Crate musli_storage

Super simple storage encoding for Müsli

The storage encoding is partially upgrade safe:

• ✔ Can tolerate missing fields if they are annotated with #[musli(default)].
• ✗ Cannot skip over extra unrecognized fields.

This means that it’s suitable as a storage format, since the data model only evolves in one place. But unsuitable as a wire format since it cannot allow clients to upgrade independent of each other.

See musli-wire for a fully upgrade safe format.

use musli::{Encode, Decode};

#[derive(Debug, PartialEq, Encode, Decode)]
struct Version1 {
    name: String,
}

#[derive(Debug, PartialEq, Encode, Decode)]
struct Version2 {
    name: String,
    #[musli(default)]
    age: Option<u32>,
}

let version2 = musli_storage::to_buffer(&Version2 {
    name: String::from("Aristotle"),
    age: Some(62),
})?;

assert!(musli_storage::decode::<_, Version1>(version2.as_slice()).is_err());

let version1 = musli_storage::to_buffer(&Version1 {
    name: String::from("Aristotle"),
})?;

let version2: Version2 = musli_storage::decode(version1.as_slice())?;

assert_eq!(version2, Version2 {
    name: String::from("Aristotle"),
    age: None,
});

Configuring

To tweak the behavior of the storage format you can use the Encoding type:

use musli_storage::Encoding;
use musli_storage::int::{Fixed, Variable};
use musli::mode::DefaultMode;
use musli::{Encode, Decode};

const CONFIG: Encoding<DefaultMode, Fixed, Variable> = Encoding::new()
    .with_fixed_integers();

#[derive(Debug, PartialEq, Encode, Decode)]
struct Struct<'a> {
    name: &'a str,
    age: u32,
}

let mut out = Vec::new();

let expected = Struct {
    name: "Aristotle",
    age: 61,
};

CONFIG.encode(&mut out, &expected)?;
let actual = CONFIG.decode(&out[..])?;

assert_eq!(expected, actual);

Re-exports

• pub use self::encoding::decode;
• pub use self::encoding::encode;
• pub use self::encoding::from_slice;
• pub use self::encoding::to_buffer;
• pub use self::encoding::to_fixed_bytes;
• pub use self::encoding::Encoding;
• pub use self::encoding::to_vec;
• pub use self::encoding::to_writer;

Modules

• buffered_writer
  A writer which buffers the writes before it outputs it into the backing storage.
• encoding
  Module that defines Encoding whith allows for customization of the encoding format, and the DEFAULT encoding configuration.
• error
  Generic error types that can be used for most Reader / Writer implementations.
• fixed_bytes
  A container which can store up to a fixed number of uninitialized bytes on the stack and read into and from it.
• int
  Traits and utilities for dealing with integers.
• reader
  Trait for governing how a particular source of bytes is read.
• wrap
  Helpers for integrating musli with I/O types like std::io and std::io::Write.
• writer
  Trait for governing how a particular sink of bytes is written to.