// -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
// vim: ts=8 sw=2 smarttab
/*
 * Ceph - scalable distributed file system
 *
 * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
 *
 * This is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License version 2.1, as published by the Free Software
 * Foundation.  See file COPYING.
 *
 */

#include "Cond.h"
#include "Timer.h"


#define dout_subsys ceph_subsys_timer
#undef dout_prefix
#define dout_prefix *_dout << "timer(" << this << ")."



class SafeTimerThread : public Thread {
  SafeTimer *parent;
public:
  explicit SafeTimerThread(SafeTimer *s) : parent(s) {}
  void *entry() override {
    parent->timer_thread();
    return NULL;
  }
};



typedef std::multimap < utime_t, Context *> scheduled_map_t;
typedef std::map < Context*, scheduled_map_t::iterator > event_lookup_map_t;

SafeTimer::SafeTimer(CephContext *cct_, Mutex &l, bool safe_callbacks)
  : cct(cct_), lock(l),
    safe_callbacks(safe_callbacks),
    thread(NULL),
    stopping(false)
{
}

SafeTimer::~SafeTimer()
{
  assert(thread == NULL);
}

void SafeTimer::init()
{
  ldout(cct,10) << "init" << dendl;
  thread = new SafeTimerThread(this);
  thread->create("safe_timer");
}

void SafeTimer::shutdown()
{
  ldout(cct,10) << "shutdown" << dendl;
  if (thread) {
    assert(lock.is_locked());
    cancel_all_events();
    stopping = true;
    cond.Signal();
    lock.Unlock();
    thread->join();
    lock.Lock();
    delete thread;
    thread = NULL;
  }
}

void SafeTimer::timer_thread()
{
  lock.Lock();
  ldout(cct,10) << "timer_thread starting" << dendl;
  while (!stopping) {
    utime_t now = ceph_clock_now();

    while (!schedule.empty()) {
      scheduled_map_t::iterator p = schedule.begin();

      // is the future now?
      if (p->first > now)
	break;

      Context *callback = p->second;
      events.erase(callback);
      schedule.erase(p);
      ldout(cct,10) << "timer_thread executing " << callback << dendl;
      
      if (!safe_callbacks)
	lock.Unlock();
      callback->complete(0);
      if (!safe_callbacks)
	lock.Lock();
    }

    // recheck stopping if we dropped the lock
    if (!safe_callbacks && stopping)
      break;

    ldout(cct,20) << "timer_thread going to sleep" << dendl;
    if (schedule.empty())
      cond.Wait(lock);
    else
      cond.WaitUntil(lock, schedule.begin()->first);
    ldout(cct,20) << "timer_thread awake" << dendl;
  }
  ldout(cct,10) << "timer_thread exiting" << dendl;
  lock.Unlock();
}

Context* SafeTimer::add_event_after(double seconds, Context *callback)
{
  assert(lock.is_locked());

  utime_t when = ceph_clock_now();
  when += seconds;
  return add_event_at(when, callback);
}

Context* SafeTimer::add_event_at(utime_t when, Context *callback)
{
  assert(lock.is_locked());
  ldout(cct,10) << __func__ << " " << when << " -> " << callback << dendl;
  if (stopping) {
    ldout(cct,5) << __func__ << " already shutdown, event not added" << dendl;
    delete callback;
    return nullptr;
  }
  scheduled_map_t::value_type s_val(when, callback);
  scheduled_map_t::iterator i = schedule.insert(s_val);

  event_lookup_map_t::value_type e_val(callback, i);
  pair < event_lookup_map_t::iterator, bool > rval(events.insert(e_val));

  /* If you hit this, you tried to insert the same Context* twice. */
  assert(rval.second);

  /* If the event we have just inserted comes before everything else, we need to
   * adjust our timeout. */
  if (i == schedule.begin())
    cond.Signal();
  return callback;
}

bool SafeTimer::cancel_event(Context *callback)
{
  assert(lock.is_locked());
  
  auto p = events.find(callback);
  if (p == events.end()) {
    ldout(cct,10) << "cancel_event " << callback << " not found" << dendl;
    return false;
  }

  ldout(cct,10) << "cancel_event " << p->second->first << " -> " << callback << dendl;
  delete p->first;

  schedule.erase(p->second);
  events.erase(p);
  return true;
}

void SafeTimer::cancel_all_events()
{
  ldout(cct,10) << "cancel_all_events" << dendl;
  assert(lock.is_locked());
  
  while (!events.empty()) {
    auto p = events.begin();
    ldout(cct,10) << " cancelled " << p->second->first << " -> " << p->first << dendl;
    delete p->first;
    schedule.erase(p->second);
    events.erase(p);
  }
}

void SafeTimer::dump(const char *caller) const
{
  if (!caller)
    caller = "";
  ldout(cct,10) << "dump " << caller << dendl;

  for (scheduled_map_t::const_iterator s = schedule.begin();
       s != schedule.end();
       ++s)
    ldout(cct,10) << " " << s->first << "->" << s->second << dendl;
}
