junrao commented on code in PR #14465: URL: https://github.com/apache/kafka/pull/14465#discussion_r1362791793
########## core/src/main/scala/kafka/log/LogManager.scala: ########## @@ -1409,6 +1410,32 @@ class LogManager(logDirs: Seq[File], None } } + + def readBrokerEpochFromCleanShutdownFiles(): Long = { + // Verify whether all the log dirs have the same broker epoch in their clean shutdown files. If there are dir is not + // live, fail the broker epoch check. + if (liveLogDirs.size < logDirs.size) { + return -1L + } + var brokerEpoch = -1L + for (dir <- liveLogDirs) { + val cleanShutdownFileHandler = new CleanShutdownFileHandler(dir.getPath) + var textBrokerEpoch = -1L + try { + textBrokerEpoch = cleanShutdownFileHandler.read Review Comment: Why is this called `textBrokerEpoch`? It stores a long, not text. ########## core/src/main/scala/kafka/log/LogManager.scala: ########## @@ -1409,6 +1410,32 @@ class LogManager(logDirs: Seq[File], None } } + + def readBrokerEpochFromCleanShutdownFiles(): Long = { + // Verify whether all the log dirs have the same broker epoch in their clean shutdown files. If there are dir is not Review Comment: If there are dir is not live => If any dir is not live ? ########## core/src/main/scala/kafka/log/LogManager.scala: ########## @@ -1409,6 +1410,32 @@ class LogManager(logDirs: Seq[File], None } } + + def readBrokerEpochFromCleanShutdownFiles(): Long = { + // Verify whether all the log dirs have the same broker epoch in their clean shutdown files. If there are dir is not + // live, fail the broker epoch check. + if (liveLogDirs.size < logDirs.size) { + return -1L + } + var brokerEpoch = -1L + for (dir <- liveLogDirs) { + val cleanShutdownFileHandler = new CleanShutdownFileHandler(dir.getPath) + var textBrokerEpoch = -1L + try { + textBrokerEpoch = cleanShutdownFileHandler.read + } catch { + case e: Throwable => + info(s"loading broker epoch from ${dir.toPath} with exception ${e.toString}") + return -1L + } + if (brokerEpoch != -1 && textBrokerEpoch != brokerEpoch) { + info(s"Found different broker epochs a=$brokerEpoch vs b=$textBrokerEpoch") Review Comment: Could we log the dir names instead of using a and b? ########## core/src/main/java/kafka/log/CleanShutdownFileHandler.java: ########## @@ -0,0 +1,114 @@ +/* + * 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 kafka.log; + +import com.fasterxml.jackson.databind.ObjectMapper; +import org.apache.kafka.common.utils.LogContext; +import org.apache.kafka.common.utils.Utils; +import org.slf4j.Logger; + +import java.io.File; +import java.io.FileOutputStream; +import java.io.BufferedWriter; +import java.io.OutputStreamWriter; +import java.nio.charset.StandardCharsets; +import java.nio.file.Files; +import java.util.HashMap; +import java.util.Locale; +import java.util.Map; + +/** + * Clean shutdown file that indicates the broker was cleanly shutdown in 0.8 and higher. + * This is used to avoid unnecessary recovery after a clean shutdown. In theory this could be + * avoided by passing in the recovery point, however finding the correct position to do this + * requires accessing the offset index which may not be safe in an unclean shutdown. + * For more information see the discussion in PR#2104 + * + * Also, the clean shutdown file can also store the broker epoch, this can be used in the broker registration to + * demonstrate the last reboot is a clean shutdown. (KIP-966) + */ + +public class CleanShutdownFileHandler { + public static final String CLEAN_SHUTDOWN_FILE_NAME = ".kafka_cleanshutdown"; + private final File cleanShutdownFile; + private static final int CURRENT_VERSION = 0; + private final Logger logger; + + private enum Fields { + VERSION, + BROKER_EPOCH; + + @Override + public String toString() { + return name().toLowerCase(Locale.ROOT); + } + } + + public CleanShutdownFileHandler(String dirPath) { + logger = new LogContext().logger(CleanShutdownFileHandler.class); + this.cleanShutdownFile = new File(dirPath, CleanShutdownFileHandler.CLEAN_SHUTDOWN_FILE_NAME); + } + + public void write(long brokerEpoch) throws Exception { + write(brokerEpoch, CURRENT_VERSION); + } + + // visible to test. + void write(long brokerEpoch, int version) throws Exception { + FileOutputStream os = new FileOutputStream(cleanShutdownFile); + BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(os, StandardCharsets.UTF_8)); + try { + Map<String, String> payload = new HashMap<>(); + payload.put(Fields.VERSION.toString(), Integer.toString(version)); + payload.put(Fields.BROKER_EPOCH.toString(), Long.toString(brokerEpoch)); + bw.write(new ObjectMapper().writeValueAsString(payload)); + bw.flush(); + os.getFD().sync(); + } finally { + bw.close(); + os.close(); + } + } + + public long read() { + long brokerEpoch = -1L; + try { + String text = Utils.readFileAsString(cleanShutdownFile.toPath().toString()); + Map<String, String> content = new ObjectMapper().readValue(text, HashMap.class); + + brokerEpoch = Long.parseLong(content.getOrDefault(Fields.BROKER_EPOCH.toString(), "-1L")); + } catch (Exception e) { + logger.warn("Fail to read the clean shutdown file:" + e); Review Comment: Could we log the file path too? ########## core/src/main/scala/kafka/log/LogManager.scala: ########## @@ -1409,6 +1410,32 @@ class LogManager(logDirs: Seq[File], None } } + + def readBrokerEpochFromCleanShutdownFiles(): Long = { + // Verify whether all the log dirs have the same broker epoch in their clean shutdown files. If there are dir is not + // live, fail the broker epoch check. + if (liveLogDirs.size < logDirs.size) { + return -1L + } + var brokerEpoch = -1L + for (dir <- liveLogDirs) { + val cleanShutdownFileHandler = new CleanShutdownFileHandler(dir.getPath) + var textBrokerEpoch = -1L + try { + textBrokerEpoch = cleanShutdownFileHandler.read + } catch { + case e: Throwable => Review Comment: `cleanShutdownFileHandler.read` doesn't throw an exception. -- 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: jira-unsubscr...@kafka.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org