pcloudcc-lneely/pclsync/ptimer.c

/*
   Copyright (c) 2013-2014 Anton Titov.

   Copyright (c) 2013-2014 pCloud Ltd.  All rights reserved.

   Redistribution and use in source and binary forms, with or without
   modification, are permitted provided that the following conditions
   are met: Redistributions of source code must retain the above
   copyright notice, this list of conditions and the following
   disclaimer.  Redistributions in binary form must reproduce the
   above copyright notice, this list of conditions and the following
   disclaimer in the documentation and/or other materials provided
   with the distribution.  Neither the name of pCloud Ltd nor the
   names of its contributors may be used to endorse or promote
   products derived from this software without specific prior written
   permission.

   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL pCloud
   Ltd BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
   EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
   PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
   PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
   OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
   USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
   DAMAGE.
*/

#include "pcache.h"
#include "pcompiler.h"
#include "plibs.h"
#include "prun.h"
#include "psys.h"
#include "ptimer.h"

/* Maximum timeout possible is TIMER_ARRAY_SIZE^TIMER_LEVELS seconds, in the
 * worst case TIMER_LEVELS operations will be preformed for each timer to
 * service it (it is log TIMER_ARRAY_SIZE(timer_seconds_after_now)). So
 * servicing a timer is generally constant time task with a maximum constant of
 * TIMER_LEVELS and increasing TIMER_ARRAY_SIZE will trade memory for less
 * processing for each timer.
 *
 * TIMER_ARRAY_SIZE should be a power of two.
 */

#define TIMER_ARRAY_SIZE_SHIFT 6 /* 64 */
#define TIMER_ARRAY_SIZE (1 << TIMER_ARRAY_SIZE_SHIFT)
#define TIMER_LEVELS 3

#define PTIMER_IS_RUNNING 1
#define PTIMER_STOP_AFTER_RUN 2

time_t psync_current_time;

struct exception_list {
  struct exception_list *next;
  psync_exception_callback func;
  pthread_t threadid;
};

static psync_list timerlists[TIMER_LEVELS][TIMER_ARRAY_SIZE];
static struct exception_list *excepions = NULL;
static struct exception_list *sleeplist = NULL;
static pthread_mutex_t timer_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_mutex_t timer_ex_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t timer_cond = PTHREAD_COND_INITIALIZER;
static uint32_t nextsecwaiters = 0;
static int timer_running = 0;

PSYNC_NOINLINE static void timer_sleep_detected(time_t lt) {
  struct exception_list *e;
  pdbg_logf(D_NOTICE, "sleep detected, current_time=%lu, last_current_time=%lu",
        (unsigned long)__atomic_load_n(&psync_current_time, __ATOMIC_RELAXED), (unsigned long)lt);
  pthread_mutex_lock(&timer_ex_mutex);
  e = sleeplist;
  while (e) {
    e->func();
    e = e->next;
  }
  pthread_mutex_unlock(&timer_ex_mutex);
  pcache_clean();
  ptimer_notify_exception();
}

static void timer_check_upper_levels(time_t tmdiv, unsigned long level,
                                     unsigned long sh) {
  psync_list *l1, *l2, *l;
  time_t m;
  m = tmdiv % TIMER_ARRAY_SIZE;
  if (m == 0 && level < TIMER_LEVELS - 2)
    timer_check_upper_levels(tmdiv / TIMER_ARRAY_SIZE, level + 1,
                             sh + TIMER_ARRAY_SIZE_SHIFT);
  l = &timerlists[level + 1][m];
  psync_list_for_each_safe(l1, l2, l) psync_list_add_tail(
      &timerlists[level][(psync_list_element(l1, psync_timer_structure_t, list)
                              ->runat >>
                          sh) %
                         TIMER_ARRAY_SIZE],
      l1);
  psync_list_init(&timerlists[level + 1][m]);
}

static void timer_prepare_timers(time_t from, time_t to, psync_list *list) {
  time_t i, m;
  psync_list *l1, *l2;
  for (i = from + 1; i <= to; i++) {
    m = i % TIMER_ARRAY_SIZE;
    if (m == 0)
      timer_check_upper_levels(i / TIMER_ARRAY_SIZE, 0, 0);
    psync_list_for_each_safe(l1, l2, &timerlists[0][m]) {
      psync_list_element(l1, psync_timer_structure_t, list)->opts |=
          PTIMER_IS_RUNNING;
      psync_list_add_tail(list, l1);
    }
    psync_list_init(&timerlists[0][m]);
  }
}

PSYNC_NOINLINE static void timer_process_timers(psync_list *timers) {
  psync_timer_t timer;
  psync_list *l1, *l2;
  psync_list_for_each_element(timer, timers, psync_timer_structure_t, list)
      timer->call(timer, timer->param);
  pthread_mutex_lock(&timer_mutex);
  psync_list_for_each_safe(l1, l2, timers) {
    timer = psync_list_element(l1, psync_timer_structure_t, list);
    if (!(timer->opts & PTIMER_STOP_AFTER_RUN)) {
      timer->opts = 0;
      psync_list_del(l1);
      timer->runat = __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED) + timer->numsec;
      psync_list_add_tail(
          &timerlists[timer->level][(timer->runat >>
                                     (timer->level * TIMER_ARRAY_SIZE_SHIFT)) %
                                    TIMER_ARRAY_SIZE],
          &timer->list);
    }
  }
  pthread_mutex_unlock(&timer_mutex);
  psync_list_for_each_element_call(timers, psync_timer_structure_t, list, free);
}

