Update request/response policies. (#12417)

changing the response and request policy of a few commands,
see https://redis.io/docs/reference/command-tips

1. RANDOMKEY used to have no response policy, which means
  that when sent to multiple shards, the responses should be aggregated.
  this normally applies to commands that return arrays, but since RANDOMKEY
  replies with a simple string, it actually requires a SPECIAL response policy
  (for the client to select just one)
2. SCAN used to have no response policy, but although the key names part of
  the response can be aggregated, the cursor part certainly can't.
3. MSETNX had a request policy of MULTI_SHARD and response policy of AGG_MIN,
  but in fact the contract with MSETNX is that when one key exists, it returns 0
  and doesn't set any key, routing it to multiple shards would mean that if one failed
  and another succeeded, it's atomicity is broken and it's impossible to return a valid
  response to the caller.

Co-authored-by: Shachar Langbeheim <shachlan@amazon.com>
Co-authored-by: Oran Agra <oran@redislabs.com>

src/commands.def

@@ -2328,6 +2328,7 @@ struct COMMAND_ARG PTTL_Args[] = {
 /* RANDOMKEY tips */
 const char *RANDOMKEY_Tips[] = {
 "request_policy:all_shards",
+"response_policy:special",
 "nondeterministic_output",
 };
 #endif
@@ -2437,6 +2438,7 @@ commandHistory SCAN_History[] = {
 const char *SCAN_Tips[] = {
 "nondeterministic_output",
 "request_policy:special",
+"response_policy:special",
 };
 #endif
 
@@ -10263,10 +10265,7 @@ struct COMMAND_ARG MSET_Args[] = {
 
 #ifndef SKIP_CMD_TIPS_TABLE
 /* MSETNX tips */
-const char *MSETNX_Tips[] = {
+#define MSETNX_Tips NULL
-"request_policy:multi_shard",
-"response_policy:agg_min",
-};
 #endif
 
