MATH-797

Added unit test.


git-svn-id: https://svn.apache.org/repos/asf/commons/proper/math/trunk@1364075 13f79535-47bb-0310-9956-ffa450edef68

src/test/java/org/apache/commons/math3/analysis/integration/gauss/BaseRuleFactoryTest.java

@@ -0,0 +1,100 @@
+/*
+ * 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.commons.math3.analysis.integration.gauss;
+
+import java.util.List;
+import java.util.ArrayList;
+import java.util.concurrent.ThreadPoolExecutor;
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.Callable;
+import java.util.concurrent.Future;
+import java.util.concurrent.atomic.AtomicInteger;
+import org.apache.commons.math3.util.Pair;
+import org.junit.Test;
+import org.junit.Assert;
+
+/**
+ * Test for {@link BaseRuleFactory}.
+ *
+ * @version $Id$
+ */
+public class BaseRuleFactoryTest {
+    /**
+     * Tests that a given rule rule will be computed and added once to the cache
+     * whatever the number of times this rule is called concurrently.
+     */
+    @Test
+    public void testConcurrentCreation() throws InterruptedException {
+        // Number of times the same rule will be called.
+        final int numTasks = 20;
+
+        final ThreadPoolExecutor exec
+            = new ThreadPoolExecutor(3, numTasks, 1, TimeUnit.SECONDS,
+                                     new ArrayBlockingQueue<Runnable>(2));
+
+        final List<RuleBuilder> tasks = new ArrayList<RuleBuilder>();
+        for (int i = 0; i < numTasks; i++) {
+            tasks.add(new RuleBuilder());
+        }
+
+        List<Future<Pair<double[], double[]>>> results = exec.invokeAll(tasks);
+
+        // Assertion would fail if "getRuleInternal" were not "synchronized".
+        final int n = RuleBuilder.getNumberOfCalls();
+        Assert.assertEquals("Rule computation was called " + n + " times", 1, n);
+    }
+}
+
+class RuleBuilder implements Callable<Pair<double[], double[]>> {
+    private static final DummyRuleFactory factory = new DummyRuleFactory();
+
+    public Pair<double[], double[]> call() {
+        final int dummy = 2; // Always request the same rule.
+        return factory.getRule(dummy);
+    }
+
+    public static int getNumberOfCalls() {
+        return factory.getNumberOfCalls();
+    }
+}
+
+class DummyRuleFactory extends BaseRuleFactory<Double> {
+    /** Rule computations counter. */
+    private static AtomicInteger nCalls = new AtomicInteger();
+
+    @Override
+    protected Pair<Double[], Double[]> computeRule(int order) {
+        // Tracks whether this computation has been called more than once.
+        nCalls.getAndIncrement();
+
+        try {
+            // Sleep to simulate computation time.
+            Thread.sleep(20);
+        } catch (InterruptedException e) {
+            Assert.fail("Unexpected interruption");
+        }
+
+         // Dummy rule (but contents must exist).
+        return new Pair<Double[], Double[]>(new Double[order],
+                                            new Double[order]);
+    }
+
+    public int getNumberOfCalls() {
+        return nCalls.get();
+    }
+}