| /* |
| * 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.lucene.util; |
| |
| import org.apache.lucene.util.ByteBlockPool.Allocator; |
| |
| |
| /** |
| * A {@link ByteBlockPool.Allocator} implementation that recycles unused byte |
| * blocks in a buffer and reuses them in subsequent calls to |
| * {@link #getByteBlock()}. |
| * <p> |
| * Note: This class is not thread-safe |
| * </p> |
| * @lucene.internal |
| */ |
| public final class RecyclingByteBlockAllocator extends ByteBlockPool.Allocator { |
| private byte[][] freeByteBlocks; |
| private final int maxBufferedBlocks; |
| private int freeBlocks = 0; |
| private final Counter bytesUsed; |
| public static final int DEFAULT_BUFFERED_BLOCKS = 64; |
| |
| /** |
| * Creates a new {@link RecyclingByteBlockAllocator} |
| * |
| * @param blockSize |
| * the block size in bytes |
| * @param maxBufferedBlocks |
| * maximum number of buffered byte block |
| * @param bytesUsed |
| * {@link Counter} reference counting internally allocated bytes |
| */ |
| public RecyclingByteBlockAllocator(int blockSize, int maxBufferedBlocks, |
| Counter bytesUsed) { |
| super(blockSize); |
| freeByteBlocks = new byte[maxBufferedBlocks][]; |
| this.maxBufferedBlocks = maxBufferedBlocks; |
| this.bytesUsed = bytesUsed; |
| } |
| |
| /** |
| * Creates a new {@link RecyclingByteBlockAllocator}. |
| * |
| * @param blockSize |
| * the block size in bytes |
| * @param maxBufferedBlocks |
| * maximum number of buffered byte block |
| */ |
| public RecyclingByteBlockAllocator(int blockSize, int maxBufferedBlocks) { |
| this(blockSize, maxBufferedBlocks, Counter.newCounter(false)); |
| } |
| |
| /** |
| * Creates a new {@link RecyclingByteBlockAllocator} with a block size of |
| * {@link ByteBlockPool#BYTE_BLOCK_SIZE}, upper buffered docs limit of |
| * {@link #DEFAULT_BUFFERED_BLOCKS} ({@value #DEFAULT_BUFFERED_BLOCKS}). |
| * |
| */ |
| public RecyclingByteBlockAllocator() { |
| this(ByteBlockPool.BYTE_BLOCK_SIZE, 64, Counter.newCounter(false)); |
| } |
| |
| @Override |
| public byte[] getByteBlock() { |
| if (freeBlocks == 0) { |
| bytesUsed.addAndGet(blockSize); |
| return new byte[blockSize]; |
| } |
| final byte[] b = freeByteBlocks[--freeBlocks]; |
| freeByteBlocks[freeBlocks] = null; |
| return b; |
| } |
| |
| @Override |
| public void recycleByteBlocks(byte[][] blocks, int start, int end) { |
| final int numBlocks = Math.min(maxBufferedBlocks - freeBlocks, end - start); |
| final int size = freeBlocks + numBlocks; |
| if (size >= freeByteBlocks.length) { |
| final byte[][] newBlocks = new byte[ArrayUtil.oversize(size, |
| RamUsageEstimator.NUM_BYTES_OBJECT_REF)][]; |
| System.arraycopy(freeByteBlocks, 0, newBlocks, 0, freeBlocks); |
| freeByteBlocks = newBlocks; |
| } |
| final int stop = start + numBlocks; |
| for (int i = start; i < stop; i++) { |
| freeByteBlocks[freeBlocks++] = blocks[i]; |
| blocks[i] = null; |
| } |
| for (int i = stop; i < end; i++) { |
| blocks[i] = null; |
| } |
| bytesUsed.addAndGet(-(end - stop) * blockSize); |
| assert bytesUsed.get() >= 0; |
| } |
| |
| /** |
| * @return the number of currently buffered blocks |
| */ |
| public int numBufferedBlocks() { |
| return freeBlocks; |
| } |
| |
| /** |
| * @return the number of bytes currently allocated by this {@link Allocator} |
| */ |
| public long bytesUsed() { |
| return bytesUsed.get(); |
| } |
| |
| /** |
| * @return the maximum number of buffered byte blocks |
| */ |
| public int maxBufferedBlocks() { |
| return maxBufferedBlocks; |
| } |
| |
| /** |
| * Removes the given number of byte blocks from the buffer if possible. |
| * |
| * @param num |
| * the number of byte blocks to remove |
| * @return the number of actually removed buffers |
| */ |
| public int freeBlocks(int num) { |
| assert num >= 0 : "free blocks must be >= 0 but was: "+ num; |
| final int stop; |
| final int count; |
| if (num > freeBlocks) { |
| stop = 0; |
| count = freeBlocks; |
| } else { |
| stop = freeBlocks - num; |
| count = num; |
| } |
| while (freeBlocks > stop) { |
| freeByteBlocks[--freeBlocks] = null; |
| } |
| bytesUsed.addAndGet(-count*blockSize); |
| assert bytesUsed.get() >= 0; |
| return count; |
| } |
| } |