Improve node registration and xmin reporting such that false log messages are

avoided at the GTM.

Also add some more debug messages to the GTM

diff --git a/src/gtm/recovery/register_common.c b/src/gtm/recovery/register_common.c
index 7279c5ba0398feebaf52fde6113394372ee82053..f8d2748a77e0fe9d7c072ea0496aa10897d5b398 100644 (file)
--- a/src/gtm/recovery/register_common.c
+++ b/src/gtm/recovery/register_common.c
@@ -241,8 +241,6 @@ pgxcnode_add_info(GTM_PGXCNodeInfo *nodeinfo)
 
        GTM_RWLockAcquire(&PGXCNodesLock, GTM_LOCKMODE_WRITE);
 
-       elog(LOG, "Nodeinfo->reported_xmin - %d:%d", nodeinfo->reported_xmin,
-                       GTM_GlobalXmin);
        if (!GlobalTransactionIdIsValid(nodeinfo->reported_xmin))
                nodeinfo->reported_xmin = GTM_GlobalXmin;
 
@@ -441,7 +439,7 @@ Recovery_PGXCNodeRegister(GTM_PGXCNodeType  type,
        nodeinfo->status = status;
        nodeinfo->socket = socket;
        nodeinfo->reported_xmin = InvalidGlobalTransactionId;
-       nodeinfo->reported_xmin_time = GTM_TimestampGetCurrent();
+       nodeinfo->reported_xmin_time = 0;
        nodeinfo->is_session = is_session;
 
        elog(DEBUG1, "Recovery_PGXCNodeRegister Request info: type=%d, nodename=%s, port=%d," \
@@ -1002,7 +1000,11 @@ GTM_HandleGlobalXmin(GTM_PGXCNodeType type, char *node_name,
        {
                *errcode = GTM_ERRCODE_NODE_EXCLUDED;
                GTM_RWLockRelease(&mynodeinfo->node_lock);
-               elog(LOG, "GTM_ERRCODE_NODE_EXCLUDED - node_name %s", node_name);
+               elog(LOG, "GTM_ERRCODE_NODE_EXCLUDED - node_name %s, reported_xmin %d "
+                               "previously reported_xmin, GTM_GlobalXmin %d", node_name,
+                               reported_xmin,
+                               mynodeinfo->reported_xmin,
+                               GTM_GlobalXmin);
                return InvalidGlobalTransactionId;
        }
 
@@ -1015,7 +1017,19 @@ GTM_HandleGlobalXmin(GTM_PGXCNodeType type, char *node_name,
        {
                *errcode = GTM_ERRCODE_TOO_OLD_XMIN;
                GTM_RWLockRelease(&mynodeinfo->node_lock);
-               elog(LOG, "GTM_ERRCODE_TOO_OLD_XMIN - node_name %s", node_name);
+
+               /*
+                * When node registers from the first time, the reported_xmin is set
+                * to GTM_GlobalXmin and what we receive from the node would most
+                * likely precedes that, especially because nodes' latestCompletedXid
+                * could precede our GTM_GlobalXmin. The node is prepared to handle
+                * that case, but we should avoid logging an useless and often
+                * confusing log message.
+                */
+               if (mynodeinfo->reported_xmin_time)
+                       elog(LOG, "GTM_ERRCODE_TOO_OLD_XMIN - node_name %s, reported_xmin %d, "
+                                       "previously reported_xmin %d", node_name,
+                                       reported_xmin, mynodeinfo->reported_xmin);
                return InvalidGlobalTransactionId;
        }
 
@@ -1042,8 +1056,6 @@ GTM_HandleGlobalXmin(GTM_PGXCNodeType type, char *node_name,
        GTM_RWLockAcquire(&PGXCNodesLock, GTM_LOCKMODE_READ);
        num_nodes = pgxcnode_get_all(all_nodes, MAX_NODES, true);
 
-       elog(DEBUG1, "num_nodes - %d", num_nodes);
-
        for (ii = 0; ii < num_nodes; ii++)
        {
                GTM_PGXCNodeInfo *nodeinfo = all_nodes[ii];
@@ -1059,12 +1071,16 @@ GTM_HandleGlobalXmin(GTM_PGXCNodeType type, char *node_name,
                                GTM_NODE_DATANODE)
                        continue;
 
-               if (GTM_TimestampDifferenceExceeds(nodeinfo->reported_xmin_time,
+               if (nodeinfo->reported_xmin_time &&
+                       GTM_TimestampDifferenceExceeds(nodeinfo->reported_xmin_time,
                                        current_time, GTM_REPORT_XMIN_DELAY_THRESHOLD))
                {
-                       elog(LOG, "Timediff exceeds threshold - %ld:%ld - excluding the "
-                                       "node from GlobalXmin calculation",
-                                       nodeinfo->reported_xmin_time, current_time);
+                       elog(LOG, "Timediff exceeds threshold - last reporting time %ld, "
+                                       "current time %ld, last reported_xmin %d, reported_xmin %d,"
+                                       " - excluding the node %s from GlobalXmin calculation",
+                                       nodeinfo->reported_xmin_time, current_time,
+                                       reported_xmin, nodeinfo->reported_xmin,
+                                       nodeinfo->nodename);
 
                        GTM_RWLockAcquire(&nodeinfo->node_lock, GTM_LOCKMODE_WRITE);
                        if (GTM_TimestampDifferenceExceeds(nodeinfo->reported_xmin_time,
@@ -1139,7 +1155,14 @@ GTM_HandleGlobalXmin(GTM_PGXCNodeType type, char *node_name,
                GTM_PGXCNodeInfo *nodeinfo = all_nodes[ii];
 
                if (nodeinfo->excluded)
+               {
+                       elog(DEBUG1, "Node %s is excluded (last reported time %ld, current"
+                               " time %ld, last reported_xmin %d. This node won't be included in "
+                               "GTM_GlobalXmin computation",
+                               nodeinfo->nodename, nodeinfo->reported_xmin_time,
+                               GTM_TimestampGetCurrent(), nodeinfo->reported_xmin);
                        continue;
+               }
 
                if (nodeinfo->type != GTM_NODE_COORDINATOR && nodeinfo->type !=
                                GTM_NODE_DATANODE)
@@ -1165,15 +1188,21 @@ GTM_HandleGlobalXmin(GTM_PGXCNodeType type, char *node_name,
                GTM_RWLockAcquire(&PGXCNodesLock, GTM_LOCKMODE_WRITE);
                if (GlobalTransactionIdPrecedes(GTM_GlobalXmin, global_xmin))
                {
+                       elog(DEBUG1, "Computed new GTM_GlobalXmin %d, old value was %d",
+                                       global_xmin, GTM_GlobalXmin);
                        GTM_GlobalXmin = global_xmin;
                        GTM_GlobalXminComputedTime = current_time;
                }
-               else
+               else if (GlobalTransactionIdFollows(GTM_GlobalXmin, global_xmin))
+               {
+                       elog(LOG, "The current (old) GTM_GlobalXmin %d is newer than what "
+                                       "we just computed %d - keeping the current value",
+                                       GTM_GlobalXmin, global_xmin);
                        global_xmin = GTM_GlobalXmin;
+               }
                GTM_RWLockRelease(&PGXCNodesLock);
        }
 
 
-       elog(DEBUG1, "GTM_HandleGlobalXmin - %d", global_xmin);
        return global_xmin;
 }