/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to

 * deal in the Software without restriction, including without limitation the

 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or

 * sell copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * 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 OR COPYRIGHT HOLDERS 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 "uv.h"

#include "task.h"

#include <string.h>

#include <errno.h>

struct worker_config;

typedef void (*signal_func)(struct worker_config* c, int* flag);

typedef int (*wait_func)(struct worker_config* c, const int* flag);

typedef struct worker_config {

  uv_sem_t sem_waiting; /* post before waiting. */

  uv_sem_t sem_signaled; /* post after signaling. */

  uv_mutex_t mutex;

  uv_cond_t cond;

  int use_broadcast;

  int posted_1;

  int posted_2;

  signal_func signal_cond;

  wait_func wait_cond;

} worker_config;

void worker_config_init(worker_config* wc,

                        int use_broadcast,

                        signal_func signal_f,

                        wait_func wait_f) {

  /* Wipe. */

  memset(wc, 0, sizeof(*wc));

  /* Copy vars. */

  wc->signal_cond = signal_f;

  wc->wait_cond = wait_f;

  wc->use_broadcast = use_broadcast;

  /* Init. */

  ASSERT(0 == uv_sem_init(&wc->sem_waiting, 0));

  ASSERT(0 == uv_sem_init(&wc->sem_signaled, 0));

  ASSERT(0 == uv_cond_init(&wc->cond));

  ASSERT(0 == uv_mutex_init(&wc->mutex));

}

void worker_config_destroy(worker_config* wc) {

  uv_mutex_destroy(&wc->mutex);

  uv_cond_destroy(&wc->cond);

  uv_sem_destroy(&wc->sem_signaled);

  uv_sem_destroy(&wc->sem_waiting);

}

/* arg is a worker_config.

 * Call signal_cond then wait_cond.

 * Partner should call wait then signal. */

static void worker(void* arg) {

  worker_config* c = arg;

  c->signal_cond(c, &c->posted_1);

  c->wait_cond(c, &c->posted_2);

}

/* 1. Signal a waiting waiter.

 * 2. Tell waiter we finished. */

static void condvar_signal(worker_config* c, int* flag) {

  /* Wait until waiter holds mutex and is preparing to wait. */

  uv_sem_wait(&c->sem_waiting);

  /* Make sure waiter has begun waiting. */

  uv_mutex_lock(&c->mutex);

  /* Help waiter differentiate between spurious and legitimate wakeup. */

  ASSERT(*flag == 0);

  *flag = 1;

  if (c->use_broadcast)

    uv_cond_broadcast(&c->cond);

  else

    uv_cond_signal(&c->cond);

  uv_mutex_unlock(&c->mutex);

  /* Done signaling. */

  uv_sem_post(&c->sem_signaled);

}

/* 1. Wait on a signal.

 * 2. Ensure that the signaler finished. */

static int condvar_wait(worker_config* c, const int* flag) {

  uv_mutex_lock(&c->mutex);

  /* Tell signal'er that I am waiting. */

  uv_sem_post(&c->sem_waiting);

  /* Wait until I get a non-spurious signal. */

  do {

    uv_cond_wait(&c->cond, &c->mutex);

  } while (*flag == 0);

  ASSERT(*flag == 1);

  uv_mutex_unlock(&c->mutex);

  /* Wait for my signal'er to finish. */

  uv_sem_wait(&c->sem_signaled);

  return 0;

}

/* uv_cond_wait: One thread signals, the other waits. */

TEST_IMPL(condvar_1) {

  worker_config wc;

  uv_thread_t thread;

  /* Helper signal-then-wait. */

  worker_config_init(&wc, 0, condvar_signal, condvar_wait);

  ASSERT(0 == uv_thread_create(&thread, worker, &wc);;

  /* We wait-then-signal. */

  ASSERT(0 == wc.wait_cond(&wc, &wc.posted_1));

  wc.signal_cond(&wc, &wc.posted_2);

  ASSERT(0 == uv_thread_join(&thread));

  worker_config_destroy(&wc);

  return 0;

