/*

 * Copyright (c) 2014, 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

 * @bug     8036823

 * @summary Creates two threads contending for the same lock and checks

 *      whether jstack reports "locked" by more than one thread.

 *

 * @library /testlibrary

 * @run main/othervm TestThreadDumpMonitorContention

 */

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.lang.management.ManagementFactory;

import java.lang.management.RuntimeMXBean;

import java.util.ArrayList;

import java.util.List;

import java.util.regex.Matcher;

import java.util.regex.Pattern;

import com.oracle.java.testlibrary.*;

public class TestThreadDumpMonitorContention {

    // jstack tends to be closely bound to the VM that we are running

    // so use getTestJDKTool() instead of getCompileJDKTool() or even

    // getJDKTool() which can fall back to "compile.jdk".

    final static String JSTACK = JDKToolFinder.getTestJDKTool("jstack");

    final static String PID = getPid();

    // looking for header lines with these patterns:

    // "ContendingThread-1" #19 prio=5 os_prio=64 tid=0x000000000079c000 nid=0x23 runnable [0xffff80ffb8b87000]

    // "ContendingThread-2" #21 prio=5 os_prio=64 tid=0x0000000000780000 nid=0x2f waiting for monitor entry [0xfffffd7fc1111000]

    final static Pattern HEADER_PREFIX_PATTERN = Pattern.compile(

        "^\"ContendingThread-.*");

        "^\"ContendingThread-.* waiting for monitor entry .*");

    final static Pattern HEADER_RUNNABLE_PATTERN = Pattern.compile(

        "^\"ContendingThread-.* runnable .*");

    // looking for thread state lines with these patterns:

    // java.lang.Thread.State: RUNNABLE

    // java.lang.Thread.State: BLOCKED (on object monitor)

    final static Pattern THREAD_STATE_PREFIX_PATTERN = Pattern.compile(

        " *java\\.lang\\.Thread\\.State: .*");

    final static Pattern THREAD_STATE_BLOCKED_PATTERN = Pattern.compile(

        " *java\\.lang\\.Thread\\.State: BLOCKED \\(on object monitor\\)");

    final static Pattern THREAD_STATE_RUNNABLE_PATTERN = Pattern.compile(

        " *java\\.lang\\.Thread\\.State: RUNNABLE");

    // looking for duplicates of this pattern:

    // - locked <0x000000076ac59e20> (a TestThreadDumpMonitorContention$1)

    final static Pattern LOCK_PATTERN = Pattern.compile(

        ".* locked \\<.*\\(a TestThreadDumpMonitorContention.*");

    // sanity checking header and thread state lines associated

    // with this pattern:

    // - waiting to lock <0x000000076ac59e20> (a TestThreadDumpMonitorContention$1)

    final static Pattern WAITING_PATTERN = Pattern.compile(

        ".* waiting to lock \\<.*\\(a TestThreadDumpMonitorContention.*");

    volatile static boolean done = false;

    static int error_cnt = 0;

    static boolean have_header_line = false;

    static boolean have_thread_state_line = false;

    static int n_samples = 15;

    static String thread_state_line = null;

    static boolean verbose = false;

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

        if (args.length != 0) {

            int arg_i = 0;

            if (args[arg_i].equals("-v")) {

                verbose = true;

                arg_i++;

            }

            try {

                n_samples = Integer.parseInt(args[arg_i]);

            } catch (NumberFormatException nfe) {

                System.err.println(nfe);

                usage();

            }

        }

        Runnable runnable = new Runnable() {

            public void run() {

                while (!done) {

                    synchronized (this) { }

                }

            }

        };

        Thread[] thread_list = new Thread[2];

        thread_list[0] = new Thread(runnable, "ContendingThread-1");

        thread_list[1] = new Thread(runnable, "ContendingThread-2");

        doSamples();

        done = true;

        thread_list[0].join();

        thread_list[1].join();

        if (error_cnt == 0) {

            System.out.println("Test PASSED.");

        } else {

            System.out.println("Test FAILED.");

            throw new AssertionError("error_cnt=" + error_cnt);

        }

    }

    // Reached a blank line which is the end of the

    // stack trace without matching either LOCK_PATTERN

    // or WAITING_PATTERN. Rare, but it's not an error.

