/*

 * Copyright (c) 2014, 2015, 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.lang.reflect.Executable;

import java.lang.reflect.Method;

import java.util.Objects;

import java.util.concurrent.Callable;

import compiler.whitebox.CompilerWhiteBoxTest;

import compiler.whitebox.SimpleTestCase;

public class LevelTransitionTest extends TieredLevelsTest {

    /** Shows if method was profiled by being executed on levels 2 or 3 */

    protected boolean isMethodProfiled;

    private int transitionCount;

    public static void main(String[] args) throws Throwable {

        assert (!CompilerWhiteBoxTest.skipOnTieredCompilation(false));

        CompilerWhiteBoxTest.main(LevelTransitionTest::new, args);

        // run extended test cases

        for (TestCase testCase : ExtendedTestCase.values()) {

            new LevelTransitionTest(testCase).runTest();

        }

    }

    protected LevelTransitionTest(TestCase testCase) {

        super(testCase);

        isMethodProfiled = testCase.isOsr(); // OSR methods were already profiled by warmup

        transitionCount = 0;

    }

    @Override

    protected void test() throws Exception {

        checkTransitions();

        deoptimize();

        printInfo();

        if (testCase.isOsr()) {

            // deoptimization makes the following transitions be unstable

            // methods go to level 3 before 4 because of uncommon_trap and reprofile

            return;

        }

        checkTransitions();

    }

    /**

     * Makes and verifies transitions between compilation levels

     */

    protected void checkTransitions() throws Exception {

        checkNotCompiled();

        boolean finish = false;

        while (!finish) {

            System.out.printf("Level transition #%d%n", ++transitionCount);

            int newLevel;

            int current = getCompLevel();

            int expected = getNextLevel(current);

            if (current == expected) {

                // if we are on expected level, just execute it more

                // to ensure that the level won't change

                System.out.printf("Method %s is already on expected level %d%n", method, expected);

                compile();

                newLevel = getCompLevel();

                finish = true;

            } else {

                newLevel = changeCompLevel();

                finish = false;

            }

            System.out.printf("Method %s is compiled on level %d. Expected level is %d%n", method, newLevel, expected);

            checkLevel(expected, newLevel);

            printInfo();

        };

    }

    /**

     * Gets next expected level for the test case on each transition.

     *

     * @param currentLevel a level the test case is compiled on

     * @return expected compilation level

     */

    protected int getNextLevel(int currentLevel) {

        int nextLevel = currentLevel;

        switch (currentLevel) {

            case CompilerWhiteBoxTest.COMP_LEVEL_NONE:

                nextLevel = isMethodProfiled ? CompilerWhiteBoxTest.COMP_LEVEL_FULL_OPTIMIZATION

                        : CompilerWhiteBoxTest.COMP_LEVEL_FULL_PROFILE;

                break;

            case CompilerWhiteBoxTest.COMP_LEVEL_LIMITED_PROFILE:

            case CompilerWhiteBoxTest.COMP_LEVEL_FULL_PROFILE:

                nextLevel = CompilerWhiteBoxTest.COMP_LEVEL_FULL_OPTIMIZATION;

                isMethodProfiled = true;

                break;

        }

        nextLevel = isTrivial() ? CompilerWhiteBoxTest.COMP_LEVEL_SIMPLE : nextLevel;

        return Math.min(nextLevel, CompilerWhiteBoxTest.TIERED_STOP_AT_LEVEL);

    }

    /**

     * Determines if tested method should be handled as trivial

     *

     * @return {@code true} for trivial methods, {@code false} otherwise

     */

    protected boolean isTrivial() {

        return testCase == ExtendedTestCase.ACCESSOR_TEST

                || testCase == SimpleTestCase.METHOD_TEST

                || testCase == SimpleTestCase.STATIC_TEST

                || (testCase == ExtendedTestCase.TRIVIAL_CODE_TEST && isMethodProfiled);

    }

    /**

     * Invokes {@linkplain #method} until its compilation level is changed.

     * Note that if the level won't change, it will be an endless loop

     *

     * @return compilation level the {@linkplain #method} was compiled on

     */

    protected int changeCompLevel() {

        int currentLevel = getCompLevel();

        int newLevel = currentLevel;

        int result = 0;

        while (currentLevel == newLevel) {

            result = compile(1);

            if (WHITE_BOX.isMethodCompiled(method, testCase.isOsr())) {

                newLevel = getCompLevel();

            }

        }

        return newLevel;

    }

    protected static class Helper {

        /**

         * Gets method from a specified class using its name

         *

         * @param aClass type method belongs to

         * @param name   the name of the method

         * @return {@link Method} that represents corresponding class method

         */

        public static Method getMethod(Class<?> aClass, String name) {

            Method method;

            try {

                method = aClass.getDeclaredMethod(name);

            } catch (NoSuchMethodException e) {

                throw new Error("TESTBUG: Unable to get method " + name, e);

            }

            return method;

        }

        /**

         * Gets {@link Callable} that invokes given method from the given object

         *

         * @param object the object the specified method is invoked from

         * @param name   the name of the method

         */

        public static Callable<Integer> getCallable(Object object, String name) {

            Method method = getMethod(object.getClass(), name);

            return () -> {

                try {

                    return Objects.hashCode(method.invoke(object));

                } catch (ReflectiveOperationException e) {

                    throw new Error("TESTBUG: Invocation failure", e);

                }

            };

        }

    }

}

enum ExtendedTestCase implements CompilerWhiteBoxTest.TestCase {

    ACCESSOR_TEST("accessor"),

    NONTRIVIAL_METHOD_TEST("nonTrivialMethod"),

    TRIVIAL_CODE_TEST("trivialCode");

    private final Executable executable;

    private final Callable<Integer> callable;

    @Override

    public Executable getExecutable() {

        return executable;

    }

    @Override

    public Callable<Integer> getCallable() {

        return callable;

    }

    @Override

    public boolean isOsr() {

        return false;

    }

    private ExtendedTestCase(String methodName) {

        this.executable = LevelTransitionTest.Helper.getMethod(CompileMethodHolder.class, methodName);

        this.callable = LevelTransitionTest.Helper.getCallable(new CompileMethodHolder(), methodName);

    }

    private static class CompileMethodHolder {

        private final int iter = 10;

        private int field = 42;

        /** Non-trivial method for threshold policy: contains loops */

        public int nonTrivialMethod() {

            int acc = 0;

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

                acc += i;

            }

            return acc;

        }

        /** Field accessor method */

        public int accessor() {

            return field;

        }

        /** Method considered as trivial by amount of code */

        public int trivialCode() {

            int var = 0xBAAD_C0DE;

            var *= field;

            return var;

        }

    }

}