Improve comments after merging #5834.

src/module.c

@@ -523,12 +523,17 @@ void RedisModuleCommandDispatcher(client *c) {
     moduleFreeContext(&ctx);
 
     /* In some cases processMultibulkBuffer uses sdsMakeRoomFor to
-     * expand the querybuf, but later in some cases it uses that query
-     * buffer as is for an argv element (see "Optimization"), which means
-     * that the sds in argv may have a lot of wasted space, and then in case
-     * modules keep that argv RedisString inside their data structure, this
-     * space waste will remain for long (until restarted from rdb). */
+     * expand the query buffer, and in order to avoid a big object copy
+     * the query buffer SDS may be used directly as the SDS string backing
+     * the client argument vectors: sometimes this will result in the SDS
+     * string having unused space at the end. Later if a module takes ownership
+     * of the RedisString, such space will be wasted forever. Inside the
+     * Redis core this is not a problem because tryObjectEncoding() is called
+     * before storing strings in the key space. Here we need to do it
+     * for the module. */
     for (int i = 0; i < c->argc; i++) {
+        /* Only do the work if the module took ownership of the object:
+         * in that case the refcount is no longer 1. */
         if (c->argv[i]->refcount > 1)
             trimStringObjectIfNeeded(c->argv[i]);
     }

src/object.c

@@ -415,10 +415,11 @@ int isObjectRepresentableAsLongLong(robj *o, long long *llval) {
     }
 }
 
+/* Optimize the SDS string inside the string object to require little space,
+ * in case there is more than 10% of free space at the end of the SDS
+ * string. This happens because SDS strings tend to overallocate to avoid
+ * wasting too much time in allocations when appending to the string. */
 void trimStringObjectIfNeeded(robj *o) {
-    /* Optimize the SDS string inside the string object to require
-     * little space, in case there is more than 10% of free space
-     * at the end of the SDS string. */
     if (o->encoding == OBJ_ENCODING_RAW &&
         sdsavail(o->ptr) > sdslen(o->ptr)/10)
     {