Github user hanm commented on a diff in the pull request:
https://github.com/apache/zookeeper/pull/615#discussion_r215129442
--- Diff: src/java/main/org/apache/zookeeper/server/util/LogChopper.java ---
@@ -0,0 +1,152 @@
+/**
+ * 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.zookeeper.server.util;
+
+import org.apache.jute.BinaryInputArchive;
+import org.apache.jute.BinaryOutputArchive;
+import org.apache.jute.Record;
+import org.apache.zookeeper.server.persistence.FileHeader;
+import org.apache.zookeeper.server.persistence.FileTxnLog;
+import org.apache.zookeeper.txn.TxnHeader;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.EOFException;
+import java.io.FileInputStream;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+import java.util.zip.Adler32;
+import java.util.zip.Checksum;
+
+/**
+ * this class will chop the log at the specified zxid
+ */
+public class LogChopper {
+ public static void main(String args[]) {
+ if (args.length != 3) {
+ System.out.println("Usage: LogChopper zxid_to_chop_to
txn_log_to_chop chopped_filename");
+ System.out.println(" this program will read the
txn_log_to_chop file and copy all the transactions");
+ System.out.println(" from it up to (and including) the
given zxid into chopped_filename.");
+ System.exit(1);
+ }
+ long zxid = Long.decode(args[0]);
+ String txnLog = args[1];
+ String choppedLog = args[2];
+
+ int rc = 2;
+ try (
+ InputStream is = new BufferedInputStream(new
FileInputStream(txnLog));
+ OutputStream os = new BufferedOutputStream(new
FileOutputStream(choppedLog))
+ ) {
+ if (chop(is, os, zxid)) {
+ rc = 0;
+ }
+ } catch (Exception e) {
+ System.out.println("Got exception: " + e.getMessage());
+ }
+ System.exit(rc);
+ }
+
+ public static boolean chop(InputStream is, OutputStream os, long zxid)
throws IOException {
+ BinaryInputArchive logStream = BinaryInputArchive.getArchive(is);
+ BinaryOutputArchive choppedStream =
BinaryOutputArchive.getArchive(os);
+ FileHeader fhdr = new FileHeader();
+ fhdr.deserialize(logStream, "fileheader");
+
+ if (fhdr.getMagic() != FileTxnLog.TXNLOG_MAGIC) {
+ System.err.println("Invalid magic number in txn log file");
+ return false;
+ }
+ System.out.println("ZooKeeper Transactional Log File with dbid "
+ + fhdr.getDbid() + " txnlog format version "
+ + fhdr.getVersion());
+
+ fhdr.serialize(choppedStream, "fileheader");
+ int count = 0;
+ boolean hasZxid = false;
+ long previousZxid = -1;
+ while (true) {
+ long crcValue;
+ byte[] bytes;
+ try {
+ crcValue = logStream.readLong("crcvalue");
+
+ bytes = logStream.readBuffer("txnEntry");
+ } catch (EOFException e) {
+ System.out.println("EOF reached after " + count + "
txns.");
+ // returning false because nothing was chopped
+ return false;
+ }
+ if (bytes.length == 0) {
+ // Since we preallocate, we define EOF to be an
+ // empty transaction
+ System.out.println("EOF reached after " + count + "
txns.");
+ // returning false because nothing was chopped
+ return false;
+ }
+
+ Checksum crc = new Adler32();
+ crc.update(bytes, 0, bytes.length);
+ if (crcValue != crc.getValue()) {
+ throw new IOException("CRC doesn't match " + crcValue +
+ " vs " + crc.getValue());
+ }
+ TxnHeader hdr = new TxnHeader();
+ Record txn = SerializeUtils.deserializeTxn(bytes, hdr);
+ if (logStream.readByte("EOR") != 'B') {
+ System.out.println("Last transaction was partial.");
+ throw new EOFException("Last transaction was partial.");
+ }
+
+ long txnZxid = hdr.getZxid();
+ if (txnZxid == zxid) {
+ hasZxid = true;
+ }
+
+ // logging the gap to make the inconsistency investigation
easier
+ if (previousZxid != -1 && txnZxid != previousZxid + 1) {
+ long txnEpoch = ZxidUtils.getEpochFromZxid(txnZxid);
+ long txnCounter = ZxidUtils.getCounterFromZxid(txnZxid);
+ long previousEpoch =
ZxidUtils.getEpochFromZxid(previousZxid);
+ if (txnEpoch == previousEpoch || txnCounter != 1) {
+ System.out.println(
+ String.format("There is gap between %x and %x",
+ previousZxid, txnZxid));
+ }
+ }
+ previousZxid = txnZxid;
+
+ if (hdr.getZxid() > zxid) {
--- End diff --
`hdr.getZxid()` is previously assigned to `txnZxid`, so maybe use `txnZxid`
here instead?
Also, would it be better to move this check before the gap detection logic
to terminate earlier?
---
