Added REDIS_NO_AUTO_FREE_REPLIES flag (redis#962)

When set hiredis will not automatically free replies in an async context, and the replies must be freed instead by the user.

Co-authored-by: Michael Grunder <michael.grunder@gmail.com>

async.c

@@ -569,7 +569,9 @@ void redisProcessCallbacks(redisAsyncContext *ac) {
 
         if (cb.fn != NULL) {
             __redisRunCallback(ac,&cb,reply);
-            c->reader->fn->freeObject(reply);
+            if (!(c->flags & REDIS_NO_AUTO_FREE_REPLIES)){
+                c->reader->fn->freeObject(reply);
+            }
 
             /* Proceed with free'ing when redisAsyncFree() was called. */
             if (c->flags & REDIS_FREEING) {

hiredis.c

@@ -804,6 +804,9 @@ redisContext *redisConnectWithOptions(const redisOptions *options) {
     if (options->options & REDIS_OPT_NOAUTOFREE) {
         c->flags |= REDIS_NO_AUTO_FREE;
     }
+    if (options->options & REDIS_OPT_NOAUTOFREEREPLIES) {
+        c->flags |= REDIS_NO_AUTO_FREE_REPLIES;
+    }
 
     /* Set any user supplied RESP3 PUSH handler or use freeReplyObject
      * as a default unless specifically flagged that we don't want one. */

hiredis.h

@@ -86,6 +86,9 @@ typedef long long ssize_t;
  */
 #define REDIS_NO_AUTO_FREE 0x200
 
+/* Flag that indicates the user does not want replies to be automatically freed */
+#define REDIS_NO_AUTO_FREE_REPLIES 0x400
+
 #define REDIS_KEEPALIVE_INTERVAL 15 /* seconds */
 
 /* number of times we retry to connect in the case of EADDRNOTAVAIL and
@@ -153,6 +156,11 @@ struct redisSsl;
 /* Don't automatically intercept and free RESP3 PUSH replies. */
 #define REDIS_OPT_NO_PUSH_AUTOFREE 0x08
 
+/**
+ * Don't automatically free replies
+ */
+#define REDIS_OPT_NOAUTOFREEREPLIES 0x10
+
 /* In Unix systems a file descriptor is a regular signed int, with -1
  * representing an invalid descriptor. In Windows it is a SOCKET
  * (32- or 64-bit unsigned integer depending on the architecture), where