[jboss-jira] [JBoss JIRA] Resolved: (JGRP-1154) FC: separate implementations for multicast and unicast messages

FC: separate implementations for multicast and unicast messages --------------------------------------------------------------- Key: JGRP-1154 URL: https://jira.jboss.org/browse/JGRP-1154 Project: JGroups Issue Type: Feature Request Reporter: Bela Ban Assignee: Bela Ban Fix For: 2.11 Currently, FC handles both multicast (=group) and unicast messages. This has a few disadvantages: - Complexity - Unicast messages are not dependent on multicast messages (and vice versa), so why should this be different for flow control ? E.g. why should a multicast message block waiting for credits from X because a recent unicast message was sent to X ? - If we have separate flow control protocols for multicasts and unicasts, we can selectively remove one or the other. This is currently not possible Design (see separate documents in ./doc/design): FC_MCAST: ----------------- (see whether some concepts can be borrowed from SFC) Sender: - Every sender has a credits AtomicLong variable - When sending a message and the message length exceeds credits, the sender blocks (until it gets credits from all current group members) - Else credits is decremented by the message length and the message is sent - When credits are received from all current group members, credits is reset to the initial value and all blocked senders are unblocked - When a new member joins, credits is also reset and all blocked senders are unblocked Receiver: - Maintains a hashmap of senders and credits (Map<Address,AtomicLong>) - When a message is received from S, the credits for S are decremented by the message length - If the remaining length is less than the threshold, new credits are sent to S and S's credits are reset to their initial value - When a new member joins, all credits (including the newly joined member) are reset to the initial value FC_UNICAST: -------------------- Sender: - A hashmap of addresses and credits is maintained: every receiver has associated credits - When a message is sent to P, if P's credits minus the message length is less than 0, the sender blocks until it gets new credits from the receiver - Else P's credits are decremented by the message length and the message is sent Receiver: -Same as for FC_MCAST