Remove support for splitting multi-key commands per slot (valkey-io#23)

- Remove support for command splitting in cluster API
  Since old days (from hiredis-vip) there has been support for sending
  some commands that contains multiple keys, but which covers multiple
  slots. The client would split a command into multiple commands and send
  to each node handling each slot.
  This is unnecessary complex, so lets remove it in this early stage.

- Refactor function that prepares cluster commands    
  Rename and remove unnecessary checks in the internal function
  `command_format_by_slot()`.

Signed-off-by: Björn Svensson <[email protected]>

src/command.c

@@ -140,42 +140,6 @@ cmddef *valkey_lookup_cmd(const char *arg0, uint32_t arg0_len, const char *arg1,
     return NULL;
 }
 
-/*
- * Return true, if the valkey command is a vector command accepting one or
- * more keys, otherwise return false
- * Format: command key [ key ... ]
- */
-static int valkey_argx(struct cmd *r) {
-    switch (r->type) {
-    case CMD_REQ_VALKEY_EXISTS:
-    case CMD_REQ_VALKEY_MGET:
-    case CMD_REQ_VALKEY_DEL:
-        return 1;
-
-    default:
-        break;
-    }
-
-    return 0;
-}
-
-/*
- * Return true, if the valkey command is a vector command accepting one or
- * more key-value pairs, otherwise return false
- * Format: command key value [ key value ... ]
- */
-static int valkey_argkvx(struct cmd *r) {
-    switch (r->type) {
-    case CMD_REQ_VALKEY_MSET:
-        return 1;
-
-    default:
-        break;
-    }
-
-    return 0;
-}
-
 /* Parses a bulk string starting at 'p' and ending somewhere before 'end'.
  * Returns the remaining of the input after consuming the bulk string. The
  * pointers *str and *len are pointed to the parsed string and its length. On
@@ -357,22 +321,6 @@ void valkey_parse_cmd(struct cmd *r) {
     if (!push_keypos(r, arg, arglen))
         goto oom;
 
-    /* Special commands where we want all keys (not only the first key). */
-    if (valkey_argx(r) || valkey_argkvx(r)) {
-        /* argx:   MGET key [ key ... ] */
-        /* argkvx: MSET key value [ key value ... ] */
-        if (valkey_argkvx(r) && rnarg % 2 == 0)
-            goto error;
-        for (uint32_t i = 2; i < rnarg; i++) {
-            if ((p = valkey_parse_bulk(p, end, &arg, &arglen)) == NULL)
-                goto error;
-            if (valkey_argkvx(r) && i % 2 == 0)
-                continue; /* not a key */
-            if (!push_keypos(r, arg, arglen))
-                goto oom;
-        }
-    }
-
 done:
     ASSERT(r->type > CMD_UNKNOWN && r->type < CMD_SENTINEL);
     r->result = CMD_PARSE_OK;
@@ -428,7 +376,6 @@ struct cmd *command_get(void) {
     command->slot_num = -1;
     command->frag_seq = NULL;
     command->reply = NULL;
-    command->sub_commands = NULL;
     command->node_addr = NULL;
 
     command->keys = vkarray_create(1, sizeof(struct keypos));
@@ -468,10 +415,6 @@ void command_destroy(struct cmd *command) {
 
     freeReplyObject(command->reply);
 
-    if (command->sub_commands != NULL) {
-        listRelease(command->sub_commands);
-    }
-
     if (command->node_addr != NULL) {
         sdsfree(command->node_addr);
         command->node_addr = NULL;

src/command.h

@@ -90,17 +90,13 @@ struct cmd {
     /* Command destination */
     int slot_num;    /* Command should be sent to slot.
                       * Set to -1 if command is sent to a given node,
-                      * or if a slot can not be found or calculated,
-                      * or if its a multi-key command cross different
-                      * nodes (cross slot) */
+                      * or if a slot can not be found or calculated. */
     char *node_addr; /* Command sent to this node address */
 
     struct cmd *
         *frag_seq; /* sequence of fragment command, map from keys to fragments*/
 
     valkeyReply *reply;
-
-    hilist *sub_commands; /* just for pipeline and multi-key commands */
 };
 
 void valkey_parse_cmd(struct cmd *r);