1. 16 Mar, 2023 1 commit
    • Meir Shpilraien (Spielrein)'s avatar
      Support for RM_Call on blocking commands (#11568) · d0da0a6a
      Meir Shpilraien (Spielrein) authored
      Allow running blocking commands from within a module using `RM_Call`.
      
      Today, when `RM_Call` is used, the fake client that is used to run command
      is marked with `CLIENT_DENY_BLOCKING` flag. This flag tells the command
      that it is not allowed to block the client and in case it needs to block, it must
      fallback to some alternative (either return error or perform some default behavior).
      For example, `BLPOP` fallback to simple `LPOP` if it is not allowed to block.
      
      All the commands must respect the `CLIENT_DENY_BLOCKING` flag (including
      module commands). When the command invocation finished, Redis asserts that
      the client was not blocked.
      
      This PR introduces the ability to call blocking command using `RM_Call` by
      passing a callback that will be called when the client will get unblocked.
      In order to do that, the user must explicitly say that he allow to perform blocking
      command by passing a new format specifier argument, `K`, to the `RM_Call`
      function. This new flag will tell Redis that it is allow to run blocking command
      and block the client. In case the command got blocked, Redis will return a new
      type of call reply (`REDISMODULE_REPLY_PROMISE`). This call reply indicates
      that the command got blocked and the user can set the on_unblocked handler using
      `RM_CallReplyPromiseSetUnblockHandler`.
      
      When clients gets unblocked, it eventually reaches `processUnblockedClients` function.
      This is where we check if the client is a fake module client and if it is, we call the unblock
      callback instead of performing the usual unblock operations.
      
      **Notice**: `RM_CallReplyPromiseSetUnblockHandler` must be called atomically
      along side the command invocation (without releasing the Redis lock in between).
      In addition, unlike other CallReply types, the promise call reply must be released
      by the module when the Redis GIL is acquired.
      
      The module can abort the execution on the blocking command (if it was not yet
      executed) using `RM_CallReplyPromiseAbort`. the API will return `REDISMODULE_OK`
      on success and `REDISMODULE_ERR` if the operation is already executed.
      **Notice** that in case of misbehave module, Abort might finished successfully but the
      operation will not really be aborted. This can only happened if the module do not respect
      the disconnect callback of the blocked client. 
      For pure Redis commands this can not happened.
      
      ### Atomicity Guarantees
      
      The API promise that the unblock handler will run atomically as an execution unit.
      This means that all the operation performed on the unblock handler will be wrapped
      with a multi exec transaction when replicated to the replica and AOF.
      The API **do not** grantee any other atomicity properties such as when the unblock
      handler will be called. This gives us the flexibility to strengthen the grantees (or not)
      in the future if we will decide that we need a better guarantees.
      
      That said, the implementation **does** provide a better guarantees when performing
      pure Redis blocking command like `BLPOP`. In this case the unblock handler will run
      atomically with the operation that got unblocked (for example, in case of `BLPOP`, the
      unblock handler will run atomically with the `LPOP` operation that run when the command
      got unblocked). This is an implementation detail that might be change in the future and the
      module writer should not count on that.
      
      ### Calling blocking commands while running on script mode (`S`)
      
      `RM_Call` script mode (`S`) was introduced on #0372. It is used for usecases where the
      command that was invoked on `RM_Call` comes from a user input and we want to make
      sure the user will not run dangerous commands like `shutdown`. Some command, such
      as `BLPOP`, are marked with `NO_SCRIPT` flag, which means they will not be allowed on
      script mode. Those commands are marked with  `NO_SCRIPT` just because they are
      blocking commands and not because they are dangerous. Now that we can run blocking
      commands on RM_Call, there is no real reason not to allow such commands on script mode.
      
      The underline problem is that the `NO_SCRIPT` flag is abused to also mark some of the
      blocking commands (notice that those commands know not to block the client if it is not
      allowed to do so, and have a fallback logic to such cases. So even if those commands
      were not marked with `NO_SCRIPT` flag, it would not harm Redis, and today we can
      already run those commands within multi exec).
      
