There is a possibility of a receiver losing out on messages in certain
corner conditions. One of the buggy case is if there is are two sender
ready with messages to be sent. Sender 1 initially gets the TOKEN lock
and proceeds.
After initial processing the sender of message 1 _will_ release TOKEN as
soon as receiver releases ACK, it does not wait till ACK CR is
re-acquired by receiver.
To illustrate the problem consider timeline for two senders and one
receiver (we will ignore receive part for Sender2 node)
Sender1 Sender2 Receiver
Get EX on TOKEN Get EX on TOKEN
<Granted> <Wait till granted>
Get EX on MSG
write LVB
down MSG to CR
Get EX of ACK
<wait till granted>
BAST for ACK
Get CR on MSG
read LVB
process
release ACK
AST for ACK
down ACK to CR
release MSG
release TOKEN
<granted>
Get EX on MSG
<... proceed ...>
release TOKEN
<lost one message>
^^^^^^^^^^^^^^^^^
Get EX on MSG
Get CR on ACK
release MSG
Abhijit
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