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The official Couchbase JVM Core IO Library

There is a newer version: 2.7.0

/*
 * Copyright 2019 Couchbase, Inc.
 *
 * Licensed 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.couchbase.client.core.json.stream;

import com.couchbase.client.core.deps.io.netty.buffer.ByteBuf;
import com.couchbase.client.core.deps.io.netty.buffer.ByteBufAllocator;

import static java.nio.charset.StandardCharsets.UTF_8;

/**
 * A stream window implementation that copies input data into a single accumulator buffer.
 */
public class CopyingStreamWindow implements StreamWindow {
  private final ByteBuf window;

  /**
   * Offset from the beginning of the stream to the end of the window.
   */
  private long streamOffset;

  public CopyingStreamWindow(ByteBufAllocator allocator) {
    this.window = allocator.buffer();
  }

  @Override
  public void add(ByteBuf buf) {
    streamOffset += buf.readableBytes();
    try {
      window.writeBytes(buf);
    } finally {
      buf.release();
    }
  }

  @Override
  public void releaseBefore(long releaseStreamOffset) {
    if (releaseStreamOffset <= 0) {
      return;
    }

    int localOffset = toLocalOffset(releaseStreamOffset);
    window.skipBytes(localOffset);
    window.discardSomeReadBytes();
  }

  @Override
  public byte[] getBytes(long startStreamOffset, long endStreamOffset) {
    final int localStartOffset = toLocalOffset(startStreamOffset);
    final int localEndOffset = toLocalOffset(endStreamOffset);
    final byte[] result = new byte[localEndOffset - localStartOffset];
    window.getBytes(window.readerIndex() + localStartOffset, result);
    return result;
  }

  /**
   * @param streamOffset offset from the beginning of the stream
   * @return corresponding offset from window's reader index
   */
  private int toLocalOffset(long streamOffset) {
    return (int) (streamOffset - this.streamOffset + window.readableBytes());
  }

  @Override
  public void close() {
    if (window.refCnt() > 0) {
      window.release();
    }
  }

  @Override
  public String toString() {
    return window + ", streamOffset=" + streamOffset + ", content=`" + window.toString(UTF_8) + "`";
  }
}