Return-Path: Delivered-To: apmail-db-derby-dev-archive@www.apache.org Received: (qmail 73686 invoked from network); 17 May 2005 19:16:49 -0000 Received: from hermes.apache.org (HELO mail.apache.org) (209.237.227.199) by minotaur.apache.org with SMTP; 17 May 2005 19:16:49 -0000 Received: (qmail 58237 invoked by uid 500); 17 May 2005 18:47:51 -0000 Delivered-To: apmail-db-derby-dev-archive@db.apache.org Received: (qmail 58149 invoked by uid 500); 17 May 2005 18:47:48 -0000 Mailing-List: contact derby-dev-help@db.apache.org; run by ezmlm Precedence: bulk list-help: list-unsubscribe: List-Post: List-Id: Reply-To: "Derby Development" Delivered-To: mailing list derby-dev@db.apache.org Received: (qmail 58130 invoked by uid 99); 17 May 2005 18:47:48 -0000 X-ASF-Spam-Status: No, hits=2.2 required=10.0 tests=DNS_FROM_RFC_ABUSE,DNS_FROM_RFC_POST,SPF_HELO_FAIL X-Spam-Check-By: apache.org Received-SPF: neutral (hermes.apache.org: local policy) Received: from e32.co.us.ibm.com (HELO e32.co.us.ibm.com) (32.97.110.130) by apache.org (qpsmtpd/0.28) with ESMTP; Tue, 17 May 2005 11:47:47 -0700 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e32.co.us.ibm.com (8.12.10/8.12.9) with ESMTP id j4HIlO0c317080 for ; Tue, 17 May 2005 14:47:24 -0400 Received: from [9.72.134.65] (dyn9072134065.usca.ibm.com [9.72.134.65]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VER6.6) with ESMTP id j4HIlNnP163774 for ; Tue, 17 May 2005 12:47:23 -0600 Message-ID: <428A3C42.6020601@sbcglobal.net> Date: Tue, 17 May 2005 11:47:30 -0700 From: Mike Matrigali User-Agent: Mozilla Thunderbird 0.7.2 (Windows/20040707) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Derby Development Subject: Re: [PATCH] increasinng the possible log file id's from 2^22 -1 to 2^33 -1 (derby-101) References: <428956A5.8050806@gmail.com> In-Reply-To: <428956A5.8050806@gmail.com> X-Enigmail-Version: 0.85.0.0 X-Enigmail-Supports: pgp-inline, pgp-mime Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Virus-Checked: Checked X-Spam-Rating: minotaur.apache.org 1.6.2 0/1000/N I am looking at committing this. The changes look good to me, but I believe there are upgrade issues to handle. For a hard upgrade either new or old databases are fine. For a soft upgrade I think there is a problem if the db generates enough log files to start using the new bits, and then the software is reverted to before the fix. Seems like using the bits needs to be somehow only enabled for hard upgrade. It would be best if it was controlled just by hard upgrade, but if that is not possible then just doing it for databases created since this version would also work - but still leave problems with old hard upgraded databases. I have reviewed the code and am running tests. I plan on committing this part of the fix and let you address upgrade issues with a follow on patch. Suresh Thalamati wrote: > Attached is the patch to increase the max possible log files number from > 2^22 -1 to > 2^33 -1. Derby creates log file names in sequential order by > incrementing log file number > by one each time(like log1.dat ....logN.dat). id's are not reused, so > the last possible log file that > can be created currently is limited to 2^22 - 1 (4194303). Problem with > this limit is , > it can be possible hit on systems that creates lot of log records very > fast with the default > log file size (1MB) , for example if 1MB of log is created every > second this limit can be hit > in (4194303 / (60 * 60 * 24)) 48 days. > > Attached fix bumps the max possible log file number to 2^33 -1 by > borrowing some unused bits in the > log file number and log file size fields in the log instant. With the > same assumption as above if a > a 1MB of log file is created for every second; it will take > ((8589934591 / (60 * 60 * 24))/365) > approximately 272 years; Which I think is a reasonable limit. :-) > > I believe the new limit is a reasonable one , and not necessary to solve > this problem by > implementing a complicated solution that reuse the ids, at this moment. > > Testing : ran derbyall ; all tests passed. > New tests : Added couple of tests to test the max log