nocopy

Types with no-copy decoding

This sub-package contains a set of typed sclices which can be useful for encoding/decoding large numerical slices faster. This is relatively unsafe and non-portable as the encoding simply copies the memory of the slice, hence disregarding byte order of the encoder/decoders. However, this lets us to avoid allocating and copying memory when encoding/decoding, making this at least 10x faster than the safe implementation.

Warning

This implementation simply maps the byte slice provided in Unmarshal call to the Go structs which need to be decoded. This simply reuses the underlying byte array to store the data and does not perform a memory copy. This can be dangerous in many cases, be careful how this is used!

Benchmark

Array of 10K elements:

BenchmarkUint64s_Safe/marshal-8         	   10000	    167612 ns/op	   78325 B/op	      11 allocs/op
BenchmarkUint64s_Safe/unmarshal-8       	    5000	    286769 ns/op	   81975 B/op	       2 allocs/op
BenchmarkUint64s_Unsafe/marshal-8         	  100000	     10711 ns/op	   82055 B/op	       3 allocs/op
BenchmarkUint64s_Unsafe/unmarshal-8       	20000000	       109 ns/op	       0 B/op	       0 allocs/op

Usage

This is a drop-in type, so simply use one of the types available in the package (Bools, Int32s, Uint64s ...) and Marshal or Unmarshal using the binary package.

// Marshal some numbers
v := nocopy.Int32s{4, 5, 6, 1, 2, 3}
encoded, err := binary.Marshal(&v)

// Unmarshal the numbers
var o nocopy.Int32s
err = binary.Unmarshal(encoded, &o)