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/*
* Derby - Class org.apache.derbyTesting.functionTests.tests.engine.ModuleLoadingTest
*
* 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.derbyTesting.functionTests.tests.engine;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.ArrayList;
import junit.framework.Test;
import org.apache.derbyTesting.junit.BaseJDBCTestCase;
import org.apache.derbyTesting.junit.BaseTestSuite;
import org.apache.derbyTesting.junit.JDBC;
import org.apache.derbyTesting.junit.TestConfiguration;
/**
* This class contains tests for correct loading (booting) of modules
* and factories.
*/
public class ModuleLoadingTest extends BaseJDBCTestCase {
public ModuleLoadingTest(String name) {
super(name);
}
public static Test suite() {
BaseTestSuite ts = new BaseTestSuite();
// Run concurrentLoadingOfSortFactory in a separate database so that
// the sort factory isn't already loaded.
ts.addTest(TestConfiguration.singleUseDatabaseDecorator(
new ModuleLoadingTest("concurrentLoadingOfSortFactory")));
return ts;
}
/**
* Test case for DERBY-2074. When multiple threads tried to load
* ExternalSortFactory concurrently, we sometimes got a
* NullPointerException.
*/
public void concurrentLoadingOfSortFactory() throws Throwable {
// number of concurrent threads
final int numThreads = 10;
// Helper object to make it easier to refer to ModuleLoadingTest.this
// from within the nested Runnable class. Used for synchronization
// between the threads.
final Object me = this;
// Flag that tells the threads whether they're allowed to start.
final boolean[] go = new boolean[1];
// Active threads count.
final int[] activeThreads = new int[1];
// List of exceptions/throwables thrown by the forked threads.
final ArrayList<Throwable> exceptions = new ArrayList<Throwable>();
Thread[] threads = new Thread[numThreads];
// Start the threads.
for (int i = 0; i < numThreads; i++) {
final Connection c = openDefaultConnection();
// Prepare a statement that ends up calling
// DistinctScalarAggregateResultSet.loadSorter().
final PreparedStatement ps = c.prepareStatement(
"select count(distinct tablename) from sys.systables");
threads[i] = new Thread(new Runnable() {
public void run() {
try {
_run();
} catch (Throwable t) {
synchronized (me) {
exceptions.add(t);
}
}
}
private void _run() throws Exception {
synchronized (me) {
// Notify the main thread that we're ready to execute.
activeThreads[0]++;
me.notifyAll();
// Wait for the main thread to notify us that we
// should go ahead.
while (!go[0]) {
me.wait();
}
}
// executeQuery() below used to get occational NPEs before
// DERBY-2074.
JDBC.assertDrainResults(ps.executeQuery());
ps.close();
c.close();
}
});
threads[i].start();
}
// We want all threads to execute the statement at the same time,
// so wait for all threads to be ready before giving them the GO
// signal.
synchronized (me) {
while (activeThreads[0] < numThreads && exceptions.isEmpty()) {
me.wait();
}
// All threads are active, or at least one of the threads have
// failed, so tell the threads to stop waiting.
go[0] = true;
me.notifyAll();
}
// The threads have been started, now wait for them to finish.
for (int i = 0; i < numThreads; i++) {
threads[i].join();
}
// At least one of the threads failed. Re-throw the first error
// reported.
if (!exceptions.isEmpty()) {
throw exceptions.get(0);
}
}
}
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