Longda's Interesting World

Longda's Interesting World

MySQL 源码解读 -- 调度器

MySQL 源码解读 -- 调度器

Thread pool & scheduler

init

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Event:init
  --> thd = new THD(); thd-> store_globals();  // 
  --> event_queue = new Event_queue
  --> scheduler = new Event_scheduler(event_queue)
  --> event_queue->init_queue() || load_events_from_db(thd, event_queue)
  --> scheduler->start(&err_no)


启动调度器 – Event_scheduler::start
event_scheduler_start

Event_scheduler::start —> 创建thd 和一个线程
event_scheduler_thread
event_scheduler_thread

Event_queue

Event_queue 核心类, 

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/* The sorted queue with the Event_queue_element objects */
  Priority_queue<Event_queue_element *,
                 std::vector<Event_queue_element *,
                             Malloc_allocator<Event_queue_element *>>,
                 Event_queue_less>
      queue;

使用
queue(Event_queue_less(),
            Malloc_allocator<Event_queue_element *>(
                key_memory_Event_scheduler_scheduler_param))

Priority_queue 定义
template <typename T, typename Container = std::vector<T>,
          typename Less = std::less<typename Container::value_type>>
class Priority_queue : public Less {
...
}

构造函数
Priority_queue(Less const &less = Less(),
                 const allocator_type &alloc = allocator_type())
      : Base(less), m_container(alloc) {}

插入event
bool Event_queue::create_event(THD *thd, Event_queue_element *new_element,
                               bool *created) 
{
    new_element->compute_next_execution_time(thd);
    *created = (queue.push(new_element) == false);
    mysql_cond_broadcast(&COND_queue_state);
}

Event_scheduler

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类定义
Event_scheduler {
    enum enum_state state; //enum enum_state { INITIALIZED = 0, RUNNING, STOPPING };
    THD *scheduler_thd;
    Event_queue *queue;
    ulonglong started_events;
}