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Subject [GitHub] [hadoop] bgaborg commented on a change in pull request #1208: HADOOP-16423. S3Guard fsck: Check metadata consistency between S3 and metadatastore (log)
Date Mon, 09 Sep 2019 21:04:02 GMT
bgaborg commented on a change in pull request #1208: HADOOP-16423. S3Guard fsck: Check metadata
consistency between S3 and metadatastore (log)
URL: https://github.com/apache/hadoop/pull/1208#discussion_r322453901
 
 

 ##########
 File path: hadoop-tools/hadoop-aws/src/main/java/org/apache/hadoop/fs/s3a/s3guard/S3GuardFsck.java
 ##########
 @@ -0,0 +1,395 @@
+/*
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hadoop.fs.s3a.s3guard;
+
+import org.apache.hadoop.fs.FileStatus;
+import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.s3a.S3AFileStatus;
+import org.apache.hadoop.fs.s3a.S3AFileSystem;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.security.InvalidParameterException;
+import java.util.ArrayDeque;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Queue;
+import java.util.Set;
+
+import static java.util.stream.Collectors.toList;
+import static java.util.stream.Collectors.toSet;
+
+/**
+ * Main class for the FSCK factored out from S3GuardTool
+ * The implementation uses fixed DynamoDBMetadataStore as the backing store
+ * for metadata.
+ *
+ * Functions:
+ * <ul>
+ *   <li>Checking metadata consistency between S3 and metadatastore</li>
+ * </ul>
+ */
+public class S3GuardFsck {
+  private static final Logger LOG = LoggerFactory.getLogger(S3GuardFsck.class);
+  public static final String ROOT_PATH_STRING = "/";
+
+  private S3AFileSystem rawFS;
+  private DynamoDBMetadataStore metadataStore;
+
+  /**
+   * Creates an S3GuardFsck.
+   * @param fs the filesystem to compare to
+   * @param ms metadatastore the metadatastore to compare with (dynamo)
+   */
+  S3GuardFsck(S3AFileSystem fs, MetadataStore ms)
+      throws InvalidParameterException {
+    this.rawFS = fs;
+
+    if (ms == null) {
+      throw new InvalidParameterException("S3AFileSystem should be guarded by"
+          + " a " + DynamoDBMetadataStore.class.getCanonicalName());
+    }
+    this.metadataStore = (DynamoDBMetadataStore) ms;
+
+    if (rawFS.hasMetadataStore()) {
+      throw new InvalidParameterException("Raw fs should not have a "
+          + "metadatastore.");
+    }
+  }
+
+  /**
+   * Compares S3 to MS.
+   * Iterative breadth first walk on the S3 structure from a given root.
+   * Creates a list of pairs (metadata in S3 and in the MetadataStore) where
+   * the consistency or any rule is violated.
+   * Uses {@link S3GuardFsckViolationHandler} to handle violations.
+   * The violations are listed in Enums: {@link Violation}
+   *
+   * @param p the root path to start the traversal
+   * @throws IOException
+   * @return
+   */
+  public List<ComparePair> compareS3RootToMs(Path p) throws IOException {
+    final Path rootPath = rawFS.qualify(p);
+    final S3AFileStatus root =
+        (S3AFileStatus) rawFS.getFileStatus(rootPath);
+    final List<ComparePair> comparePairs = new ArrayList<>();
+    final Queue<S3AFileStatus> queue = new ArrayDeque<>();
+    queue.add(root);
+
+    while (!queue.isEmpty()) {
+      // pop front node from the queue
+      final S3AFileStatus currentDir = queue.poll();
+
+      // Get a listing of that dir from s3 and add just the files.
+      // (Each directory will be added as a root.)
+      // Files should be casted to S3AFileStatus instead of plain FileStatus
+      // to get the VersionID and Etag.
+      final Path currentDirPath = currentDir.getPath();
+
+      final FileStatus[] s3DirListing = rawFS.listStatus(currentDirPath);
+      final List<S3AFileStatus> children =
+          Arrays.asList(s3DirListing).stream()
+              .filter(status -> !status.isDirectory())
+              .map(S3AFileStatus.class::cast).collect(toList());
+
+      // Compare the directory contents if the listing is authoritative
+      final DirListingMetadata msDirListing =
+          metadataStore.listChildren(currentDirPath);
+      if (msDirListing != null && msDirListing.isAuthoritative()) {
+        final ComparePair cP =
+            compareAuthDirListing(s3DirListing, msDirListing);
+        if (cP.containsViolation()) {
+          comparePairs.add(cP);
+        }
+      }
+
+      // Compare directory and contents, but not the listing
+      final List<ComparePair> compareResult =
+          compareS3DirToMs(currentDir, children).stream()
+              .filter(comparePair -> comparePair.containsViolation())
+              .collect(toList());
+      comparePairs.addAll(compareResult);
+
+      // Add each dir to queue
+      children.stream().filter(pm -> pm.isDirectory())
+          .forEach(pm -> queue.add(pm));
+    }
+
+    // Create a handler and handle each violated pairs
+    S3GuardFsckViolationHandler handler =
+        new S3GuardFsckViolationHandler(rawFS, metadataStore);
+    comparePairs.forEach(handler::handle);
+
+    return comparePairs;
