[wip] feat: willow implementation

[Frando]

Description

Work in progress! Implementation of https://willowprotocol.org/ for iroh

Protocol

The protocol module contains the data structures and basic interactions as defined by the Willow specs. It is IO-less and not generic, all types are concrete.

• Willow data model proto::willow
  • Use willow-rs (see refactor(iroh-willow): use willow-rs #2616 )
• Meadowcap proto::meadowcap
  • Use willow-rs (see refactor(iroh-willow): use willow-rs #2616 )
• Groupings proto::groupings
  • Use willow-rs (see refactor(iroh-willow): use willow-rs #2616 )
• Willow Geneal Sync Protocol (WGSP) proto::sync
  • Most message type structs written down
  • Private Area Intersection
  • Cryptographic fingerprint (uses only XOR atm)
  • Protocol-compliant encoding

Session

The session module contains the implementation of the WGPS protocol session.

• Session setup
• Private area intersection
• Set reconciliation
• Resource control
  • Binding resources
  • Freeing resources
  • Issue initial guarantees
  • Respect issued guarantees
  • Issue new guarantees
• Live data mode between two peers
  • Subscribe to new inserts and send to active sessions
  • Only send entries for matcing shared areas of interest
• Verified streaming for payloads with bao outboards embedded
• Payload requests
• Live data mode in a swarm setting

Net

The net module opens sessions over iroh-net QUIC connections.

• Commitment exchange
• Separate channels for each logical channel
• Basic session lifecycle (allow to close sessions)
• Properly terminate connections gracefully (fixed by [wip] feat(iroh-willow): refactor peer manager to properly close connections and drop duplicates #2599)
• Properly deal with simultaenous connections by only using one of them deterministicaly (fixed by [wip] feat(iroh-willow): refactor peer manager to properly close connections and drop duplicates #2599)
• Do not drop intents if the session is about to be closed when submitting a new intent (fixed by [wip] feat(iroh-willow): refactor peer manager to properly close connections and drop duplicates #2599)

Store

The store module contains backing stores for entries and keys

• Store traits and generic functionality
  • Entry store trait
  • Key store trait
  • Use iroh-blobs for payload storage
  • Store capabilities by hash and do reference counting
  • Expose hook to prevent GC of payloads and/or do reference counting for payloads
• PoC memory store
• move store to own thread & sessions to local pools
• redb store
  • port @rklaehn's redb PoC
  • figure out if the traits need to change for our delayed commit strategy
  • add commit to the store trait
• subscriptions
  • reliable/persistent subscriptions

Engine

• PeerManager (1 session peer peer only)
• Intents
  • changing between ReconcileOnce and Live modes

Other

•  How can builder APIs be done nicely over FFI

Breaking Changes

Once we integrate, this will be a very much breaking changes for everything around docs: This will break not only APIs, but also the protocol and the storage. We cannot offer automatic migration even, because signatures change. How exactly we deal with this situation is tbd. Likely we will offer an out-of-tree tool to migrate data from the old iroh-docs to the new willow iroh-docs.

Notes & open questions

Change checklist

• Self-review.
• Documentation updates if relevant.
• Tests if relevant.
• All breaking changes documented.