serde_rustler provides a Serde Serializer and Deserializer for Rustler types, so you can easily serialize and deserialize native Rust types directly to and from native Elixir terms within your NIFs.
Install from Crates.io:
toml
[dependencies]
serde_rustler = "0.0.3"
```rust
use serde::{Serialize, Deserialize} use serderustler::{fromterm, to_term};
rustlerexportnifs! { "Elixir.SerdeRustlerTests", [("nif", 1, nif)], None }
struct Animal = { ... };
fn nif<'a>(env: Env<'a>, args: &[Term<'a>]) -> NifResult
// Serialize a type into an Elixir term.
to_term(env, animal).map_err(|err| err.into())
} ```
Below is a more comprehensive example of how you might use serde_rustler within a rust NIF...
```rust
extern crate rustler;
use rustler::{Env, error::Error as NifError, NifResult, Term}; use serde::{Serialize, Deserialize}; use serderustler::{fromterm, to_term};
rustlerexportnifs! { "Elixir.SerdeNif", [("readme", 1, readme)], None }
// NOTE: to serialize to the correct Elixir record, you MUST tell serde to // rename the variants to the full Elixir record module atom.
enum AnimalType { #[serde(rename = "Elixir.SerdeNif.AnimalType.Cat")] Cat(String), #[serde(rename = "Elixir.SerdeNif.AnimalType.Dog")] Dog(String), }
// NOTE: to serialize to an actual Elixir struct (rather than a just map with // a :struct key), you MUST tell serde to rename the struct to the full // Elixir struct module atom.
struct Animal {
#[serde(rename = "type")]
_type: AnimalType,
name: String,
age: u8,
owner: Option
fn readme<'a>(env: Env<'a>, args: &[Term<'a>]) -> NifResult
... and how you might structure your corresponding Elixir types (code structure, imports, aliases and requires simplified or omitted for brevity):
```elixir defmodule SerdeNif do use Rustler, otpapp: :serdenif
def readme(term), do: :erlang.niferror(:nifnotloaded)
defmodule Animal do @type t :: %Animal{ type: Cat.t() | Dog.t(), name: bitstring, age: pos_integer, owner: nil | bitstring } defstruct type: Cat.record(), name: "", age: 0, owner: nil
@doc """
Deserializes term as a Rust `Animal` struct, then serializes it back into
an Elixir `Animal` struct. Should return true.
"""
def test() do
animal = %Animal{
type: Animal.Cat.record(),
name: "Garfield",
age: 41,
}
SerdeNif.readme(animal) == animal
end
end
defmodule AnimalType.Cat do require Record @type t {MODULE, String.t()} Record.defrecord(:record, MODULE, breed: "tabby") end
defmodule AnimalType.Dog do # omitted end end ```
| Type Name | Serde (Rust) Values | Elixir Terms (default behaviour) | deserialize_any into Elixir Term |
|-----|-----|-----|-----|
| bool | true or false | true or false | true or false |
| 1 number | i8, i16, i32, i64, u8, u16, u32, u64, f32, f64 (TODO: i128 and u128) | number | number as f64, i64, or u64 |
| char | 'A' | [u32] | [u32] |
| string | "" | bitstring | bitstring |
| byte array | &[u8] or Vec<u8> | <<_::_*8>> | bitstring |
| option | Some(T) or None | T or :nil | T or :nil |
| unit | None | :nil | :nil |
| unit struct | struct Unit | :nil | :nil |
| 3 unit variant | E::A in enum UnitVariant { A } | :A | "A" |
| 3 newtype struct | struct Millimeters(u8) | {:Millimeters, u8} | ["Millimeters", u8] |
| 3 newtype variant | E::N in enum E { N(u8) } | {:N, u8} | ["N", u8] |
| 3 newtype variant (any Ok and Err tagged enum) | enum R<T, E> { Ok(T), Err(E) } | {:ok, T} or {:error, E} | ["Ok", T] or ["Err", E] |
| seq | Vec<T> | [T,] | [T,] |
| tuple | (u8,) | {u8,} | [u8,] |
| 3 tuple struct | struct Rgb(u8, u8, u8) | {:Rgb, u8, u8, u8} | ["Rgb", u8, u8, u8] |
| 3 tuple variant | E::T in enum E { T(u8, u8) } | {:T, u8, u8} | ["T", u8, u8] |
| 1 map | HashMap<K, V> | %{} | %{} |
| 3 struct | struct Rgb { r: u8, g: u8, b: u8 } | %Rgb{ r: u8, g: u8, b: u8 } | %{"r" => u8, "g" => u8, "b" => u8} |
| 3 struct variant | E::S in enum E { Rgb { r: u8, g: u8, b: u8 } } | %Rgb{ r: u8, g: u8, b: u8 } | %{"r" => u8, "g" => u8, "b" => u8} |
1: API still being decided / implemented.
2: When serializing unknown input to terms, atoms will not be created and will instead be replaced with Elixir bitstrings. Therefore "records" will be tuples ({bitstring, ...}) and "structs" will be maps containing %{:__struct__ => bitstring}. The unfortunate consequence of this is that deserialize_any will lack the necessary information needed deserialize many terms without type hints, such as structs, enums and enum variants, and tuples. (Feedback on how best to solve this is very welcome here).
To run:
sh
cd serde_rustler_tests
MIX_ENV=bench mix run test/benchmarks.exs
Benchmarks were ripped from the Poison repo. The NIFs being called were implemented using serde-transcode to translate between serde_rustler and serde_json and were compiled in :release mode by rustler.
NOTE: If someone can point out any mistakes I made that led to these ridiculous results, please let me know :)
Benchmarks suggest that serde_rustler is somewhat faster than jiffy when encoding JSON, and generally comparable to / no more than ~2-3x as slow as jiffy or jason when decoding JSON, and in almost all cases, serde_rustler seems to use significantly less memory than pure-Elixir alternatives, though this is likely has to do with running a NIF rather than an pure-Elixir function.
Also take note of the results for any test taking longer than 1ms or tests involving the larger inputs govtrack.json (3.74 MB) and issue-90.json (7.75 MB) - the encode_json_compact and decode_json NIFs have significantly higher variation in performance while their dirty equivalents encode_json_compact_dirty and decode_json_dirty are comparable to the originals in speed and have more reliable performance.
i128 and u128decode_json (Serializer?) performance degradation| Version | Change Summary |
| ------- | ---------------|
| v0.0.3 | better char and tuple support, adds benchmarks |
| v0.0.2 | cleanup, better deserialize_any support |
| v0.0.1 | initial release |
git checkout -b feature/fooBar)git commit -am 'Add some fooBar')git push origin feature/fooBar)MIT