The eviction callback, for convenience (and to avoid code
duplication), use to call opal_hotel_checkout(). However,
opal_hotel_checkout() deletes the eviction event -- which is fine to
do when opal_hotel_checkout() is invoked by the application. But when
it's invoked by the same event that it's deleting, it can cause Bad
Things to happen.
For simplicity, instead of invoking opal_hotel_checkout() from the
eviction callback, just duplicate the checkout logic into the eviction
callback function (and skip the delete-the-evict-event part).
For good measure, put a comment in all three places where the checkout
logic occurs (because it's inlined): don't change this logic without
changing all 3 places.
Finally, also add a line in the docs for opal_hotel_init() warning
users from calling opal_hotel_checkout() from their eviction
callback.
following:
* Provides a fixed number of resource slots (i.e., "hotel rooms").
* Allows one thing to occupy a resource slot at a time (i.e., each
hotel room can have an occupant check in to that room).
* Resource slots can be vacated at any time (i.e., occupants can
voluntarily check out of their hotel room).
* Resource slots can be occupied for a specific maximum amount of
time. If that time expires, the occupant is forcibly evicted and
the upper layer is notified via (libevent) callback (i.e., the maid
will kick an occupant of out of their room when their reservation
is over).
This class can be to be used for things like retransmission schemes
for unreliable transports. For example, a message sent on an
unreliable transport can be checked in to a hotel room. If an ACK for
that message is received, the message can be checked out. But if the
ACK is never received, the message will eventually be evicted from its
room and the upper layer will be notified that the message failed to
check out in time (i.e., that an ACK for that message was not received
in time).
Code using this class is currently being developed off-trunk, but will
be coming to SVN soon.
This commit was SVN r27067.
