io.logspace.jvm.agent.shaded.quartz.impl.jdbcjobstore.StdRowLockSemaphore Maven / Gradle / Ivy
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/*
* Copyright 2001-2009 Terracotta, Inc.
*
* 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 io.logspace.jvm.agent.shaded.quartz.impl.jdbcjobstore;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* Internal database based lock handler for providing thread/resource locking
* in order to protect resources from being altered by multiple threads at the
* same time.
*
* @author jhouse
*/
public class StdRowLockSemaphore extends DBSemaphore {
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Constants.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
public static final String SELECT_FOR_LOCK = "SELECT * FROM "
+ TABLE_PREFIX_SUBST + TABLE_LOCKS + " WHERE " + COL_SCHEDULER_NAME + " = " + SCHED_NAME_SUBST
+ " AND " + COL_LOCK_NAME + " = ? FOR UPDATE";
public static final String INSERT_LOCK = "INSERT INTO "
+ TABLE_PREFIX_SUBST + TABLE_LOCKS + "(" + COL_SCHEDULER_NAME + ", " + COL_LOCK_NAME + ") VALUES ("
+ SCHED_NAME_SUBST + ", ?)";
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Constructors.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
public StdRowLockSemaphore() {
super(DEFAULT_TABLE_PREFIX, null, SELECT_FOR_LOCK, INSERT_LOCK);
}
public StdRowLockSemaphore(String tablePrefix, String schedName, String selectWithLockSQL) {
super(tablePrefix, schedName, selectWithLockSQL != null ? selectWithLockSQL : SELECT_FOR_LOCK, INSERT_LOCK);
}
/*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*
* Interface.
*
* ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
*/
/**
* Execute the SQL select for update that will lock the proper database row.
*/
@Override
protected void executeSQL(Connection conn, final String lockName, final String expandedSQL, final String expandedInsertSQL) throws LockException {
PreparedStatement ps = null;
ResultSet rs = null;
SQLException initCause = null;
// attempt lock two times (to work-around possible race conditions in inserting the lock row the first time running)
int count = 0;
do {
count++;
try {
ps = conn.prepareStatement(expandedSQL);
ps.setString(1, lockName);
if (getLog().isDebugEnabled()) {
getLog().debug(
"Lock '" + lockName + "' is being obtained: " +
Thread.currentThread().getName());
}
rs = ps.executeQuery();
if (!rs.next()) {
getLog().debug(
"Inserting new lock row for lock: '" + lockName + "' being obtained by thread: " +
Thread.currentThread().getName());
rs.close();
rs = null;
ps.close();
ps = null;
ps = conn.prepareStatement(expandedInsertSQL);
ps.setString(1, lockName);
int res = ps.executeUpdate();
if(res != 1) {
if(count < 3) {
// pause a bit to give another thread some time to commit the insert of the new lock row
try {
Thread.sleep(1000L);
} catch (InterruptedException ignore) {
Thread.currentThread().interrupt();
}
// try again ...
continue;
}
throw new SQLException(Util.rtp(
"No row exists, and one could not be inserted in table " + TABLE_PREFIX_SUBST + TABLE_LOCKS +
" for lock named: " + lockName, getTablePrefix(), getSchedulerNameLiteral()));
}
}
return; // obtained lock, go
} catch (SQLException sqle) {
//Exception src =
// (Exception)getThreadLocksObtainer().get(lockName);
//if(src != null)
// src.printStackTrace();
//else
// System.err.println("--- ***************** NO OBTAINER!");
if(initCause == null)
initCause = sqle;
if (getLog().isDebugEnabled()) {
getLog().debug(
"Lock '" + lockName + "' was not obtained by: " +
Thread.currentThread().getName() + (count < 3 ? " - will try again." : ""));
}
if(count < 3) {
// pause a bit to give another thread some time to commit the insert of the new lock row
try {
Thread.sleep(1000L);
} catch (InterruptedException ignore) {
Thread.currentThread().interrupt();
}
// try again ...
continue;
}
throw new LockException("Failure obtaining db row lock: "
+ sqle.getMessage(), sqle);
} finally {
if (rs != null) {
try {
rs.close();
} catch (Exception ignore) {
}
}
if (ps != null) {
try {
ps.close();
} catch (Exception ignore) {
}
}
}
} while(count < 4);
throw new LockException("Failure obtaining db row lock, reached maximum number of attempts. Initial exception (if any) attached as root cause.", initCause);
}
protected String getSelectWithLockSQL() {
return getSQL();
}
public void setSelectWithLockSQL(String selectWithLockSQL) {
setSQL(selectWithLockSQL);
}
}