file ids using > debug flags. > > svn status > M java\engine\org\apache\derby\impl\store\raw\log\LogCounter.java > M java\engine\org\apache\derby\impl\store\raw\log\LogToFile.java > M > java\testing\org\apache\derbyTesting\functionTests\tests\store\copyfiles.ant > > A > java\testing\org\apache\derbyTesting\functionTests\tests\store\MaxLogNumberRecovery_derby.properties > > A > java\testing\org\apache\derbyTesting\functionTests\tests\store\MaxLogNumber_app.properties > > A > java\testing\org\apache\derbyTesting\functionTests\tests\store\MaxLogNumberRecovery_app.properties > > A > java\testing\org\apache\derbyTesting\functionTests\tests\store\MaxLogNumber_derby.properties > > A > java\testing\org\apache\derbyTesting\functionTests\tests\store\MaxLogNumber.java > > A > java\testing\org\apache\derbyTesting\functionTests\tests\store\MaxLogNumberRecovery.java > > A > java\testing\org\apache\derbyTesting\functionTests\master\MaxLogNumber.out > A > java\testing\org\apache\derbyTesting\functionTests\master\MaxLogNumberRecovery.out > > M > java\testing\org\apache\derbyTesting\functionTests\suites\storerecovery.runall > > $ > Thanks > -suresht > > > ------------------------------------------------------------------------ > > Index: java/engine/org/apache/derby/impl/store/raw/log/LogCounter.java > =================================================================== > --- java/engine/org/apache/derby/impl/store/raw/log/LogCounter.java (revision 170490) > +++ java/engine/org/apache/derby/impl/store/raw/log/LogCounter.java (working copy) > @@ -62,13 +62,15 @@ > public static final long INVALID_LOG_INSTANT = 0; > > > - // reserve top 10 bits in log file number for future use > - public static final long MAX_LOGFILE_NUMBER = (long)0x003FFFFFL; // 4194303 > - private static final long FILE_NUMBER_SHIFT = 32; > + // max possible log file number is 2^33 -1 (8589934591) > + public static final long MAX_LOGFILE_NUMBER = (long)0x1FFFFFFFFL ; > + // lower end of 30 bits in a long type are used to store the log file postion. > + private static final long FILE_NUMBER_SHIFT = 30; > > - // reserve top 4 bits in log file size for future use > + // reserve top 2 bits in log file size for future use > public static final long MAX_LOGFILE_SIZE = (long)0x0FFFFFFFL; // 268435455 > - private static final long FILE_POSITION_MASK = (long)0x7FFFFFFFL; > + // 30 bits are used to store the log file postion > + private static final long FILE_POSITION_MASK = (long)0x3FFFFFFFL; > > private long fileNumber; > private long filePosition; > Index: java/engine/org/apache/derby/impl/store/raw/log/LogToFile.java > =================================================================== > --- java/engine/org/apache/derby/impl/store/raw/log/LogToFile.java (revision 170490) > +++ java/engine/org/apache/derby/impl/store/raw/log/LogToFile.java (working copy) > @@ -649,7 +649,7 @@ > if (beginLogFileNumber != null) > { > logFileNumber = > - Integer.valueOf(beginLogFileNumber).intValue(); > + Long.valueOf(beginLogFileNumber).longValue(); > } > else > { > @@ -2975,6 +2975,17 @@ > { > firstLogFileNumber = 1; > logFileNumber = 1; > + if (SanityManager.DEBUG) > + { > + if (SanityManager.DEBUG_ON(TEST_MAX_LOGFILE_NUMBER)) > + { > + // set the value to be two less than max possible > + // log number, test case will perform some ops to > + // hit the max number case. > + firstLogFileNumber = LogCounter.MAX_LOGFILE_NUMBER -2; > + logFileNumber = LogCounter.MAX_LOGFILE_NUMBER -2; > + } > + } > logFile = getLogFileName(logFileNumber); > > if (privExists(logFile)) > @@ -4293,7 +4304,12 @@ > */ > public static final String TEST_RECORD_TO_FILL_LOG = SanityManager.DEBUG ? "db2j.unittest.recordToFillLog" : null; > > + /** > + * Set to true if we want to simulate max possible log file number is being used. > + */ > + public static final String TEST_MAX_LOGFILE_NUMBER = SanityManager.DEBUG ? "testMaxLogFileNumber" : null; > > + > //enable the log archive mode > public void enableLogArchiveMode() throws StandardException > { > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/copyfiles.ant > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/copyfiles.ant (revision 170490) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/copyfiles.ant (working copy) > @@ -131,3 +131,8 @@ > LogChecksumRecovery_derby.properties > LogChecksumRecovery1_app.properties > LogChecksumRecovery1_derby.properties > +MaxLogNumber_app.properties > +MaxLogNumber_derby.properties > +MaxLogNumberRecovery_app.properties > +MaxLogNumberRecovery_derby.properties > + > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_derby.properties > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_derby.properties (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_derby.properties (revision 0) > @@ -0,0 +1 @@ > +derby.debug.true=testMaxLogFileNumber > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_derby.properties > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_app.properties > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_app.properties (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_app.properties (revision 0) > @@ -0,0 +1,13 @@ > +# > +# *** DO NOT PUT PROPERTIES FOR THE DERBY SYSTEM IN THIS FILE. THEY BELONG > +# *** IN the _derby.properties file. > +# > +# It will get handed to the test on the command line in a -p > +# argument. > +# > +# This causes ij (or the GUI on ij) to load the driver and make an > +# initial connection to the database. > +# > +# > +database=jdbc:derby:maxlogwombat;create=true > + > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_app.properties > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_app.properties > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_app.properties (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_app.properties (revision 0) > @@ -0,0 +1,12 @@ > +# > +# *** DO NOT PUT PROPERTIES FOR THE DERBY SYSTEM IN THIS FILE. THEY BELONG > +# *** IN the _derby.properties file. > +# > +# It will get handed to the test on the command line in a -p > +# argument. > +# > +# This causes ij (or the GUI on ij) to load the driver and make an > +# initial connection to the database. > +# > +# > +database=jdbc:derby:maxlogwombat > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery_app.properties > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_derby.properties > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_derby.properties (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_derby.properties (revision 0) > @@ -0,0 +1 @@ > +derby.debug.true=testMaxLogFileNumber > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber_derby.properties > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber.java > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber.java (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber.java (revision 0) > @@ -0,0 +1,216 @@ > +/* > + > + Derby - Class org.apache.derbyTesting.functionTests.store.MaxLogNumber > + > + Copyright 2005 The Apache Software Foundation or its licensors, as applicable. > + > + Licensed 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.derbyTesting.functionTests.tests.store; > +import java.sql.Connection; > +import java.sql.Statement; > +import java.sql.PreparedStatement; > +import java.sql.ResultSet; > +import java.sql.SQLException; > +import org.apache.derby.tools.ij; > + > +/* > + * This class tests log writes to the transaction log files with large log file > + * id's and do a setup to test recovery with large log file id's in > + * MaxLogNumberRecovery.java test. large log file id's are simulated using > + * a debug flag 'testMaxLogFileNumber' in the log factory, this is enabled > + * by setting derby.debug.true=testMaxLogFileNumber in the properties file. > + * In Non debug mode, this tests just acts as a plain log recovery test. > + * > + * @author Suresh Thalamati > + * @version 1.0 > + */ > + > +public class MaxLogNumber{ > + > + MaxLogNumber() { > + } > + > + > + private void runTest(Connection conn) throws SQLException { > + logMessage("Begin MaxLogNumber Test"); > + // perform a checkpoint otherwise recovery test will look at log1 > + // instead of the log number that gets by the testMaxLogFileNumber > + // debug