| /* |
| * 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.iotdb.rpc; |
| |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| import java.util.Arrays; |
| |
| /** |
| * Helper class that wraps a byte[] so that it can expand and be reused. Users should call |
| * resizeIfNecessary to make sure the buffer has suitable capacity, and then use the array as |
| * needed. |
| * |
| * <p>Resizing policies: Expanding: If the required size > current capacity * 1.5, expand to the |
| * required size, otherwise expand to current capacity * 1.5. Shrinking: If initial size < the |
| * required size < current capacity * 0.6, and such small requests last for more than 5 times, |
| * shrink to the middle of the required size and current capacity. |
| */ |
| class AutoResizingBuffer { |
| |
| private byte[] array; |
| private int bufTooLargeCounter = RpcUtils.MAX_BUFFER_OVERSIZE_TIME; |
| private final int initialCapacity; |
| private long lastShrinkTime; |
| |
| private static final Logger logger = LoggerFactory.getLogger(AutoResizingBuffer.class); |
| |
| public AutoResizingBuffer(int initialCapacity) { |
| this.array = new byte[initialCapacity]; |
| this.initialCapacity = initialCapacity; |
| } |
| |
| public void resizeIfNecessary(int size) { |
| final int currentCapacity = this.array.length; |
| final double loadFactor = 0.6; |
| if (currentCapacity < size) { |
| // Increase by a factor of 1.5x |
| int growCapacity = currentCapacity + (currentCapacity >> 1); |
| int newCapacity = Math.max(growCapacity, size); |
| this.array = Arrays.copyOf(array, newCapacity); |
| bufTooLargeCounter = RpcUtils.MAX_BUFFER_OVERSIZE_TIME; |
| logger.debug( |
| "{} expand from {} to {}, request: {}", this, currentCapacity, newCapacity, size); |
| } else if (size > initialCapacity |
| && currentCapacity * loadFactor > size |
| && bufTooLargeCounter-- <= 0 |
| && System.currentTimeMillis() - lastShrinkTime > RpcUtils.MIN_SHRINK_INTERVAL) { |
| // do not resize if it is reading the request size and do not shrink too often |
| array = Arrays.copyOf(array, size + (currentCapacity - size) / 2); |
| bufTooLargeCounter = RpcUtils.MAX_BUFFER_OVERSIZE_TIME; |
| lastShrinkTime = System.currentTimeMillis(); |
| logger.debug("{} shrink from {} to {}", this, currentCapacity, size); |
| } |
| } |
| |
| public byte[] array() { |
| return this.array; |
| } |
| } |