Re: Clarify wait versus poll behavior in ExecAppendAsyncEventWait

Hi Chao,

On Thu, Nov 5, 2026 at 2:59 PM Chao Li <li(dot)evan(dot)chao(at)gmail(dot)com> wrote:
> This is a follow-up to patch [1] that I recently reviewed. The header comment of ExecAppendAsyncEventWait can be enhanced, but Etsuro-san considered that a pure improvement, so he asked for a separate patch.

Thanks for the patch! Here are my comments:

* ExecAppendAsyncEventWait
*
* Wait or poll for file descriptor events and fire callbacks.
+ *
+ * If node->as_syncdone is true, wait until at least one event
+ * occurs; otherwise, poll without waiting so synchronous
+ * execution can proceed.

I don't think this is 100% correct, because even when polling for
events, we will do async execution if some were ready.

BTW: I noticed we are clarifying this by this comment within that function:

/*
* If the timeout is -1, wait until at least one event occurs. If the
* timeout is 0, poll for events, but do not wait at all.
*/

This seems more accurate to me, so how about modifying the latter of
the proposed comments using this, like the attached? This change
makes the above comment redundant, so I removed it and instead added a
brief comment.

Best regards,
Etsuro Fujita