wuzhanpeng commented on code in PR #3111: URL: https://github.com/apache/bookkeeper/pull/3111#discussion_r851168306
########## bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/ReadAheadManager.java: ########## @@ -0,0 +1,655 @@ +/** + * + * 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.bookkeeper.bookie.storage.ldb; + +import io.netty.buffer.ByteBuf; +import io.netty.util.concurrent.DefaultThreadFactory; +import java.io.IOException; +import java.util.ArrayList; +import java.util.List; +import java.util.Map; +import java.util.NavigableMap; +import java.util.Objects; +import java.util.TreeMap; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentLinkedQueue; +import java.util.concurrent.ExecutorService; +import java.util.concurrent.Executors; +import java.util.concurrent.ScheduledExecutorService; +import java.util.concurrent.TimeUnit; +import java.util.concurrent.atomic.AtomicBoolean; +import java.util.concurrent.locks.Condition; +import java.util.concurrent.locks.ReentrantLock; +import org.apache.bookkeeper.bookie.Bookie; +import org.apache.bookkeeper.bookie.EntryLogger; +import org.apache.bookkeeper.conf.ServerConfiguration; +import org.apache.bookkeeper.stats.Counter; +import org.apache.bookkeeper.stats.OpStatsLogger; +import org.apache.bookkeeper.util.MathUtils; +import org.apache.bookkeeper.util.SafeRunnable; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * A management tool that supports asynchronous read-ahead operations for {@link SingleDirectoryDbLedgerStorage}. + **/ +public class ReadAheadManager { + + private static final Logger log = LoggerFactory.getLogger(ReadAheadManager.class); + + public static final String READ_AHEAD_MAX_MESSAGES = "dbStorage_readAheadMaxMessages"; + public static final String READ_AHEAD_MAX_BYTES = "dbStorage_readAheadMaxBytes"; + public static final String READ_AHEAD_PRE_TRIGGER_RATIO = "dbStorage_readAheadPreTriggerRatio"; + public static final String READ_AHEAD_TASK_EXPIRED_TIME_MS = "dbStorage_readAheadTaskExpiredTimeMs"; + public static final String READ_AHEAD_TIMEOUT_MS = "dbStorage_readAheadTimeoutMs"; + + // operation behavior indicator + public static final String SUBMIT_READ_AHEAD_TASK_IMMEDIATELY = "dbStorage_submitReadAheadTaskImmediately"; + public static final String READ_AHEAD_TASK_POOL_SIZE = "dbStorage_readAheadTaskPoolSize"; + + private static final int DEFAULT_READ_AHEAD_MESSAGES = 1000; Review Comment: In our practice, it is more cost-effective to read more consecutive entries when the entry size is small. In addition, because the termination condition of the read-ahead task depends on the maximum number of bytes and the maximum number of entries, under the default limit of reading up to 256KB, generally speaking, the number of entries in read-ahead task will not be too many. -- 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: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
