networking: optimize unlinkClient() in freeClient()

src/networking.c

@@ -135,7 +135,12 @@ client *createClient(int fd) {
     c->peerid = NULL;
     listSetFreeMethod(c->pubsub_patterns,decrRefCountVoid);
     listSetMatchMethod(c->pubsub_patterns,listMatchObjects);
-    if (fd != -1) listAddNodeTail(server.clients,c);
+    if (fd != -1) {
+        listAddNodeTail(server.clients,c);
+        c->client_list_node = listLast(server.clients);
+    } else {
+        c->client_list_node = NULL;
+    }
     initClientMultiState(c);
     return c;
 }
@@ -752,9 +757,10 @@ void unlinkClient(client *c) {
      * fd is already set to -1. */
     if (c->fd != -1) {
         /* Remove from the list of active clients. */
-        ln = listSearchKey(server.clients,c);
-        serverAssert(ln != NULL);
-        listDelNode(server.clients,ln);
+        if (c->client_list_node) {
+            listDelNode(server.clients,c->client_list_node);
+            c->client_list_node = NULL;
+        }
 
         /* Unregister async I/O handlers and close the socket. */
         aeDeleteFileEvent(server.el,c->fd,AE_READABLE);

src/replication.c

@@ -2215,6 +2215,7 @@ void replicationResurrectCachedMaster(int newfd) {
 
     /* Re-add to the list of clients. */
     listAddNodeTail(server.clients,server.master);
+    server.master->client_list_node = listLast(server.clients);
     if (aeCreateFileEvent(server.el, newfd, AE_READABLE,
                           readQueryFromClient, server.master)) {
         serverLog(LL_WARNING,"Error resurrecting the cached master, impossible to add the readable handler: %s", strerror(errno));

src/server.h

@@ -723,6 +723,7 @@ typedef struct client {
     dict *pubsub_channels;  /* channels a client is interested in (SUBSCRIBE) */
     list *pubsub_patterns;  /* patterns a client is interested in (SUBSCRIBE) */
     sds peerid;             /* Cached peer ID. */
+    listNode *client_list_node; /* list node in client list */
 
     /* Response buffer */
     int bufpos;