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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
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 *
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 */

/*
 * @test
 * @summary Test implementations of ExecutorService.close
 * @library ../lib
 * @run junit CloseTest
 */

import java.time.Duration;
import java.util.List;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.ForkJoinPool;
import java.util.concurrent.Future;
import java.util.concurrent.Phaser;
import java.util.concurrent.TimeUnit;
import java.util.stream.Stream;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import static org.junit.jupiter.api.Assertions.*;

class CloseTest {

    static Stream<ExecutorService> executors() {
        return Stream.of(
                // ensures that default close method is tested
                new DelegatingExecutorService(Executors.newCachedThreadPool()),

                // implementations that may override close
                Executors.newCachedThreadPool(),
                Executors.newVirtualThreadPerTaskExecutor(),
                new ForkJoinPool()
        );
    }

    /**
     * Test close with no tasks running.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testCloseWithNoTasks(ExecutorService executor) throws Exception {
        executor.close();
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10,  TimeUnit.MILLISECONDS));
    }

    /**
     * Test close with tasks running.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testCloseWithRunningTasks(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(2);
        Future<?> future = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "foo";
        });
        phaser.arriveAndAwaitAdvance();   // wait for task to start

        executor.close();  // waits for task to complete
        assertFalse(Thread.interrupted());
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10,  TimeUnit.MILLISECONDS));
        assertEquals("foo", future.resultNow());
    }

    /**
     * Test shutdown with tasks running.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testShutdownWithRunningTasks(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(2);
        Future<?> future = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "foo";
        });
        phaser.arriveAndAwaitAdvance();   // wait for task to start

        executor.shutdown();
        assertFalse(Thread.interrupted());
        assertTrue(executor.isShutdown());
        assertTrue(executor.awaitTermination(1,  TimeUnit.MINUTES));
        assertTrue(executor.isTerminated());
        assertEquals("foo", future.resultNow());
    }

    /**
     * Test close with multiple tasks running
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testCloseWith2RunningTasks(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(3);
        Future<?> f1 = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "foo";
        });
        Future<?> f2 = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "bar";
        });
        phaser.arriveAndAwaitAdvance();   // wait for tasks to start

        executor.close();  // waits for task to complete
        assertFalse(Thread.interrupted());
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10,  TimeUnit.MILLISECONDS));
        assertEquals("foo", f1.resultNow());
        assertEquals("bar", f2.resultNow());
    }

    /**
     * Test shutdown with multiple tasks running
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testShutdownWith2RunningTasks(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(3);
        Future<?> f1 = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "foo";
        });
        Future<?> f2 = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "bar";
        });
        phaser.arriveAndAwaitAdvance();   // wait for tasks to start

        executor.shutdown();
        assertFalse(Thread.interrupted());
        assertTrue(executor.isShutdown());
        assertTrue(executor.awaitTermination(1,  TimeUnit.MINUTES));
        assertTrue(executor.isTerminated());
        assertEquals("foo", f1.resultNow());
        assertEquals("bar", f2.resultNow());
    }

    /**
     * Test close when executor is shutdown but not terminated.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testShutdownBeforeClose(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(2);
        Future<?> future = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofMillis(100));
            return "foo";
        });
        phaser.arriveAndAwaitAdvance();   // wait for task to start

        executor.shutdown();  // shutdown, will not immediately terminate
        executor.close();
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10,  TimeUnit.MILLISECONDS));
        Object s = future.resultNow();
        assertEquals("foo", s);
    }

    /**
     * Test close when terminated.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testTerminateBeforeClose(ExecutorService executor) throws Exception {
        executor.shutdown();
        assertTrue(executor.isTerminated());
        executor.close();
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10,  TimeUnit.MILLISECONDS));
    }

    /**
     * Test invoking close with interrupt status set.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testInterruptBeforeClose(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(2);
        Future<?> future = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofDays(1));
            return null;
        });
        phaser.arriveAndAwaitAdvance();  // wait for task to start

        Thread.currentThread().interrupt();
        try {
            executor.close();
            assertTrue(Thread.currentThread().isInterrupted());
        } finally {
            Thread.interrupted();  // clear interrupt status
        }
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10, TimeUnit.MILLISECONDS));
        assertThrows(ExecutionException.class, future::get);
    }

    /**
     * Test interrupting thread blocked in close.
     */
    @ParameterizedTest
    @MethodSource("executors")
    void testInterruptDuringClose(ExecutorService executor) throws Exception {
        Phaser phaser = new Phaser(2);
        Future<?> future = executor.submit(() -> {
            phaser.arriveAndAwaitAdvance();
            Thread.sleep(Duration.ofDays(1));
            return null;
        });
        phaser.arriveAndAwaitAdvance();  // wait for task to start

        // schedule main thread to be interrupted
        Thread thread = Thread.currentThread();
        new Thread(() -> {
            try {
                Thread.sleep( Duration.ofMillis(100));
            } catch (Exception ignore) { }
            thread.interrupt();
        }).start();
        try {
            executor.close();
            assertTrue(Thread.currentThread().isInterrupted());
        } finally {
            Thread.interrupted();  // clear interrupt status
        }
        assertTrue(executor.isShutdown());
        assertTrue(executor.isTerminated());
        assertTrue(executor.awaitTermination(10, TimeUnit.MILLISECONDS));
        assertThrows(ExecutionException.class, future::get);
    }
}