Bitcode

A bitwise encoder/decoder similar to bincode, which attempts to shrink the serialized size without sacrificing speed (as would be the case with compression).

The format may change between major versions, so we are free to optimize it.

Comparison with bincode

Features

• Bitwise serialization
• Gamma encoded lengths and enum variant indices

Additional features with #[derive(bitcode::Encode, bitcode::Decode)]

• Enums use the fewest possible bits, e.g. an enum with 4 variants uses 2 bits
• Apply attributes to fields/enum variants:

Limitations

• Doesn't support streaming APIs
• Format may change between major versions
• With feature = "derive", types containing themselves must use #[bitcode(recursive)] to compile

Benchmarks vs. bincode and postcard

Primitives (size in bits)

^{Note: These are defaults, and can be optimized with hints in the case of Bitcode (derive) or custom impl Serialize in the case of serde serializers.}

Values (size in bits)

Random Structs and Enums (average size and speed)

More benchmarks

rust_serialization_benchmark

Acknowledgement

Some test cases were derived from bincode (see comment in tests.rs).

License

Licensed under either of

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