+  }
+
+  private ComparePair compareAuthDirListing(FileStatus[] s3DirListing,
+      DirListingMetadata msDirListing) {
+    ComparePair cP = new ComparePair(s3DirListing, msDirListing);
+
+    if (!msDirListing.isAuthoritative()) {
+      return cP;
+    }
+
+    if (s3DirListing.length != msDirListing.numEntries()) {
+      cP.violations.add(Violation.AUTHORITATIVE_DIRECTORY_CONTENT_MISMATCH);
+    } else {
+      final Set<Path> msPaths = msDirListing.getListing().stream()
+              .map(pm -> pm.getFileStatus().getPath()).collect(toSet());
+      final Set<Path> s3Paths = Arrays.stream(s3DirListing)
+              .map(pm -> pm.getPath()).collect(toSet());
+      if (!s3Paths.equals(msPaths)) {
+        cP.violations.add(Violation.AUTHORITATIVE_DIRECTORY_CONTENT_MISMATCH);
+      }
+    }
+
+    return cP;
+  }
+
+  protected List<ComparePair> compareS3DirToMs(S3AFileStatus s3CurrentDir,
+      List<S3AFileStatus> children) throws IOException {
+    final Path path = s3CurrentDir.getPath();
+    final PathMetadata pathMetadata = metadataStore.get(path);
+    List<ComparePair> violationComparePairs = new ArrayList<>();
+
+    final ComparePair rootComparePair =
+        compareFileStatusToPathMetadata(s3CurrentDir, pathMetadata);
+    if (rootComparePair.containsViolation()) {
+      violationComparePairs.add(rootComparePair);
+    }
+
+    children.forEach(s3ChildMeta -> {
+      try {
+        final PathMetadata msChildMeta =
+            metadataStore.get(s3ChildMeta.getPath());
+        final ComparePair comparePair =
+            compareFileStatusToPathMetadata(s3ChildMeta, msChildMeta);
+        if (comparePair.containsViolation()) {
+          violationComparePairs.add(comparePair);
+        }
+      } catch (Exception e) {
+        e.printStackTrace();
+      }
+    });
+
+    return violationComparePairs;
+  }
+
+  protected ComparePair compareFileStatusToPathMetadata(
+      S3AFileStatus s3FileStatus,
+      PathMetadata msPathMetadata) throws IOException {
+    final Path path = s3FileStatus.getPath();
+    System.out.println("== Path: " + path);
+    ComparePair comparePair = new ComparePair(s3FileStatus, msPathMetadata);
+
+    if (!path.equals(path(ROOT_PATH_STRING))) {
+      final Path parentPath = path.getParent();
+      final PathMetadata parentPm = metadataStore.get(parentPath);
+
+      if (parentPm == null) {
+        comparePair.violations.add(Violation.NO_PARENT_ENTRY);
+      } else {
+        if (!parentPm.getFileStatus().isDirectory()) {
+          comparePair.violations.add(Violation.PARENT_IS_A_FILE);
+        }
+        if (parentPm.isDeleted()) {
+          comparePair.violations.add(Violation.PARENT_TOMBSTONED);
+        }
+      }
+    } else {
+      LOG.info("Entry is in the root, so there's no parent");
+    }
+
+    if (msPathMetadata == null) {
+      comparePair.violations.add(Violation.NO_METADATA_ENTRY);
+      return comparePair;
+    }
+    final S3AFileStatus msFileStatus = msPathMetadata.getFileStatus();
+    if (s3FileStatus.isDirectory() && !msFileStatus.isDirectory()) {
+      comparePair.violations.add(Violation.DIR_IN_S3_FILE_IN_MS);
+    }
+    if (!s3FileStatus.isDirectory() && msFileStatus.isDirectory()) {
+      comparePair.violations.add(Violation.FILE_IN_S3_DIR_IN_MS);
+    }
+
+    /**
+     * Attribute check
+     */
+    if (s3FileStatus.getLen() != msFileStatus.getLen()) {
+      comparePair.violations.add(Violation.LENGTH_MISMATCH);
+    }
+
+    if (s3FileStatus.getModificationTime() !=
+        msFileStatus.getModificationTime()) {
+      comparePair.violations.add(Violation.MOD_TIME_MISMATCH);
+    }
+
+    if(msPathMetadata.getFileStatus().getVersionId() == null) {
+      LOG.debug("Missing versionIDs are skipped right now. A HEAD request is "
+          + "required for each object to get the versionID.");
+    } else if(s3FileStatus.getVersionId() != msFileStatus.getVersionId()) {
+      comparePair.violations.add(Violation.VERSIONID_MISMATCH);
+    }
+
+
+    if (msPathMetadata.getFileStatus().getETag() == null) {
+      comparePair.violations.add(Violation.NO_ETAG);
+    } else if (s3FileStatus.getETag() != null &&
+        !s3FileStatus.getETag().equals(msFileStatus.getETag())) {
+      comparePair.violations.add(Violation.ETAG_MISMATCH);
+    }
+
+    return comparePair;
+  }
+
+  private Path path(String s) {
+    return rawFS.makeQualified(new Path(s));
+  }
+
+  /**
+   * A compare pair with the pair of metadata and the list of violations.
+   */
+  public static class ComparePair {
+    private final S3AFileStatus s3FileStatus;
+    private final PathMetadata msPathMetadata;
+
+    private final List<FileStatus> s3DirListing;
+    private final DirListingMetadata msDirListing;
+
+    private final Path path;
+
+    private Set<Violation> violations = new HashSet<>();
 
 Review comment:
   ![final](https://www.brainyquote.com/photos_tr/en/w/winstonchurchill/124653/winstonchurchill1-2x.jpg)

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