[SPARK-23966][SS] Refactoring all checkpoint file writing logic in a …

…common CheckpointFileManager interface

## What changes were proposed in this pull request?

Checkpoint files (offset log files, state store files) in Structured Streaming must be written atomically such that no partial files are generated (would break fault-tolerance guarantees). Currently, there are 3 locations which try to do this individually, and in some cases, incorrectly.

1. HDFSOffsetMetadataLog - This uses a FileManager interface to use any implementation of `FileSystem` or `FileContext` APIs. It preferably loads `FileContext` implementation as FileContext of HDFS has atomic renames.
1. HDFSBackedStateStore (aka in-memory state store)
  - Writing a version.delta file - This uses FileSystem APIs only to perform a rename. This is incorrect as rename is not atomic in HDFS FileSystem implementation.
  - Writing a snapshot file - Same as above.

#### Current problems:
1. State Store behavior is incorrect - HDFS FileSystem implementation does not have atomic rename.
1. Inflexible - Some file systems provide mechanisms other than write-to-temp-file-and-rename for writing atomically and more efficiently. For example, with S3 you can write directly to the final file and it will be made visible only when the entire file is written and closed correctly. Any failure can be made to terminate the writing without making any partial files visible in S3. The current code does not abstract out this mechanism enough that it can be customized.

#### Solution:

1. Introduce a common interface that all 3 cases above can use to write checkpoint files atomically.
2. This interface must provide the necessary interfaces that allow customization of the write-and-rename mechanism.

This PR does that by introducing the interface `CheckpointFileManager` and modifying `HDFSMetadataLog` and `HDFSBackedStateStore` to use the interface. Similar to earlier `FileManager`, there are implementations based on `FileSystem` and `FileContext` APIs, and the latter implementation is preferred to make it work correctly with HDFS.

The key method this interface has is `createAtomic(path, overwrite)` which returns a `CancellableFSDataOutputStream` that has the method `cancel()`. All users of this method need to either call `close()` to successfully write the file, or `cancel()` in case of an error.

## How was this patch tested?
New tests in `CheckpointFileManagerSuite` and slightly modified existing tests.

Author: Tathagata Das <[email protected]>

Closes apache#21048 from tdas/SPARK-23966.

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -930,6 +930,13 @@ object SQLConf {
       .intConf
       .createWithDefault(100)
 
+  val STREAMING_CHECKPOINT_FILE_MANAGER_CLASS =
+    buildConf("spark.sql.streaming.checkpointFileManagerClass")
+      .doc("The class used to write checkpoint files atomically. This class must be a subclass " +
+        "of the interface CheckpointFileManager.")
+      .internal()
+      .stringConf
+
   val NDV_MAX_ERROR =
     buildConf("spark.sql.statistics.ndv.maxError")
       .internal()

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/CheckpointFileManager.scala

