feat(Core/Utilities): Introduce a task scheduler which schedules task (#4932)

src/common/Utilities/TaskScheduler.cpp

@@ -0,0 +1,218 @@
+/*
+ * Copyright (C) 2016+  AzerothCore <www.azerothcore.org>, released under GNU AGPL v3 license: https://github.com/azerothcore/azerothcore-wotlk/blob/master/LICENSE-AGPL3
+ * Copyright (C) 2008+  TrinityCore <http://www.trinitycore.org/>
+ */
+
+#include "TaskScheduler.h"
+#include "Errors.h"
+
+TaskScheduler& TaskScheduler::ClearValidator()
+{
+    _predicate = EmptyValidator;
+    return *this;
+}
+
+TaskScheduler& TaskScheduler::Update(success_t const& callback)
+{
+    _now = clock_t::now();
+    Dispatch(callback);
+    return *this;
+}
+
+TaskScheduler& TaskScheduler::Update(size_t const milliseconds, success_t const& callback)
+{
+    return Update(std::chrono::milliseconds(milliseconds), callback);
+}
+
+TaskScheduler& TaskScheduler::Async(std::function<void()> const& callable)
+{
+    _asyncHolder.push(callable);
+    return *this;
+}
+
+TaskScheduler& TaskScheduler::CancelAll()
+{
+    /// Clear the task holder
+    _task_holder.Clear();
+    _asyncHolder = AsyncHolder();
+    return *this;
+}
+
+TaskScheduler& TaskScheduler::CancelGroup(group_t const group)
+{
+    _task_holder.RemoveIf([group](TaskContainer const & task) -> bool
+    {
+        return task->IsInGroup(group);
+    });
+    return *this;
+}
+
+TaskScheduler& TaskScheduler::CancelGroupsOf(std::vector<group_t> const& groups)
+{
+    std::for_each(groups.begin(), groups.end(),
+                  std::bind(&TaskScheduler::CancelGroup, this, std::placeholders::_1));
+
+    return *this;
+}
+
+TaskScheduler& TaskScheduler::InsertTask(TaskContainer task)
+{
+    _task_holder.Push(std::move(task));
+    return *this;
+}
+
+void TaskScheduler::Dispatch(success_t const& callback)
+{
+    // If the validation failed abort the dispatching here.
+    if (!_predicate())
+        return;
+
+    // Process all asyncs
+    while (!_asyncHolder.empty())
+    {
+        _asyncHolder.front()();
+        _asyncHolder.pop();
+
+        // If the validation failed abort the dispatching here.
+        if (!_predicate())
+            return;
+    }
+
+    while (!_task_holder.IsEmpty())
+    {
+        if (_task_holder.First()->_end > _now)
+            break;
+
+        // Perfect forward the context to the handler
+        // Use weak references to catch destruction before callbacks.
+        TaskContext context(_task_holder.Pop(), std::weak_ptr<TaskScheduler>(self_reference));
+
+        // Invoke the context
+        context.Invoke();
+
+        // If the validation failed abort the dispatching here.
+        if (!_predicate())
+            return;
+    }
+
+    // On finish call the final callback
+    callback();
+}
+
+void TaskScheduler::TaskQueue::Push(TaskContainer&& task)
+{
+    container.insert(task);
+}
+
+auto TaskScheduler::TaskQueue::Pop() -> TaskContainer
+{
+    TaskContainer result = *container.begin();
+    container.erase(container.begin());
+    return result;
+}
+
+auto TaskScheduler::TaskQueue::First() const -> TaskContainer const&
+{
+    return *container.begin();
+}
+
+void TaskScheduler::TaskQueue::Clear()
+{
+    container.clear();
+}
+
+void TaskScheduler::TaskQueue::RemoveIf(std::function<bool(TaskContainer const&)> const& filter)
+{
+    for (auto itr = container.begin(); itr != container.end();)
+        if (filter(*itr))
+            itr = container.erase(itr);
+        else
+            ++itr;
+}
+
+void TaskScheduler::TaskQueue::ModifyIf(std::function<bool(TaskContainer const&)> const& filter)
+{
+    std::vector<TaskContainer> cache;
+    for (auto itr = container.begin(); itr != container.end();)
+        if (filter(*itr))
+        {
+            cache.push_back(*itr);
+            itr = container.erase(itr);
+        }
+        else
+            ++itr;
+
+    container.insert(cache.begin(), cache.end());
+}
+
+bool TaskScheduler::TaskQueue::IsEmpty() const
+{
+    return container.empty();
+}
+
+TaskContext& TaskContext::Dispatch(std::function<TaskScheduler&(TaskScheduler&)> const& apply)
+{
+    if (auto const owner = _owner.lock())
+        apply(*owner);
+
+    return *this;
+}
+
+bool TaskContext::IsExpired() const
+{
+    return _owner.expired();
+}
+
+bool TaskContext::IsInGroup(TaskScheduler::group_t const group) const
+{
+    return _task->IsInGroup(group);
+}
+
+TaskContext& TaskContext::SetGroup(TaskScheduler::group_t const group)
+{
+    _task->_group = group;
+    return *this;
+}
+
+TaskContext& TaskContext::ClearGroup()
+{
+    _task->_group = std::nullopt;
+    return *this;
+}
+
+TaskScheduler::repeated_t TaskContext::GetRepeatCounter() const
+{
+    return _task->_repeated;
+}
+
+TaskContext& TaskContext::Async(std::function<void()> const& callable)
+{
+    return Dispatch(std::bind(&TaskScheduler::Async, std::placeholders::_1, callable));
+}
+
+TaskContext& TaskContext::CancelAll()
+{
+    return Dispatch(std::mem_fn(&TaskScheduler::CancelAll));
+}
+
+TaskContext& TaskContext::CancelGroup(TaskScheduler::group_t const group)
+{
+    return Dispatch(std::bind(&TaskScheduler::CancelGroup, std::placeholders::_1, group));
+}
+
+TaskContext& TaskContext::CancelGroupsOf(std::vector<TaskScheduler::group_t> const& groups)
+{
+    return Dispatch(std::bind(&TaskScheduler::CancelGroupsOf, std::placeholders::_1, std::cref(groups)));
+}
+
+void TaskContext::AssertOnConsumed() const
+{
+    // This was adapted to TC to prevent static analysis tools from complaining.
+    // If you encounter this assertion check if you repeat a TaskContext more then 1 time!
+    ASSERT(!(*_consumed) && "Bad task logic, task context was consumed already!");
+}
+
+void TaskContext::Invoke()
+{
+    _task->_task(*this);
+}