[Cluster-devel] cluster/cman-kernel/src sm_message.c

[teigland at sourceware.org]

CVSROOT:	/cvs/cluster
Module name:	cluster
Branch: 	STABLE
Changes by:	teigland at sourceware.org	2006-09-21 15:46:54

Modified files:
	cman-kernel/src: sm_message.c 

Log message:
	Before choosing a new global id for a new group, a node discovers
	what the current max group id seen by any node in the cluster is
	and picks new=max+1.  The problem is when two nodes do this in
	parallel for two different new groups (that are at the same level)
	and end up assigning the same global id to the two different groups.
	To fix this, we have a node take this max group id and add its own nodeid
	to it, so new=max+our_nodeid.  This is similar to designating some of the
	id bits to be the nodeid of the node creating the group, but that method
	would break backward compatibility.  bz 206193
	
	Also, if we reach the max value of the global id counter (0xFFFFFF),
	then print a message and refuse to go ahead forming the group.

Patches:
http://sourceware.org/cgi-bin/cvsweb.cgi/cluster/cman-kernel/src/sm_message.c.diff?cvsroot=cluster&only_with_tag=STABLE&r1=1.4.8.1&r2=1.4.8.2

--- cluster/cman-kernel/src/Attic/sm_message.c	2005/06/22 04:45:57	1.4.8.1
+++ cluster/cman-kernel/src/Attic/sm_message.c	2006/09/21 15:46:54	1.4.8.2
@@ -41,14 +41,16 @@
 
 uint32_t sm_new_global_id(int level)
 {
-	uint32_t id = global_last_id++;
+	uint32_t id = global_last_id + sm_our_nodeid;
 	uint8_t l = (uint8_t) level;
 
 	if (level > 255)
 		return 0;
 
-	if (id > 0x00FFFFFF)
+	if (id > 0x00FFFFFF) {
+		log_print("ERROR: max global group id");
 		return 0;
+	}
 
 	id |= (l << 24);
 	return id;