@@ -0,0 +1,349 @@
+/*
+ * 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
+
+import java.io.{FileNotFoundException, IOException, OutputStream}
+import java.util.{EnumSet, UUID}
+
+import scala.util.control.NonFatal
+
+import org.apache.hadoop.conf.Configuration
+import org.apache.hadoop.fs._
+import org.apache.hadoop.fs.local.{LocalFs, RawLocalFs}
+import org.apache.hadoop.fs.permission.FsPermission
+
+import org.apache.spark.internal.Logging
+import org.apache.spark.sql.execution.streaming.CheckpointFileManager.RenameHelperMethods
+import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.util.Utils
+
+/**
+ * An interface to abstract out all operation related to streaming checkpoints. Most importantly,
+ * the key operation this interface provides is `createAtomic(path, overwrite)` which returns a
+ * `CancellableFSDataOutputStream`. This method is used by [[HDFSMetadataLog]] and
+ * [[org.apache.spark.sql.execution.streaming.state.StateStore StateStore]] implementations
+ * to write a complete checkpoint file atomically (i.e. no partial file will be visible), with or
+ * without overwrite.
+ *
+ * This higher-level interface above the Hadoop FileSystem is necessary because
+ * different implementation of FileSystem/FileContext may have different combination of operations
+ * to provide the desired atomic guarantees (e.g. write-to-temp-file-and-rename,
+ * direct-write-and-cancel-on-failure) and this abstraction allow different implementations while
+ * keeping the usage simple (`createAtomic` -> `close` or `cancel`).
+ */
+trait CheckpointFileManager {
+
+  import org.apache.spark.sql.execution.streaming.CheckpointFileManager._
+
+  /**
+   * Create a file and make its contents available atomically after the output stream is closed.
+   *
+   * @param path                Path to create
+   * @param overwriteIfPossible If true, then the implementations must do a best-effort attempt to
+   *                            overwrite the file if it already exists. It should not throw
+   *                            any exception if the file exists. However, if false, then the
+   *                            implementation must not overwrite if the file alraedy exists and
+   *                            must throw `FileAlreadyExistsException` in that case.
+   */
+  def createAtomic(path: Path, overwriteIfPossible: Boolean): CancellableFSDataOutputStream
+
+  /** Open a file for reading, or throw exception if it does not exist. */
+  def open(path: Path): FSDataInputStream
+
+  /** List the files in a path that match a filter. */
+  def list(path: Path, filter: PathFilter): Array[FileStatus]
+
+  /** List all the files in a path. */
+  def list(path: Path): Array[FileStatus] = {
+    list(path, new PathFilter { override def accept(path: Path): Boolean = true })
+  }
+
+  /** Make directory at the give path and all its parent directories as needed. */
+  def mkdirs(path: Path): Unit
+
+  /** Whether path exists */
+  def exists(path: Path): Boolean
+
+  /** Recursively delete a path if it exists. Should not throw exception if file doesn't exist. */
+  def delete(path: Path): Unit
+
+  /** Is the default file system this implementation is operating on the local file system. */
+  def isLocal: Boolean
+}
+
+object CheckpointFileManager extends Logging {
+
+  /**
+   * Additional methods in CheckpointFileManager implementations that allows
+   * [[RenameBasedFSDataOutputStream]] get atomicity by write-to-temp-file-and-rename
+   */
+  sealed trait RenameHelperMethods { self => CheckpointFileManager
+    /** Create a file with overwrite. */
+    def createTempFile(path: Path): FSDataOutputStream
+
+    /**
+     * Rename a file.
+     *
+     * @param srcPath             Source path to rename
+     * @param dstPath             Destination path to rename to
+     * @param overwriteIfPossible If true, then the implementations must do a best-effort attempt to
+     *                            overwrite the file if it already exists. It should not throw
+     *                            any exception if the file exists. However, if false, then the
+     *                            implementation must not overwrite if the file alraedy exists and
