Module wire 

On-the-wire codec for cluster-coordinated FT.SEARCH.

This module defines the binary serialisation format the coordinator uses when broadcasting an FT.SEARCH to remote peers via the crate::proto::dnode::DmsgType::FtSearchReq and crate::proto::dnode::DmsgType::FtSearchRep DNODE frames.

Format choice

The codec is a small, hand-rolled length-prefixed layout that uses only the standard library, mirroring the crate::proto::dnode::Handshake approach. Pulling in a heavier serde codec was rejected because:

• the message shapes are tiny and stable;
• the FT.SEARCH path is hot, so allocation and parse cost matter;
• keeping the codec in this module keeps the cluster-FT surface honest: any new field shows up here and is covered by the round-trip tests below.

All multi-byte integers are little-endian. Lengths are u32 so individual fields are bounded at 4 GiB which is well above any realistic vector / pattern payload.

Wire layout

Request (FtSearchReq)

magic(4)   = "FTQ1"
flags(2)   = 0
top_k(4)   = u32 (LE)
table_len  = u32 (LE)
table      = utf-8 bytes
query_tag  = u8  (0=KNN, 1=Text, 2=Regex)
query body = ...   (depends on tag, see below)

Reply (FtSearchRep)

magic(4)        = "FTR1"
flags(2)        = 0
timed_out(1)    = 0|1
hit_count(4)    = u32 (LE)
repeat hit_count times:
    doc_id_len  = u32 (LE)
    doc_id      = bytes
    score       = f32 (LE)

Tag bodies:

KNN:    field_len(4) field_utf8 bytes_len(4) vector_bytes
        ef_present(1) [ef(4)]
Text:   field_len(4) field_utf8 query_len(4) query_bytes
Regex:  field_len(4) field_utf8 pattern_len(4) pattern_utf8
        max_errors(2)

Enums

CodecError

Errors raised by the cluster-FT codec.

Constants

REP_MAGIC

Magic literal that opens every encoded PeerReply payload.

REQ_MAGIC

Magic literal that opens every encoded BroadcastRequest payload.

Functions

decode_reply

Decode a PeerReply previously produced by encode_reply.

decode_request

Decode a BroadcastRequest previously produced by encode_request.

encode_reply

Encode a PeerReply (one peer’s per-peer top-K) for the crate::proto::dnode::DmsgType::FtSearchRep DNODE frame.

encode_request

Encode a BroadcastRequest to a binary payload suitable for the crate::proto::dnode::DmsgType::FtSearchReq DNODE frame.