TaskScheduler.h

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/*
 * This file is part of the TrinityCore Project. See AUTHORS file for Copyright information
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the
 * Free Software Foundation; either version 2 of the License, or (at your
 * option) any later version.
 *
 * This program 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 for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef TRINITYCORE_TASK_SCHEDULER_H
#define TRINITYCORE_TASK_SCHEDULER_H
 
#include "Duration.h"
#include "Optional.h"
#include "Random.h"
#include <algorithm>
#include <functional>
#include <vector>
#include <queue>
#include <memory>
#include <utility>
#include <set>
 
class TaskContext;
 
class TC_COMMON_API TaskScheduler
{
 friend class TaskContext;
 
 // Time definitions (use steady clock)
 typedef std::chrono::steady_clock clock_t;
 typedef clock_t::time_point timepoint_t;
 typedef clock_t::duration duration_t;
 
 // Task group type
 typedef uint32 group_t;
 // Task repeated type
 typedef uint32 repeated_t;
 // Task handle type
 typedef std::function<void(TaskContext)> task_handler_t;
 // Predicate type
 typedef std::function<bool()> predicate_t;
 // Success handle type
 typedef std::function<void()> success_t;
 
 class Task
 {
 friend class TaskContext;
 friend class TaskScheduler;
 
 timepoint_t _end;
 duration_t _duration;
 Optional<group_t> _group;
 repeated_t _repeated;
 task_handler_t _task;
 
 public:
 // All Argument construct
 Task(timepoint_t end, duration_t duration, Optional<group_t> group,
 repeated_t const repeated, task_handler_t task)
 : _end(end), _duration(duration), _group(group), _repeated(repeated), _task(std::move(task)) { }
 
 // Minimal Argument construct
 Task(timepoint_t end, duration_t duration, task_handler_t task)
 : _end(end), _duration(duration), _group(std::nullopt), _repeated(0), _task(std::move(task)) { }
 
 // Copy construct
 Task(Task const&) = delete;
 // Move construct
 Task(Task&&) = delete;
 // Copy Assign
 Task& operator= (Task const&) = default;
 // Move Assign
 Task& operator= (Task&& right) = delete;
 
 ~Task() = default;
 
 // Order tasks by its end
 std::weak_ordering operator<=> (Task const& other) const
 {
 return std::compare_weak_order_fallback(_end, other._end);
 }
 
 // Compare tasks with its end
 bool operator== (Task const& other) const
 {
 return _end == other._end;
 }
 
 // Returns true if the task is in the given group
 inline bool IsInGroup(group_t const group) const
 {
 return _group == group;
 }
 };
 
 typedef std::shared_ptr<Task> TaskContainer;
 
 struct Compare
 {
 bool operator() (TaskContainer const& left, TaskContainer const& right) const
 {
 return (*left.get()) < (*right.get());
 }
 };
 
 class TC_COMMON_API TaskQueue
 {
 std::multiset<TaskContainer, Compare> container;
 
 public:
 // Pushes the task in the container
 void Push(TaskContainer&& task);
 
 TaskContainer Pop();
 
 TaskContainer const& First() const;
 
 void Clear();
 
 void RemoveIf(std::function<bool(TaskContainer const&)> const& filter);
 
 void ModifyIf(std::function<bool(TaskContainer const&)> const& filter);
 
 bool IsEmpty() const;
 };
 
 std::shared_ptr<TaskScheduler> self_reference;
 
 timepoint_t _now;
 
 TaskQueue _task_holder;
 
 typedef std::queue<std::function<void()>> AsyncHolder;
 
 AsyncHolder _asyncHolder;
 
 predicate_t _predicate;
 
 static bool EmptyValidator()
 {
 return true;
 }
 
public:
 TaskScheduler()
 : self_reference(this, [](TaskScheduler const*) { }), _now(clock_t::now()), _predicate(EmptyValidator) { }
 
 template<typename P>
 TaskScheduler(P&& predicate)
 : self_reference(this, [](TaskScheduler const*) { }), _now(clock_t::now()), _predicate(std::forward<P>(predicate)) { }
 
 TaskScheduler(TaskScheduler const&) = delete;
 TaskScheduler(TaskScheduler&&) = delete;
 TaskScheduler& operator= (TaskScheduler const&) = delete;
 TaskScheduler& operator= (TaskScheduler&&) = delete;
 
 ~TaskScheduler() = default;
 
 template<typename P>
 TaskScheduler& SetValidator(P&& predicate)
 {
 _predicate = std::forward<P>(predicate);
 return *this;
 }
 
 TaskScheduler& ClearValidator();
 
 TaskScheduler& Update(success_t const& callback = nullptr);
 
