Desse

Ultra fast binary serialization and deserialization for types with a constant size (known at compile time). This crate cannot be used to serialize or deserialize dynamically allocated types, such as, String, Vec, HashMap, etc., and types with unknown size at compile time such as slices, &str, etc.

Binary Encoding Scheme

This crate uses a minimal binary encoding scheme such that the size of encoded object will be smaller than (in cases where Rust adds padding bytes for alignment) or equal to it's size in a running Rust program. For example, consider the following struct:

struct MyStruct {
    a: u8,
    b: u16,
}

Desse::serialize will serialize this struct in [u8; 3] where 3 is the sum of sizes of u8 and u16.

Usage

Add desse in your Cargo.toml's dependencies section.

[dependencies]
desse = "0.2"

Desse trait can be implemented for any struct or enum (whose size is known at compile time) using derive macro. This crate also provides a derive macro for implementing DesseSized trait which is necessary for implementing Desse trait.

use desse::{Desse, DesseSized};

#[derive(Debug, PartialEq, Desse, DesseSized)]
struct MyStruct {
    a: u8,
    b: u16,
}

Now, you can use Desse::serialize and Desse::deserialize_from for serialization and deserialization of this struct.

let my_struct = MyStruct { a: 5, b: 1005 };
let serialized: [u8; 3] = my_struct.serialize();
let new_struct = MyStruct::deserialize_from(&serialized);

assert_eq!(my_struct, new_struct);

Note that Desse::serialize returns an array of fixed length (3 in above case) and Desse::deserialize takes reference to an array of fixed length as argument.

Performance

This crate values performance more than anything. We don't shy away from using tested and verified unsafe code if it improves performance.

Benchmarks

Below are the benchmark results of comparison between desse and bincode serializing and deserializing same struct:

struct::serialize/desse::serialize
                        time:   [1.6228 ns 1.6326 ns 1.6434 ns]
                        change: [-1.1985% +0.0554% +1.2769%] (p = 0.94 > 0.05)
                        No change in performance detected.
Found 8 outliers among 100 measurements (8.00%)
  2 (2.00%) high mild
  6 (6.00%) high severe

struct::serialize/bincode::serialize
                        time:   [19.991 ns 20.081 ns 20.201 ns]
                        change: [-1.0739% +0.3569% +1.7361%] (p = 0.63 > 0.05)
                        No change in performance detected.
Found 12 outliers among 100 measurements (12.00%)
  3 (3.00%) high mild
  9 (9.00%) high severe

struct::deserialize/desse::deserialize
                        time:   [1.6063 ns 1.6101 ns 1.6144 ns]
                        change: [-1.3079% -0.1278% +1.0394%] (p = 0.84 > 0.05)
                        No change in performance detected.
Found 7 outliers among 100 measurements (7.00%)
  1 (1.00%) high mild
  6 (6.00%) high severe

struct::deserialize/bincode::deserialize
                        time:   [22.004 ns 22.094 ns 22.209 ns]
                        change: [-1.1573% +0.0698% +1.3631%] (p = 0.92 > 0.05)
                        No change in performance detected.
Found 9 outliers among 100 measurements (9.00%)
  3 (3.00%) high mild
  6 (6.00%) high severe

It is clear from above benchmarks that bincode takes 20.081 ns on an average for serialization whereas desse takes 1.6326 ns. The results are also similar for deserialization where bincode takes 22.094 ns and desse takes 1.6101 ns.

You can run benchmarks by running following command:

cargo bench

Future Improvements

Once const_generics is implemented in Rust, we can provide default implementations for many types such as, impl Desse for [T; n] where T: Desse, and other variable size statically allocated types in Rust.

License

Licensed under either of

• Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.