From 9122379abc3b15dfd2af3624586cc1e3f826eb55 Mon Sep 17 00:00:00 2001
From: Oran Agra <oran@redislabs.com>
Date: Tue, 3 Nov 2020 14:56:57 +0200
Subject: [PATCH] Propagate GETSET and SET-GET as SET (#7957)

- Generates a more backwards compatible command stream
- Slightly more efficient execution in replica/AOF
- Add a test for coverage
---
 src/t_string.c                    | 25 ++++++++++++++++++++++++-
 tests/integration/replication.tcl | 21 +++++++++++++++++++++
 2 files changed, 45 insertions(+), 1 deletion(-)

diff --git a/src/t_string.c b/src/t_string.c
index 188f27dc0..e8b37663d 100644
--- a/src/t_string.c
+++ b/src/t_string.c
@@ -90,7 +90,7 @@ void setGenericCommand(client *c, int flags, robj *key, robj *val, robj *expire,
     }
 
     if (flags & OBJ_SET_GET) {
-       getGenericCommand(c);
+        getGenericCommand(c);
     }
 
     genericSetKey(c,c->db,key,val,flags & OBJ_SET_KEEPTTL,1);
@@ -160,6 +160,24 @@ void setCommand(client *c) {
 
     c->argv[2] = tryObjectEncoding(c->argv[2]);
     setGenericCommand(c,flags,c->argv[1],c->argv[2],expire,unit,NULL,NULL);
+
+    /* Propagate without the GET argument */
+    if (flags & OBJ_SET_GET) {
+        int argc = 0;
+        robj **argv = zmalloc((c->argc-1)*sizeof(robj*));
+        for (j=0; j < c->argc; j++) {
+            char *a = c->argv[j]->ptr;
+            /* Skip GET which may be repeated multiple times. */
+            if (j >= 3 &&
+                (a[0] == 'g' || a[0] == 'G') &&
+                (a[1] == 'e' || a[1] == 'E') &&
+                (a[2] == 't' || a[2] == 'T') && a[3] == '\0')
+                continue;
+            argv[argc++] = c->argv[j];
+            incrRefCount(c->argv[j]);
+        }
+        replaceClientCommandVector(c, argc, argv);
+    }
 }
 
 void setnxCommand(client *c) {
@@ -201,6 +219,11 @@ void getsetCommand(client *c) {
     setKey(c,c->db,c->argv[1],c->argv[2]);
     notifyKeyspaceEvent(NOTIFY_STRING,"set",c->argv[1],c->db->id);
     server.dirty++;
+
+    /* Propagate as SET command */
+    robj *setcmd = createStringObject("SET",3);
+    rewriteClientCommandArgument(c,0,setcmd);
+    decrRefCount(setcmd);
 }
 
 void setrangeCommand(client *c) {
diff --git a/tests/integration/replication.tcl b/tests/integration/replication.tcl
index fb0b9b965..6c437ba71 100644
--- a/tests/integration/replication.tcl
+++ b/tests/integration/replication.tcl
@@ -77,6 +77,27 @@ start_server {tags {"repl"}} {
             assert_equal [$A debug digest] [$B debug digest]
         }
 
+        test {GETSET replication} {
+            $A config resetstat
+            $A config set loglevel debug
+            $B config set loglevel debug
+            r set test foo
+            assert_equal [r getset test bar] foo
+            wait_for_condition 500 10 {
+                [$A get test] eq "bar"
+            } else {
+                fail "getset wasn't propagated"
+            }
+            assert_equal [r set test vaz get] bar
+            wait_for_condition 500 10 {
+                [$A get test] eq "vaz"
+            } else {
+                fail "set get wasn't propagated"
+            }
+            assert_match {*calls=3,*} [cmdrstat set $A]
+            assert_match {} [cmdrstat getset $A]
+        }
+
         test {BRPOPLPUSH replication, when blocking against empty list} {
             $A config resetstat
             set rd [redis_deferring_client]