package work

import (

"reflect"

"github.com/google/uuid"

"github.com/vmihailenco/msgpack/v5"

)

// uuidExtID is the msgpack extension id used to encode uuid.UUID values inside

// job payloads. It is 3 for historical reasons: the polytomic application

// previously registered this codec from its own package, and jobs already

// persisted in Redis encode UUIDs as fixext16 with this type id. Changing it

// would make those queued jobs undecodable.

const uuidExtID = 3

// The msgpack ext codec for uuid.UUID is registered here, in the work package,

// because this is the package that owns (Un)MarshalPayload and the underlying

// marshal/unmarshal helpers. msgpack's ext registry is process-global, so the

// encoder and decoder must be registered before any payload containing a

// uuid.UUID is (de)serialized.

//

// Previously this registration lived only in the application's top-level `app`

// package as an init() side effect. Because the job enqueue paths

// (e.g. sync/executor) do not import `app`, any binary built without it -- most

// notably per-package test binaries -- had no encoder registered and serialized

// uuid.UUID ([16]byte) as msgpack bin8 (code c4) instead of the ext type

// (fixext16, code d8). The worker, which does register the ext decoder, then

// could not decode those payloads and failed with

// "invalid job payload: msgpack: invalid code=c4 decoding ext len", wedging the

// single-slot dequeuer on the undecodable job.

//

// Registering on the work package guarantees encode/decode symmetry: a payload

// cannot be (un)marshaled without importing this package, and importing it runs

// this init().

func uuidEncoder(e *msgpack.Encoder, v reflect.Value) ([]byte, error) {

uu := v.Interface().(uuid.UUID)

return uu.MarshalBinary()

}

func uuidDecoder(d *msgpack.Decoder, v reflect.Value, extLen int) error {

b := make([]byte, extLen)

if err := d.ReadFull(b); err != nil {

return err

}

uu, err := uuid.FromBytes(b)

if err != nil {

return err

}

*v.Addr().Interface().(*uuid.UUID) = uu

return nil

}

func init() {

msgpack.RegisterExtDecoder(uuidExtID, uuid.UUID{}, uuidDecoder)

msgpack.RegisterExtEncoder(uuidExtID, uuid.UUID{}, uuidEncoder)

}