[GitHub] [hudi] vinothchandar commented on a change in pull request #1756: [HUDI-839] Introducing support for rollbacks using marker files

[GitBox <gi...@apache.org>]

vinothchandar commented on a change in pull request #1756:
URL: https://github.com/apache/hudi/pull/1756#discussion_r457651663



##########
File path: hudi-client/src/main/java/org/apache/hudi/table/MarkerFiles.java
##########
@@ -0,0 +1,153 @@
+/*
+ * 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.hudi.table;
+
+import org.apache.hadoop.fs.FileSystem;
+import org.apache.hadoop.fs.Path;
+import org.apache.hudi.common.fs.FSUtils;
+import org.apache.hudi.common.table.HoodieTableMetaClient;
+import org.apache.hudi.common.util.ValidationUtils;
+import org.apache.hudi.exception.HoodieException;
+import org.apache.hudi.exception.HoodieIOException;
+import org.apache.hudi.io.IOType;
+import org.apache.log4j.LogManager;
+import org.apache.log4j.Logger;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.LinkedList;
+import java.util.List;
+
+/**
+ * Operates on marker files for a given write action (commit, delta commit, compaction).
+ */
+public class MarkerFiles {
+
+  private static final Logger LOG = LogManager.getLogger(MarkerFiles.class);
+
+  public static String stripMarkerSuffix(String path) {
+    return path.substring(0, path.indexOf(HoodieTableMetaClient.MARKER_EXTN));
+  }
+
+  private final String instantTime;
+  private final FileSystem fs;
+  private final Path markerDirPath;
+  private final String basePath;
+
+  public MarkerFiles(FileSystem fs, String basePath, String markerFolderPath, String instantTime) {
+    this.instantTime = instantTime;
+    this.fs = fs;
+    this.markerDirPath = new Path(markerFolderPath);
+    this.basePath = basePath;
+  }
+
+  public MarkerFiles(HoodieTable<?> table, String instantTime) {
+    this(table.getMetaClient().getFs(),
+        table.getMetaClient().getBasePath(),
+        table.getMetaClient().getMarkerFolderPath(instantTime),
+        instantTime);
+  }
+
+  public void quietDeleteMarkerDir() {
+    try {
+      deleteMarkerDir();
+    } catch (HoodieIOException ioe) {
+      LOG.warn("Error deleting marker directory for instant " + instantTime, ioe);
+    }
+  }
+
+  /**
+   * Delete Marker directory corresponding to an instant.
+   */
+  public boolean deleteMarkerDir() {
+    try {
+      boolean result = fs.delete(markerDirPath, true);
+      if (result) {
+        LOG.info("Removing marker directory at " + markerDirPath);
+      } else {
+        LOG.info("No marker directory to delete at " + markerDirPath);
+      }
+      return result;
+    } catch (IOException ioe) {
+      throw new HoodieIOException(ioe.getMessage(), ioe);
+    }
+  }
+
+  public boolean doesMarkerDirExist() throws IOException {
+    return fs.exists(markerDirPath);
+  }
+
+  public List<String> createdAndMergedDataPaths() throws IOException {
+    List<String> dataFiles = new LinkedList<>();
+    FSUtils.processFiles(fs, markerDirPath.toString(), (status) -> {
+      String pathStr = status.getPath().toString();
+      if (pathStr.contains(HoodieTableMetaClient.MARKER_EXTN) && !pathStr.endsWith(IOType.APPEND.name())) {

Review comment:
       yes. we will be performing an upgrade anyway to 0.6.0., which will list the inflight instant at the time of upgrade and then subsequently, write compatible, corresponding marker files 




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