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 * The Universal Permissive License (UPL), Version 1.0
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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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package com.oracle.truffle.js.test.threading;

import static org.junit.Assert.assertEquals;

import java.util.concurrent.Callable;

import org.graalvm.polyglot.Context;
import org.graalvm.polyglot.Value;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class SingleThreadAccess {

    public Context cx;

    @Before
    public void start() {
        cx = TestUtil.newContextBuilder().build();
    }

    @After
    public void end() {
        if (cx != null) {
            cx.close();
        }
    }

    
A primitive value created by one thread can be accessed from another thread.
/**
     * A primitive value created by one thread can be accessed from another thread.
     */
    @Test
    public void valueInTwoThreads() {
        TestingThread t = new TestingThread(new Callable<Value>() {

            @Override
            public Value call() throws Exception {
                return cx.eval("js", "42;");
            }
        });

        t.start();
        assertEquals(t.joinWithReturnValue().asInt(), 42);
        cx.close();
    }

    
Executable code created by one thread can be evaluated in another thread.
/**
     * Executable code created by one thread can be evaluated in another thread.
     */
    @Test
    public void functionInTwoThreads() {
        TestingThread t = new TestingThread(new Callable<Value>() {

            @Override
            public Value call() throws Exception {
                return cx.eval("js", "(function() { return 42; })");
            }
        });

        t.start();
        assertEquals(t.joinWithReturnValue().execute().asInt(), 42);
        cx.close();
    }

    
A Graal.js context can be created in one thread, and used from another thread.
/**
     * A Graal.js context can be created in one thread, and used from another thread.
     */
    @Test
    public void evalInTwoThreads() {
        cx.eval("js", "var foo = 42;");

        TestingThread t = new TestingThread(new Callable<Value>() {

            @Override
            public Value call() throws Exception {
                cx.enter();
                try {
                    return cx.eval("js", "foo;");
                } finally {
                    cx.leave();
                }
            }
        });

        t.start();
        assertEquals(t.joinWithReturnValue().asInt(), 42);
        cx.close();
    }

    
A Graal.js context can be created in one thread, and used from another thread.
/**
     * A Graal.js context can be created in one thread, and used from another thread.
     */
    @Test
    public void createThread() {
        cx.eval("js", "var foo = 42;");

        TestingThread t = new TestingThread(new Callable<Value>() {

            @Override
            public Value call() throws Exception {
                cx.enter();
                try {
                    return cx.eval("js", "foo;");
                } finally {
                    cx.leave();
                }
            }
        });

        t.start();
        assertEquals(t.joinWithReturnValue().asInt(), 42);
        cx.close();
    }

    static class TestingThread extends Thread {

        private final Runnable task;
        private volatile Object result;

        TestingThread(Callable<Value> task) {
            this.result = null;
            this.task = new Runnable() {

                @Override
                public void run() {
                    try {
                        result = task.call();
                    } catch (Exception e) {
                        result = null;
                        throw new AssertionError(e);
                    }
                }
            };
        }

        @Override
        public void run() {
            task.run();
        }

        public Value joinWithReturnValue() {
            try {
                join();
            } catch (InterruptedException e) {
                throw new AssertionError(e);
            }
            return (Value) result;
        }

    }
}