1. 09 Mar, 2022 1 commit
    • Oran Agra's avatar
      Some adjustments to command hints. (#10375) · 311a757c
      Oran Agra authored
      * stats and latency commands have non-deterministic output.
      * the ones about latency should be sent to ALL_NODES (considering
        reads from replicas)
      * the ones about running scripts and memory usage only to masters.
      * stats aggregation is SPECIAL (like in INFO)
      311a757c
  2. 05 Jan, 2022 1 commit
    • filipe oliveira's avatar
      Added INFO LATENCYSTATS section: latency by percentile distribution/latency by... · 5dd15443
      filipe oliveira authored
      
      Added INFO LATENCYSTATS section: latency by percentile distribution/latency by cumulative distribution of latencies (#9462)
      
      # Short description
      
      The Redis extended latency stats track per command latencies and enables:
      - exporting the per-command percentile distribution via the `INFO LATENCYSTATS` command.
        **( percentile distribution is not mergeable between cluster nodes ).**
      - exporting the per-command cumulative latency distributions via the `LATENCY HISTOGRAM` command.
        Using the cumulative distribution of latencies we can merge several stats from different cluster nodes
        to calculate aggregate metrics .
      
      By default, the extended latency monitoring is enabled since the overhead of keeping track of the
      command latency is very small.
       
      If you don't want to track extended latency metrics, you can easily disable it at runtime using the command:
       - `CONFIG SET latency-tracking no`
      
      By default, the exported latency percentiles are the p50, p99, and p999.
      You can alter them at runtime using the command:
      - `CONFIG SET latency-tracking-info-percentiles "0.0 50.0 100.0"`
      
      
      ## Some details:
      - The total size per histogram should sit around 40 KiB. We only allocate those 40KiB when a command
        was called for the first time.
      - With regards to the WRITE overhead As seen below, there is no measurable overhead on the achievable
        ops/sec or full latency spectrum on the client. Including also the measured redis-benchmark for unstable
        vs this branch. 
      - We track from 1 nanosecond to 1 second ( everything above 1 second is considered +Inf )
      
      ## `INFO LATENCYSTATS` exposition format
      
         - Format: `latency_percentiles_usec_<CMDNAME>:p0=XX,p50....` 
      
      ## `LATENCY HISTOGRAM [command ...]` exposition format
      
      Return a cumulative distribution of latencies in the format of a histogram for the specified command names.
      
      The histogram is composed of a map of time buckets:
      - Each representing a latency range, between 1 nanosecond and roughly 1 second.
      - Each bucket covers twice the previous bucket's range.
      - Empty buckets are not printed.
      - Everything above 1 sec is considered +Inf.
      - At max there will be log2(1000000000)=30 buckets
      
      We reply a map for each command in the format:
      `<command name> : { `calls`: <total command calls> , `histogram` : { <bucket 1> : latency , < bucket 2> : latency, ...  } }`
      Co-authored-by: default avatarOran Agra <oran@redislabs.com>
      5dd15443
  3. 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