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/*
 * @test TestG1ConcRefinementThreads
 * @key gc
 * @bug 8047976
 * @requires vm.gc.G1
 * @summary Tests argument processing for G1ConcRefinementThreads
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 *          java.management
 */

import jdk.test.lib.process.OutputAnalyzer;
import jdk.test.lib.process.ProcessTools;
import java.util.*;
import java.util.regex.*;

public class TestG1ConcRefinementThreads {

  static final int AUTO_SELECT_THREADS_COUNT = -1;
  static final int PASSED_THREADS_COUNT = 11;

  public static void main(String args[]) throws Exception {
    // default case
    runG1ConcRefinementThreadsTest(
        new String[]{}, // automatically selected
        AUTO_SELECT_THREADS_COUNT /* use default setting */);

    // zero setting case
    runG1ConcRefinementThreadsTest(
        new String[]{"-XX:G1ConcRefinementThreads=0"},
        0);

    // non-zero sestting case
    runG1ConcRefinementThreadsTest(
        new String[]{"-XX:G1ConcRefinementThreads="+Integer.toString(PASSED_THREADS_COUNT)},
        PASSED_THREADS_COUNT);
  }

  private static void runG1ConcRefinementThreadsTest(String[] passedOpts,
          int expectedValue) throws Exception {
    List<String> vmOpts = new ArrayList<>();
    if (passedOpts.length > 0) {
      Collections.addAll(vmOpts, passedOpts);
    }
    Collections.addAll(vmOpts, "-XX:+UseG1GC", "-XX:+PrintFlagsFinal", "-version");

    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(vmOpts.toArray(new String[vmOpts.size()]));
    OutputAnalyzer output = new OutputAnalyzer(pb.start());

    output.shouldHaveExitValue(0);
    String stdout = output.getStdout();
    checkG1ConcRefinementThreadsConsistency(stdout, expectedValue);
  }

  private static void checkG1ConcRefinementThreadsConsistency(String output, int expectedValue) {
    int actualValue = getIntValue("G1ConcRefinementThreads", output);

    if (expectedValue == AUTO_SELECT_THREADS_COUNT) {
      // If expectedValue is automatically selected, set it same as ParallelGCThreads.
      expectedValue = getIntValue("ParallelGCThreads", output);
    }

    if (expectedValue != actualValue) {
      throw new RuntimeException(
            "Actual G1ConcRefinementThreads(" + Integer.toString(actualValue)
            + ") is not equal to expected value(" + Integer.toString(expectedValue) + ")");
    }
  }

  public static int getIntValue(String flag, String where) {
    Matcher m = Pattern.compile(flag + "\\s+:?=\\s+\\d+").matcher(where);
    if (!m.find()) {
      throw new RuntimeException("Could not find value for flag " + flag + " in output string");
    }
    String match = m.group();
    return Integer.parseInt(match.substring(match.lastIndexOf(" ") + 1, match.length()));
  }
}