Jon Häggblad
20f40fbd12
* grandpa: persist block number for last block of authority set * grandpa: fix authority_set_changes field in tests * grandpa: fix date on copyright notice * grandpa-rpc: implement cleaner api for prove finality rpc * grandpa-rpc: replace the old prove_finality with the new one * grandpa: undo accidental whitespace change * grandpa-rpc: start work on redo of the finality_proof RPC API * grandpa: manual impl of Decode for AuthoritySet * grandpa: add comment about appending changes for forced changes * grandpa: flip order in set changes, tidy up some comments * grandpa: update some of the doc comments * grandpa: store authority set changes when applying forced changes * grandpa: simplify finality_proof.rs * grandpa: move checks and extend tests in finality_proof * grandpa: address first set of review comments * grandpa: check that set changes have well-defined start * grandpa: rework prove_finality and assocated tests * grandpa: make AuthoritySetChanges tuple struct * grandpa: add assertions for tracking auth set changes * grandpa: remove StorageAndProofProvider trait * grandpa: return more informative results for unexpected input to RPC * grandpa: tiny tweak to error msg * grandpa: fix tests * grandpa: add error specific to finality_proof * grandpa: fix review comments * grandpa: proper migration to new AuthoritySet * grandpa: fix long lines * grandpa: fix unused warning after merge Co-authored-by: André Silva <andrerfosilva@gmail.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