Dmitry Markin
5208bed7d2
Extract `WarpSync` (and `StateSync` as part of warp sync) from `ChainSync` as independent syncing strategy called by `SyncingEngine`. Introduce `SyncingStrategy` enum as a proxy between `SyncingEngine` and specific syncing strategies. ## Limitations Gap sync is kept in `ChainSync` for now because it shares the same set of peers as block syncing implementation in `ChainSync`. Extraction of a common context responsible for peer management in syncing strategies able to run in parallel is planned for a follow-up PR. ## Further improvements A possibility of conversion of `SyncingStartegy` into a trait should be evaluated. The main stopper for this is that different strategies need to communicate different actions to `SyncingEngine` and respond to different events / provide different APIs (e.g., requesting justifications is only possible via `ChainSync` and not through `WarpSync`; `SendWarpProofRequest` action is only relevant to `WarpSync`, etc.) --------- Co-authored-by: Aaro Altonen <48052676+altonen@users.noreply.github.com>
Integration of the GRANDPA finality gadget into Substrate.
This crate is unstable and the API and usage may change.
This crate provides a long-running future that produces finality notifications.
Usage
First, create a block-import wrapper with the block_import function. The
GRANDPA worker needs to be linked together with this block import object, so
a LinkHalf is returned as well. All blocks imported (from network or
consensus or otherwise) must pass through this wrapper, otherwise consensus
is likely to break in unexpected ways.
Next, use the LinkHalf and a local configuration to run_grandpa_voter.
This requires a Network implementation. The returned future should be
driven to completion and will finalize blocks in the background.
Changing authority sets
The rough idea behind changing authority sets in GRANDPA is that at some point, we obtain agreement for some maximum block height that the current set can finalize, and once a block with that height is finalized the next set will pick up finalization from there.
Technically speaking, this would be implemented as a voting rule which says, "if there is a signal for a change in N blocks in block B, only vote on chains with length NUM(B) + N if they contain B". This conditional-inclusion logic is complex to compute because it requires looking arbitrarily far back in the chain.
Instead, we keep track of a list of all signals we've seen so far (across all forks), sorted ascending by the block number they would be applied at. We never vote on chains with number higher than the earliest handoff block number (this is num(signal) + N). When finalizing a block, we either apply or prune any signaled changes based on whether the signaling block is included in the newly-finalized chain.
License: GPL-3.0-or-later WITH Classpath-exception-2.0