}

/* uv_cond_wait: One thread broadcasts, the other waits. */

TEST_IMPL(condvar_2) {

  worker_config wc;

  uv_thread_t thread;

  /* Helper to signal-then-wait. */

  worker_config_init(&wc, 1, condvar_signal, condvar_wait);

  ASSERT(0 == uv_thread_create(&thread, worker, &wc);;

  /* We wait-then-signal. */

  ASSERT(0 == wc.wait_cond(&wc, &wc.posted_1));

  wc.signal_cond(&wc, &wc.posted_2);

  ASSERT(0 == uv_thread_join(&thread));

  worker_config_destroy(&wc);

  return 0;

}

/* 1. Wait on a signal (hopefully not timeout, else we'll hang).

 * 2. Ensure that the signaler finished. */

static int condvar_timedwait(worker_config* c, const int* flag) {

  int r;

  r = 0;

  uv_mutex_lock(&c->mutex);

  /* Tell signal'er that I am waiting. */

  uv_sem_post(&c->sem_waiting);

  /* Wait until I get a non-spurious signal. */

  do {

    r = uv_cond_timedwait(&c->cond, &c->mutex, (uint64_t)(1 * 1e9)); /* 1 s */

    ASSERT(r == 0); /* Should not time out. */

  } while (*flag == 0);

  ASSERT(*flag == 1);

  uv_mutex_unlock(&c->mutex);

  /* Wait for my signal'er to finish. */

  uv_sem_wait(&c->sem_signaled);

  return r;

}

/* uv_cond_timedwait: One thread signals, the other timedwaits. */

TEST_IMPL(condvar_3) {

  worker_config wc;

  uv_thread_t thread;

  /* Helper to signal-then-wait. */

  worker_config_init(&wc, 0, condvar_signal, condvar_timedwait);

  ASSERT(0 == uv_thread_create(&thread, worker, &wc);;

  /* We wait-then-signal. */

  wc.wait_cond(&wc, &wc.posted_1);

  wc.signal_cond(&wc, &wc.posted_2);

  ASSERT(0 == uv_thread_join(&thread));

  worker_config_destroy(&wc);

  return 0;

}

/* uv_cond_timedwait: One thread broadcasts, the other waits. */

TEST_IMPL(condvar_4) {

  worker_config wc;

  uv_thread_t thread;

  /* Helper to signal-then-wait. */

  worker_config_init(&wc, 1, condvar_signal, condvar_timedwait);

  ASSERT(0 == uv_thread_create(&thread, worker, &wc);;

  /* We wait-then-signal. */

  wc.wait_cond(&wc, &wc.posted_1);

  wc.signal_cond(&wc, &wc.posted_2);

  ASSERT(0 == uv_thread_join(&thread));

  worker_config_destroy(&wc);

  return 0;

}

/* uv_cond_timedwait: One thread waits, no signal. Timeout should be delivered. */

TEST_IMPL(condvar_5) {

  worker_config wc;

  int r;

  /* ns */

  uint64_t before;

  uint64_t after;

  uint64_t elapsed;

  uint64_t timeout;

  timeout = 100 * 1e6; /* 100 ms in ns */

  /* Mostly irrelevant. We need cond and mutex initialized. */

  worker_config_init(&wc, 0, NULL, NULL);

  uv_mutex_lock(&wc.mutex);

  /* We wait.

   * No signaler, so this will only return if timeout is delivered. */

  before = uv_hrtime();

  r = uv_cond_timedwait(&wc.cond, &wc.mutex, timeout);

  after = uv_hrtime();

  uv_mutex_unlock(&wc.mutex);

  /* It timed out. */

  ASSERT(r == UV_ETIMEDOUT);

  /* It must have taken at least timeout, modulo system timer ticks.

   * But it should not take too much longer.

   * cf. MSDN docs:

   * https://msdn.microsoft.com/en-us/library/ms687069(VS.85).aspx */

  elapsed = after - before;

  ASSERT(0.75 * timeout <= elapsed); /* 1.0 too large for Windows. */

  ASSERT(elapsed <= 5.0 * timeout); /* MacOS has reported failures up to 1.75. */

  worker_config_destroy(&wc);

  return 0;

}