Github user tdas commented on a diff in the pull request: https://github.com/apache/spark/pull/11645#discussion_r56227475 --- Diff: sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/state/HDFSBackedStateStoreProvider.scala --- @@ -0,0 +1,454 @@ +/* + * 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.streaming.state + +import scala.collection.mutable +import scala.util.Random +import scala.util.control.NonFatal + +import org.apache.hadoop.conf.Configuration +import org.apache.hadoop.fs.{FileStatus, Path} + +import org.apache.spark.{Logging, SparkConf} +import org.apache.spark.serializer.{DeserializationStream, KryoSerializer, SerializationStream} +import org.apache.spark.sql.catalyst.InternalRow +import org.apache.spark.sql.catalyst.expressions.JoinedRow +import org.apache.spark.util.{CompletionIterator, Utils} + + +/** + * An implementation of [[StateStoreProvider]] and [[StateStore]] in which all the data is backed + * by files in a HDFS-compatible file system. All updates to the store has to be done in sets + * transactionally, and each set of updates increments the store's version. These versions can + * be used to re-execute the updates (by retries in RDD operations) on the correct version of + * the store, and regenerate the store version. + * + * Usage: + * To update the data in the state store, the following order of operations are needed. + * + * - val store = StateStore.get(operatorId, partitionId, version) // to get the right store + * - store.update(...) + * - store.remove(...) + * - store.commit() // commits all the updates to made with version number + * - store.iterator() // key-value data after last commit as an iterator + * - store.updates() // updates made in the last as an iterator + * + * Fault-tolerance model: + * - Every set of updates is written to a delta file before committing. + * - The state store is responsible for managing, collapsing and cleaning up of delta files. + * - Multiple attempts to commit the same version of updates must have the same updates. + * - Background management of files ensures that last versions of the store is always recoverable + * to ensure re-executed RDD operations re-apply updates on the correct past version of the + * store. + */ +class HDFSBackedStateStoreProvider( + val id: StateStoreId, + val directory: String, + numBatchesToRetain: Int = 2, + maxDeltaChainForSnapshots: Int = 10 + ) extends StateStoreProvider with Logging { + type MapType = mutable.HashMap[InternalRow, InternalRow] + + import StateStore._ + + + class HDFSBackedStateStore( val version: Long, mapToUpdate: MapType) + extends StateStore { + + trait STATE + case object UPDATING extends STATE + case object COMMITTED extends STATE + case object CANCELLED extends STATE + + private val newVersion = version + 1 + private val tempDeltaFile = new Path(baseDir, s"temp-${Random.nextLong}") + private val tempDeltaFileStream = + serializer.newInstance().serializeStream(fs.create(tempDeltaFile, true)) + private val allUpdates = new mutable.HashMap[InternalRow, StoreUpdate] + + @volatile private var state: STATE = UPDATING + @volatile private var finalDeltaFile: Path = null + + override def id: StateStoreId = HDFSBackedStateStoreProvider.this.id + + /** Update the value of a key using the value generated by the update function */ + override def update(key: InternalRow, updateFunc: Option[InternalRow] => InternalRow): Unit = { + verify(state == UPDATING, "Cannot update after already committed or cancelled") + val oldValueOption = mapToUpdate.get(key) + val value = updateFunc(oldValueOption) + mapToUpdate.put(key, value) + allUpdates.get(key) match { + case Some(ValueAdded(_, _)) => + allUpdates.put(key, ValueAdded(key, value)) + case Some(ValueUpdated(_, _)) | Some(KeyRemoved(_)) => + allUpdates.put(key, ValueUpdated(key, value)) + case None => + val update = + if (oldValueOption.nonEmpty) ValueUpdated(key, value) else ValueAdded(key, value) + allUpdates.put(key, update) + } + tempDeltaFileStream.writeObject(ValueUpdated(key, value)) + } + + /** Remove keys that match the following condition */ + override def remove(condition: InternalRow => Boolean): Unit = { + verify(state == UPDATING, "Cannot remove after already committed or cancelled") + val keyIter = mapToUpdate.keysIterator + while (keyIter.hasNext) { + val key = keyIter.next + if (condition(key)) { + mapToUpdate.remove(key) + allUpdates.get(key) match { + case Some(ValueUpdated(_, _)) | None => + allUpdates.put(key, KeyRemoved(key)) + case Some(ValueAdded(_, _)) => + allUpdates.remove(key) + case Some(KeyRemoved(_)) => + // Remove already in update map, no need to change + } + tempDeltaFileStream.writeObject(KeyRemoved(key)) + } + } + } + + /** Commit all the updates that have been made to the store. */ + override def commit(): Long = { + verify(state == UPDATING, "Cannot commit again after already committed or cancelled") + + try { + tempDeltaFileStream.close() + finalDeltaFile = commitUpdates(newVersion, mapToUpdate, tempDeltaFile) + state = COMMITTED + newVersion + } catch { + case NonFatal(e) => + throw new IllegalStateException( + s"Error committing version $newVersion into ${HDFSBackedStateStoreProvider.this}", e) + } + } + + /** Cancel all the updates made on this store. This store will not be usable any more. */ + override def cancel(): Unit = { + state = CANCELLED + if (tempDeltaFileStream != null) { + tempDeltaFileStream.close() + } + if (tempDeltaFile != null && fs.exists(tempDeltaFile)) { + fs.delete(tempDeltaFile, true) + } + } + + /** + * Get an iterator of all the store data. This can be called only after committing the + * updates. + */ + override def iterator(): Iterator[InternalRow] = { + verify(state == COMMITTED, "Cannot get iterator of store data before comitting") + HDFSBackedStateStoreProvider.this.iterator(newVersion) + } + + /** + * Get an iterator of all the updates made to the store in the current version. + * This can be called only after committing the updates. + */ + override def updates(): Iterator[StoreUpdate] = { + verify(state == COMMITTED, "Cannot get iterator of updates before committing") + allUpdates.valuesIterator + } + + /** + * Whether all updates have been committed + */ + override def hasCommitted: Boolean = { + state == COMMITTED + } + } + + /** Get the state store for making updates to create a new `version` of the store. */ + override def getStore(version: Long): StateStore = synchronized { + require(version >= 0, "Version cannot be less than 0") + val newMap = new MapType() + if (version > 0) { + newMap ++= loadMap(version) + } + new HDFSBackedStateStore(version, newMap) + } + + override def manage(): Unit = { + try { + doSnapshot() + cleanup() + } catch { + case NonFatal(e) => + logWarning(s"Error performing snapshot and cleaning up $this") + } + } + + override def toString(): String = { + s"StateStore[id = (op=${id.operatorId},part=${id.partitionId}), dir = $baseDir]" + } + + /* Internal classes and methods */ + + private val loadedMaps = new mutable.HashMap[Long, MapType] + private val baseDir = new Path(directory, s"${id.operatorId}/${id.partitionId.toString}") + private val fs = baseDir.getFileSystem(new Configuration()) + private val serializer = new KryoSerializer(new SparkConf) + + initialize() + + private case class StoreFile(version: Long, path: Path, isSnapshot: Boolean) + + /** Commit a set of updates to the store with the given new version */ + private def commitUpdates(newVersion: Long, map: MapType, tempDeltaFile: Path): Path = { + synchronized { + val finalDeltaFile = deltaFile(newVersion) + fs.rename(tempDeltaFile, finalDeltaFile) + loadedMaps.put(newVersion, map) + finalDeltaFile + } + } + + /** + * Get iterator of all the data of the latest version of the store. + * Note that this will look up the files to determined the latest known version. + */ + private[state] def latestIterator(): Iterator[InternalRow] = synchronized { + val versionsInFiles = fetchFiles().map(_.version).toSet + val versionsLoaded = loadedMaps.keySet + val allKnownVersions = versionsInFiles ++ versionsLoaded + if (allKnownVersions.nonEmpty) { + loadMap(allKnownVersions.max) + .iterator + .map { case (key, value) => new JoinedRow(key, value) } + } else Iterator.empty + } + + /** Get iterator of a specific version of the store */ + private[state] def iterator(version: Long): Iterator[InternalRow] = synchronized { + loadMap(version) + .iterator + .map { case (key, value) => new JoinedRow(key, value) } + } + + /** Initialize the store provider */ + private def