From b3e80d2f654a66358c53addffd34945363cce2bb Mon Sep 17 00:00:00 2001
From: "zhaozhao.zz" <zhaozhao.zz@alibaba-inc.com>
Date: Mon, 8 Oct 2018 21:23:38 +0800
Subject: [PATCH] Stream & AOF: rewrite stream in correct way

---
 src/aof.c | 46 +++++++++++++++++++++++++++++++---------------
 1 file changed, 31 insertions(+), 15 deletions(-)

diff --git a/src/aof.c b/src/aof.c
index f8f26bdf..3f914b77 100644
--- a/src/aof.c
+++ b/src/aof.c
@@ -1121,23 +1121,39 @@ int rewriteStreamObject(rio *r, robj *key, robj *o) {
     streamID id;
     int64_t numfields;
 
-    /* Reconstruct the stream data using XADD commands. */
-    while(streamIteratorGetID(&si,&id,&numfields)) {
-        /* Emit a two elements array for each item. The first is
-         * the ID, the second is an array of field-value pairs. */
+    if (s->length) {
+        /* Reconstruct the stream data using XADD commands. */
+        while(streamIteratorGetID(&si,&id,&numfields)) {
+            /* Emit a two elements array for each item. The first is
+             * the ID, the second is an array of field-value pairs. */
 
-        /* Emit the XADD <key> <id> ...fields... command. */
-        if (rioWriteBulkCount(r,'*',3+numfields*2) == 0) return 0;
-        if (rioWriteBulkString(r,"XADD",4) == 0) return 0;
-        if (rioWriteBulkObject(r,key) == 0) return 0;
-        if (rioWriteBulkStreamID(r,&id) == 0) return 0;
-        while(numfields--) {
-            unsigned char *field, *value;
-            int64_t field_len, value_len;
-            streamIteratorGetField(&si,&field,&value,&field_len,&value_len);
-            if (rioWriteBulkString(r,(char*)field,field_len) == 0) return 0;
-            if (rioWriteBulkString(r,(char*)value,value_len) == 0) return 0;
+            /* Emit the XADD <key> <id> ...fields... command. */
+            if (rioWriteBulkCount(r,'*',3+numfields*2) == 0) return 0;
+            if (rioWriteBulkString(r,"XADD",4) == 0) return 0;
+            if (rioWriteBulkObject(r,key) == 0) return 0;
+            if (rioWriteBulkStreamID(r,&id) == 0) return 0;
+            while(numfields--) {
+                unsigned char *field, *value;
+                int64_t field_len, value_len;
+                streamIteratorGetField(&si,&field,&value,&field_len,&value_len);
+                if (rioWriteBulkString(r,(char*)field,field_len) == 0) return 0;
+                if (rioWriteBulkString(r,(char*)value,value_len) == 0) return 0;
+            }
         }
+        /* Append XSTREAM SETID after XADD, make sure lastid is correct,
+         * in case of XDEL lastid. */
+        if (rioWriteBulkCount(r,'*',4) == 0) return 0;
+        if (rioWriteBulkString(r,"XSTREAM",7) == 0) return 0;
+        if (rioWriteBulkString(r,"SETID",5) == 0) return 0;
+        if (rioWriteBulkObject(r,key) == 0) return 0;
+        if (rioWriteBulkStreamID(r,&s->last_id) == 0) return 0;
+    } else {
+        /* Using XSTREAM CREATE if the stream is empty. */
+        if (rioWriteBulkCount(r,'*',4) == 0) return 0;
+        if (rioWriteBulkString(r,"XSTREAM",7) == 0) return 0;
+        if (rioWriteBulkString(r,"CREATE",6) == 0) return 0;
+        if (rioWriteBulkObject(r,key) == 0) return 0;
+        if (rioWriteBulkStreamID(r,&s->last_id) == 0) return 0;
     }
 
     /* Create all the stream consumer groups. */