[GitHub] [bookkeeper] Vanlightly commented on a change in pull request #2774: ISSUE-2773: Add db ledgers index rebuild op

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

Vanlightly commented on a change in pull request #2774:
URL: https://github.com/apache/bookkeeper/pull/2774#discussion_r695603700



##########
File path: bookkeeper-server/src/main/java/org/apache/bookkeeper/bookie/storage/ldb/LedgersIndexRebuildOp.java
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@@ -0,0 +1,214 @@
+/**
+ *
+ * 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.bookkeeper.bookie.storage.ldb;
+
+import com.google.common.collect.Lists;
+import com.google.protobuf.ByteString;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import java.io.File;
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.file.FileSystems;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.text.SimpleDateFormat;
+import java.util.Date;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import org.apache.bookkeeper.bookie.BookieImpl;
+import org.apache.bookkeeper.bookie.EntryLogger;
+import org.apache.bookkeeper.bookie.EntryLogger.EntryLogScanner;
+import org.apache.bookkeeper.bookie.Journal;
+import org.apache.bookkeeper.bookie.LedgerDirsManager;
+import org.apache.bookkeeper.bookie.storage.ldb.KeyValueStorageFactory.DbConfigType;
+import org.apache.bookkeeper.conf.ServerConfiguration;
+import org.apache.bookkeeper.util.BookKeeperConstants;
+import org.apache.bookkeeper.util.DiskChecker;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Scan all entries in the journal and entry log files then rebuilds the ledgers index.
+ * Notable stuff:
+ * - Fences every ledger as even if we check the metadata, we cannot guarantee that
+ *   a fence request was served while the rebuild was taking place (even if the bookie
+ *   is running in read-only mode).
+ *   Losing the fenced status of a ledger is UNSAFE.
+ * - Sets the master key as an empty byte array. This is correct as empty master keys
+ *   are overwritten and we cannot use the password from metadata, and cannot know 100%
+ *   for sure how a digest for the password was generated.
+ */
+public class LedgersIndexRebuildOp {
+    private static final Logger LOG = LoggerFactory.getLogger(LedgersIndexRebuildOp.class);
+
+    private final ServerConfiguration conf;
+    private final boolean verbose;
+    private static final String LedgersSubPath = "ledgers";
+
+    public LedgersIndexRebuildOp(ServerConfiguration conf, boolean verbose) {
+        this.conf = conf;
+        this.verbose = verbose;
+    }
+
+    public boolean initiate()  {
+        LOG.info("Starting ledger index rebuilding");
+
+        // Move locations index to a backup directory
+        String basePath = BookieImpl.getCurrentDirectory(conf.getLedgerDirs()[0]).toString();
+        Path currentPath = FileSystems.getDefault().getPath(basePath, LedgersSubPath);
+        String timestamp = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss.SSSZ").format(new Date());
+        Path backupPath = FileSystems.getDefault().getPath(basePath, LedgersSubPath + ".BACKUP-" + timestamp);
+        Path abortPath = FileSystems.getDefault().getPath(basePath, LedgersSubPath + ".ABORT-" + timestamp);
+        try {
+            Files.move(currentPath, backupPath);
+        } catch (IOException e) {
+            LOG.error("Could not move index to a backup location", e);
+            return false;
+        }
+
+        LOG.info("Created ledgers index backup at {}", backupPath);
+        LOG.info("Starting scan phase (scans journal and entry log files)");
+
+        try {
+            Set<Long> ledgers = new HashSet<>();
+            scanJournals(ledgers);
+            scanEntryLogFiles(ledgers);
+
+            LOG.info("Scan complete, found {} ledgers. "
+                    + "Starting to build a new ledgers index", ledgers.size());
+
+            KeyValueStorage newIndex = KeyValueStorageRocksDB.factory.newKeyValueStorage(
+                    basePath, LedgersSubPath, DbConfigType.Small, conf);
+
+            for (Long ledgerId : ledgers) {
+                DbLedgerStorageDataFormats.LedgerData ledgerData =
+                        DbLedgerStorageDataFormats.LedgerData.newBuilder()
+                                .setExists(true)
+                                .setFenced(true)
+                                .setMasterKey(ByteString.EMPTY).build();
+
+                byte[] ledgerArray = new byte[16];
+                ArrayUtil.setLong(ledgerArray, 0, ledgerId);
+                newIndex.put(ledgerArray, ledgerData.toByteArray());
+            }
+
+            newIndex.sync();
+            newIndex.close();
+        } catch (Throwable t) {
+            LOG.error("Error during rebuild", t);
+            restoreBackup(currentPath, backupPath, abortPath);

Review comment:
       Good point, I was copying from the LocationsIndexRebuildOp which does it that way. I have updated this rebuild to swap them at the end once a new index has been generated.




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