    //

    // Example:

    // "ContendingThread-1" #21 prio=5 os_prio=64 tid=0x00000000007b9000 nid=0x2f runnable [0xfffffd7fc1111000]

    //    java.lang.Thread.State: RUNNABLE

    //         at java.lang.Thread.run(Thread.java:745)

    //

    static boolean checkBlankLine(String line) {

        if (line.length() == 0) {

            have_header_line = false;

            have_thread_state_line = false;

            return true;

        }

        return false;

    }

    // Process the locked line here if we found one.

    //

    // Example 1:

    // "ContendingThread-1" #21 prio=5 os_prio=64 tid=0x00000000007b9000 nid=0x2f runnable [0xfffffd7fc1111000]

    //    java.lang.Thread.State: RUNNABLE

    //         - locked <0xfffffd7e6a2912f8> (a TestThreadDumpMonitorContention$1)

    //         at java.lang.Thread.run(Thread.java:745)

    //

    // Example 2:

    // "ContendingThread-1" #21 prio=5 os_prio=64 tid=0x00000000007b9000 nid=0x2f waiting for monitor entry [0xfffffd7fc1111000]

    //    java.lang.Thread.State: BLOCKED (on object monitor)

    //         - locked <0xfffffd7e6a2912f8> (a TestThreadDumpMonitorContention$1)

    //         at java.lang.Thread.run(Thread.java:745)

    //

    static boolean checkLockedLine(String line) {

        Matcher matcher = LOCK_PATTERN.matcher(line);

        if (matcher.matches()) {

            if (verbose) {

                System.out.println("locked_line='" + line + "'");

            }

            matcher = HEADER_RUNNABLE_PATTERN.matcher(header_line);

                // It's strange, but a locked line can also

                }

            }

            matcher = THREAD_STATE_RUNNABLE_PATTERN.matcher(thread_state_line);

                // It's strange, but a locked line can also

                // match the THREAD_STATE_BLOCKED_PATTERN.

                matcher = THREAD_STATE_BLOCKED_PATTERN.matcher(

                              thread_state_line);

                    System.err.println();

                    System.err.println("ERROR: thread state line does not " +

                        "match runnable or waiting patterns.");

                    System.err.println("ERROR: " + "thread_state_line='" +

                        thread_state_line + "'");

                    System.err.println("ERROR: locked_line='" + line + "'");

                    error_cnt++;

                }

            }

            // Have everything we need from this thread stack

            // that matches the LOCK_PATTERN.

            have_header_line = false;

            have_thread_state_line = false;

            return true;

        }

        return false;

    }

    // Process the waiting line here if we found one.

    //

    // Example:

    // "ContendingThread-2" #22 prio=5 os_prio=64 tid=0x00000000007b9800 nid=0x30 waiting for monitor entry [0xfffffd7fc1010000]

    //    java.lang.Thread.State: BLOCKED (on object monitor)

    //         - waiting to lock <0xfffffd7e6a2912f8> (a TestThreadDumpMonitorContention$1)

    //         at java.lang.Thread.run(Thread.java:745)

    //

    static boolean checkWaitingLine(String line) {

        Matcher matcher = WAITING_PATTERN.matcher(line);

        if (matcher.matches()) {

            if (verbose) {

                System.out.println("waiting_line='" + line + "'");

            }

                System.err.println();

                System.err.println("ERROR: header line does " +

                    "not match a waiting pattern.");

                System.err.println("ERROR: header_line='" + header_line + "'");

                System.err.println("ERROR: waiting_line='" + line + "'");

                error_cnt++;

            }

            matcher = THREAD_STATE_BLOCKED_PATTERN.matcher(thread_state_line);

