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RESP3: FUNCTION LIST/STATS, ARLASTITEMS and FT.* replies inside scripts don't follow the client's protocol #439
Description
These were found while fixing #431 (#436), which fixed Lua script replies. These other replies still send RESP2 shapes, or ignore the script's protocol:
FUNCTION LISTandFUNCTION STATS(src/commands/lua.rs). They send$-1for a function with no description, and forrunning_scriptwhen nothing is running. Both are also arrays where Redis 7+ sends maps to RESP3 clients.ARLASTITEMS(src/commands/array.rs,cmd_arlastitems) sends$-1for empty slots inside a RESP3 array.- FT.SEARCH, FT.AGGREGATE, the hybrid and vector commands, and
ARINFOreadctx.respinstead ofeffective_resp_for_reply. Called from a script, they ignoreredis.setresp. Inside MULTI/EXEC on a RESP3 connection, they send RESP3 shapes even under the script's default RESP2.
Compare each one byte for byte with Redis 8 on RESP2 and RESP3 clients, and from scripts with setresp(2) and setresp(3).
Activity
murtazayusuf commentedon Nov 5, 2026
More pre-existing differences in Lua reply conversion, found while reviewing #436. Each was checked against Redis source semantics, not run:
{big_number=…}replaces only the\r\npair and then trims. Redis maps each\rand\nto a space and doesn't trim.setis checked beforemap; Redis checksmapfirst. This only matters for a table that has both.verbatim_stringwhoseformatorstringisn't a string is an error here. Redis falls through to the map, set and array checks.{err='x\r\n'}keeps trailing spaces; Redis trims trailing CR/LF first.okanderruseto_string_lossy, so non-UTF-8 bytes become U+FFFD where Redis sends the raw bytes.murtazayusuf commentedon Nov 5, 2026
One more, left deliberately by #436: a Lua reply table with both
errandok(return {err='e1', ok='o1'}) is sent as the status+o1, where Redis checkserrfirst and sends-e1. Checkingerrfirst costs every status reply an extra table lookup, measured at +1.4–3.8% on a SET-lock script. If it's fixed, it should be done without that cost, for example by reading reply tables through raw FFI.