 #ifndef SKIP_CMD_KEY_SPECS_TABLE
@@ -10621,11 +10620,11 @@ struct COMMAND_STRUCT redisCommandTable[] = {
 {MAKE_CMD("pexpireat","Sets the expiration time of a key to a Unix milliseconds timestamp.","O(1)","2.6.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,PEXPIREAT_History,1,PEXPIREAT_Tips,0,pexpireatCommand,-3,CMD_WRITE|CMD_FAST,ACL_CATEGORY_KEYSPACE,PEXPIREAT_Keyspecs,1,NULL,3),.args=PEXPIREAT_Args},
 {MAKE_CMD("pexpiretime","Returns the expiration time of a key as a Unix milliseconds timestamp.","O(1)","7.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,PEXPIRETIME_History,0,PEXPIRETIME_Tips,0,pexpiretimeCommand,2,CMD_READONLY|CMD_FAST,ACL_CATEGORY_KEYSPACE,PEXPIRETIME_Keyspecs,1,NULL,1),.args=PEXPIRETIME_Args},
 {MAKE_CMD("pttl","Returns the expiration time in milliseconds of a key.","O(1)","2.6.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,PTTL_History,1,PTTL_Tips,1,pttlCommand,2,CMD_READONLY|CMD_FAST,ACL_CATEGORY_KEYSPACE,PTTL_Keyspecs,1,NULL,1),.args=PTTL_Args},
-{MAKE_CMD("randomkey","Returns a random key name from the database.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,RANDOMKEY_History,0,RANDOMKEY_Tips,2,randomkeyCommand,1,CMD_READONLY|CMD_TOUCHES_ARBITRARY_KEYS,ACL_CATEGORY_KEYSPACE,RANDOMKEY_Keyspecs,0,NULL,0)},
+{MAKE_CMD("randomkey","Returns a random key name from the database.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,RANDOMKEY_History,0,RANDOMKEY_Tips,3,randomkeyCommand,1,CMD_READONLY|CMD_TOUCHES_ARBITRARY_KEYS,ACL_CATEGORY_KEYSPACE,RANDOMKEY_Keyspecs,0,NULL,0)},
 {MAKE_CMD("rename","Renames a key and overwrites the destination.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,RENAME_History,0,RENAME_Tips,0,renameCommand,3,CMD_WRITE,ACL_CATEGORY_KEYSPACE,RENAME_Keyspecs,2,NULL,2),.args=RENAME_Args},
 {MAKE_CMD("renamenx","Renames a key only when the target key name doesn't exist.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,RENAMENX_History,1,RENAMENX_Tips,0,renamenxCommand,3,CMD_WRITE|CMD_FAST,ACL_CATEGORY_KEYSPACE,RENAMENX_Keyspecs,2,NULL,2),.args=RENAMENX_Args},
 {MAKE_CMD("restore","Creates a key from the serialized representation of a value.","O(1) to create the new key and additional O(N*M) to reconstruct the serialized value, where N is the number of Redis objects composing the value and M their average size. For small string values the time complexity is thus O(1)+O(1*M) where M is small, so simply O(1). However for sorted set values the complexity is O(N*M*log(N)) because inserting values into sorted sets is O(log(N)).","2.6.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,RESTORE_History,3,RESTORE_Tips,0,restoreCommand,-4,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_KEYSPACE|ACL_CATEGORY_DANGEROUS,RESTORE_Keyspecs,1,NULL,7),.args=RESTORE_Args},
-{MAKE_CMD("scan","Iterates over the key names in the database.","O(1) for every call. O(N) for a complete iteration, including enough command calls for the cursor to return back to 0. N is the number of elements inside the collection.","2.8.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,SCAN_History,1,SCAN_Tips,2,scanCommand,-2,CMD_READONLY|CMD_TOUCHES_ARBITRARY_KEYS,ACL_CATEGORY_KEYSPACE,SCAN_Keyspecs,0,NULL,4),.args=SCAN_Args},
+{MAKE_CMD("scan","Iterates over the key names in the database.","O(1) for every call. O(N) for a complete iteration, including enough command calls for the cursor to return back to 0. N is the number of elements inside the collection.","2.8.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,SCAN_History,1,SCAN_Tips,3,scanCommand,-2,CMD_READONLY|CMD_TOUCHES_ARBITRARY_KEYS,ACL_CATEGORY_KEYSPACE,SCAN_Keyspecs,0,NULL,4),.args=SCAN_Args},
 {MAKE_CMD("sort","Sorts the elements in a list, a set, or a sorted set, optionally storing the result.","O(N+M*log(M)) where N is the number of elements in the list or set to sort, and M the number of returned elements. When the elements are not sorted, complexity is O(N).","1.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,SORT_History,0,SORT_Tips,0,sortCommand,-2,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_SET|ACL_CATEGORY_SORTEDSET|ACL_CATEGORY_LIST|ACL_CATEGORY_DANGEROUS,SORT_Keyspecs,3,sortGetKeys,7),.args=SORT_Args},
