1. 14 Jan, 2022 1 commit
    • Meir Shpilraien (Spielrein)'s avatar
      Function Flags support (no-writes, no-cluster, allow-state, allow-oom) (#10066) · 4db4b434
      Meir Shpilraien (Spielrein) authored
      # Redis Functions Flags
      
      Following the discussion on #10025 Added Functions Flags support.
      The PR is divided to 2 sections:
      * Add named argument support to `redis.register_function` API.
      * Add support for function flags
      
      ## `redis.register_function` named argument support
      
      The first part of the PR adds support for named argument on `redis.register_function`, example:
      ```
      redis.register_function{
          function_name='f1',
          callback=function()
              return 'hello'
          end,
          description='some desc'
      }
      ```
      
      The positional arguments is also kept, which means that it still possible to write:
      ```
      redis.register_function('f1', function() return 'hello' end)
      ```
      
      But notice that it is no longer possible to pass the optional description argument on the positional
      argument version. Positional argument was change to allow passing only the mandatory arguments
      (function name and callback). To pass more arguments the user must use the named argument version.
      
      As with positional arguments, the `function_name` and `callback` is mandatory and an error will be
      raise if those are missing. Also, an error will be raise if an unknown argument name is given or the
      arguments type is wrong.
      
      Tests was added to verify the new syntax.
      
      ## Functions Flags
      
      The second part of the PR is adding functions flags support.
      Flags are given to Redis when the engine calls `functionLibCreateFunction`, supported flags are:
      
      * `no-writes` - indicating the function perform no writes which means that it is OK to run it on:
         * read-only replica
         * Using FCALL_RO
         * If disk error detected
         
         It will not be possible to run a function in those situations unless the function turns on the `no-writes` flag
      
      * `allow-oom` - indicate that its OK to run the function even if Redis is in OOM state, if the function will
        not turn on this flag it will not be possible to run it if OOM reached (even if the function declares `no-writes`
        and even if `fcall_ro` is used). If this flag is set, any command will be allow on OOM (even those that is
        marked with CMD_DENYOOM). The assumption is that this flag is for advance users that knows its
        meaning and understand what they are doing, and Redis trust them to not increase the memory usage.
        (e.g. it could be an INCR or a modification on an existing key, or a DEL command)
      
      * `allow-state` - indicate that its OK to run the function on stale replica, in this case we will also make
        sure the function is only perform `stale` commands and raise an error if not.
      
      * `no-cluster` - indicate to disallow running the function if cluster is enabled.
      
      Default behaviure of functions (if no flags is given):
      1. Allow functions to read and write
      2. Do not run functions on OOM
      3. Do not run functions on stale replica
      4. Allow functions on cluster
      
      ### Lua API for functions flags
      
      On Lua engine, it is possible to give functions flags as `flags` named argument:
      
      ```
      redis.register_function{function_name='f1', callback=function() return 1 end, flags={'no-writes', 'allow-oom'}, description='description'}
      ```
      
      The function flags argument must be a Lua table that contains all the requested flags, The following
      will result in an error:
      * Unknown flag
      * Wrong flag type
      
      Default behaviour is the same as if no flags are used.
      
      Tests were added to verify all flags functionality
      
      ## Additional changes
      * mark FCALL and FCALL_RO with CMD_STALE flag (unlike EVAL), so that they can run if the function was
        registered with the `allow-stale` flag.
      * Verify `CMD_STALE` on `scriptCall` (`redis.call`), so it will not be possible to call commands from script while
        stale unless the command is marked with the `CMD_STALE` flags. so that even if the function is allowed while
        stale we do not allow it to bypass the `CMD_STALE` flag of commands.
      * Flags section was added to `FUNCTION LIST` command to provide the set of flags for each function:
      ```
      > FUNCTION list withcode
      1)  1) "library_name"
          2) "test"
          3) "engine"
          4) "LUA"
          5) "description"
          6) (nil)
          7) "functions"
          8) 1) 1) "name"
                2) "f1"
                3) "description"
                4) (nil)
                5) "flags"
                6) (empty array)
          9) "library_code"
         10) "redis.register_function{function_name='f1', callback=function() return 1 end}"
      ```
      * Added API to get Redis version from within a script, The redis version can be provided using:
         1. `redis.REDIS_VERSION` - string representation of the redis version in the format of MAJOR.MINOR.PATH
         2. `redis.REDIS_VERSION_NUM` - number representation of the redis version in the format of `0x00MMmmpp`
            (`MM` - major, `mm` - minor,  `pp` - patch). The number version can be used to check if version is greater or less 
            another version. The string version can be used to return to the user or print as logs.
      
