From e4a4a536bed6225d1bf04bdca67e2e21f99a3f4a Mon Sep 17 00:00:00 2001
From: Huang Zhw <huang_zhw@126.com>
Date: Tue, 26 Jul 2022 14:06:51 +0800
Subject: [PATCH] When client tracking is on, invalidation message of flushdb
 in a transaction is interleaved with transaction response.

---
 src/tracking.c          |  7 ++++++-
 tests/unit/tracking.tcl | 14 ++++++++++++++
 2 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/src/tracking.c b/src/tracking.c
index a659e98dd687..c98421edbfe0 100644
--- a/src/tracking.c
+++ b/src/tracking.c
@@ -454,7 +454,12 @@ void trackingInvalidateKeysOnFlush(int async) {
         while ((ln = listNext(&li)) != NULL) {
             client *c = listNodeValue(ln);
             if (c->flags & CLIENT_TRACKING) {
-                sendTrackingMessage(c,shared.null[c->resp]->ptr,sdslen(shared.null[c->resp]->ptr),1);
+                if (c == server.current_client) {
+                    incrRefCount(shared.null[c->resp]);
+                    listAddNodeTail(server.tracking_pending_keys,shared.null[c->resp]);
+                } else {
+                    sendTrackingMessage(c,shared.null[c->resp]->ptr,sdslen(shared.null[c->resp]->ptr),1);
+                }
             }
         }
     }
diff --git a/tests/unit/tracking.tcl b/tests/unit/tracking.tcl
index 6270ce47290a..9660b487bf46 100644
--- a/tests/unit/tracking.tcl
+++ b/tests/unit/tracking.tcl
@@ -548,6 +548,20 @@ start_server {tags {"tracking network"}} {
         assert_equal [lindex [$rd_redirection read] 2] {}
     }
 
+    test {flushdb tracking invalidation message is not interleaved with transaction response} {
+        clean_all
+        r HELLO 3
+        r CLIENT TRACKING on
+        r SET a{t} 1
+        r GET a{t}
+        r MULTI
+        r FLUSHDB
+        set res [r EXEC]
+        assert_equal $res {OK}
+        # Consume the invalidate message which is after command response
+        r read
+    } {invalidate *_*}
+
     # Keys are defined to be evicted 100 at a time by default.
     # If after eviction the number of keys still surpasses the limit
     # defined in tracking-table-max-keys, we increases eviction