static void timer_thread() {
  psync_list timers;
  time_t lt;
  lt = __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED);
  while (psync_do_run) {
    psync_list_init(&timers);
    psys_sleep_milliseconds(1000);
    __atomic_store_n(&psync_current_time, psys_time_seconds(), __ATOMIC_RELAXED);
    pthread_mutex_lock(&timer_mutex);
    timer_prepare_timers(lt, __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED), &timers);
    if (nextsecwaiters)
      pthread_cond_broadcast(&timer_cond);
    pthread_mutex_unlock(&timer_mutex);
    if (unlikely(!psync_list_isempty(&timers)))
      timer_process_timers(&timers);
    if (unlikely(__atomic_load_n(&psync_current_time, __ATOMIC_RELAXED) - lt >= 25))
      timer_sleep_detected(lt);
    else if (pdbg_unlikely(__atomic_load_n(&psync_current_time, __ATOMIC_RELAXED) == lt)) {
      if (!psync_do_run)
        break;
      psys_sleep_milliseconds(1000);
    }
    lt = __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED);
  }
}

void ptimer_init() {
  unsigned long i, j;
  for (i = 0; i < TIMER_LEVELS; i++)
    for (j = 0; j < TIMER_ARRAY_SIZE; j++)
      psync_list_init(&timerlists[i][j]);
  __atomic_store_n(&psync_current_time, psys_time_seconds(), __ATOMIC_RELAXED);
  prun_thread("timer", timer_thread);
  timer_running = 1;
}

time_t ptimer_time() {
  if (timer_running)
    return __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED);
  else
    return psys_time_seconds();
}

void ptimer_wake() { pthread_cond_signal(&timer_cond); }

psync_timer_t ptimer_register(psync_timer_callback func, time_t numsec,
                                   void *param) {
  psync_timer_t timer;
  uint32_t i;
  time_t n;
  timer = malloc(sizeof(psync_timer_structure_t));
  timer->call = func;
  timer->param = param;
  n = TIMER_ARRAY_SIZE;
  for (i = 0; i < TIMER_LEVELS; i++) {
    if (numsec <= n)
      break;
    else
      n *= TIMER_ARRAY_SIZE;
  }
  if (unlikely(i == TIMER_LEVELS)) {
    n /= TIMER_ARRAY_SIZE;
    pdbg_logf(D_ERROR, "requested timeout %lu is larger than the maximum of %lu",
          (unsigned long)numsec, (unsigned long)n);
    numsec = n;
    i--;
  }
  timer->numsec = numsec;
  timer->level = i;
  timer->opts = 0;
  pthread_mutex_lock(&timer_mutex);
  timer->runat = __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED) + numsec;
  psync_list_add_tail(
      &timerlists[i][(timer->runat >> (i * TIMER_ARRAY_SIZE_SHIFT)) %
                     TIMER_ARRAY_SIZE],
      &timer->list);
  pthread_mutex_unlock(&timer_mutex);
  return timer;
}

int ptimer_stop(psync_timer_t timer) {
  int needfree = 0;
  pthread_mutex_lock(&timer_mutex);
  if (timer->opts & PTIMER_IS_RUNNING)
    timer->opts |= PTIMER_STOP_AFTER_RUN;
  else {
    psync_list_del(&timer->list);
    needfree = 1;
  }
  pthread_mutex_unlock(&timer_mutex);
  if (needfree) {
    free(timer);
    return 0;
  } else
    return 1;
}

void ptimer_exception_handler(psync_exception_callback func) {
  struct exception_list *t;
  t = malloc(sizeof(struct exception_list));
  t->next = NULL;
  t->func = func;
  t->threadid = pthread_self();
  pthread_mutex_lock(&timer_ex_mutex);
  t->next = excepions;
  excepions = t;
  pthread_mutex_unlock(&timer_ex_mutex);
}

void ptimer_sleep_handler(psync_exception_callback func) {
  struct exception_list *t;
  t = malloc(sizeof(struct exception_list));
  t->next = NULL;
  t->func = func;
  t->threadid = pthread_self();
  pthread_mutex_lock(&timer_ex_mutex);
  t->next = sleeplist;
  sleeplist = t;
  pthread_mutex_unlock(&timer_ex_mutex);
}

void ptimer_do_notify_exception() {
  struct exception_list *e;
  pthread_t threadid;
  threadid = pthread_self();
  pthread_mutex_lock(&timer_ex_mutex);
  e = excepions;
  while (e) {
    if (!pthread_equal(threadid, e->threadid))
      e->func();
    e = e->next;
  }
  pthread_mutex_unlock(&timer_ex_mutex);
}

void ptimer_wait_next_sec() {
  time_t ctime;
  pthread_mutex_lock(&timer_mutex);
  ctime = __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED);
  do {
    nextsecwaiters++;
    pthread_cond_wait(&timer_cond, &timer_mutex);
    nextsecwaiters--;
  } while (ctime == __atomic_load_n(&psync_current_time, __ATOMIC_RELAXED));
  pthread_mutex_unlock(&timer_mutex);
}