flags. > + performCheckPoint(conn); > + createTable(conn); > + insert(conn, 100, COMMIT, 10); > + insert(conn, 100, ROLLBACK, 10); > + update(conn, 50, COMMIT, 10); > + update(conn, 50, ROLLBACK, 10); > + verifyData(conn, 100); > + //do some inserts that will be rolled back by recovey > + insert(conn, 2000, NOACTION, 2000); > + logMessage("End MaxLogNumber Test"); > + } > + > + void performCheckPoint(Connection conn) throws SQLException > + { > + Statement stmt = conn.createStatement(); > + //wait to make sure that checkpoint thread finished it's work > + stmt.executeUpdate("CALL SYSCS_UTIL.SYSCS_CHECKPOINT_DATABASE()"); > + stmt.close(); > + } > + > + > + /** > + * Insert some rows into the table. > + */ > + void insert(Connection conn, int rowCount, > + int txStatus, int commitCount) throws SQLException { > + > + PreparedStatement ps = conn.prepareStatement("INSERT INTO " + > + "emp" + > + " VALUES(?,?,?)"); > + for (int i = 0; i < rowCount; i++) { > + > + ps.setInt(1, i); // ID > + ps.setString(2 , "skywalker" + i); > + ps.setFloat(3, (float)(i * 2000)); > + ps.executeUpdate(); > + if ((i % commitCount) == 0) > + { > + endTransaction(conn, txStatus); > + } > + } > + > + endTransaction(conn, txStatus); > + ps.close(); > + } > + > + > + static final int COMMIT = 1; > + static final int ROLLBACK = 2; > + static final int NOACTION = 3; > + > + void endTransaction(Connection conn, int txStatus) throws SQLException > + { > + switch(txStatus){ > + case COMMIT: > + conn.commit(); > + break; > + case ROLLBACK: > + conn.rollback(); > + break; > + case NOACTION: > + //do nothing > + break; > + } > + } > + > + /** > + * update some rows in the table. > + */ > + > + void update(Connection conn, int rowCount, > + int txStatus, int commitCount) throws SQLException > + { > + > + PreparedStatement ps = conn.prepareStatement("update " + "emp" + > + " SET salary=? where id=?"); > + > + for (int i = 0; i < rowCount; i++) { > + > + ps.setFloat(1, (float)(i * 2000 * 0.08)); > + ps.setInt(2, i); // ID > + ps.executeUpdate(); > + if ((i % commitCount) == 0) > + { > + endTransaction(conn, txStatus); > + } > + } > + endTransaction(conn, txStatus); > + ps.close(); > + } > + > + > + /* > + * verify the rows in the table. > + */ > + void verifyData(Connection conn, int expectedRowCount) throws SQLException { > + > + Statement s = conn.createStatement(); > + ResultSet rs = s.executeQuery("SELECT ID, name from emp order by id" ); > + int count = 0; > + int id = 0; > + while(rs.next()) > + { > + int tid = rs.getInt(1); > + String name = rs.getString(2); > + if(name.equals("skywalker" + id) && tid!= id) > + { > + > + logMessage("DATA IN THE TABLE IS NOT AS EXPECTED"); > + logMessage("Got :ID=" + tid + " Name=:" + name); > + logMessage("Expected: ID=" + id + "Name=" + "skywalker" + id ); > + } > + > + id++; > + count++; > + } > + > + if(count != expectedRowCount) > + { > + logMessage("Expected Number Of Rows (" + > + expectedRowCount + ")" + "!=" + > + "No Of rows in the Table(" + > + count + ")"); > + } > + s.close(); > + } > + > + /* > + * create the tables that are used by this test. > + */ > + void createTable(Connection conn) throws SQLException { > + > + Statement s = conn.createStatement(); > + s.executeUpdate("CREATE TABLE " + "emp" + > + "(id INT," + > + "name CHAR(200),"+ > + "salary float)"); > + s.executeUpdate("create index emp_idx on emp(id) "); > + conn.commit(); > + s.close(); > + } > + > + void logMessage(String str) > + { > + System.out.println(str); > + } > + > + > + public static void main(String[] argv) throws Throwable { > + > + MaxLogNumber test = new MaxLogNumber(); > + ij.getPropertyArg(argv); > + Connection conn = ij.startJBMS(); > + conn.setAutoCommit(false); > + > + try { > + test.runTest(conn); > + } > + catch (SQLException sqle) { > + org.apache.derby.tools.JDBCDisplayUtil.ShowSQLException( > + System.out, sqle); > + sqle.printStackTrace(System.out); > + } > + } > +} > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumber.java > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery.java > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery.java (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery.java (revision 0) > @@ -0,0 +1,104 @@ > +/* > + > + Derby - Class org.apache.derbyTesting.functionTests.store.MaxLogNumber > + > + Copyright 2005 The Apache Software Foundation or its licensors, as applicable. > + > + Licensed 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.derbyTesting.functionTests.tests.store; > +import java.sql.Connection; > +import java.sql.SQLException; > +import org.apache.derby.tools.ij; > +import org.apache.derby.iapi.services.sanity.SanityManager; > + > +/* > + * This class tests recovery logic with large log file id's and the error > + * handling logic when Max possible log file limit is reached. MaxLogNumber.java > + * test does the setup, so it should be run before this test. > + * In Non debug mode, this tests just acts as a plain log recovery test. > + * > + * @author Suresh Thalamati > + * @version 1.0 > + * @see MaxLogNumber > + */ > + > +public class MaxLogNumberRecovery extends MaxLogNumber { > + > + MaxLogNumberRecovery() { > + super(); > + } > + > + private void runTest(Connection conn) throws SQLException { > + logMessage("Begin MaxLogNumberRecovery Test"); > + verifyData(conn, 100); > + boolean hitMaxLogLimitError = false; > + try{ > + insert(conn, 110, COMMIT, 11); > + update(conn, 110, ROLLBACK, 5); > + update(conn, 110, NOACTION, 5); > + verifyData(conn, 210); > + if (SanityManager.DEBUG) > + { > + // do lot of inserts in debug mode , > + // so that actuall reach the max log file number > + // limit > + insert(conn, 11000, COMMIT, 5); > + } > + } catch(SQLException se) { > + > + SQLException ose = se; > + while (se != null) { > + if ("XSLAK".equals(se.getSQLState())) { > + hitMaxLogLimitError = true; > + break; > + } > + se = se.getNextException(); > + } > + if(!hitMaxLogLimitError) > + throw ose; > + } > + > + if (SanityManager.DEBUG) > + { > + // In the debug build mode , this test should hit the max log limit while > + // doing above DML. > + if(!hitMaxLogLimitError) > + logMessage("Expected: ERROR XSLAK:" + > + "Database has exceeded largest log file" + > + "number 8,589,934,591."); > + } > + > + logMessage("End MaxLogNumberRecovery Test"); > + } > + > + > + public static void main(String[] argv) throws Throwable { > + > + MaxLogNumberRecovery test = new MaxLogNumberRecovery(); > + ij.getPropertyArg(argv); > + Connection conn = ij.startJBMS(); > + conn.setAutoCommit(false); > + > + try { > + test.runTest(conn); > + } > + catch (SQLException sqle) { > + org.apache.derby.tools.JDBCDisplayUtil.ShowSQLException( > + System.out, sqle); > + sqle.printStackTrace(System.out); > + } > + } > +} > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/tests/store/MaxLogNumberRecovery.java > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumber.out > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumber.out (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumber.out (revision 0) > @@ -0,0 +1,2 @@ > +Begin MaxLogNumber Test > +End MaxLogNumber Test > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumber.out > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumberRecovery.out > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumberRecovery.out (revision 0) > +++ java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumberRecovery.out (revision 0) > @@ -0,0 +1,2 @@ > +Begin MaxLogNumberRecovery Test > +End MaxLogNumberRecovery Test > > Property changes on: java/testing/org/apache/derbyTesting/functionTests/master/MaxLogNumberRecovery.out > ___________________________________________________________________ > Name: svn:eol-style > + native > > Index: java/testing/org/apache/derbyTesting/functionTests/suites/storerecovery.runall > =================================================================== > --- java/testing/org/apache/derbyTesting/functionTests/suites/storerecovery.runall (revision 170490) > +++ java/testing/org/apache/derbyTesting/functionTests/suites/storerecovery.runall (working copy) > @@ -1,3 +1,5 @@ > store/LogChecksumSetup.java > store/LogChecksumRecovery.java > store/LogChecksumRecovery1.java > +store/MaxLogNumber.java > +store/MaxLogNumberRecovery.java