+     *                            must throw `FileAlreadyExistsException` in that case.
+     */
+    def renameTempFile(srcPath: Path, dstPath: Path, overwriteIfPossible: Boolean): Unit
+  }
+
+  /**
+   * An interface to add the cancel() operation to [[FSDataOutputStream]]. This is used
+   * mainly by `CheckpointFileManager.createAtomic` to write a file atomically.
+   *
+   * @see [[CheckpointFileManager]].
+   */
+  abstract class CancellableFSDataOutputStream(protected val underlyingStream: OutputStream)
+    extends FSDataOutputStream(underlyingStream, null) {
+    /** Cancel the `underlyingStream` and ensure that the output file is not generated. */
+    def cancel(): Unit
+  }
+
+  /**
+   * An implementation of [[CancellableFSDataOutputStream]] that writes a file atomically by writing
+   * to a temporary file and then renames.
+   */
+  sealed class RenameBasedFSDataOutputStream(
+      fm: CheckpointFileManager with RenameHelperMethods,
+      finalPath: Path,
+      tempPath: Path,
+      overwriteIfPossible: Boolean)
+    extends CancellableFSDataOutputStream(fm.createTempFile(tempPath)) {
+
+    def this(fm: CheckpointFileManager with RenameHelperMethods, path: Path, overwrite: Boolean) = {
+      this(fm, path, generateTempPath(path), overwrite)
+    }
+
+    logInfo(s"Writing atomically to $finalPath using temp file $tempPath")
+    @volatile private var terminated = false
+
+    override def close(): Unit = synchronized {
+      try {
+        if (terminated) return
+        underlyingStream.close()
+        try {
+          fm.renameTempFile(tempPath, finalPath, overwriteIfPossible)
+        } catch {
+          case fe: FileAlreadyExistsException =>
+            logWarning(
+              s"Failed to rename temp file $tempPath to $finalPath because file exists", fe)
+            if (!overwriteIfPossible) throw fe
+        }
+        logInfo(s"Renamed temp file $tempPath to $finalPath")
+      } finally {
+        terminated = true
+      }
+    }
+
+    override def cancel(): Unit = synchronized {
+      try {
+        if (terminated) return
+        underlyingStream.close()
+        fm.delete(tempPath)
+      } catch {
+        case NonFatal(e) =>
+          logWarning(s"Error cancelling write to $finalPath", e)
+      } finally {
+        terminated = true
+      }
+    }
+  }
+
+
+  /** Create an instance of [[CheckpointFileManager]] based on the path and configuration. */
+  def create(path: Path, hadoopConf: Configuration): CheckpointFileManager = {
+    val fileManagerClass = hadoopConf.get(
+      SQLConf.STREAMING_CHECKPOINT_FILE_MANAGER_CLASS.parent.key)
+    if (fileManagerClass != null) {
+      return Utils.classForName(fileManagerClass)
+        .getConstructor(classOf[Path], classOf[Configuration])
+        .newInstance(path, hadoopConf)
+        .asInstanceOf[CheckpointFileManager]
+    }
+    try {
+      // Try to create a manager based on `FileContext` because HDFS's `FileContext.rename()
+      // gives atomic renames, which is what we rely on for the default implementation
+      // `CheckpointFileManager.createAtomic`.
+      new FileContextBasedCheckpointFileManager(path, hadoopConf)
+    } catch {
+      case e: UnsupportedFileSystemException =>
+        logWarning(
+          "Could not use FileContext API for managing Structured Streaming checkpoint files at " +
+            s"$path. Using FileSystem API instead for managing log files. If the implementation " +
+            s"of FileSystem.rename() is not atomic, then the correctness and fault-tolerance of" +
+            s"your Structured Streaming is not guaranteed.")
+        new FileSystemBasedCheckpointFileManager(path, hadoopConf)
+    }
+  }
+
+  private def generateTempPath(path: Path): Path = {
+    val tc = org.apache.spark.TaskContext.get
+    val tid = if (tc != null) ".TID" + tc.taskAttemptId else ""
+    new Path(path.getParent, s".${path.getName}.${UUID.randomUUID}${tid}.tmp")
+  }
+}
+
+
+/** An implementation of [[CheckpointFileManager]] using Hadoop's [[FileSystem]] API. */
+class FileSystemBasedCheckpointFileManager(path: Path, hadoopConf: Configuration)
+  extends CheckpointFileManager with RenameHelperMethods with Logging {