initialize(): Unit = { + if (!fs.exists(baseDir)) { + fs.mkdirs(baseDir) + } else { + if (!fs.isDirectory(baseDir)) { + throw new IllegalStateException( + s"Cannot use $directory for storing state data as" + + s"$baseDir already exists and is not a directory") + } + } + } + + /** Load the required version of the map data from the backing files */ + private def loadMap(version: Long): MapType = { + if (version <= 0) return new MapType + synchronized { loadedMaps.get(version) }.getOrElse { + val mapFromFile = readSnapshotFile(version).getOrElse { + val prevMap = loadMap(version - 1) + val deltaUpdates = readDeltaFile(version) + val newMap = new MapType() + newMap ++= prevMap + newMap.sizeHint(prevMap.size) + while (deltaUpdates.hasNext) { + deltaUpdates.next match { + case ValueAdded(key, value) => newMap.put(key, value) + case ValueUpdated(key, value) => newMap.put(key, value) + case KeyRemoved(key) => newMap.remove(key) + } + } + newMap + } + loadedMaps.put(version, mapFromFile) + mapFromFile + } + } + + private def readDeltaFile(version: Long): Iterator[StoreUpdate] = { + val fileToRead = deltaFile(version) + if (!fs.exists(fileToRead)) { + throw new IllegalStateException( + s"Cannot read delta file $fileToRead of $this: $fileToRead does not exist") + } + val deser = serializer.newInstance() + var deserStream: DeserializationStream = null + deserStream = deser.deserializeStream(fs.open(fileToRead)) + val iter = deserStream.asIterator.asInstanceOf[Iterator[StoreUpdate]] + CompletionIterator[StoreUpdate, Iterator[StoreUpdate]]( + iter, { + deserStream.close() + }) + } + + private def writeSnapshotFile(version: Long, map: MapType): Unit = { + val fileToWrite = snapshotFile(version) + val ser = serializer.newInstance() + var outputStream: SerializationStream = null + Utils.tryWithSafeFinally { + outputStream = ser.serializeStream(fs.create(fileToWrite, false)) + outputStream.writeAll(map.iterator) + } { + if (outputStream != null) outputStream.close() + } + } + + private def readSnapshotFile(version: Long): Option[MapType] = { + val fileToRead = snapshotFile(version) + if (!fs.exists(fileToRead)) return None + + val deser = serializer.newInstance() + val map = new MapType() + var deserStream: DeserializationStream = null + + try { + deserStream = deser.deserializeStream(fs.open(fileToRead)) + val iter = deserStream.asIterator.asInstanceOf[Iterator[(InternalRow, InternalRow)]] + while (iter.hasNext) { + map += iter.next() + } + Some(map) + } finally { + if (deserStream != null) deserStream.close() + } + } + + + /** Perform a snapshot of the store to allow delta files to be consolidated */ + private def doSnapshot(): Unit = { + try { + val files = fetchFiles() + if (files.nonEmpty) { + val lastVersion = files.last.version + val deltaFilesForLastVersion = + filesForVersion(files, lastVersion).filter(_.isSnapshot == false) + synchronized { loadedMaps.get(lastVersion) } match { + case Some(map) => + if (deltaFilesForLastVersion.size > maxDeltaChainForSnapshots) { + writeSnapshotFile(lastVersion, map) + } + case None => + // The last map is not loaded, probably some other instance is incharge + } + + } + } catch { + case NonFatal(e) => + logWarning(s"Error doing snapshots for $this", e) + } + } + + /** + * Clean up old snapshots and delta files that are not needed any more. It ensures that last + * few versions of the store can be recovered from the files, so re-executed RDD operations + * can re-apply updates on the past versions of the store. + */ + private[state] def cleanup(): Unit = { + try { + val files = fetchFiles() + if (files.nonEmpty) { + val earliestVersionToRetain = files.last.version - numBatchesToRetain + if (earliestVersionToRetain > 0) { + val earliestFileToRetain = filesForVersion(files, earliestVersionToRetain).head + synchronized { + loadedMaps.keys.filter(_ < earliestVersionToRetain).foreach(loadedMaps.remove) + } + files.filter(_.version < earliestFileToRetain.version).foreach { f => + fs.delete(f.path, true) + } + } + } + } catch { + case NonFatal(e) => + logWarning(s"Error cleaning up files for $this", e) + } + } + + private def filesForVersion(allFiles: Seq[StoreFile], version: Long): Seq[StoreFile] = { --- End diff -- add docs
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