mirror of
https://github.com/pezkuwichain/pezkuwi-subxt.git
synced 2026-04-26 14:37:57 +00:00
8ee4042c3b
This PR refactors the staking ledger logic to encapsulate all reads and mutations of `Ledger`, `Bonded`, `Payee` and stake locks within the `StakingLedger` struct implementation. With these changes, all the reads and mutations to the `Ledger`, `Payee` and `Bonded` storage map should be done through the methods exposed by StakingLedger to ensure the data and lock consistency of the operations. The new introduced methods that mutate and read Ledger are: - `ledger.update()`: inserts/updates a staking ledger in storage; updates staking locks accordingly (and ledger.bond(), which is synthatic sugar for ledger.update()) - `ledger.kill()`: removes all Bonded and StakingLedger related data for a given ledger; updates staking locks accordingly; `StakingLedger::get(account)`: queries both the `Bonded` and `Ledger` storages and returns a `Option<StakingLedger>`. The pallet impl exposes fn ledger(account) as synthatic sugar for `StakingLedger::get(account)`. Retrieving a ledger with `StakingLedger::get()` can be done by providing either a stash or controller account. The input must be wrapped in a `StakingAccount` variant (Stash or Controller) which is treated accordingly. This simplifies the caller API but will eventually be deprecated once we completely get rid of the controller account in staking. However, this refactor will help with the work necessary when completely removing the controller. Other goals: - No logical changes have been introduced in this PR; - No breaking changes or updates in wallets required; - No new storage items or need to perform storage migrations; - Centralise the changes to bonds and ledger updates to simplify the OnStakingUpdate updates to the target list (related to https://github.com/paritytech/polkadot-sdk/issues/443) Note: it would be great to prevent or at least raise a warning if `Ledger<T>`, `Payee<T>` and `Bonded<T>` storage types are accessed outside the `StakingLedger` implementation. This PR should not get blocked by that feature, but there's a tracking issue here https://github.com/paritytech/polkadot-sdk/issues/149 Related and step towards https://github.com/paritytech/polkadot-sdk/issues/443
Session Pallet
The Session module allows validators to manage their session keys, provides a function for changing the session length, and handles session rotation.
Overview
Terminology
- Session: A session is a period of time that has a constant set of validators. Validators can only join or exit the
validator set at a session change. It is measured in block numbers. The block where a session is ended is determined by
the
ShouldEndSessiontrait. When the session is ending, a new validator set can be chosen byOnSessionEndingimplementations. - Session key: A session key is actually several keys kept together that provide the various signing functions required by network authorities/validators in pursuit of their duties.
- Validator ID: Every account has an associated validator ID. For some simple staking systems, this may just be the same as the account ID. For staking systems using a stash/controller model, the validator ID would be the stash account ID of the controller.
- Session key configuration process: Session keys are set using
set_keysfor use not in the next session, but the session after next. They are stored inNextKeys, a mapping between the caller'sValidatorIdand the session keys provided.set_keysallows users to set their session key prior to being selected as validator. It is a public call since it usesensure_signed, which checks that the origin is a signed account. As such, the account ID of the origin stored inNextKeysmay not necessarily be associated with a block author or a validator. The session keys of accounts are removed once their account balance is zero. - Session length: This pallet does not assume anything about the length of each session. Rather, it relies on an
implementation of
ShouldEndSessionto dictate a new session's start. This pallet provides thePeriodicSessionsstruct for simple periodic sessions. - Session rotation configuration: Configure as either a 'normal' (rewardable session where rewards are applied) or 'exceptional' (slashable) session rotation.
- Session rotation process: At the beginning of each block, the
on_initializefunction queries the provided implementation ofShouldEndSession. If the session is to end the newly activated validator IDs and session keys are taken from storage and passed to theSessionHandler. The validator set supplied bySessionManager::new_sessionand the corresponding session keys, which may have been registered viaset_keysduring the previous session, are written to storage where they will wait one session before being passed to theSessionHandlerthemselves.
Goals
The Session pallet is designed to make the following possible:
- Set session keys of the validator set for upcoming sessions.
- Control the length of sessions.
- Configure and switch between either normal or exceptional session rotations.
Interface
Dispatchable Functions
set_keys- Set a validator's session keys for upcoming sessions.
Public Functions
rotate_session- Change to the next session. Register the new authority set. Queue changes for next session rotation.disable_index- Disable a validator by index.disable- Disable a validator by Validator ID
Usage
Example from the FRAME
The Staking pallet uses the Session pallet to get the validator set.
use pallet_session as session;
fn validators<T: pallet_session::Config>() -> Vec<<T as pallet_session::Config>::ValidatorId> {
<pallet_session::Pallet<T>>::validators()
}
Related Pallets
License: Apache-2.0