Crate willow_data_model

Willow Data Model

This crate provides implementation of the Willow Data Model, including:

• Traits to assist in your implementation of Willow parameters, such as NamespaceId and SubspaceId.
• A zero-copy implementation of Willow paths and their constituent components.
• An implementation of Willow’s entries.
• Utilities for Willow’s entry groupings, such as ranges and areas
• Implementations of various relative encodings.

This crate does not yet have anything for Willow’s concept of stores. Stay tuned!

Type parameters

Willow is a parametrised family of protocols, and so this crate makes heavy use of generic parameters.

The following generic parameter names are used consistently across this crate:

• MCL - A usize representing max_component_length.
• MCC - A usize representing max_component_count.
• MPL - A usize representing max_path_length.
• N - The type used for NamespaceId (willowprotocol.org), must implement the NamespaceId trait.
• S - The type used for SubspaceId (willowprotocol.org), must implement the SubspaceId trait.
• PD - The type used for PayloadDigest (willowprotocol.org), must implement the PayloadDigest trait.
• AT - The type used for AuthorisationToken (willowprotocol.org), must implement the AuthorisationToken trait.

Modules

grouping

Utilities for Willow’s entry groupings.

Structs

AreaNotAlmostIncludedError

AuthorisedEntry

An AuthorisedEntry is a pair of an Entry and AuthorisationToken for which AuthorisationToken::is_authorised_write returns true.

Component

A component of a Willow Path.

ComponentsNotRelatedError

Entry

The metadata associated with each Payload.

EventSystem

InternalSubscriber

The internal part of a subscriber.

LengthyAuthorisedEntry

An AuthorisedEntry together with information about how much of its payload a given crate::Store holds.

LengthyEntry

An Entry together with information about how much of its payload a given crate::Store holds.

OwnedComponent

An owned component of a Willow Path that uses reference counting for cheap cloning.

Path

An immutable Willow path. Thread-safe, cheap to clone, cheap to take prefixes of, expensive to append to (linear time complexity).

PathBuilder

A helper struct for creating a Path with exactly one memory allocation. Requires total length and component count to be known in advance.

PrivateAreaContext

The context necessary to privately encode Areas.

PrivateInterest

Confidential data that relates to determining the AreasOfInterest that peers might be interested in synchronising.

PrivatePathContext

The context necessary to privately encode Paths.

QueryIgnoreParams

Describes which entries to ignore during a query.

Subscriber

The public-facing part of a subscriber (to be returned by Store::subscribe_area).

UnauthorisedWriteError

An error indicating an AuthorisationToken does not authorise the writing of this entry.

Enums

EntryIngestionError

Returned when an entry cannot be ingested into a Store.

EntryIngestionSuccess

Returned when an entry could be ingested into a Store.

EntryOrigin

The origin of an entry ingestion event.

ForgetEntryError

Returned when forgetting an entry fails.

ForgetPayloadError

Returned when forgetting a payload fails.

InvalidPathError

An error arising from trying to construct a invalid Path from valid components.

PayloadAppendError

Returned when a payload fails to be appended into the Store.

PayloadAppendSuccess

Returned when a payload is successfully appended to the Store.

PayloadError

Returned when retrieving a payload fails.

StoreEvent

A notification about changes in a Store. You can obtain a producer of these via the Store::subscribe_area method.

Traits

AuthorisationToken

Determines whether this type (nominally an AuthorisationToken) is able to prove write permission for a given Entry.

NamespaceId

A type for identifying namespaces.

PayloadDigest

A totally ordered type for content-addressing the data that Willow stores.

Store

A Store is a set of AuthorisedEntry belonging to a single namespace, and a (possibly partial) corresponding set of payloads.

SubspaceId

A type for identifying subspaces.

TrustedDecodable

Methods for decoding trusted encodings,that is, data which was already deemed trustworthy prior to encoding.

TrustedRelativeDecodable

Methods for decoding trusted encodings (that is, data which was deemed trustworthy prior to encoding), relative to type R.

Functions

decode_path_extends_path

encode_path_extends_path

Type Aliases

Timestamp

A Timestamp is a 64-bit unsigned integer, that is, a natural number between zero (inclusive) and 2^64 (exclusive). Timestamps are to be interpreted as a time in microseconds since the Unix epoch.