                System.err.println();

                System.err.println("ERROR: thread state line " +

                    "does not match a waiting pattern.");

                System.err.println("ERROR: thread_state_line='" +

                    thread_state_line + "'");

                System.err.println("ERROR: waiting_line='" + line + "'");

                error_cnt++;

            }

            // Have everything we need from this thread stack

            // that matches the WAITING_PATTERN.

            have_header_line = false;

            have_thread_state_line = false;

            return true;

        }

        return false;

    }

    static void doSamples() throws Exception {

        for (int count = 0; count < n_samples; count++) {

            // verbose mode or an error has a lot of output so add more space

            if (verbose || error_cnt > 0) System.out.println();

            System.out.println("Sample #" + count);

            // We don't use the ProcessTools, OutputBuffer or

            // OutputAnalyzer classes from the testlibrary because

            // we have a complicated multi-line parse to perform

            // on a narrow subset of the JSTACK output.

            //

            // - we only care about stack traces that match

            //   HEADER_PREFIX_PATTERN; only two should match

            // - we care about at most three lines from each stack trace

            // - if both stack traces match LOCKED_PATTERN, then that's

            //   a failure and we report it

            // - for a stack trace that matches LOCKED_PATTERN, we verify:

            //   - the header line matches HEADER_RUNNABLE_PATTERN

            //   - the thread state line matches THREAD_STATE_BLOCKED_PATTERN

            //     or THREAD_STATE_RUNNABLE_PATTERN

            //   - we report any mismatches as failures

            // - for a stack trace that matches WAITING_PATTERN, we verify:

            //   - the thread state line matches THREAD_STATE_BLOCKED_PATTERN

            //   - we report any mismatches as failures

            // - the stack traces that match HEADER_PREFIX_PATTERN may

            //   not match either LOCKED_PATTERN or WAITING_PATTERN

            //   because we might observe the thread outside of

            //   monitor operations; this is not considered a failure

            //

            // When we do observe LOCKED_PATTERN or WAITING_PATTERN,

            // then we are checking the header and thread state patterns

            // that occurred earlier in the current stack trace that

            // matched HEADER_PREFIX_PATTERN. We don't use data from

            // stack traces that don't match HEADER_PREFIX_PATTERN and

            // we don't mix data between the two stack traces that do

            // match HEADER_PREFIX_PATTERN.

            //

            Process process = new ProcessBuilder(JSTACK, PID)

                .redirectErrorStream(true).start();

            BufferedReader reader = new BufferedReader(new InputStreamReader(

                                        process.getInputStream()));

            String line;

            while ((line = reader.readLine()) != null) {

                Matcher matcher = null;

                // process the header line here

                if (!have_header_line) {

                    matcher = HEADER_PREFIX_PATTERN.matcher(line);

                    if (matcher.matches()) {

                        if (verbose) {

                            System.out.println();

                            System.out.println("header='" + line + "'");

                        }

                        header_line = new String(line);

                        have_header_line = true;

                        continue;

                    }

                    continue;  // skip until have a header line

                }

                // process the thread state line here

                if (!have_thread_state_line) {

                    matcher = THREAD_STATE_PREFIX_PATTERN.matcher(line);

                    if (matcher.matches()) {

                        if (verbose) {

                            System.out.println("thread_state='" + line + "'");

                        }

                        thread_state_line = new String(line);

                        have_thread_state_line = true;

                        continue;

                    }

                    continue;  // skip until we have a thread state line

                }

                // process the locked line here if we find one

                if (checkLockedLine(line)) {

                    continue;

                }

                // process the waiting line here if we find one

                if (checkWaitingLine(line)) {

                    continue;

                }

                // process the blank line here if we find one

                if (checkBlankLine(line)) {

                    continue;

                }

            }

            process.waitFor();

            // slight delay between jstack launches

            Thread.sleep(500);

        }

    }

    // This helper relies on RuntimeMXBean.getName() returning a string