package valkey

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package valkey
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Module Valkey.Command_specSource

Per-command default routing.

A cluster-aware client needs to know, for each command, where it belongs: which argument is the key (so we can compute its slot), whether it is safe to serve from a replica, and whether it must fan out to every primary. This module is the single source of truth for those facts.

The table covers the commands this library exposes as typed wrappers. Unknown commands receive a conservative default (Keyless_random); callers who know better can bypass the default by passing an explicit target to Client.exec.

Sourcetype t =
  1. | Single_key of {
    1. key_index : int;
    2. readonly : bool;
    }
    (*

    Classic one-key command. Slot is computed from args.(key_index).

    *)
  2. | Multi_key of {
    1. first_key_index : int;
    2. readonly : bool;
    }
    (*

    Multi-key command where the caller is expected to have co-located the keys via hashtags. Slot is computed from the first key; any MOVED that results means the hashtag assumption was violated.

    *)
  3. | Keyless_random of {
    1. readonly : bool;
    }
    (*

    No key (PING, TIME, CLIENT ID, …). Any node will do.

    *)
  4. | Fan_primaries
    (*

    Must hit every primary (FLUSHALL, SCRIPT LOAD, WAIT). Dispatch via Router.exec_multi, not exec.

    *)
  5. | Fan_all_nodes
    (*

    Must hit every node (CLIENT LIST aggregation, CLUSTER NODES). Dispatch via Router.exec_multi, not exec.

    *)
Sourceval lookup : string array -> t

Resolve the default spec for a command. Inspects args.(0) and, for two-word commands (SCRIPT LOAD, XINFO STREAM, CONFIG SET), args.(1) as well. Case-insensitive.

Returns Keyless_random { readonly = false } for anything not in the table.

Sourceval readonly : t -> bool

Whether a command is safe to serve from a replica. Writes (readonly = false) must be forced to the primary regardless of the user's Read_from preference.

Sourceval target_and_rf : Router.Read_from.t -> string array -> (Router.Target.t * Router.Read_from.t) option

High-level convenience: return Some (target, effective_read_from) for a command dispatchable through Router.exec, or None if the command should go through Router.exec_multi (fan-out).

  • Writes override the caller's Read_from to Primary.
  • Single-key commands map to By_slot (slot_of key).
  • Unknown / keyless commands map to Random with the caller's Read_from preserved.
Sourceval command_count : unit -> int

Number of commands + sub-commands in the routing table. Useful for debug / sanity logs.

Sourceval one_word_commands : unit -> string list

All single-word (no sub-command) entries in the routing table. Used by spec-validation tests that walk the table and cross-check against the live server's COMMAND INFO.