinkedBlockingQueue queue = writer.getReturnQueue();
		for (int i = memory.size() - 1; i >= 0; --i) {
			final MemorySegment seg = memory.get(i);
			if (seg.size() != segmentSize) {
				throw new IllegalArgumentException("This segment are not of the specified size.");
			}
			queue.add(seg);
		}

		// get the first segment
		try {
			advance();
		} catch (IOException ioex) {
			throw new RuntimeException(ioex);
		}
	}

	/**
	 * Closes this OutputView, closing the underlying writer. And return number bytes in last
	 * memory segment.
	 */
	@Override
	public int close() throws IOException {
		if (!writer.isClosed()) {
			int currentPositionInSegment = getCurrentPositionInSegment();
			// write last segment
			writer.writeBlock(getCurrentSegment());
			clear();

			writer.getReturnQueue().clear();
			this.writer.close();

			return currentPositionInSegment;
		}
		return -1;
	}

	@Override
	public int getBlockCount() {
		return this.blockCount;
	}

	@Override
	public long getNumBytes() throws IOException {
		return writer.getSize();
	}

	@Override
	public long getNumCompressedBytes() throws IOException {
		return writer.getSize();
	}

	@Override
	public MemorySegment nextSegment(MemorySegment current, int posInSegment) throws IOException {
		if (current != null) {
			writer.writeBlock(current);
		}

		final MemorySegment next = this.writer.getNextReturnedBlock();
		this.blockCount++;
		return next;
	}
}