      In addition, not all blocking commands are marked with `NO_SCRIPT` flag, for example
      `blmpop` are not marked and can run from within a script.
      
      Those facts shows that there are some ambiguity about the meaning of the `NO_SCRIPT`
      flag, and its not fully clear where it should be use.
      
      The PR suggest that blocking commands should not be marked with `NO_SCRIPT` flag,
      those commands should handle `CLIENT_DENY_BLOCKING` flag and only block when
      it's safe (like they already does today). To achieve that, the PR removes the `NO_SCRIPT`
      flag from the following commands:
      * `blmove`
      * `blpop`
      * `brpop`
      * `brpoplpush`
      * `bzpopmax`
      * `bzpopmin`
      * `wait`
      
      This might be considered a breaking change as now, on scripts, instead of getting
      `command is not allowed from script` error, the user will get some fallback behavior
      base on the command implementation. That said, the change matches the behavior
      of scripts and multi exec with respect to those commands and allow running them on
      `RM_Call` even when script mode is used.
      
      ### Additional RedisModule API and changes
      
      * `RM_BlockClientSetPrivateData` - Set private data on the blocked client without the
        need to unblock the client. This allows up to set the promise CallReply as the private
        data of the blocked client and abort it if the client gets disconnected.
      * `RM_BlockClientGetPrivateData` - Return the current private data set on a blocked client.
        We need it so we will have access to this private data on the disconnect callback.
      * On RM_Call, the returned reply will be added to the auto memory context only if auto
        memory is enabled, this allows us to keep the call reply for longer time then the context
        lifetime and does not force an unneeded borrow relationship between the CallReply and
        the RedisModuleContext.
      d0da0a6a
  2. 11 Mar, 2023 1 commit
    • guybe7's avatar
      Add reply_schema to command json files (internal for now) (#10273) · 4ba47d2d
      guybe7 authored
      Work in progress towards implementing a reply schema as part of COMMAND DOCS, see #9845
      Since ironing the details of the reply schema of each and every command can take a long time, we
      would like to merge this PR when the infrastructure is ready, and let this mature in the unstable branch.
      Meanwhile the changes of this PR are internal, they are part of the repo, but do not affect the produced build.
      
      ### Background
      In #9656 we add a lot of information about Redis commands, but we are missing information about the replies
      
      ### Motivation
      1. Documentation. This is the primary goal.
      2. It should be possible, based on the output of COMMAND, to be able to generate client code in typed
        languages. In order to do that, we need Redis to tell us, in detail, what each reply looks like.
      3. We would like to build a fuzzer that verifies the reply structure (for now we use the existing
        testsuite, see the "Testing" section)
      
      ### Schema
      The idea is to supply some sort of schema for the various replies of each command.
      The schema will describe the conceptual structure of the reply (for generated clients), as defined in RESP3.
      Note that the reply structure itself may change, depending on the arguments (e.g. `XINFO STREAM`, with
      and without the `FULL` modifier)
      We decided to use the standard json-schema (see https://json-schema.org/) as the reply-schema.
      
      Example for `BZPOPMIN`:
      ```
      "reply_schema": {
          "oneOf": [
              {
                  "description": "Timeout reached and no elements were popped.",
                  "type": "null"
              },
              {
                  "description": "The keyname, popped member, and its score.",
                  "type": "array",
                  "minItems": 3,
                  "maxItems": 3,
                  "items": [
                      {
                          "description": "Keyname",
                          "type": "string"
                      },
                      {
                          "description": "Member",
                          "type": "string"
                      },
                      {
                          "description": "Score",
                          "type": "number"
                      }
                  ]
              }
          ]
      }
      ```
      
