/*
 * Copyright (c) 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.
 */

/*
 * @test TestDisableExplicitGCFlag
 * @requires (vm.opt.DisplayVMOutput == null) | (vm.opt.DisplayVMOutput == true)
 * @summary Verify that DisableExplicitGC flag affects System.gc() behavior.
 * @library /testlibrary /../../test/lib
 * @build TestDisableExplicitGCFlag
 * @run main ClassFileInstaller sun.hotspot.WhiteBox
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDisableExplicitGCFlag true  false 1 1
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDisableExplicitGCFlag false false 1 1
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDisableExplicitGCFlag false true  1 0
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDisableExplicitGCFlag true  false 3 2
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDisableExplicitGCFlag false false 3 2
 * @run main/othervm -Xbootclasspath/a:. -XX:+UnlockDiagnosticVMOptions -XX:+WhiteBoxAPI TestDisableExplicitGCFlag false true  3 1
 */
import com.oracle.java.testlibrary.*;
import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import sun.hotspot.WhiteBox;

public class TestDisableExplicitGCFlag {

    public final static String DIS_EXPLICIT_GC_FLAG = "DisableExplicitGC";
    public final static String[] PARALLEL_GC_OPTIONS = {"UseParallelGC", "UseParallelOldGC"};
    public final static Pattern SYSTEM_GC_PATTERN = Pattern.compile("System.gc\\(\\)");
    // Parallel and ParallelOld GC produces different output - System.gc() message occurred twice per System.gc() call
    public final static Pattern SYSTEM_GC_PARALLEL_PATTERN = Pattern.compile("Full GC \\(System.gc\\(\\)\\)");
    public final static WhiteBox WHITE_BOX = WhiteBox.getWhiteBox();

    public static void main(String args[]) throws Exception {
        boolean checkDefaultValue = Boolean.parseBoolean(args[0]);
        boolean checkValue = Boolean.parseBoolean(args[1]);
        int iterationCount = Integer.parseInt(args[2]);
        int expectedGCCount = Integer.parseInt(args[3]);
        testDisableExplicitGC(checkDefaultValue, checkValue, iterationCount, expectedGCCount);
    }

    /**
     * @param checkDefaultValue Check default value of DisableExplicitGC VM flag
     * @param checkValue check VM behavior with DisableExplicitGC=checkValue
     * @param iterationCount how many times provoke System.gc() with changing DisableExplicitGC flag
     * @param expectedGCCount how many System.gc() messages should be in VM output
     * @throws RuntimeException if expected count of System.gc() message does not match with occurred
     * @throws Exception from OutputAnalyzer or ProcessTools
     */
    public static void testDisableExplicitGC(boolean checkDefaultValue, boolean checkValue, int iterationCount, int expectedGCCount) throws Exception {
        List<String> vmOpts = new LinkedList(
                Arrays.asList(
                        new String[]{
                            "-Xbootclasspath/a:.",
                            "-XX:+UnlockDiagnosticVMOptions",
                            "-XX:+WhiteBoxAPI",
                            "-XX:+PrintGC",
                            "-XX:+PrintGCCause",
                            GCProvoker.class.getName(),
                            Integer.toString(iterationCount)
                        }));
        // In case if we don't need to check default flag behavior - add VM option
        if (checkDefaultValue == false) {
            vmOpts.add(0, "-XX:" + (checkValue ? "+" : "-") + DIS_EXPLICIT_GC_FLAG);
        }
        vmOpts.addAll(0, Utils.getVmOptions());
        ProcessBuilder procBuilder
                = ProcessTools.createJavaProcessBuilder(true, vmOpts.toArray(new String[0]));
        OutputAnalyzer analyzer = new OutputAnalyzer(procBuilder.start());
        analyzer.shouldHaveExitValue(0);
        String output = analyzer.getOutput();
        System.out.println(output);
        checkResults(output, expectedGCCount);
    }

    private static void checkResults(String output, int expectedGCCount) {
        int multiplier = 1;
        Pattern pattern = SYSTEM_GC_PATTERN;
        for (String option : PARALLEL_GC_OPTIONS) {
            if (WHITE_BOX.getBooleanVMFlag(option)) {
                pattern = SYSTEM_GC_PARALLEL_PATTERN;
            }
        }
        System.out.println("Expect " + expectedGCCount * multiplier + " System.gc() messages.");
        Matcher matcher = pattern.matcher(output);
        int occurrence = 0;
        while (matcher.find()) {
            ++occurrence;
        }
        if (occurrence != expectedGCCount) {
            throw new RuntimeException("Occurred " + occurrence + " System.gc() messages.");
        }
    }

    public static class GCProvoker {

        public static void main(String args[]) {
            int iterationCount = Integer.parseInt(args[0]);
            if (iterationCount == 1) {
                System.gc();
            } else {
                System.out.println("Will perform " + iterationCount + " iterations.");
                for (int i = 0; i < iterationCount; i++) {
                    System.gc();
                    // Invert flag for next iteration
                    boolean value = WHITE_BOX.getBooleanVMFlag(DIS_EXPLICIT_GC_FLAG);
                    WHITE_BOX.setBooleanVMFlag(DIS_EXPLICIT_GC_FLAG, !value);
                }
            }
        }
    }
}