Can I detect who detached from a channel very easily?

QNX USERS QNX6 - OS
1

Hi,

I’m not sure if I’m missing something obvious here but I want to be able to detect who detached from my resource manager.

In my manager, I spawn a thread for each connection. When one closes, I’d like to remove the thread that was assigned to that connection. The reason I care is that I do some statistics gathering so I can’t just re-assign the thread to the next connection, I need to reset all the stats on it so I need to know when someone disconnects, which thread they were assigned.

The problem is that I don’t seem to get the information I need when a process detaches to figure this out. Looking in MsgReceive() I see I can get pulses for DISCONNECT, THREADDEATH and COIDDEATH. I currently handle all these and I get them when processes/threads disconnect (or die). But most of these don’t give any information that would let me determine who the other side was.

DISCONNECT - Gives nothing. I looked at the scoid value and it’s a number I don’t recognize as a thread id or process id or connection
THREADDEATH - Gives a thread id. So I can handle this one by having my remote sides pass in their thread id.
COIDDEATH - The value here seems to be the scoid value in DISCONNECT

So is there a way to associate the scoid value with a thread/process? I tried looking at the IO_CONNECT message and what it passes in but it does not seem to give the scoid value (unless I missed it someplace)

TIA,

Tim

2

You can the scoid you see in the DISCONNECT and COIDDEATH pulse from your IO_CONNECT message, it’s just hidden in the _msg_info structure.

You can either extract the msg_info from the message using the MsgInfo() function or always have it by including a msg_info struct in your MsgReceive.

For example:

struct _msg_info msg_info;
MsgReceive( chid, &recv_buf, sizeof (recv_buf), &msg_info );

if ( recv_buf.type == _IO_CONNECT ) {
my_connection_scoid = msg_info.scoid;
MsgReply( rcvid, EOK, NULL, 0 );
}

OR:

MsgReceive( chid, &recv_buf, sizeof (recv_buf), NULL );

if ( recv_buf.type == _IO_CONNECT ) {
struct _msg_info msg_info;
MsgInfo(rcvid, &msg_info);
my_connection_scoid = msg_info.scoid;
MsgReply( rcvid, EOK, NULL, 0 );
}

You can then handle your connection scoid differently wherever you handle the DISCONNECT

case _PULSE_CODE_DISCONNECT:
if (recv_buf.pulse.scoid == my_connection_scoid) {
//received disconnect for my connection, do something with it
}
ConnectDetach( recv_buf.pulse.scoid );
break;

Does that work for you?

3

Note … if you have a scoid, this is kind of a reverse handle back to the process and you can extract more information using ConnectClientInfo() in addition to what Steven wrote.

4

If you use the resource manager frame work, all these would be handled in the frame work (library) for you.

A CODE_DISCONNECT pulse, would be changed into a close() message, so your close_ocb() callout
get called, and from the ocb, you know which open() it belongs to.