Java tutorial
/* * Licensed to Elasticsearch under one or more contributor * license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright * ownership. Elasticsearch 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.elasticsearch.http.nio; import io.netty.buffer.ByteBuf; import io.netty.buffer.CompositeByteBuf; import io.netty.buffer.Unpooled; import io.netty.buffer.UnpooledByteBufAllocator; import io.netty.buffer.UnpooledHeapByteBuf; import org.elasticsearch.nio.InboundChannelBuffer; import java.nio.ByteBuffer; import java.util.ArrayList; import java.util.List; public class PagedByteBuf extends UnpooledHeapByteBuf { private final Runnable releasable; private PagedByteBuf(byte[] array, Runnable releasable) { super(UnpooledByteBufAllocator.DEFAULT, array, array.length); this.releasable = releasable; } static ByteBuf byteBufFromPages(InboundChannelBuffer.Page[] pages) { int componentCount = pages.length; if (componentCount == 0) { return Unpooled.EMPTY_BUFFER; } else if (componentCount == 1) { return byteBufFromPage(pages[0]); } else { int maxComponents = Math.max(16, componentCount); final List<ByteBuf> components = new ArrayList<>(componentCount); for (InboundChannelBuffer.Page page : pages) { components.add(byteBufFromPage(page)); } return new CompositeByteBuf(UnpooledByteBufAllocator.DEFAULT, false, maxComponents, components); } } private static ByteBuf byteBufFromPage(InboundChannelBuffer.Page page) { ByteBuffer buffer = page.getByteBuffer(); assert buffer.isDirect() == false && buffer.hasArray() : "Must be a heap buffer with an array"; int offset = buffer.arrayOffset() + buffer.position(); PagedByteBuf newByteBuf = new PagedByteBuf(buffer.array(), page::close); return newByteBuf.slice(offset, buffer.remaining()); } @Override protected void deallocate() { try { super.deallocate(); } finally { releasable.run(); } } }