Benjamin Kampmann
c78c2892a4
* mark template and utils as non-publish * switch to development version for testing * activate unleash check * maybe if I disable all rules... * Fix isolated compilation of `max-encoded-len-derive` with `syn` error[E0369]: binary operation `==` cannot be applied to type `syn::Path` --> src/lib.rs:88:29 | 88 | .filter(|attr| attr.path == parse_quote!(max_encoded_len_crate)) | --------- ^^ ----------------------------------- _ | | | syn::Path error: aborting due to previous error For more information about this error, try `rustc --explain E0369`. Error: could not compile `max-encoded-len-derive` * WIP: bump changes crates since v3 tag to next breaking cargo unleash version bump-breaking --changed-since v3.0.0 cargo unleash version set-pre dev --changed-since v3.0.0 FIXME: Don't modify crates that are not yet released, e.g. `max-encoded-len-derive` * Update lockfile * WIP: Bump sp-transaction-pool as well * WIP: Bump sp-offchain as well * WIP: Bump frame-system-rpc-runtime-api as well * WIP: Bump sp-authority-discovery as well * Manually deactivate dev-deps before `cargo unleash check` Otherwise we run into `Cycle detected` error. * Bump sp-consensus-slots * Add missing Cargo.lock change * Bump sp-consensus-vrf as well * Bump sp-keyring as well * Bump sp-consensus-pow as well * Try to speed up the `unleash-check` job Previously, the job took 106 minutes - let's see if explicitly specifying a `CARGO_TARGET_DIR` will help * fixup: Ensure the temp target dir exists for unleash check * Bump pallet-transaction-payment-rpc-runtime-api as well Needed for Polkadot * Bump pallet-transaction-payment-rpc as well Needed for Polkadot * Try updating crates after patching in the Polkadot CI job * Use another approach to update patched Substrate crates * Try to update all sp-core versions in Polkadot CI job * Simplify sp-core version checking * Apply another shellcheck lint * Just do the simplest thing I guess * Welp don't do --offline then * Clean up `unleash-check` job triggers Co-authored-by: Denis Pisarev <denis.pisarev@parity.io> * Fix a note in unleash-check cache step * Add a note about temporary optimization in cargo-unleash * Pin a newer version of cargo-unleash Co-authored-by: Igor Matuszewski <xanewok@gmail.com> Co-authored-by: Denis Pisarev <denis.pisarev@parity.io>
BABE (Blind Assignment for Blockchain Extension)
BABE is a slot-based block production mechanism which uses a VRF PRNG to randomly perform the slot allocation. On every slot, all the authorities generate a new random number with the VRF function and if it is lower than a given threshold (which is proportional to their weight/stake) they have a right to produce a block. The proof of the VRF function execution will be used by other peer to validate the legitimacy of the slot claim.
The engine is also responsible for collecting entropy on-chain which will be used to seed the given VRF PRNG. An epoch is a contiguous number of slots under which we will be using the same authority set. During an epoch all VRF outputs produced as a result of block production will be collected on an on-chain randomness pool. Epoch changes are announced one epoch in advance, i.e. when ending epoch N, we announce the parameters (randomness, authorities, etc.) for epoch N+2.
Since the slot assignment is randomized, it is possible that a slot is assigned to multiple validators in which case we will have a temporary fork, or that a slot is assigned to no validator in which case no block is produced. Which means that block times are not deterministic.
The protocol has a parameter c [0, 1] for which 1 - c is the probability
of a slot being empty. The choice of this parameter affects the security of
the protocol relating to maximum tolerable network delays.
In addition to the VRF-based slot assignment described above, which we will call primary slots, the engine also supports a deterministic secondary slot assignment. Primary slots take precedence over secondary slots, when authoring the node starts by trying to claim a primary slot and falls back to a secondary slot claim attempt. The secondary slot assignment is done by picking the authority at index:
blake2_256(epoch_randomness ++ slot_number) % authorities_len.
The secondary slots supports either a SecondaryPlain or SecondaryVRF
variant. Comparing with SecondaryPlain variant, the SecondaryVRF variant
generates an additional VRF output. The output is not included in beacon
randomness, but can be consumed by parachains.
The fork choice rule is weight-based, where weight equals the number of primary blocks in the chain. We will pick the heaviest chain (more primary blocks) and will go with the longest one in case of a tie.
An in-depth description and analysis of the protocol can be found here: https://research.web3.foundation/en/latest/polkadot/block-production/Babe.html
License: GPL-3.0-or-later WITH Classpath-exception-2.0