junrao commented on a change in pull request #11060: URL: https://github.com/apache/kafka/pull/11060#discussion_r696789655
########## File path: server-common/src/main/java/org/apache/kafka/server/common/SnapshotFile.java ########## @@ -0,0 +1,198 @@ +/* + * 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.kafka.server.common; + +import org.apache.kafka.common.KafkaException; +import org.apache.kafka.common.utils.Utils; + +import java.io.BufferedReader; +import java.io.BufferedWriter; +import java.io.File; +import java.io.FileOutputStream; +import java.io.IOException; +import java.io.OutputStreamWriter; +import java.nio.charset.StandardCharsets; +import java.nio.file.FileAlreadyExistsException; +import java.nio.file.Files; +import java.nio.file.Path; +import java.nio.file.Paths; +import java.util.ArrayList; +import java.util.Collection; +import java.util.Collections; +import java.util.List; +import java.util.Optional; + +/** + * This class represents a utility to capture a snapshot in a file. It writes down to the file in the below format. + * + * ========= File beginning ========= + * version: int + * entries-count: int + * entry-as-string-on-each-line + * ========= File end =============== + * + * Each entry is represented as a string on each line in the snapshot file. {@link EntryFormatter} is used + * to convert the entry into a string and vice versa. + * + * @param <T> entry type. + */ +public class SnapshotFile<T> { Review comment: Since KRaft introduced Snapshot for metadata, perhaps we could call this CheckpointFile and rename CheckpointFile to sth like CheckpointFileWithFailureHandler. ########## File path: core/src/main/scala/kafka/server/checkpoints/CheckpointFile.scala ########## @@ -16,127 +16,41 @@ */ package kafka.server.checkpoints -import java.io._ -import java.nio.charset.StandardCharsets -import java.nio.file.{FileAlreadyExistsException, Files, Paths} - import kafka.server.LogDirFailureChannel -import kafka.utils.Logging import org.apache.kafka.common.errors.KafkaStorageException -import org.apache.kafka.common.utils.Utils - -import scala.collection.{Seq, mutable} +import org.apache.kafka.server.common.SnapshotFile +import org.apache.kafka.server.common.SnapshotFile.EntryFormatter -trait CheckpointFileFormatter[T]{ - def toLine(entry: T): String - - def fromLine(line: String): Option[T] -} - -class CheckpointReadBuffer[T](location: String, - reader: BufferedReader, - version: Int, - formatter: CheckpointFileFormatter[T]) extends Logging { - def read(): Seq[T] = { - def malformedLineException(line: String) = - new IOException(s"Malformed line in checkpoint file ($location): '$line'") - - var line: String = null - try { - line = reader.readLine() - if (line == null) - return Seq.empty - line.toInt match { - case fileVersion if fileVersion == version => - line = reader.readLine() - if (line == null) - return Seq.empty - val expectedSize = line.toInt - val entries = mutable.Buffer[T]() - line = reader.readLine() - while (line != null) { - val entry = formatter.fromLine(line) - entry match { - case Some(e) => - entries += e - line = reader.readLine() - case _ => throw malformedLineException(line) - } - } - if (entries.size != expectedSize) - throw new IOException(s"Expected $expectedSize entries in checkpoint file ($location), but found only ${entries.size}") - entries - case _ => - throw new IOException(s"Unrecognized version of the checkpoint file ($location): " + version) - } - } catch { - case _: NumberFormatException => throw malformedLineException(line) - } - } -} +import java.io._ +import scala.collection.Seq +import scala.jdk.CollectionConverters._ class CheckpointFile[T](val file: File, version: Int, - formatter: CheckpointFileFormatter[T], + formatter: EntryFormatter[T], logDirFailureChannel: LogDirFailureChannel, - logDir: String) extends Logging { - private val path = file.toPath.toAbsolutePath - private val tempPath = Paths.get(path.toString + ".tmp") - private val lock = new Object() - - try Files.createFile(file.toPath) // create the file if it doesn't exist - catch { case _: FileAlreadyExistsException => } + logDir: String) { + private val snapshotFile = new SnapshotFile[T](file, version, formatter) def write(entries: Iterable[T]): Unit = { - lock synchronized { try { - // write to temp file and then swap with the existing file - val fileOutputStream = new FileOutputStream(tempPath.toFile) - val writer = new BufferedWriter(new OutputStreamWriter(fileOutputStream, StandardCharsets.UTF_8)) - try { - writer.write(version.toString) - writer.newLine() - - writer.write(entries.size.toString) - writer.newLine() - - entries.foreach { entry => - writer.write(formatter.toLine(entry)) - writer.newLine() - } - - writer.flush() - fileOutputStream.getFD().sync() - } finally { - writer.close() - } - - Utils.atomicMoveWithFallback(tempPath, path) + snapshotFile.write(entries.toSeq.asJava); Review comment: No need for ; -- This is an automated message from the Apache Git Service. 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