netudima commented on code in PR #3606: URL: https://github.com/apache/cassandra/pull/3606#discussion_r1936087652
########## src/java/org/apache/cassandra/io/util/ThreadLocalReadAheadBuffer.java: ########## @@ -0,0 +1,151 @@ +/* + * 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.cassandra.io.util; + +import java.nio.ByteBuffer; +import java.util.Map; +import java.util.concurrent.ConcurrentHashMap; + +import io.netty.util.concurrent.FastThreadLocal; +import org.apache.cassandra.io.compress.BufferType; +import org.apache.cassandra.io.compress.CorruptBlockException; +import org.apache.cassandra.io.sstable.CorruptSSTableException; + +public final class ThreadLocalReadAheadBuffer +{ + private static class Block { + ByteBuffer buffer = null; + int index = -1; + } + + private final ChannelProxy channel; + + private final BufferType bufferType; + + private static final Map<String, FastThreadLocal<Block>> allBlocks = new ConcurrentHashMap<>(); + + private final FastThreadLocal<Block> blockHolder; + + private final int bufferSize; + + public ThreadLocalReadAheadBuffer(ChannelProxy channel, int bufferSize, BufferType bufferType) + { + this.channel = channel; + this.bufferSize = bufferSize; + this.bufferType = bufferType; + allBlocks.putIfAbsent(channel.filePath(), new FastThreadLocal<>() { + @Override + public Block initialValue() + { + return new Block(); + } + }); + blockHolder = allBlocks.get(channel.filePath()); + } + + public boolean hasBuffer() + { + return blockHolder.get().buffer != null; + } + + /** + * Safe to call only if {@link #hasBuffer()} is true + */ + public int remaining() + { + return getBlock().buffer.remaining(); + } + + public void allocateBuffer() + { + getBlock(); + } + + private Block getBlock() + { + Block block = blockHolder.get(); + if (block.buffer == null) + { + block.buffer = bufferType.allocate(bufferSize); + block.buffer.clear(); + } + return block; + } + + public void fill(long position) throws CorruptBlockException + { + Block block = getBlock(); + ByteBuffer blockBuffer = block.buffer; + long channelSize = channel.size(); Review Comment: channel.size() causes a system call, assuming that we have a read-only file we can get it once and store as a field of ThreadLocalReadAheadBuffer <img width="1774" alt="image" src="https://github.com/user-attachments/assets/d73469b4-f3a6-4d14-a8a6-3710bbaa9e88"; /> -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: pr-unsubscr...@cassandra.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: pr-unsubscr...@cassandra.apache.org For additional commands, e-mail: pr-h...@cassandra.apache.org
