Change #271558

Comments

multi: xfers_really_alive
Yes, we were counting the "live" transfers before, but were they
*really* alive?

When determining to add the wakeup socket to fdset/waitfds etc, we
should only do that when the multi handle is actually processing
transfers. Other wise, the application could wait on the wakeup socket
forever.

For this, we counted `multi->xfers_alive` (e.g. the "running" number
returned by `curl_multi_perform()`). This was almost correct.

The problem is that added easy handles are counted as "alive" right away
on the addition. But the processing has not started yet. They did not
trigger any DNS resolves or opened any sockets yet.

Add two fields in multi and easy handle:

* `multi->xfers_really_alive`: counts the "alive" transfers that have
  passed `MSTATE_INIT` (at least once)
* `data->state.really_alive`: to track if the transfer has been counted

Add test 2412 to check that adding transfers without perform will not
trigger the wakeup socket to be added.

Fixes #22050
Reported-by: Bryan Henderson
Closes #22066

Changed files

• lib/multi.c
• lib/multihandle.h
• lib/urldata.h
• tests/data/Makefile.am
• tests/data/test2412
• tests/libtest/Makefile.inc
• tests/libtest/lib2412.c
• tests/libtest/lib530.c