/*-
 * Public Domain 2014-present MongoDB, Inc.
 * Public Domain 2008-2014 WiredTiger, Inc.
 *
 * This is free and unencumbered software released into the public domain.
 *
 * Anyone is free to copy, modify, publish, use, compile, sell, or
 * distribute this software, either in source code form or as a compiled
 * binary, for any purpose, commercial or non-commercial, and by any
 * means.
 *
 * In jurisdictions that recognize copyright laws, the author or authors
 * of this software dedicate any and all copyright interest in the
 * software to the public domain. We make this dedication for the benefit
 * of the public at large and to the detriment of our heirs and
 * successors. We intend this dedication to be an overt act of
 * relinquishment in perpetuity of all present and future rights to this
 * software under copyright law.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
 * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 */
#include "test_util.h"

/*
 * JIRA ticket reference: HELP-4355 Test rwlock collapse under load.
 */
#define MAX_THREADS 1000
#define READS_PER_WRITE 10000
//#define	READS_PER_WRITE	1000000
//#define	READS_PER_WRITE	100

#define CHECK_CORRECTNESS 1
//#define	USE_POSIX	1

static WT_RWLOCK rwlock;
static pthread_rwlock_t p_rwlock;
static bool running;
static uint64_t shared_counter;

void *thread_rwlock(void *);
void *thread_dump(void *);

int
main(int argc, char *argv[])
{
    struct timespec te, ts;
    TEST_OPTS *opts, _opts;
    pthread_t dump_id, id[MAX_THREADS];
    int i;

    opts = &_opts;
    memset(opts, 0, sizeof(*opts));
    opts->nthreads = 100;
    opts->nops = 1000000; /* per thread */
    testutil_check(testutil_parse_opts(argc, argv, opts));
    running = true;

    testutil_make_work_dir(opts->home);
    testutil_check(
      wiredtiger_open(opts->home, NULL, "create,session_max=1000,statistics=(fast)", &opts->conn));

    testutil_check(__wt_rwlock_init(NULL, &rwlock));
    testutil_check(pthread_rwlock_init(&p_rwlock, NULL));

    testutil_check(pthread_create(&dump_id, NULL, thread_dump, opts));

    __wt_epoch(NULL, &ts);
    for (i = 0; i < (int)opts->nthreads; ++i)
        testutil_check(pthread_create(&id[i], NULL, thread_rwlock, opts));

    while (--i >= 0)
        testutil_check(pthread_join(id[i], NULL));
    __wt_epoch(NULL, &te);
    printf("%.2lf\n", WT_TIMEDIFF_MS(te, ts) / 1000.0);

    running = false;
    testutil_check(pthread_join(dump_id, NULL));

    testutil_check(pthread_rwlock_destroy(&p_rwlock));
    testutil_cleanup(opts);
    return (EXIT_SUCCESS);
}

/*
 * Acquire a rwlock, every Nth operation, acquire exclusive.
 */
void *
thread_rwlock(void *arg)
{
    TEST_OPTS *opts;
    WT_SESSION *wt_session;
    WT_SESSION_IMPL *session;
    uint64_t i, counter;
    bool writelock;

    opts = (TEST_OPTS *)arg;
    testutil_check(opts->conn->open_session(opts->conn, NULL, NULL, &wt_session));
    session = (WT_SESSION_IMPL *)wt_session;

    if (opts->verbose)
        printf("Running rwlock thread\n");
    for (i = 1; i <= opts->nops; ++i) {
        writelock = (i % READS_PER_WRITE == 0);

#ifdef USE_POSIX
        if (writelock)
            testutil_check(pthread_rwlock_wrlock(&p_rwlock));
        else
            testutil_check(pthread_rwlock_rdlock(&p_rwlock));
#else
        if (writelock)
            __wt_writelock(session, &rwlock);
        else
            __wt_readlock(session, &rwlock);
#endif

        /*
         * Do a tiny amount of work inside the lock so the compiler can't optimize everything away.
         */
        (void)__wt_atomic_add64(&counter, 1);

#ifdef CHECK_CORRECTNESS
        if (writelock)
            counter = ++shared_counter;
        else
            counter = shared_counter;

        __wt_yield();

        testutil_assert(counter == shared_counter);
#endif

#ifdef USE_POSIX
        testutil_check(pthread_rwlock_unlock(&p_rwlock));
#else
        if (writelock)
            __wt_writeunlock(session, &rwlock);
        else
            __wt_readunlock(session, &rwlock);
#endif

        if (opts->verbose && i % 10000 == 0) {
            printf("%s", session->id == 20 ? ".\n" : ".");
            fflush(stdout);
        }
    }

    opts->running = false;

    return (NULL);
}

void *
thread_dump(void *arg)
{
    TEST_OPTS *opts;

    opts = arg;

    while (running) {
        sleep(1);
        if (opts->verbose)
            printf(
              "\n"
              "rwlock { current %" PRIu8 ", next %" PRIu8 ", reader %" PRIu8
              ", readers_active %" PRIu32 ", readers_queued %" PRIu8 " }\n",
              rwlock.u.s.current, rwlock.u.s.next, rwlock.u.s.reader, rwlock.u.s.readers_active,
              rwlock.u.s.readers_queued);
    }

    return (NULL);
}