Andrew Dunstan <[EMAIL PROTECTED]> writes: > My current (possibly naive) thought is that I'll need two structures, > one of <pid, event> listeners and one of <pid, event, message> > notifications waiting to be picked up, each protected by a lock. In the > case of the second structure, we would just separate the event and the > message by a null byte. Does that seem reasonable?
No. I think you should do it like sinval: the message ring carries *all* messages and it's up to the readers to take or discard individual messages. A backend would read the buffer at reasonable intervals and cache the messages it was interested in locally, for delivery to the client after the next transaction end (similar to current semantics). This way, the information about who is listening to what doesn't need to be in shared memory, and there's only one configuration parameter, the message ring buffer size, which the DBA can size based on estimates of message traffic rate. regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 1: if posting/reading through Usenet, please send an appropriate subscribe-nomail command to [EMAIL PROTECTED] so that your message can get through to the mailing list cleanly