/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * 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

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

import java.math.BigInteger;

import java.security.NoSuchAlgorithmException;

import java.security.SecureRandom;

import java.security.Security;

import java.util.concurrent.Callable;

import java.util.concurrent.CompletionService;

import java.util.concurrent.CountDownLatch;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.ExecutorCompletionService;

import java.util.concurrent.ExecutorService;

import java.util.concurrent.Executors;

import java.util.concurrent.ThreadFactory;

import static java.lang.Math.*;

/*

 * @test

 * @bug 8141039

 * @library /lib/testlibrary

 * @summary Test behavior of a shared SecureRandom object when it is operated

 *          by multiple threads concurrently.

 * @run main/othervm -Djava.security.egd=file:/dev/urandom MultiThreadTest

 */

public class MultiThreadTest {

    private static final byte[] GEN_RND_BYTES = {1};

    private static final String DRBG_CONFIG = "securerandom.drbg.config";

    private static final String DRBG_CONFIG_VALUE

            = Security.getProperty(DRBG_CONFIG);

    private enum SEED {

        NONE, RESEED, SETSEED

    }

    public static void main(String[] args) {

        boolean success = true;

        for (int byteLen : GEN_RND_BYTES) {

            for (SEED reSeed : SEED.values()) {

                for (String mech : new String[]{

                    "SHA1PRNG", "Hash_DRBG", "HMAC_DRBG", "CTR_DRBG"}) {

                    try {

                        forEachMech(mech, byteLen, reSeed);

                    } catch (Exception e) {

                        success = false;

                        e.printStackTrace(System.out);

                    } finally {

                        Security.setProperty(DRBG_CONFIG, DRBG_CONFIG_VALUE);

                    }

                }

            }

        }

        if (!success) {

            throw new RuntimeException("At least one test failed.");

        }

    }

    /**

     * Generate a number of threads to fetch random numbers of certain bits

     * generated through a shared SecureRandom instance.

     * @param mech Mechanism name

     * @param byteLen Number of bytes of random number to produce

     * @param reSeed Call reseed() before generating random numbers

     * @throws NoSuchAlgorithmException

     * @throws InterruptedException

     * @throws ExecutionException

     */

    private static void forEachMech(String mech, int byteLen, SEED reSeed)

            throws NoSuchAlgorithmException, InterruptedException,

            ExecutionException {

        if ("SHA1PRNG".equals(mech) && SEED.RESEED.equals(reSeed)) {

            System.out.printf(

                    "%nreseed() api is not supported for '%s'", mech);

            return;

        }

        System.out.printf("%nTest SecureRandom mechanism: '%s' with support of"

                + " reseed: '%s'", mech, reSeed);

        int threadCount = (int) pow(2, 8 * byteLen);

        System.out.printf("%nCreating %s number of threads to generate secure "

                + "random numbers concurrently.", threadCount);

        ExecutorService executor

                = Executors.newCachedThreadPool(new ThreadFactory() {

                    @Override

                    public Thread newThread(Runnable r) {

                        Thread t = Executors.defaultThreadFactory()

                        .newThread(r);

                        t.setDaemon(true);

                        return t;

                    }

                });

        CompletionService<Integer> completionService

                = new ExecutorCompletionService<Integer>(executor);

        CountDownLatch latch = new CountDownLatch(1);

        SecureRandom rnd = null;

        if (!mech.contains("_DRBG")) {

            rnd = SecureRandom.getInstance(mech);

        } else {

            Security.setProperty(DRBG_CONFIG, mech);

            rnd = SecureRandom.getInstance("DRBG");

        }

        try {

            for (int i = 0; i < threadCount; i++) {

                completionService.submit(new Task(rnd, latch, byteLen, reSeed));

            }

            latch.countDown();

            for (int i = 0; i < threadCount; i++) {

                completionService.take();

            }

        } finally {

            executor.shutdown();

        }

        System.out.printf("%nCompleted Test for algorithm '%s' with thread "

                + "counts to '%s' using reseeding '%s'",

                mech, threadCount, reSeed);

    }

    /**

     * Define a Task to be executed by multiple thread to produce random numbers

     * from a shared SecureRandom instance.

     */

    private static class Task implements Callable<Integer> {

        private final SecureRandom random;

        private final CountDownLatch latch;

        private final SEED reSeed;

        private final int byteSize;

        public Task(SecureRandom random, CountDownLatch latch, int byteSize,

                SEED reSeed) {

            this.random = random;

            this.latch = latch;

            this.byteSize = byteSize;

            this.reSeed = reSeed;

        }

        @Override

        public Integer call() throws Exception {

            latch.await();

            switch (this.reSeed) {

                case RESEED:

                    this.random.reseed();

                    break;

                case SETSEED:

                    this.random.setSeed(1l);

                    break;

            }

            byte[] bytes = new byte[byteSize];

            random.nextBytes(bytes);

            return new BigInteger(bytes).intValue();

        }

    }

}