Streams: propagate specified MAXLEN instead of approximated

Slaves and rebooting redis may have different radix tree struct,
by different stream* config options. So propagating approximated
MAXLEN to AOF/slaves may lead to date inconsistency.

1 files changed, 35 insertions, 6 deletions

diff --git a/src/t_stream.c b/src/t_stream.c
index 7533ba7b0..7eaf0c547 100644
--- a/src/t_stream.c
+++ b/src/t_stream.c
@@ -1114,8 +1114,7 @@ int streamParseStrictIDOrReply(client *c, robj *o, streamID *id, uint64_t missin
     return streamGenericParseIDOrReply(c,o,id,missing_seq,1);
 }
 
-
-/* XADD key [MAXLEN <count>] <ID or *> [field value] [field value] ... */
+/* XADD key [MAXLEN [~|=] <count>] <ID or *> [field value] [field value] ... */
 void xaddCommand(client *c) {
     streamID id;
     int id_given = 0; /* Was an ID different than "*" specified? */
@@ -1141,6 +1140,8 @@ void xaddCommand(client *c) {
             if (moreargs >= 2 && next[0] == '~' && next[1] == '\0') {
                 approx_maxlen = 1;
                 i++;
+            } else if (moreargs >= 2 && next[0] == '=' && next[1] == '\0') {
+                i++;
             }
             if (getLongLongFromObjectOrReply(c,c->argv[i+1],&maxlen,NULL)
                 != C_OK) return;
@@ -1187,9 +1188,22 @@ void xaddCommand(client *c) {
     notifyKeyspaceEvent(NOTIFY_STREAM,"xadd",c->argv[1],c->db->id);
     server.dirty++;
 
-    /* Notify xtrim event if needed. */
-    if (maxlen >= 0 && streamTrimByLength(s,maxlen,approx_maxlen)) {
-        notifyKeyspaceEvent(NOTIFY_STREAM,"xtrim",c->argv[1],c->db->id);
+    if (maxlen >= 0) {
+        /* Notify xtrim event if needed. */
+        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);
+        }
     }
 
     /* Let's rewrite the ID argument with the one actually generated for
@@ -2174,7 +2188,7 @@ void xdelCommand(client *c) {
  *
  * List of options:
  *
- * MAXLEN [~] <count>       -- Trim so that the stream will be capped at
+ * MAXLEN [~|=] <count>     -- Trim so that the stream will be capped at
  *                             the specified length. Use ~ before the
  *                             count in order to demand approximated trimming
  *                             (like XADD MAXLEN option).
@@ -2196,6 +2210,7 @@ void xtrimCommand(client *c) {
     long long maxlen = -1;  /* If left to -1 no trimming is performed. */
     int approx_maxlen = 0;  /* If 1 only delete whole radix tree nodes, so
                                the maxium length is not applied verbatim. */
+    int maxlen_arg_idx = 0; /* Index of the count in MAXLEN, for rewriting. */
 
     /* Parse options. */
     int i = 2; /* Start of options. */
@@ -2210,6 +2225,8 @@ void xtrimCommand(client *c) {
             if (moreargs >= 2 && next[0] == '~' && next[1] == '\0') {
                 approx_maxlen = 1;
                 i++;
+            } else if (moreargs >= 2 && next[0] == '=' && next[1] == '\0') {
+                i++;
             }
             if (getLongLongFromObjectOrReply(c,c->argv[i+1],&maxlen,NULL)
                 != C_OK) return;
@@ -2219,6 +2236,7 @@ void xtrimCommand(client *c) {
                 return;
             }
             i++;
+            maxlen_arg_idx = i;
         } else {
             addReply(c,shared.syntaxerr);
             return;
@@ -2239,6 +2257,17 @@ 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);
+        }
     }
     addReplyLongLong(c,deleted);
 }