         This new API is provided to eval scripts and functions, it also possible to use this API during functions loading phase.
      4db4b434
  2. 15 Dec, 2021 1 commit
    • guybe7's avatar
      Auto-generate the command table from JSON files (#9656) · 86781600
      guybe7 authored
      Delete the hardcoded command table and replace it with an auto-generated table, based
      on a JSON file that describes the commands (each command must have a JSON file).
      
      These JSON files are the SSOT of everything there is to know about Redis commands,
      and it is reflected fully in COMMAND INFO.
      
      These JSON files are used to generate commands.c (using a python script), which is then
      committed to the repo and compiled.
      
      The purpose is:
      * Clients and proxies will be able to get much more info from redis, instead of relying on hard coded logic.
      * drop the dependency between Redis-user and the commands.json in redis-doc.
      * delete help.h and have redis-cli learn everything it needs to know just by issuing COMMAND (will be
        done in a separate PR)
      * redis.io should stop using commands.json and learn everything from Redis (ultimately one of the release
        artifacts should be a large JSON, containing all the information about all of the commands, which will be
        generated from COMMAND's reply)
      * the byproduct of this is:
        * module commands will be able to provide that info and possibly be more of a first-class citizens
        * in theory, one may be able to generate a redis client library for a strictly typed language, by using this info.
      
      ### Interface changes
      
      #### COMMAND INFO's reply change (and arg-less COMMAND)
      
      Before this commit the reply at index 7 contained the key-specs list
      and reply at index 8 contained the sub-commands list (Both unreleased).
      Now, reply at index 7 is a map of:
      - summary - short command description
      - since - debut version
      - group - command group
      - complexity - complexity string
      - doc-flags - flags used for documentation (e.g. "deprecated")
      - deprecated-since - if deprecated, from which version?
      - replaced-by - if deprecated, which command replaced it?
      - history - a list of (version, what-changed) tuples
      - hints - a list of strings, meant to provide hints for clients/proxies. see https://github.com/redis/redis/issues/9876
      - arguments - an array of arguments. each element is a map, with the possibility of nesting (sub-arguments)
      - key-specs - an array of keys specs (already in unstable, just changed location)
      - subcommands - a list of sub-commands (already in unstable, just changed location)
      - reply-schema - will be added in the future (see https://github.com/redis/redis/issues/9845)
      
      more details on these can be found in https://github.com/redis/redis-doc/pull/1697
      
      only the first three fields are mandatory 
      
      #### API changes (unreleased API obviously)
      
      now they take RedisModuleCommand opaque pointer instead of looking up the command by name
      
      - RM_CreateSubcommand
      - RM_AddCommandKeySpec
      - RM_SetCommandKeySpecBeginSearchIndex
      - RM_SetCommandKeySpecBeginSearchKeyword
      - RM_SetCommandKeySpecFindKeysRange
      - RM_SetCommandKeySpecFindKeysKeynum
      
      Currently, we did not add module API to provide additional information about their commands because
      we couldn't agree on how the API should look like, see https://github.com/redis/redis/issues/9944
      
      .
      
      ### Somehow related changes
      1. Literals should be in uppercase while placeholder in lowercase. Now all the GEO* command
         will be documented with M|KM|FT|MI and can take both lowercase and uppercase
      
      ### Unrelated changes
      1. Bugfix: no_madaory_keys was absent in COMMAND's reply
      2. expose CMD_MODULE as "module" via COMMAND
      3. have a dedicated uint64 for ACL categories (instead of having them in the same uint64 as command flags)
      Co-authored-by: default avatarItamar Haber <itamar@garantiadata.com>
      86781600