      #### Notes
      1.  It is ok that some commands' reply structure depends on the arguments and it's the caller's responsibility
        to know which is the relevant one. this comes after looking at other request-reply systems like OpenAPI,
        where the reply schema can also be oneOf and the caller is responsible to know which schema is the relevant one.
      2. The reply schemas will describe RESP3 replies only. even though RESP3 is structured, we want to use reply
        schema for documentation (and possibly to create a fuzzer that validates the replies)
      3. For documentation, the description field will include an explanation of the scenario in which the reply is sent,
        including any relation to arguments. for example, for `ZRANGE`'s two schemas we will need to state that one
        is with `WITHSCORES` and the other is without.
      4. For documentation, there will be another optional field "notes" in which we will add a short description of
        the representation in RESP2, in case it's not trivial (RESP3's `ZRANGE`'s nested array vs. RESP2's flat
        array, for example)
      
      Given the above:
      1. We can generate the "return" section of all commands in [redis-doc](https://redis.io/commands/)
        (given that "description" and "notes" are comprehensive enough)
      2. We can generate a client in a strongly typed language (but the return type could be a conceptual
        `union` and the caller needs to know which schema is relevant). see the section below for RESP2 support.
      3. We can create a fuzzer for RESP3.
      
      ### Limitations (because we are using the standard json-schema)
      The problem is that Redis' replies are more diverse than what the json format allows. This means that,
      when we convert the reply to a json (in order to validate the schema against it), we lose information (see
      the "Testing" section below).
      The other option would have been to extend the standard json-schema (and json format) to include stuff
      like sets, bulk-strings, error-string, etc. but that would mean also extending the schema-validator - and that
      seemed like too much work, so we decided to compromise.
      
      Examples:
      1. We cannot tell the difference between an "array" and a "set"
      2. We cannot tell the difference between simple-string and bulk-string
      3. we cannot verify true uniqueness of items in commands like ZRANGE: json-schema doesn't cover the
        case of two identical members with different scores (e.g. `[["m1",6],["m1",7]]`) because `uniqueItems`
        compares (member,score) tuples and not just the member name. 
      
      ### Testing
      This commit includes some changes inside Redis in order to verify the schemas (existing and future ones)
      are indeed correct (i.e. describe the actual response of Redis).
      To do that, we added a debugging feature to Redis that causes it to produce a log of all the commands
      it executed and their replies.
      For that, Redis needs to be compiled with `-DLOG_REQ_RES` and run with
      `--reg-res-logfile <file> --client-default-resp 3` (the testsuite already does that if you run it with
      `--log-req-res --force-resp3`)
      You should run the testsuite with the above args (and `--dont-clean`) in order to make Redis generate
      `.reqres` files (same dir as the `stdout` files) which contain request-response pairs.
      These files are later on processed by `./utils/req-res-log-validator.py` which does:
      1. Goes over req-res files, generated by redis-servers, spawned by the testsuite (see logreqres.c)
      2. For each request-response pair, it validates the response against the request's reply_schema
        (obtained from the extended COMMAND DOCS)
      5. In order to get good coverage of the Redis commands, and all their different replies, we chose to use
        the existing redis test suite, rather than attempt to write a fuzzer.
      
      #### Notes about RESP2
      1. We will not be able to use the testing tool to verify RESP2 replies (we are ok with that, it's time to
        accept RESP3 as the future RESP)
      2. Since the majority of the test suite is using RESP2, and we want the server to reply with RESP3
        so that we can validate it, we will need to know how to convert the actual reply to the one expected.
         - number and boolean are always strings in RESP2 so the conversion is easy
         - objects (maps) are always a flat array in RESP2
         - others (nested array in RESP3's `ZRANGE` and others) will need some special per-command
           handling (so the client will not be totally auto-generated)
      
      Example for ZRANGE:
      ```
      "reply_schema": {
          "anyOf": [
              {
                  "description": "A list of member elements",
                  "type": "array",
                  "uniqueItems": true,
                  "items": {
                      "type": "string"
                  }
              },
              {
                  "description": "Members and their scores. Returned in case `WITHSCORES` was used.",
                  "notes": "In RESP2 this is returned as a flat array",
                  "type": "array",
                  "uniqueItems": true,
                  "items": {
                      "type": "array",
                      "minItems": 2,
                      "maxItems": 2,
                      "items": [
                          {
                              "description": "Member",
                              "type": "string"
                          },
                          {
                              "description": "Score",
                              "type": "number"
                          }
                      ]
                  }
              }
          ]
      }
      ```
      
