• Meir Shpilraien (Spielrein)'s avatar
    Unified Lua and modules reply parsing and added RESP3 support to RM_Call (#9202) · 2237131e
    Meir Shpilraien (Spielrein) authored
    
    
    ## Current state
    1. Lua has its own parser that handles parsing `reds.call` replies and translates them
      to Lua objects that can be used by the user Lua code. The parser partially handles
      resp3 (missing big number, verbatim, attribute, ...)
    2. Modules have their own parser that handles parsing `RM_Call` replies and translates
      them to RedisModuleCallReply objects. The parser does not support resp3.
    
    In addition, in the future, we want to add Redis Function (#8693) that will probably
    support more languages. At some point maintaining so many parsers will stop
    scaling (bug fixes and protocol changes will need to be applied on all of them).
    We will probably end up with different parsers that support different parts of the
    resp protocol (like we already have today with Lua and modules)
    
    ## PR Changes
    This PR attempt to unified the reply parsing of Lua and modules (and in the future
    Redis Function) by introducing a new parser unit (`resp_parser.c`). The new parser
    handles parsing the reply and calls different callbacks to allow the users (another
    unit that uses the parser, i.e, Lua, modules, or Redis Function) to analyze the reply.
    
    ### Lua API Additions
    The code that handles reply parsing on `scripting.c` was removed. Instead, it uses
    the resp_parser to parse and create a Lua object out of the reply. As mentioned
    above the Lua parser did not handle parsing big numbers, verbatim, and attribute.
    The new parser can handle those and so Lua also gets it for free.
    Those are translated to Lua objects in the following way:
    1. Big Number - Lua table `{'big_number':'<str representation for big number>'}`
    2. Verbatim - Lua table `{'verbatim_string':{'format':'<verbatim format>', 'string':'<verbatim string value>'}}`
    3. Attribute - currently ignored and not expose to the Lua parser, another issue will be open to decide how to expose it.
    
    Tests were added to check resp3 reply parsing on Lua
    
    ### Modules API Additions
    The reply parsing code on `module.c` was also removed and the new resp_parser is used instead.
    In addition, the RedisModuleCallReply was also extracted to a separate unit located on `call_reply.c`
    (in the future, this unit will also be used by Redis Function). A nice side effect of unified parsing is
    that modules now also support resp3. Resp3 can be enabled by giving `3` as a parameter to the
    fmt argument of `RM_Call`. It is also possible to give `0`, which will indicate an auto mode. i.e, Redis
    will automatically chose the reply protocol base on the current client set on the RedisModuleCtx
    (this mode will mostly be used when the module want to pass the reply to the client as is).
    In addition, the following RedisModuleAPI were added to allow analyzing resp3 replies:
    
    * New RedisModuleCallReply types:
       * `REDISMODULE_REPLY_MAP`
       * `REDISMODULE_REPLY_SET`
       * `REDISMODULE_REPLY_BOOL`
       * `REDISMODULE_REPLY_DOUBLE`
       * `REDISMODULE_REPLY_BIG_NUMBER`
       * `REDISMODULE_REPLY_VERBATIM_STRING`
       * `REDISMODULE_REPLY_ATTRIBUTE`
    
    * New RedisModuleAPI:
       * `RedisModule_CallReplyDouble` - getting double value from resp3 double reply
       * `RedisModule_CallReplyBool` - getting boolean value from resp3 boolean reply
       * `RedisModule_CallReplyBigNumber` - getting big number value from resp3 big number reply
       * `RedisModule_CallReplyVerbatim` - getting format and value from resp3 verbatim reply
       * `RedisModule_CallReplySetElement` - getting element from resp3 set reply
       * `RedisModule_CallReplyMapElement` - getting key and value from resp3 map reply
       * `RedisModule_CallReplyAttribute` - getting a reply attribute
       * `RedisModule_CallReplyAttributeElement` - getting key and value from resp3 attribute reply
       
    * New context flags:
       * `REDISMODULE_CTX_FLAGS_RESP3` - indicate that the client is using resp3
    
    Tests were added to check the new RedisModuleAPI
    
    ### Modules API Changes
    * RM_ReplyWithCallReply might return REDISMODULE_ERR if the given CallReply is in resp3
      but the client expects resp2. This is not a breaking change because in order to get a resp3
      CallReply one needs to specifically specify `3` as a parameter to the fmt argument of
      `RM_Call` (as mentioned above).
    
    Tests were added to check this change
    
    ### More small Additions
    * Added `debug set-disable-deny-scripts` that allows to turn on and off the commands no-script
    flag protection. This is used by the Lua resp3 tests so it will be possible to run `debug protocol`
    and check the resp3 parsing code.
    Co-authored-by: default avatarOran Agra <oran@redislabs.com>
    Co-authored-by: default avatarYossi Gottlieb <yossigo@gmail.com>
    2237131e
resp_parser.c 8.78 KB