codec support

[Carbrex]

No description provided.

[Carbrex]

@joncrlsn

[Carbrex]

@joncrlsn We have found heavy impact of dque on our systems cpu, because of expensive gob encoding. This pr is to add support for a user provided codec like msgPack or protobuf for cheaper encoding to bytes.

[Carbrex]

I can add an example to show how to use the codec, if needed.

[Carbrex]

 go test -bench=. -benchtime=4s
goos: linux
goarch: amd64
pkg: carbrex.dev/dque-testing/helper
cpu: 11th Gen Intel(R) Core(TM) i5-1155G7 @ 2.50GHz
BenchmarkGobCodec_Complete-8              323029             14146 ns/op
BenchmarkMsgPackCodec_Complete-8          578898              7987 ns/op
BenchmarkProtoCodec_Complete-8            657218              7207 ns/op
PASS
ok      carbrex.dev/dque-testing/helper 16.452s

go bench results for testing done on a simple User struct

type User struct {
	ID   int
	Name string
}

bench snippet

	for n := 0; n < b.N; n++ {
		err := q.Enqueue(&helper.User{n, "UserIHelping"})
		if err != nil {
			b.Fatal("Error enqueuing to dque:", err)
		}
		if decode {
			_, err = q.Dequeue()
			if err != nil {
				b.Fatal(err)
			}
		}

	}