Add unit test to verify concurrency issue #1461

References pr #75

pmd-core/src/test/java/net/sourceforge/pmd/processor/MultiThreadProcessorTest.java

@@ -0,0 +1,109 @@
+/**
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+package net.sourceforge.pmd.processor;
+
+import java.io.ByteArrayInputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import net.sourceforge.pmd.PMDConfiguration;
+import net.sourceforge.pmd.ReportListener;
+import net.sourceforge.pmd.RuleContext;
+import net.sourceforge.pmd.RuleSetFactory;
+import net.sourceforge.pmd.RuleViolation;
+import net.sourceforge.pmd.lang.ast.Node;
+import net.sourceforge.pmd.lang.rule.AbstractRule;
+import net.sourceforge.pmd.renderers.Renderer;
+import net.sourceforge.pmd.stat.Metric;
+import net.sourceforge.pmd.util.datasource.DataSource;
+
+public class MultiThreadProcessorTest {
+
+    @Test
+    public void testRulesThreadSafety() {
+        PMDConfiguration configuration = new PMDConfiguration();
+        configuration.setRuleSets("rulesets/MultiThreadProcessorTest/basic.xml");
+        configuration.setThreads(2);
+        List<DataSource> files = new ArrayList<>();
+        files.add(new StringDataSource("file1-violation.dummy", "ABC"));
+        files.add(new StringDataSource("file2-foo.dummy", "DEF"));
+
+        SimpleReportListener reportListener = new SimpleReportListener();
+        RuleContext ctx = new RuleContext();
+        ctx.getReport().addListener(reportListener);
+
+        MultiThreadProcessor processor = new MultiThreadProcessor(configuration);
+        RuleSetFactory ruleSetFactory = new RuleSetFactory();
+        processor.processFiles(ruleSetFactory, files, ctx, Collections.<Renderer>emptyList());
+
+        // if the rule is not executed, then maybe a ConcurrentModificationException happened
+        Assert.assertEquals("Test rule has not been executed", 2, NotThreadSafeRule.count.get());
+        // if the violation is not reported, then the rule instances have been shared between the threads
+        Assert.assertEquals("Missing violation", 1, reportListener.violations.get());
+    }
+
+    private static class StringDataSource implements DataSource {
+        private final String data;
+        private final String name;
+        public StringDataSource(String name, String data) {
+            this.name = name;
+            this.data = data;
+        }
+        @Override
+        public InputStream getInputStream() throws IOException {
+            return new ByteArrayInputStream(data.getBytes("UTF-8"));
+        }
+        @Override
+        public String getNiceFileName(boolean shortNames, String inputFileName) {
+            return name;
+        }
+    }
+
+    public static class NotThreadSafeRule extends AbstractRule {
+        public static AtomicInteger count = new AtomicInteger(0);
+        private boolean hasViolation; // this variable will be overridden between the threads
+        @Override
+        public void apply(List<? extends Node> nodes, RuleContext ctx) {
+            count.incrementAndGet();
+
+            if (ctx.getSourceCodeFilename().contains("violation")) {
+                hasViolation = true;
+            } else {
+                letTheOtherThreadRun(10);
+                hasViolation = false;
+            }
+
+            letTheOtherThreadRun(100);
+            if (hasViolation) {
+                addViolation(ctx, nodes.get(0));
+            }
+        }
+        private void letTheOtherThreadRun(int millis) {
+            try {
+                Thread.yield();
+                Thread.sleep(millis);
+            } catch (InterruptedException e) {
+                // ignored
+            }
+        }
+    }
+
+    private static class SimpleReportListener implements ReportListener {
+        public AtomicInteger violations = new AtomicInteger(0);
+        @Override
+        public void ruleViolationAdded(RuleViolation ruleViolation) {
+            violations.incrementAndGet();
+        }
+        @Override
+        public void metricAdded(Metric metric) {
+        }
+    }
+}

pmd-core/src/test/resources/rulesets/MultiThreadProcessorTest/basic.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0"?>
+<ruleset name="Test Ruleset" xmlns="http://pmd.sourceforge.net/ruleset/2.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 http://pmd.sourceforge.net/ruleset_2_0_0.xsd">
+
+    <description>
+  Ruleset used by test RuleSetReferenceIdTest
+  </description>
+
+    <rule name="NotThreadSafeRule" language="dummy" since="1.0" message="Not thread safe" class="net.sourceforge.pmd.processor.MultiThreadProcessorTest$NotThreadSafeRule"
+        externalInfoUrl="foo">
+        <description>Foo</description>
+        <priority>3</priority>
+        <example></example>
+    </rule>
+</ruleset>