MINOR: debug: add a new DEBUG_FD build option
When DEBUG_FD is set at build time, we'll keep a counter of per-FD events
in the fdtab. This counter is reported in "show fd" even for closed FDs if
not zero. The purpose is to help spot situations where an apparently closed
FD continues to be reported in loops, or where some events are dismissed.
diff --git a/src/ev_epoll.c b/src/ev_epoll.c
index 92c000f..ba7f2e0 100644
--- a/src/ev_epoll.c
+++ b/src/ev_epoll.c
@@ -222,6 +222,9 @@
e = epoll_events[count].events;
fd = epoll_events[count].data.fd;
+#ifdef DEBUG_FD
+ _HA_ATOMIC_ADD(&fdtab[fd].event_count, 1);
+#endif
if (!fdtab[fd].owner) {
activity[tid].poll_dead_fd++;
continue;