Crate rkyv[][src]

Expand description

rkyv

rkyv (archive) is a zero-copy deserialization framework for Rust.

It’s similar to other zero-copy deserialization frameworks such as Cap’n Proto and FlatBuffers. However, while the former have external schemas and heavily restricted data types, rkyv allows all serialized types to be defined in code and can serialize a wide variety of types that the others cannot. Additionally, rkyv is designed to have little to no overhead, and in most cases will perform exactly the same as native types.

Design

Like serde, rkyv uses Rust’s powerful trait system to serialize data without the need for reflection. Despite having a wide array of features, you also only pay for what you use. If your data checks out, the serialization process can be as simple as a memcpy! Like serde, this allows rkyv to perform at speeds similar to handwritten serializers.

Unlike serde, rkyv produces data that is guaranteed deserialization free. If you wrote your data to disk, you can just mmap your file into memory, cast a pointer, and your data is ready to use. This makes it ideal for high-performance and IO-bound applications.

Limited data mutation is supported through Pin APIs, and archived values can be truly deserialized with Deserialize if full mutation capabilities are needed.

Type support

rkyv has a hashmap implementation that is built for zero-copy deserialization, so you can serialize your hashmaps with abandon. The implementation performs perfect hashing with the compress, hash and displace algorithm to use as little memory as possible while still performing fast lookups.

rkyv also has support for contextual serialization, deserialization, and validation. It can properly serialize and deserialize shared pointers like Rc and Arc, and can be extended to support custom contextual types.

One of the most impactful features made possible by rkyv is the ability to serialize trait objects and use them as trait objects without deserialization. See the archive_dyn crate for more details.

Tradeoffs

rkyv is designed primarily for loading bulk game data as efficiently as possible. While rkyv is a great format for final data, it lacks a full schema system and isn’t well equipped for data migration. Using a serialization library like serde can help fill these gaps, and you can use serde with the same types as rkyv conflict-free.

Features

  • size_16: Archives *size as *16. This is for small archive support.
  • size_32: Archives *size as *32 (enabled by default)
  • size_64: Archives *size as *64. This is for large archive support.
  • specialization: Enables support for the unstable specialization feature for increased performance for a few specific cases
  • std: Enables standard library support (enabled by default)
  • strict: Guarantees that types will have the same representations across platforms and compilations. This is already the case in practice, but this feature provides a guarantee. It additionally provides C type compatibility.
  • validation: Enables validation support through bytecheck

Crate support

Some common crates need to be supported by rkyv before an official integration has been made. Support is provided by rkyv for these crates, but in the future crates should depend on rkyv and provide their own implementations. The crates that already have support provided by rkyv should work toward integrating the implementations into themselves.

Crates supported by rkyv:

Examples

See Archive for examples of how to use rkyv.

Re-exports

pub use util::*;
pub use validation::check_archived_root_with_context;
pub use validation::check_archived_value_with_context;
pub use validation::validators::check_archived_root;
pub use validation::validators::check_archived_value;

Modules

boxed

An archived version of Box.

collections

Archived versions of standard library containers.

de

Deserialization traits, deserializers, and adapters.

ffi

Archived versions of FFI types.

impls

Trait implementations for core, alloc, and std types.

net

Archived versions of network types.

option

An archived version of Option.

rc

Archived versions of shared pointers.

rel_ptr

Relative pointer implementations and options.

ser

Serialization traits, serializers, and adapters.

string

Archived versions of string types.

util

Utilities for common archive operations.

validation

Validation implementations and helper types.

vec

An archived version of Vec.

with

Wrapper type support and commonly used wrappers.

Macros

from_archived

Returns the unarchived value of the given archived primitive.

out_field

Returns a tuple of the field offset and a mutable MaybeUninit to the given field of the given MaybeUninit struct.

to_archived

Returns the archived value of the given archived primitive.

Structs

Infallible

A fallible type that cannot produce errors

Traits

Archive

A type that can be used without deserializing.

ArchivePointee

An archived type with associated metadata for its relative pointer.

ArchiveUnsized

A counterpart of Archive that’s suitable for unsized types.

Deserialize

Converts a type back from its archived form.

DeserializeUnsized

A counterpart of Deserialize that’s suitable for unsized types.

Fallible

Contains the error type for traits with methods that can fail

Serialize

Converts a type to its archived form.

SerializeUnsized

A counterpart of Serialize that’s suitable for unsized types.

Type Definitions

Archived

Alias for the archived version of some Archive type.

ArchivedMetadata

Alias for the archived metadata for some ArchiveUnsized type.

FixedIsize

The native type that isize is converted to for archiving.

FixedUsize

The native type that usize is converted to for archiving.

MetadataResolver

Alias for the metadata resolver for some ArchiveUnsized type.

RawRelPtr

The default raw relative pointer.

RelPtr

The default relative pointer.

Resolver

Alias for the resolver for some Archive type.

Derive Macros

Archive

Derives Archive for the labeled type.

Deserialize

Derives Deserialize for the labeled type.

Serialize

Derives Serialize for the labeled type.