/*
* GetPreferredReplicationNode
* Pick any Datanode from given list, however fetch a preferred node first.
*/
List *
GetPreferredReplicationNode(List *relNodes)
{
/*
* Try to find the first node in given list relNodes
* that is in the list of preferred nodes
*/
if (num_preferred_data_nodes != 0)
{
ListCell *item;
foreach(item, relNodes)
{
int relation_nodeid = lfirst_int(item);
int i;
for (i = 0; i < num_preferred_data_nodes; i++)
{
#ifdef XCP
char nodetype = PGXC_NODE_DATANODE;
int nodeid = PGXCNodeGetNodeId(preferred_data_node[i],
&nodetype);
#else
int nodeid = PGXCNodeGetNodeId(preferred_data_node[i], PGXC_NODE_DATANODE);
#endif
/* OK, found one */
if (nodeid == relation_nodeid)
return lappend_int(NULL, nodeid);
}
}
/*
* GetAnyDataNode
* Pick any data node from given set, but try a preferred node
*/
int
GetAnyDataNode(Bitmapset *nodes)
{
Bitmapset *preferred = NULL;
int i, nodeid;
int nmembers = 0;
int members[NumDataNodes];
for (i = 0; i < num_preferred_data_nodes; i++)
{
char ntype = PGXC_NODE_DATANODE;
nodeid = PGXCNodeGetNodeId(preferred_data_node[i], &ntype);
/* OK, found one */
if (bms_is_member(nodeid, nodes))
preferred = bms_add_member(preferred, nodeid);
}
/*
* If no preferred data nodes or they are not in the desired set, pick up
* from the original set.
*/
if (bms_is_empty(preferred))
preferred = bms_copy(nodes);
/*
* Load balance.
* We can not get item from the set, convert it to array
*/
while ((nodeid = bms_first_member(preferred)) >= 0)
members[nmembers++] = nodeid;
bms_free(preferred);
/* If there is a single member nothing to balance */
if (nmembers == 1)
return members[0];
/*
* In general, the set may contain any number of nodes, and if we save
* previous returned index for load balancing the distribution won't be
* flat, because small set will probably reset saved value, and lower
* indexes will be picked up more often.
* So we just get a random value from 0..nmembers-1.
*/
return members[((unsigned int) random()) % nmembers];
}
/*
* GetAnyDataNode
* Pick any Datanode from given list, but try a preferred node
*/
List *
GetAnyDataNode(List *relNodes)
{
/*
* Try to find the first node in given list relNodes
* that is in the list of preferred nodes
*/
if (num_preferred_data_nodes != 0)
{
ListCell *item;
foreach(item, relNodes)
{
int relation_nodeid = lfirst_int(item);
int i;
for (i = 0; i < num_preferred_data_nodes; i++)
{
int nodeid = PGXCNodeGetNodeId(preferred_data_node[i], PGXC_NODE_DATANODE);
/* OK, found one */
if (nodeid == relation_nodeid)
return lappend_int(NULL, nodeid);
}
}