+
+  import CheckpointFileManager._
+
+  protected val fs = path.getFileSystem(hadoopConf)
+
+  override def list(path: Path, filter: PathFilter): Array[FileStatus] = {
+    fs.listStatus(path, filter)
+  }
+
+  override def mkdirs(path: Path): Unit = {
+    fs.mkdirs(path, FsPermission.getDirDefault)
+  }
+
+  override def createTempFile(path: Path): FSDataOutputStream = {
+    fs.create(path, true)
+  }
+
+  override def createAtomic(
+      path: Path,
+      overwriteIfPossible: Boolean): CancellableFSDataOutputStream = {
+    new RenameBasedFSDataOutputStream(this, path, overwriteIfPossible)
+  }
+
+  override def open(path: Path): FSDataInputStream = {
+    fs.open(path)
+  }
+
+  override def exists(path: Path): Boolean = {
+    try
+      return fs.getFileStatus(path) != null
+    catch {
+      case e: FileNotFoundException =>
+        return false
+    }
+  }
+
+  override def renameTempFile(srcPath: Path, dstPath: Path, overwriteIfPossible: Boolean): Unit = {
+    if (!overwriteIfPossible && fs.exists(dstPath)) {
+      throw new FileAlreadyExistsException(
+        s"Failed to rename $srcPath to $dstPath as destination already exists")
+    }
+
+    if (!fs.rename(srcPath, dstPath)) {
+      // FileSystem.rename() returning false is very ambiguous as it can be for many reasons.
+      // This tries to make a best effort attempt to return the most appropriate exception.
+      if (fs.exists(dstPath)) {
+        if (!overwriteIfPossible) {
+          throw new FileAlreadyExistsException(s"Failed to rename as $dstPath already exists")
+        }
+      } else if (!fs.exists(srcPath)) {
+        throw new FileNotFoundException(s"Failed to rename as $srcPath was not found")
+      } else {
+        val msg = s"Failed to rename temp file $srcPath to $dstPath as rename returned false"
+        logWarning(msg)
+        throw new IOException(msg)
+      }
+    }
+  }
+
+  override def delete(path: Path): Unit = {
+    try {
+      fs.delete(path, true)
+    } catch {
+      case e: FileNotFoundException =>
+        logInfo(s"Failed to delete $path as it does not exist")
+        // ignore if file has already been deleted
+    }
+  }
+
+  override def isLocal: Boolean = fs match {
+    case _: LocalFileSystem | _: RawLocalFileSystem => true
+    case _ => false
+  }
+}
+
+
+/** An implementation of [[CheckpointFileManager]] using Hadoop's [[FileContext]] API. */
+class FileContextBasedCheckpointFileManager(path: Path, hadoopConf: Configuration)
+  extends CheckpointFileManager with RenameHelperMethods with Logging {
+
+  import CheckpointFileManager._
+
+  private val fc = if (path.toUri.getScheme == null) {
+    FileContext.getFileContext(hadoopConf)
+  } else {
+    FileContext.getFileContext(path.toUri, hadoopConf)
+  }
+
+  override def list(path: Path, filter: PathFilter): Array[FileStatus] = {
+    fc.util.listStatus(path, filter)
+  }
+
+  override def mkdirs(path: Path): Unit = {
+    fc.mkdir(path, FsPermission.getDirDefault, true)
+  }
+
+  override def createTempFile(path: Path): FSDataOutputStream = {
+    import CreateFlag._
+    import Options._
+    fc.create(
+      path, EnumSet.of(CREATE, OVERWRITE), CreateOpts.checksumParam(ChecksumOpt.createDisabled()))
+  }
+
+  override def createAtomic(
+      path: Path,
+      overwriteIfPossible: Boolean): CancellableFSDataOutputStream = {
+    new RenameBasedFSDataOutputStream(this, path, overwriteIfPossible)
+  }
+
+  override def open(path: Path): FSDataInputStream = {
+    fc.open(path)
+  }
+
+  override def exists(path: Path): Boolean = {
+    fc.util.exists(path)
+  }
+
+  override def renameTempFile(srcPath: Path, dstPath: Path, overwriteIfPossible: Boolean): Unit = {
+    import Options.Rename._
+    fc.rename(srcPath, dstPath, if (overwriteIfPossible) OVERWRITE else NONE)
+  }
+
+
+  override def delete(path: Path): Unit = {
+    try {
+      fc.delete(path, true)
+    } catch {
+      case e: FileNotFoundException =>
+      // ignore if file has already been deleted
+    }
+  }
+
+  override def isLocal: Boolean = fc.getDefaultFileSystem match {
+    case _: LocalFs | _: RawLocalFs => true // LocalFs = RawLocalFs + ChecksumFs
+    case _ => false
+  }
+}
+