 TaskScheduler& Update(size_t milliseconds, success_t const& callback = nullptr);
 
 template<class Rep, class Period>
 TaskScheduler& Update(std::chrono::duration<Rep, Period> difftime,
 success_t const& callback = nullptr)
 {
 _now += difftime;
 Dispatch(callback);
 return *this;
 }
 
 TaskScheduler& Async(std::function<void()> callable);
 
 template<class Rep, class Period>
 TaskScheduler& Schedule(std::chrono::duration<Rep, Period> time,
 task_handler_t task)
 {
 return this->ScheduleAt(_now, time, std::move(task));
 }
 
 template<class Rep, class Period>
 TaskScheduler& Schedule(std::chrono::duration<Rep, Period> time,
 group_t const group, task_handler_t task)
 {
 return this->ScheduleAt(_now, time, group, std::move(task));
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskScheduler& Schedule(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max, task_handler_t task)
 {
 return this->Schedule(::randtime(min, max), std::move(task));
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskScheduler& Schedule(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max, group_t const group,
 task_handler_t task)
 {
 return this->Schedule(::randtime(min, max), group, std::move(task));
 }
 
 TaskScheduler& CancelAll();
 
 TaskScheduler& CancelGroup(group_t group);
 
 TaskScheduler& CancelGroupsOf(std::vector<group_t> const& groups);
 
 template<class Rep, class Period>
 TaskScheduler& DelayAll(std::chrono::duration<Rep, Period> duration)
 {
 _task_holder.ModifyIf([&duration](TaskContainer const& task) -> bool
 {
 task->_end += duration;
 return true;
 });
 return *this;
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskScheduler& DelayAll(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->DelayAll(::randtime(min, max));
 }
 
 template<class Rep, class Period>
 TaskScheduler& DelayGroup(group_t const group, std::chrono::duration<Rep, Period> duration)
 {
 _task_holder.ModifyIf([&duration, group](TaskContainer const& task) -> bool
 {
 if (task->IsInGroup(group))
 {
 task->_end += duration;
 return true;
 }
 else
 return false;
 });
 return *this;
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskScheduler& DelayGroup(group_t const group,
 std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->DelayGroup(group, ::randtime(min, max));
 }
 
 template<class Rep, class Period>
 TaskScheduler& RescheduleAll(std::chrono::duration<Rep, Period> duration)
 {
 auto const end = _now + duration;
 _task_holder.ModifyIf([end](TaskContainer const& task) -> bool
 {
 task->_end = end;
 return true;
 });
 return *this;
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskScheduler& RescheduleAll(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->RescheduleAll(::randtime(min, max));
 }
 
 template<class Rep, class Period>
 TaskScheduler& RescheduleGroup(group_t const group, std::chrono::duration<Rep, Period> duration)
 {
 auto const end = _now + duration;
 _task_holder.ModifyIf([end, group](TaskContainer const& task) -> bool
 {
 if (task->IsInGroup(group))
 {
 task->_end = end;
 return true;
 }
 else
 return false;
 });
 return *this;
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskScheduler& RescheduleGroup(group_t const group,
 std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->RescheduleGroup(group, ::randtime(min, max));
 }
 
private:
 TaskScheduler& InsertTask(TaskContainer task);
 
 template<class Rep, class Period>
 TaskScheduler& ScheduleAt(timepoint_t end,
 std::chrono::duration<Rep, Period> time, task_handler_t task)
 {
 return InsertTask(TaskContainer(new Task(end + time, time, std::move(task))));
 }
 
 template<class Rep, class Period>
 TaskScheduler& ScheduleAt(timepoint_t end,
 std::chrono::duration<Rep, Period> time,
 group_t const group, task_handler_t task)
 {
 static constexpr repeated_t DEFAULT_REPEATED = 0;
 return InsertTask(TaskContainer(new Task(end + time, time, group, DEFAULT_REPEATED, std::move(task))));
 }
 
 void Dispatch(success_t const& callback);
};
 
class TC_COMMON_API TaskContext
{
 friend class TaskScheduler;
 
 TaskScheduler::TaskContainer _task;
 
 std::weak_ptr<TaskScheduler> _owner;
 
 std::shared_ptr<bool> _consumed;
 
 TaskContext& Dispatch(std::function<TaskScheduler&(TaskScheduler&)> const& apply);
 
public:
 // Empty constructor
 TaskContext()
 : _task(), _owner(), _consumed(std::make_shared<bool>(true)) { }
 
 // Construct from task and owner
 explicit TaskContext(TaskScheduler::TaskContainer&& task, std::weak_ptr<TaskScheduler>&& owner)
 : _task(std::move(task)), _owner(std::move(owner)), _consumed(std::make_shared<bool>(false)) { }
 
 // Copy construct
 TaskContext(TaskContext const& right)
 : _task(right._task), _owner(right._owner), _consumed(right._consumed) { }
 
