viirya commented on a change in pull request #33748: URL: https://github.com/apache/spark/pull/33748#discussion_r689852287
########## File path: sql/core/src/main/scala/org/apache/spark/sql/execution/datasources/FileMetaCacheManager.scala ########## @@ -0,0 +1,94 @@ +/* + * 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.spark.sql.execution.datasources + +import java.util.concurrent.TimeUnit + +import com.github.benmanes.caffeine.cache.{CacheLoader, Caffeine} +import com.github.benmanes.caffeine.cache.stats.CacheStats +import org.apache.hadoop.conf.Configuration +import org.apache.hadoop.fs.Path + +import org.apache.spark.SparkEnv +import org.apache.spark.internal.Logging +import org.apache.spark.sql.internal.SQLConf + +/** + * A singleton Cache Manager to caching file meta. We cache these file metas in order to speed up + * iterated queries over the same dataset. Otherwise, each query would have to hit remote storage + * in order to fetch file meta before read files. + * + * We should implement the corresponding `FileMetaKey` for a specific file format, for example + * `ParquetFileMetaKey` or `OrcFileMetaKey`. By default, the file path is used as the identification + * of the `FileMetaKey` and the `getFileMeta` method of `FileMetaKey` is used to return the file + * meta of the corresponding file format. + */ +object FileMetaCacheManager extends Logging { + + private lazy val cacheLoader = new CacheLoader[FileMetaKey, FileMeta]() { + override def load(fileMetaKey: FileMetaKey): FileMeta = { + logDebug(s"Loading Data File Meta ${fileMetaKey.path}") + fileMetaKey.getFileMeta + } + } + + private lazy val ttlTime = + SparkEnv.get.conf.get(SQLConf.FILE_META_CACHE_TTL_SINCE_LAST_ACCESS) + + private lazy val maximumSize = + SparkEnv.get.conf.get(SQLConf.FILE_META_CACHE_MAXIMUM_SIZE) + + private lazy val cache = Caffeine + .newBuilder() + .expireAfterAccess(ttlTime, TimeUnit.SECONDS) + .maximumSize(maximumSize) + .recordStats() + .build[FileMetaKey, FileMeta](cacheLoader) + + /** + * Returns the `FileMeta` associated with the `FileMetaKey` in the `FileMetaCacheManager`, + * obtaining that the `FileMeta` from `cacheLoader.load(FileMetaKey)` if necessary. + */ + def get(fileMeteKey: FileMetaKey): FileMeta = cache.get(fileMeteKey) + + /** + * Return current snapshot of FileMeta Cache's cumulative statistics + * include cache hitCount, missCount and so on. + * This method is only called when testing now. + */ + private def cacheStats: CacheStats = cache.stats() + + /** + * Use to cleanUp entries in the FileMeta Cache. + * This method is only called when testing now. + */ + private def cleanUp(): Unit = cache.cleanUp() +} + +abstract class FileMetaKey { + def path: Path + def configuration: Configuration + def getFileMeta: FileMeta + override def hashCode(): Int = path.hashCode + override def equals(other: Any): Boolean = other match { + case df: FileMetaKey => path.equals(df.path) + case _ => false Review comment: Ideally, if there will be different types of `FileMetaKey` later, e.g. `ParquetFileMetaKey` or `OrcFileMetaKey`, they should be considered different. So besides comparing `path`, should we also check if they are same type? -- 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: reviews-unsubscr...@spark.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org For additional commands, e-mail: reviews-h...@spark.apache.org
