问题

ACE_NonBlocking_Connect_Handler在处理异步时存在问题

分析

当connect选择的同步参数为ACE_Synch_Options::USE_REACTOR时，连接超时时间为ACE_Time_Value::zero，在同步发起连接返回的错误码为EWOULDBLOCK时，会发起异步连接nonblocking_connect，事件类型为CONNECT_MASK，事件处理器为ACE_NonBlocking_Connect_Handler。 CONNECT_MASK在window平台上select reactor会注册可读，可写，异常，在linux平台下dev poll reactor中注册可读可写
select reactor和dev poll reactor在处理io事件时，处理优先顺序为可写，异常，可读

template <typename SVC_HANDLER, typename PEER_CONNECTOR> int
ACE_Connector<SVC_HANDLER, PEER_CONNECTOR>::connect_i
(SVC_HANDLER *&sh,SVC_HANDLER **sh_copy,const typename PEER_CONNECTOR::PEER_ADDR &remote_addr,const ACE_Synch_Options &synch_options,const typename PEER_CONNECTOR::PEER_ADDR &local_addr,int reuse_addr,int flags,int perms)
{ACE_TRACE ("ACE_Connector<SVC_HANDLER, PEER_CONNECTOR>::connect_i");// If the user hasn't supplied us with a <SVC_HANDLER> we'll use the// factory method to create one.  Otherwise, things will remain as// they are...if (this->make_svc_handler (sh) == -1)return -1;ACE_Time_Value *timeout = 0;int const use_reactor = synch_options[ACE_Synch_Options::USE_REACTOR];if (use_reactor)timeout = const_cast<ACE_Time_Value *> (&ACE_Time_Value::zero);elsetimeout = const_cast<ACE_Time_Value *> (synch_options.time_value ());int result;if (sh_copy == 0)result = this->connect_svc_handler (sh,remote_addr,timeout,local_addr,reuse_addr,flags,perms);elseresult = this->connect_svc_handler (sh,*sh_copy,remote_addr,timeout,local_addr,reuse_addr,flags,perms);// Activate immediately if we are connected.if (result != -1)return this->activate_svc_handler (sh);// Delegate to connection strategy.if (use_reactor && ACE_OS::last_error () == EWOULDBLOCK){// If the connection hasn't completed and we are using// non-blocking semantics then register// ACE_NonBlocking_Connect_Handler with the ACE_Reactor so that// it will call us back when the connection is complete or we// timeout, whichever comes first...if (sh_copy == 0)result = this->nonblocking_connect (sh, synch_options);elseresult = this->nonblocking_connect (*sh_copy, synch_options);// If for some reason the <nonblocking_connect> call failed, then <errno>// will be set to the new error.  If the call succeeds, however,// we need to make sure that <errno> remains set to// <EWOULDBLOCK>.if (result == 0)errno = EWOULDBLOCK;}else{// Save/restore errno.ACE_Errno_Guard error (errno);// Make sure to close down the service handler to avoid handle// leaks.if (sh_copy == 0){if (sh)sh->close (CLOSE_DURING_NEW_CONNECTION);}else if (*sh_copy)(*sh_copy)->close (CLOSE_DURING_NEW_CONNECTION);}return -1;
}template <typename SVC_HANDLER, typename PEER_CONNECTOR> int
ACE_Connector<SVC_HANDLER, PEER_CONNECTOR>::nonblocking_connect
(SVC_HANDLER *sh,const ACE_Synch_Options &synch_options)
{ACE_TRACE ("ACE_Connector<SVC_HANDLER, PEER_CONNECTOR>::nonblocking_connect");// Must have a valid Reactor for non-blocking connects to work.if (this->reactor () == 0)return -1;// Register the pending SVC_HANDLER so that it can be activated// later on when the connection completes.ACE_HANDLE handle = sh->get_handle ();long timer_id = -1;ACE_Time_Value *tv = 0;NBCH *nbch = 0;ACE_NEW_RETURN (nbch,NBCH (*this,sh,-1),-1);ACE_Event_Handler_var safe_nbch (nbch);// Exclusive access to the Reactor.ACE_GUARD_RETURN (ACE_Lock, ace_mon, this->reactor ()->lock (), -1);// Register handle with the reactor for connection events.ACE_Reactor_Mask mask = ACE_Event_Handler::CONNECT_MASK;if (this->reactor ()->register_handler (handle,nbch,mask) == -1)goto reactor_registration_failure;// Add handle to non-blocking handle set.this->non_blocking_handles ().insert (handle);// If we're starting connection under timer control then we need to// schedule a timeout with the ACE_Reactor.tv = const_cast<ACE_Time_Value *> (synch_options.time_value ());if (tv != 0){timer_id =this->reactor ()->schedule_timer (nbch,synch_options.arg (),*tv);if (timer_id == -1)goto timer_registration_failure;// Remember timer id.nbch->timer_id (timer_id);}return 0;// Undo previous actions using the ol' "goto label and fallthru"// trick...timer_registration_failure:// Remove from Reactor.this->reactor ()->remove_handler (handle, mask);// Remove handle from the set of non-blocking handles.this->non_blocking_handles ().remove (handle);/* FALLTHRU */reactor_registration_failure:// Close the svc_handlersh->close (CLOSE_DURING_NEW_CONNECTION);return -1;
}

但是在ACE_NonBlocking_Connect_Handler代码注释中为,handle_input 是处理连接失败， handle_output 是处理连接成功，但是在可写时需要获取套接字的错误码，如果错误码为0，则表示真正的连接成功

/// Called by ACE_Reactor when asynchronous connections fail.virtual int handle_input (ACE_HANDLE);/// Called by ACE_Dev_Poll_Reactor when asynchronous connections fail.virtual int handle_close (ACE_HANDLE, ACE_Reactor_Mask);/// Called by ACE_Reactor when asynchronous connections succeed.virtual int handle_output (ACE_HANDLE);/// Called by ACE_Reactor when asynchronous connections suceeds (on/// some platforms only).virtual int handle_exception (ACE_HANDLE fd);