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package com.oracle.truffle.js.test.threading;

import org.graalvm.polyglot.Context;
import org.graalvm.polyglot.Engine;
import org.junit.Assert;
import org.junit.Test;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class SharedEngineTest {

    
See: https://github.com/oracle/graal/issues/1942.
/**
     * See: https://github.com/oracle/graal/issues/1942.
     */
    @Test
    public void testGitHub1942() {
        parallelEval("(async () => { return 1 })");
    }

    
See: https://github.com/graalvm/graaljs/issues/262.
/**
     * See: https://github.com/graalvm/graaljs/issues/262.
     */
    @Test
    public void testGitHub262() {
        parallelEval("(function() {" +
                        "    let it = infinite();" +
                        "    do {" +
                        "        var i = it.next();" +
                        "    } while (i < 100);" +
                        "    function* infinite() {" +
                        "        let n = 0;" +
                        "        while (true) {" +
                        "            yield n++;" +
                        "        }" +
                        "    }" +
                        "})();");
    }

    @Test
    public void testParallelAsyncGenerators() {
        parallelEval("async function* run() {" +
                        "    for (var i = 0; i < 10; i++) {" +
                        "        yield 'Hello '+ i;" +
                        "    }" +
                        "    await Promise.resolve(42);" +
                        "};" +
                        "(async () => {" +
                        "    var it = 0;" +
                        "    for await (const val of run()) {" +
                        "        it++;" +
                        "    };" +
                        "})();");
    }

    private static void parallelEval(String source) {
        final int contexts = 16;
        final int perThreadIterations = 100;
        ExecutorService executorService = Executors.newWorkStealingPool(contexts);
        Engine sharedEngine = Engine.newBuilder().build();

        final AtomicInteger exceptions = new AtomicInteger(0);
        final AtomicInteger executions = new AtomicInteger(0);
        CountDownLatch startBarrier = new CountDownLatch(contexts);

        for (int i = 0; i < contexts; i++) {
            executorService.submit(() -> {
                Context context = Context.newBuilder().engine(sharedEngine).build();
                startBarrier.countDown();
                try {
                    startBarrier.await();
                    for (int e = 0; e < perThreadIterations; e++) {
                        try {
                            context.eval("js", source);
                            executions.incrementAndGet();
                        } catch (Throwable t) {
                            exceptions.incrementAndGet();
                        }
                    }
                } catch (InterruptedException e) {
                    exceptions.incrementAndGet();
                }
            });
        }
        executorService.shutdown();
        try {
            executorService.awaitTermination(5, TimeUnit.MINUTES);
        } catch (InterruptedException e) {
            throw new AssertionError(e);
        }
        Assert.assertEquals(0, exceptions.get());
        Assert.assertEquals(contexts * perThreadIterations, executions.get());
    }

}