 // Move construct
 TaskContext(TaskContext&& right) noexcept
 : _task(std::move(right._task)), _owner(std::move(right._owner)), _consumed(std::move(right._consumed)) { }
 
 // Copy assign
 TaskContext& operator=(TaskContext const& right)
 {
 if (this != &right)
 {
 _task = right._task;
 _owner = right._owner;
 _consumed = right._consumed;
 }
 return *this;
 }
 
 // Move assign
 TaskContext& operator=(TaskContext&& right) noexcept
 {
 if (this != &right)
 {
 _task = std::move(right._task);
 _owner = std::move(right._owner);
 _consumed = std::move(right._consumed);
 }
 return *this;
 }
 
 ~TaskContext() = default;
 
 bool IsExpired() const;
 
 bool IsInGroup(TaskScheduler::group_t const group) const;
 
 TaskContext& SetGroup(TaskScheduler::group_t const group);
 
 TaskContext& ClearGroup();
 
 TaskScheduler::repeated_t GetRepeatCounter() const;
 
 template<class Rep, class Period>
 TaskContext& Repeat(std::chrono::duration<Rep, Period> duration)
 {
 AssertOnConsumed();
 
 // Set new duration, in-context timing and increment repeat counter
 _task->_duration = duration;
 _task->_end += duration;
 _task->_repeated += 1;
 (*_consumed) = true;
 return this->Dispatch([this](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.InsertTask(_task);
 });
 }
 
 TaskContext& Repeat()
 {
 return Repeat(_task->_duration);
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& Repeat(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->Repeat(::randtime(min, max));
 }
 
 TaskContext& Async(std::function<void()> const& callable);
 
 template<class Rep, class Period>
 TaskContext& Schedule(std::chrono::duration<Rep, Period> time,
 TaskScheduler::task_handler_t task)
 {
 auto const end = _task->_end;
 return this->Dispatch([end, time, task = std::move(task)](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.ScheduleAt<Rep, Period>(end, time, std::move(task));
 });
 }
 
 template<class Rep, class Period>
 TaskContext& Schedule(std::chrono::duration<Rep, Period> time,
 TaskScheduler::group_t const group, TaskScheduler::task_handler_t task)
 {
 auto const end = _task->_end;
 return this->Dispatch([end, time, group, task = std::move(task)](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.ScheduleAt<Rep, Period>(end, time, group, std::move(task));
 });
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& Schedule(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max, TaskScheduler::task_handler_t task)
 {
 return this->Schedule(::randtime(min, max), std::move(task));
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& Schedule(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max, TaskScheduler::group_t const group,
 TaskScheduler::task_handler_t task)
 {
 return this->Schedule(::randtime(min, max), group, std::move(task));
 }
 
 TaskContext& CancelAll();
 
 TaskContext& CancelGroup(TaskScheduler::group_t const group);
 
 TaskContext& CancelGroupsOf(std::vector<TaskScheduler::group_t> const& groups);
 
 template<class Rep, class Period>
 TaskContext& DelayAll(std::chrono::duration<Rep, Period> duration)
 {
 return this->Dispatch([=](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.DelayAll(duration);
 });
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& DelayAll(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->DelayAll(::randtime(min, max));
 }
 
 template<class Rep, class Period>
 TaskContext& DelayGroup(TaskScheduler::group_t const group, std::chrono::duration<Rep, Period> duration)
 {
 return this->Dispatch([=](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.DelayGroup(group, duration);
 });
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& DelayGroup(TaskScheduler::group_t const group,
 std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->DelayGroup(group, ::randtime(min, max));
 }
 
 template<class Rep, class Period>
 TaskContext& RescheduleAll(std::chrono::duration<Rep, Period> duration)
 {
 return this->Dispatch([=](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.RescheduleAll(duration);
 });
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& RescheduleAll(std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->RescheduleAll(::randtime(min, max));
 }
 
 template<class Rep, class Period>
 TaskContext& RescheduleGroup(TaskScheduler::group_t const group, std::chrono::duration<Rep, Period> duration)
 {
 return this->Dispatch([=](TaskScheduler& scheduler) -> TaskScheduler&
 {
 return scheduler.RescheduleGroup(group, duration);
 });
 }
 
 template<class RepLeft, class PeriodLeft, class RepRight, class PeriodRight>
 TaskContext& RescheduleGroup(TaskScheduler::group_t const group,
 std::chrono::duration<RepLeft, PeriodLeft> min,
 std::chrono::duration<RepRight, PeriodRight> max)
 {
 return this->RescheduleGroup(group, ::randtime(min, max));
 }
 
private:
 void AssertOnConsumed() const;
 
 void Invoke();
};
 
#endif