Refactoring of XADD / XTRIM MAXLEN rewriting.

See #5141.

1 files changed, 15 insertions, 22 deletions

diff --git a/src/t_stream.c b/src/t_stream.c
index 54d49bd28..4387e08a5 100644
--- a/src/t_stream.c
+++ b/src/t_stream.c
@@ -1119,6 +1119,19 @@ int streamParseStrictIDOrReply(client *c, robj *o, streamID *id, uint64_t missin
     return streamGenericParseIDOrReply(c,o,id,missing_seq,1);
 }
 
+/* We propagate MAXLEN ~ <count> as MAXLEN = <resulting-len-of-stream>
+ * otherwise trimming is no longer determinsitic on replicas / AOF. */
+void streamRewriteApproxMaxlen(client *c, stream *s, int maxlen_arg_idx) {
+    robj *maxlen_obj = createStringObjectFromLongLong(s->length);
+    robj *equal_obj = createStringObject("=",1);
+
+    rewriteClientCommandArgument(c,maxlen_arg_idx,maxlen_obj);
+    rewriteClientCommandArgument(c,maxlen_arg_idx-1,equal_obj);
+
+    decrRefCount(equal_obj);
+    decrRefCount(maxlen_obj);
+}
+
 /* XADD key [MAXLEN [~|=] <count>] <ID or *> [field value] [field value] ... */
 void xaddCommand(client *c) {
     streamID id;
@@ -1198,17 +1211,7 @@ void xaddCommand(client *c) {
         if (streamTrimByLength(s,maxlen,approx_maxlen)) {
             notifyKeyspaceEvent(NOTIFY_STREAM,"xtrim",c->argv[1],c->db->id);
         }
-
-        /* Rewrite approximated MAXLEN as specified s->length. */
-        if (approx_maxlen) {
-            robj *maxlen_obj = createStringObjectFromLongLong(s->length);
-            rewriteClientCommandArgument(c,maxlen_arg_idx,maxlen_obj);
-            decrRefCount(maxlen_obj);
-
-            robj *equal_obj = createStringObject("=",1);
-            rewriteClientCommandArgument(c,maxlen_arg_idx-1,equal_obj);
-            decrRefCount(equal_obj);
-        }
+        if (approx_maxlen) streamRewriteApproxMaxlen(c,s,maxlen_arg_idx);
     }
 
     /* Let's rewrite the ID argument with the one actually generated for
@@ -2262,17 +2265,7 @@ void xtrimCommand(client *c) {
         signalModifiedKey(c->db,c->argv[1]);
         notifyKeyspaceEvent(NOTIFY_STREAM,"xtrim",c->argv[1],c->db->id);
         server.dirty += deleted;
-
-        /* Rewrite approximated MAXLEN as specified s->length. */
-        if (approx_maxlen) {
-            robj *maxlen_obj = createStringObjectFromLongLong(s->length);
-            rewriteClientCommandArgument(c,maxlen_arg_idx,maxlen_obj);
-            decrRefCount(maxlen_obj);
-
-            robj *equal_obj = createStringObject("=",1);
-            rewriteClientCommandArgument(c,maxlen_arg_idx-1,equal_obj);
-            decrRefCount(equal_obj);
-        }
+        if (approx_maxlen) streamRewriteApproxMaxlen(c,s,maxlen_arg_idx);
     }
     addReplyLongLong(c,deleted);
 }