[CSV-318] printRecord() hangs if fed a parallel stream

Add tests

Author: garydgregory

src/test/java/org/apache/commons/csv/JiraCsv318Test.java

@@ -0,0 +1,145 @@
+/*
+ * 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
+ *
+ *   https://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.csv;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.PrintWriter;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Stream;
+
+import org.apache.commons.io.function.IOConsumer;
+import org.apache.commons.io.function.IOStream;
+import org.apache.commons.lang3.ArrayUtils;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+/**
+ * Tests https://issues.apache.org/jira/projects/CSV/issues/CSV-318?filter=allopenissues
+ *
+ * @see CSVPrinter
+ */
+public class JiraCsv318Test {
+
+    private void checkOutput(final ByteArrayOutputStream baos) {
+        checkOutput(baos.toString());
+    }
+
+    private void checkOutput(final String string) {
+        assertEquals("col a,col b,col c", string.trim());
+    }
+
+    private Stream<String> newParallelStream() {
+        // returned stream is intermediate
+        return newStream().parallel();
+    }
+
+    private CSVPrinter newPrinter(final ByteArrayOutputStream baos) throws IOException {
+        return new CSVPrinter(new PrintWriter(baos), CSVFormat.DEFAULT);
+    }
+
+    private Stream<String> newSequentialStream() {
+        // returned stream is intermediate
+        return newStream().sequential();
+    }
+
+    private Stream<String> newStream() {
+        return Stream.of("col a", "col b", "col c");
+    }
+
+    public synchronized void printRecord(final Stream<?> values) throws IOException {
+        // IOStream.adapt(values).forEachOrdered(this::print);
+    }
+
+    @Test
+    void testDefaultStream() throws IOException {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            printer.printRecord(newStream());
+        }
+        checkOutput(baos);
+    }
+
+    @SuppressWarnings("resource")
+    @Test
+    void testParallelIOStream() throws IOException {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            IOStream.adapt(newParallelStream()).forEachOrdered(printer::print);
+        }
+        // No EOR marker in this test intentionally, so checkOutput will trim.
+        checkOutput(baos);
+    }
+
+    @SuppressWarnings("resource")
+    @Test
+    @Disabled("Deadlock because CSVPrinter.print(Object) is synchronized")
+    void testParallelIOStreamSynchronizedPrinter() throws IOException {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            synchronized (printer) {
+                IOStream.adapt(newParallelStream()).forEachOrdered(printer::print);
+            }
+        }
+        // No EOR marker in this test intentionally, so checkOutput will trim.
+        checkOutput(baos);
+    }
+
+    @SuppressWarnings("resource")
+    @Test
+    void testParallelIOStreamSynchronizedPrinterNotUsed() throws IOException {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            synchronized (printer) {
+                IOStream.adapt(newParallelStream()).forEachOrdered(IOConsumer.noop());
+            }
+        }
+        final List<String> list = new ArrayList<>();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            synchronized (printer) {
+                IOStream.adapt(newParallelStream()).forEachOrdered(list::add);
+            }
+        }
+        // No EOR marker in this test intentionally, so checkOutput will trim.
+        checkOutput(String.join(",", list.toArray(ArrayUtils.EMPTY_STRING_ARRAY)));
+    }
+
+    @Test
+    @Disabled("Deadlock because CSVPrinter.print(Object) is synchronized")
+    void testParallelStream() throws IOException {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            printer.printRecord(newParallelStream());
+        }
+        checkOutput(baos);
+    }
+
+    @Test
+    void testSequentialStream() throws IOException {
+        final ByteArrayOutputStream baos = new ByteArrayOutputStream();
+        try (CSVPrinter printer = newPrinter(baos)) {
+            printer.printRecord(newSequentialStream());
+        }
+        checkOutput(baos);
+    }
+}