[][src]Crate rkyv

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.

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.

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.

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. Archived values can be truly deserialized with Unarchive if full mutation capabilities are needed.

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

  • const_generics: Improves the trait implementations for arrays with support for all lengths
  • long_rel_ptrs: Increases the size of relative pointers to 64 bits for large archive support
  • 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

Examples

See Archive for examples of how to use rkyv.

Re-exports

pub use validation::check_archive;
pub use validation::ArchiveContext;

Modules

core_impl

Archive implementations for core types.

std_impl

Archive implementations for std types.

validation

Validation implementations and helper types.

Macros

offset_of

Calculates the offset of the specified field from the start of the named struct.

Structs

Aligned

Wraps a type and aligns it to at least 16 bytes. Mainly used to align byte buffers for ArchiveBuffer.

ArchiveBuffer

Wraps a byte buffer and writes into it.

ArchiveWriter

Wraps a type that implements io::Write and equips it with Write.

CopyResolver

A resolver that always resolves to the unarchived value. This can be useful while implementing ArchiveCopy.

RelPtr

A pointer which resolves to relative to its position in memory.

Enums

ArchiveBufferError

The error type returned by an ArchiveBuffer.

Traits

Archive

Writes a type to a Writer so it can be used without deserializing.

ArchiveCopy

A trait that indicates that some Archive type can be copied directly to an archive without additional processing.

ArchiveRef

This trait is a counterpart of Archive that's suitable for unsized types.

Resolve

Creates an archived value when given a value and position.

Seek

A writer that can seek to an absolute position.

Unarchive

Converts a type back from its archived form.

UnarchiveRef

A counterpart of Unarchive that's suitable for unsized types.

Write

A #![no_std] compliant writer that knows where it is.

Functions

archived_ref

Casts an archived reference from the given byte array at the given position.

archived_ref_mut

Casts a mutable archived reference from the given byte array at the given position.

archived_value

Casts an archived value from the given byte array at the given position.

archived_value_mut

Casts a mutable archived value from the given byte array at the given position.

Type Definitions

Archived

Alias for the archived version of some Archive type.

Offset

The type used for offsets in relative pointers.

Reference

Alias for the reference for some ArchiveRef type.

ReferenceResolver

Alias for the resolver of the reference for some ArchiveRef type.

Resolver

Alias for the resolver for some Archive type.

Derive Macros

Archive

Derives Archive for the labeled type.

Unarchive

Derives Unarchive for the labeled type.