ACE_TP_Reactor保证同一处理器(Handle)的SOCKET事件,在同一时间不会由多个线程同时调用,但并没有保证多个线程不在同一时间分别处理同一处理器(Handle)的SOCKET和定时器,而且如果在定时器处理中超过定时器间隔,将会有另一线程再次调用定时器处理函数,带来不必要的线程同步工作。
通过查看源码(TP_Reactor.cpp)可以看出,当处理一个SOCK事件时,TP_Reactor会调用suspend_i函数把这个句柄从处理列表里暂时移掉,处理完以后再调用resume_handler函数把它放入列表,所以可以保证不会有2个线程同时处理同一处理器的SOCK事件。
所以我们只要在处理定时器前一样处理就可以了。注意,在处理SOCK事件时,suspend_i处理的是SOCK的句柄,所以我们也要获得处理器的SOCK句柄。直接调用handler->peer().get_handler()是不可取的,比较好的做法是直接调用handler->get_handler(),这是个虚函数,默认返回ACE_INVALID_HANDLER,值为0,我们可以重载这个函数,让它返回SOCK句柄。
以下是修改的部分(TP_Reactpor.cpp文件):
int
ACE_TP_Reactor::handle_timer_events (int & /*event_count*/,
ACE_TP_Token_Guard &guard)
{
// Get the current time
ACE_Time_Value cur_time (this->timer_queue_->gettimeofday () +
this->timer_queue_->timer_skew ());
// Look for a node in the timer queue whose timer <= the present
// time.
ACE_Timer_Node_Dispatch_Info info;
if (this->timer_queue_->dispatch_info (cur_time,
info))
{
// ******** fixed by lijie ***********
if (info.type_->get_handle () != ACE_INVALID_HANDLE)
{
if (this->is_suspended_i (info.type_->get_handle ()))
return 0;
this->suspend_handler (info.type_->get_handle ());
}
// ******** end **********************
const void *upcall_act = 0;
// Preinvoke.
this->timer_queue_->preinvoke (info,
cur_time,
upcall_act);
// Release the token before dispatching notifies
guard.release_token ();
// call the functor
this->timer_queue_->upcall (info,
cur_time);
// Postinvoke
this->timer_queue_->postinvoke (info,
cur_time,
upcall_act);
// We have dispatched a timer
return 1;
}
return 0;
}
ACE_TP_Reactor::handle_timer_events (int & /*event_count*/,
ACE_TP_Token_Guard &guard)
{
// Get the current time
ACE_Time_Value cur_time (this->timer_queue_->gettimeofday () +
this->timer_queue_->timer_skew ());
// Look for a node in the timer queue whose timer <= the present
// time.
ACE_Timer_Node_Dispatch_Info info;
if (this->timer_queue_->dispatch_info (cur_time,
info))
{
// ******** fixed by lijie ***********
if (info.type_->get_handle () != ACE_INVALID_HANDLE)
{
if (this->is_suspended_i (info.type_->get_handle ()))
return 0;
this->suspend_handler (info.type_->get_handle ());
}
// ******** end **********************
const void *upcall_act = 0;
// Preinvoke.
this->timer_queue_->preinvoke (info,
cur_time,
upcall_act);
// Release the token before dispatching notifies
guard.release_token ();
// call the functor
this->timer_queue_->upcall (info,
cur_time);
// Postinvoke
this->timer_queue_->postinvoke (info,
cur_time,
upcall_act);
// We have dispatched a timer
return 1;
}
return 0;
}
由于计时器处理函数是分给一个线程调用的,当调用结束以后,我们suspend过的SOCK句柄还没有恢复,我找了一下,还真不好找地方放这一句,只好暂时放在handle_timer处理完以后,返回以前:
this->reactor ()->resume_handler (this->get_handle ());
这一行必须加上,否则不会再激发SOCK和TIMER事件。
当然别忘了为Handler编写get_handle()函数:
ACE_HANDLE Test_Handler::get_handle () const
{
return this->peer ().get_handle ();
}
{
return this->peer ().get_handle ();
}
补充一点:假如在handle_timeout中返回-1的话,则不要调用resume_handler ,否则可能会段错误,因为返回-1会导致处理器被析构,但resume_handler却把对象重新放入列表。如果handle_timeout返回0则需要调用。