From ff6419658bd8c8800734a7f19520c2aa7cd68a90 Mon Sep 17 00:00:00 2001
From: judeng <abc3844@126.com>
Date: Tue, 21 Jun 2022 12:02:22 +0800
Subject: Optimize the performance of clusterSendPing for large clusters
 (#10624)

Optimize the performance of clusterSendPing by improving speed of checking for duplicate items in gossip.
---
 src/cluster.c | 19 +++++--------------
 1 file changed, 5 insertions(+), 14 deletions(-)

(limited to 'src/cluster.c')

diff --git a/src/cluster.c b/src/cluster.c
index 0975db53a..cdbc565ec 100644
--- a/src/cluster.c
+++ b/src/cluster.c
@@ -964,6 +964,7 @@ clusterNode *createClusterNode(char *nodename, int flags) {
     node->numslaves = 0;
     node->slaves = NULL;
     node->slaveof = NULL;
+    node->last_in_ping_gossip = 0;
     node->ping_sent = node->pong_received = 0;
     node->data_received = 0;
     node->fail_time = 0;
@@ -2847,18 +2848,6 @@ void clusterBuildMessageHdr(clusterMsg *hdr, int type) {
      * totlen field is up to the caller. */
 }
 
-/* Return non zero if the node is already present in the gossip section of the
- * message pointed by 'hdr' and having 'count' gossip entries. Otherwise
- * zero is returned. Helper for clusterSendPing(). */
-int clusterNodeIsInGossipSection(clusterMsg *hdr, int count, clusterNode *n) {
-    int j;
-    for (j = 0; j < count; j++) {
-        if (memcmp(hdr->data.ping.gossip[j].nodename,n->name,
-                CLUSTER_NAMELEN) == 0) break;
-    }
-    return j != count;
-}
-
 /* Set the i-th entry of the gossip section in the message pointed by 'hdr'
  * to the info of the specified node 'n'. */
 void clusterSetGossipEntry(clusterMsg *hdr, int i, clusterNode *n) {
@@ -2878,6 +2867,8 @@ void clusterSetGossipEntry(clusterMsg *hdr, int i, clusterNode *n) {
 /* Send a PING or PONG packet to the specified node, making sure to add enough
  * gossip information. */
 void clusterSendPing(clusterLink *link, int type) {
+    static unsigned long long cluster_pings_sent = 0;
+    cluster_pings_sent++;
     unsigned char *buf;
     clusterMsg *hdr;
     int gossipcount = 0; /* Number of gossip sections added so far. */
@@ -2967,10 +2958,11 @@ void clusterSendPing(clusterLink *link, int type) {
         }
 
         /* Do not add a node we already have. */
-        if (clusterNodeIsInGossipSection(hdr,gossipcount,this)) continue;
+        if (this->last_in_ping_gossip == cluster_pings_sent) continue;
 
         /* Add it */
         clusterSetGossipEntry(hdr,gossipcount,this);
+        this->last_in_ping_gossip = cluster_pings_sent;
         freshnodes--;
         gossipcount++;
     }
@@ -2987,7 +2979,6 @@ void clusterSendPing(clusterLink *link, int type) {
             if (node->flags & CLUSTER_NODE_NOADDR) continue;
             if (!(node->flags & CLUSTER_NODE_PFAIL)) continue;
             clusterSetGossipEntry(hdr,gossipcount,node);
-            freshnodes--;
             gossipcount++;
             /* We take the count of the slots we allocated, since the
              * PFAIL stats may not match perfectly with the current number
-- 
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