Re: WIP: Failover Slots

Hi,

here is my code level review:

0001:
This one looks ok except for broken indentation in the new notes in
xlogreader.c and .h.

+                while (slot->in_use && slot->active_pid == active_pid
+                        && max_sleep_micros > 0)
+                {
+                    usleep(micros_per_sleep);
+                    max_sleep_micros -= micros_per_sleep;
+                }

Not sure I buy this, what about postmaster crashes and fast shutdown
requests etc.

0003:
There is a lot of documentation improvements here that are not related
to failover slots or timeline following, it might be good idea to
split those into separate patch as they are separately useful IMHO.