 {MAKE_CMD("sort_ro","Returns the sorted elements of a list, a set, or a sorted set.","O(N+M*log(M)) where N is the number of elements in the list or set to sort, and M the number of returned elements. When the elements are not sorted, complexity is O(N).","7.0.0",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,SORT_RO_History,0,SORT_RO_Tips,0,sortroCommand,-2,CMD_READONLY,ACL_CATEGORY_SET|ACL_CATEGORY_SORTEDSET|ACL_CATEGORY_LIST|ACL_CATEGORY_DANGEROUS,SORT_RO_Keyspecs,2,sortROGetKeys,6),.args=SORT_RO_Args},
 {MAKE_CMD("touch","Returns the number of existing keys out of those specified after updating the time they were last accessed.","O(N) where N is the number of keys that will be touched.","3.2.1",CMD_DOC_NONE,NULL,NULL,"generic",COMMAND_GROUP_GENERIC,TOUCH_History,0,TOUCH_Tips,2,touchCommand,-2,CMD_READONLY|CMD_FAST,ACL_CATEGORY_KEYSPACE,TOUCH_Keyspecs,1,NULL,1),.args=TOUCH_Args},
@@ -10827,7 +10826,7 @@ struct COMMAND_STRUCT redisCommandTable[] = {
 {MAKE_CMD("lcs","Finds the longest common substring.","O(N*M) where N and M are the lengths of s1 and s2, respectively","7.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,LCS_History,0,LCS_Tips,0,lcsCommand,-3,CMD_READONLY,ACL_CATEGORY_STRING,LCS_Keyspecs,1,NULL,6),.args=LCS_Args},
 {MAKE_CMD("mget","Atomically returns the string values of one or more keys.","O(N) where N is the number of keys to retrieve.","1.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,MGET_History,0,MGET_Tips,1,mgetCommand,-2,CMD_READONLY|CMD_FAST,ACL_CATEGORY_STRING,MGET_Keyspecs,1,NULL,1),.args=MGET_Args},
 {MAKE_CMD("mset","Atomically creates or modifies the string values of one or more keys.","O(N) where N is the number of keys to set.","1.0.1",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,MSET_History,0,MSET_Tips,2,msetCommand,-3,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_STRING,MSET_Keyspecs,1,NULL,1),.args=MSET_Args},
-{MAKE_CMD("msetnx","Atomically modifies the string values of one or more keys only when all keys don't exist.","O(N) where N is the number of keys to set.","1.0.1",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,MSETNX_History,0,MSETNX_Tips,2,msetnxCommand,-3,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_STRING,MSETNX_Keyspecs,1,NULL,1),.args=MSETNX_Args},
+{MAKE_CMD("msetnx","Atomically modifies the string values of one or more keys only when all keys don't exist.","O(N) where N is the number of keys to set.","1.0.1",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,MSETNX_History,0,MSETNX_Tips,0,msetnxCommand,-3,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_STRING,MSETNX_Keyspecs,1,NULL,1),.args=MSETNX_Args},
 {MAKE_CMD("psetex","Sets both string value and expiration time in milliseconds of a key. The key is created if it doesn't exist.","O(1)","2.6.0",CMD_DOC_DEPRECATED,"`SET` with the `PX` argument","2.6.12","string",COMMAND_GROUP_STRING,PSETEX_History,0,PSETEX_Tips,0,psetexCommand,4,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_STRING,PSETEX_Keyspecs,1,NULL,3),.args=PSETEX_Args},
 {MAKE_CMD("set","Sets the string value of a key, ignoring its type. The key is created if it doesn't exist.","O(1)","1.0.0",CMD_DOC_NONE,NULL,NULL,"string",COMMAND_GROUP_STRING,SET_History,4,SET_Tips,0,setCommand,-3,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_STRING,SET_Keyspecs,1,setGetKeys,5),.args=SET_Args},
 {MAKE_CMD("setex","Sets the string value and expiration time of a key. Creates the key if it doesn't exist.","O(1)","2.0.0",CMD_DOC_DEPRECATED,"`SET` with the `EX` argument","2.6.12","string",COMMAND_GROUP_STRING,SETEX_History,0,SETEX_Tips,0,setexCommand,4,CMD_WRITE|CMD_DENYOOM,ACL_CATEGORY_STRING,SETEX_Keyspecs,1,NULL,3),.args=SETEX_Args},

src/commands/msetnx.json

@@ -13,10 +13,6 @@
         "acl_categories": [
             "STRING"
         ],
-        "command_tips": [
-            "REQUEST_POLICY:MULTI_SHARD",
-            "RESPONSE_POLICY:AGG_MIN"
-        ],
         "key_specs": [
             {
                 "flags": [

src/commands/randomkey.json

@@ -15,6 +15,7 @@
         ],
         "command_tips": [
             "REQUEST_POLICY:ALL_SHARDS",
+            "RESPONSE_POLICY:SPECIAL",
             "NONDETERMINISTIC_OUTPUT"
         ],
         "reply_schema": {

src/commands/scan.json

@@ -21,7 +21,8 @@
         ],
         "command_tips": [
             "NONDETERMINISTIC_OUTPUT",
-            "REQUEST_POLICY:SPECIAL"
+            "REQUEST_POLICY:SPECIAL",
+            "RESPONSE_POLICY:SPECIAL"
         ],
         "arguments": [
             {