Crate pot

A concise storage format, written for BonsaiDb.

Pot is an encoding format used within BonsaiDb. Its purpose is to provide an encoding format for serde that:

• Is self-describing.

• Is safe to run in production.

• Is compact. While still being self-describing, Pot’s main space-saving feature is not repeating symbols/identifiers more than one time while serializing. When serializing arrays of structures, this can make a major difference. The logs.rs example demonstrates this:

  $ cargo test --example logs -- average_sizes --nocapture
  Generating 1000 LogArchives with 100 entries.
  +-----------------+-----------+-----------------+
  | Format          | Bytes     | Self-Describing |
  +-----------------+-----------+-----------------+
  | pot             | 2,627,586 | yes             |
  +-----------------+-----------+-----------------+
  | cbor            | 3,072,369 | yes             |
  +-----------------+-----------+-----------------+
  | msgpack(named)  | 3,059,915 | yes             |
  +-----------------+-----------+-----------------+
  | msgpack         | 2,559,907 | no              |
  +-----------------+-----------+-----------------+
  | bincode(varint) | 2,506,844 | no              |
  +-----------------+-----------+-----------------+
  | bincode         | 2,755,137 | no              |
  +-----------------+-----------+-----------------+

Example

use serde_derive::{Deserialize, Serialize};
#[derive(Serialize, Deserialize, Debug, Eq, PartialEq)]
pub struct User {
    id: u64,
    name: String,
}

fn main() -> Result<(), pot::Error> {
    let user = User {
        id: 42,
        name: String::from("ecton"),
    };
    let serialized = pot::to_vec(&user)?;
    println!("User serialized: {serialized:02x?}");
    let deserialized: User = pot::from_slice(&serialized)?;
    assert_eq!(deserialized, user);

    // Pot also provides a "Value" type for serializing Pot-encoded payloads
    // without needing the original structure.
    let user: pot::Value<'_> = pot::from_slice(&serialized)?;
    println!("User decoded as value: {user}");

    Ok(())
}

Outputs:

User serialized: [50, 6f, 74, 00, a2, c4, 69, 64, 40, 2a, c8, 6e, 61, 6d, 65, e5, 65, 63, 74, 6f, 6e]
User decoded as value: {id: 42, name: ecton}

Benchmarks

Because benchmarks can be subjective and often don’t mirror real-world usage, this library’s authors aren’t making any specific performance claims. The way Pot achieves space savings requires some computational overhead. As such, it is expected that a hypothetically perfect CBOR implementation could outperform a hypothetically perfect Pot implementation.

The results from the current benchmark suite executed on GitHub Actions are viewable here. The current suite is only aimed at comparing the default performance for each library.

Serialize into new Vec<u8>

Serialize into reused Vec<u8>

Deserialize

Modules

de

Types for deserializing pots.

format

Low-level interface for reading and writing the pot format.

reader

Types for reading data.

ser

Types for serializing pots.

Structs

Config

Serialization and deserialization configuration.

OwnedValue

A Value<'static> wrapper that supports DeserializeOwned.

ValueIter

An iterator over values contained within a Value.

Enums

Compatibility

Compatibility settings for Pot.

Error

All errors that Pot may return.

Value

A Pot-encoded value. This type can be used to deserialize to and from Pot without knowing the original data structure.

ValueError

An error from deserializing a type using Value::deserialize_as.

Functions

from_reader

Restores a previously Pot-serialized value from a Read implementer.

from_slice

Restores a previously Pot-serialized value from a slice.

to_vec

Serialize value using Pot into a Vec<u8>.

to_writer

Serialize value using Pot into writer.

Type Aliases

Result

A result alias that returns Error.