      ### Other changes
      1. Some tests that behave differently depending on the RESP are now being tested for both RESP,
        regardless of the special log-req-res mode ("Pub/Sub PING" for example)
      2. Update the history field of CLIENT LIST
      3. Added basic tests for commands that were not covered at all by the testsuite
      
      ### TODO
      
      - [x] (maybe a different PR) add a "condition" field to anyOf/oneOf schemas that refers to args. e.g.
        when `SET` return NULL, the condition is `arguments.get||arguments.condition`, for `OK` the condition
        is `!arguments.get`, and for `string` the condition is `arguments.get` - https://github.com/redis/redis/issues/11896
      - [x] (maybe a different PR) also run `runtest-cluster` in the req-res logging mode
      - [x] add the new tests to GH actions (i.e. compile with `-DLOG_REQ_RES`, run the tests, and run the validator)
      - [x] (maybe a different PR) figure out a way to warn about (sub)schemas that are uncovered by the output
        of the tests - https://github.com/redis/redis/issues/11897
      - [x] (probably a separate PR) add all missing schemas
      - [x] check why "SDOWN is triggered by misconfigured instance replying with errors" fails with --log-req-res
      - [x] move the response transformers to their own file (run both regular, cluster, and sentinel tests - need to
        fight with the tcl including mechanism a bit)
      - [x] issue: module API - https://github.com/redis/redis/issues/11898
      - [x] (probably a separate PR): improve schemas: add `required` to `object`s - https://github.com/redis/redis/issues/11899
      
      Co-authored-by: default avatarOzan Tezcan <ozantezcan@gmail.com>
      Co-authored-by: default avatarHanna Fadida <hanna.fadida@redislabs.com>
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      Co-authored-by: default avatarShaya Potter <shaya@redislabs.com>
      4ba47d2d
  3. 20 Jan, 2022 1 commit
    • guybe7's avatar
      Add command tips to COMMAND DOCS (#10104) · 10bbeb68
      guybe7 authored
      Adding command tips (see https://redis.io/topics/command-tips) to commands.
      
      Breaking changes:
      1. Removed the "random" and "sort_for_script" flags. They are now command tips.
      (this isn't affecting redis behavior since #9812, but could affect some client applications
      that's relying on COMMAND command flags)
      
      Summary of changes:
      1. add BLOCKING flag (new flag) for all commands that could block. The ACL category with
        the same name is now implicit.
      2. move RANDOM flag to a `nondeterministic_output` tip
      3. move SORT_FOR_SCRIPT flag to `nondeterministic_output_order` tip
      3. add REQUEST_POLICY and RESPONSE_POLICY where appropriate as documented in the tips
      4. deprecate (ignore) the `random` flag for RM_CreateCommand
      
      Other notes:
      1. Proxies need to send `RANDOMKEY` to all shards and then select one key randomly.
        The other option is to pick a random shard and transfer `RANDOMKEY `to it, but that scheme
        fails if this specific shard is empty
      2. Remove CMD_RANDOM from `XACK` (i.e. XACK does not have RANDOM_OUTPUT)
         It was added in 9e4fb96c, I guess by mistake.
         Also from `(P)EXPIRETIME` (new command, was flagged "random" by mistake).
      3. Add `nondeterministic_output` to `OBJECT ENCODING` (for the same reason `XTRIM` has it:
         the reply may differ depending on the internal representation in memory)
      4. RANDOM on `HGETALL` was wrong (there due to a limitation of the old script sorting logic), now
        it's `nondeterministic_output_order`
      5. Unrelated: Hide CMD_PROTECTED from COMMAND
      10bbeb68
  4. 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