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// This file is part of Substrate.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//! # Session Pallet
//!
//! The Session pallet allows validators to manage their session keys, provides a function for
//! changing the session length, and handles session rotation.
//!
//! - [`Config`]
//! - [`Call`]
//! - [`Pallet`]
//!
//! ## Overview
//!
//! ### Terminology
//! <!-- Original author of paragraph: @gavofyork -->
//!
//! - **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 `ShouldEndSession` trait. When the
//! session is ending, a new validator set can be chosen by `OnSessionEnding` implementations.
//!
//! - **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_keys` for use not in
//! the next session, but the session after next. They are stored in `NextKeys`, a mapping between
//! the caller's `ValidatorId` and the session keys provided. `set_keys` allows users to set their
//! session key prior to being selected as validator. It is a public call since it uses
//! `ensure_signed`, which checks that the origin is a signed account. As such, the account ID of
//! the origin stored in `NextKeys` may 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 `ShouldEndSession` to dictate a new session's start.
//! This pallet provides the `PeriodicSessions` struct 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_initialize` function
//! queries the provided implementation of `ShouldEndSession`. If the session is to end the newly
//! activated validator IDs and session keys are taken from storage and passed to the
//! `SessionHandler`. The validator set supplied by `SessionManager::new_session` and the
//! corresponding session keys, which may have been registered via `set_keys` during the previous
//! session, are written to storage where they will wait one session before being passed to the
//! `SessionHandler` themselves.
//!
//! ### 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](../pallet_staking/index.html) 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::Validators::<T>::get()
//! }
//! # fn main(){}
//! ```
//!
//! ## Related Pallets
//!
//! - [Staking](../pallet_staking/index.html)
#![cfg_attr(not(feature = "std"), no_std)]
#[cfg(feature = "historical")]
pub mod historical;
pub mod migrations;
#[cfg(test)]
mod mock;
#[cfg(test)]
mod tests;
pub mod weights;
extern crate alloc;
use alloc::{boxed::Box, vec::Vec};
use codec::{Decode, MaxEncodedLen};
use core::{
marker::PhantomData,
ops::{Rem, Sub},
};
use frame_support::{
dispatch::DispatchResult,
ensure,
traits::{
EstimateNextNewSession, EstimateNextSessionRotation, FindAuthor, Get, OneSessionHandler,
ValidatorRegistration, ValidatorSet,
},
weights::Weight,
Parameter,
};
use frame_system::pallet_prelude::BlockNumberFor;
use sp_runtime::{
traits::{AtLeast32BitUnsigned, Convert, Member, One, OpaqueKeys, Zero},
ConsensusEngineId, DispatchError, KeyTypeId, Permill, RuntimeAppPublic,
};
use sp_staking::SessionIndex;
pub use pallet::*;
pub use weights::WeightInfo;
/// Decides whether the session should be ended.
pub trait ShouldEndSession<BlockNumber> {
/// Return `true` if the session should be ended.
fn should_end_session(now: BlockNumber) -> bool;
}
/// Ends the session after a fixed period of blocks.
///
/// The first session will have length of `Offset`, and
/// the following sessions will have length of `Period`.
/// This may prove nonsensical if `Offset` >= `Period`.
pub struct PeriodicSessions<Period, Offset>(PhantomData<(Period, Offset)>);
impl<
BlockNumber: Rem<Output = BlockNumber> + Sub<Output = BlockNumber> + Zero + PartialOrd,
Period: Get<BlockNumber>,
Offset: Get<BlockNumber>,
> ShouldEndSession<BlockNumber> for PeriodicSessions<Period, Offset>
{
fn should_end_session(now: BlockNumber) -> bool {
let offset = Offset::get();
now >= offset && ((now - offset) % Period::get()).is_zero()
}
}
impl<
BlockNumber: AtLeast32BitUnsigned + Clone,
Period: Get<BlockNumber>,
Offset: Get<BlockNumber>,
> EstimateNextSessionRotation<BlockNumber> for PeriodicSessions<Period, Offset>
{
fn average_session_length() -> BlockNumber {
Period::get()
}
fn estimate_current_session_progress(now: BlockNumber) -> (Option<Permill>, Weight) {
let offset = Offset::get();
let period = Period::get();
// NOTE: we add one since we assume that the current block has already elapsed,
// i.e. when evaluating the last block in the session the progress should be 100%
// (0% is never returned).
let progress = if now >= offset {
let current = (now - offset) % period.clone() + One::one();
Some(Permill::from_rational(current, period))
} else {
Some(Permill::from_rational(now + One::one(), offset))
};
// Weight note: `estimate_current_session_progress` has no storage reads and trivial
// computational overhead. There should be no risk to the chain having this weight value be
// zero for now. However, this value of zero was not properly calculated, and so it would be
// reasonable to come back here and properly calculate the weight of this function.
(progress, Zero::zero())
}
fn estimate_next_session_rotation(now: BlockNumber) -> (Option<BlockNumber>, Weight) {
let offset = Offset::get();
let period = Period::get();
let next_session = if now > offset {
let block_after_last_session = (now.clone() - offset) % period.clone();
if block_after_last_session > Zero::zero() {
now.saturating_add(period.saturating_sub(block_after_last_session))
} else {
// this branch happens when the session is already rotated or will rotate in this
// block (depending on being called before or after `session::on_initialize`). Here,
// we assume the latter, namely that this is called after `session::on_initialize`,
// and thus we add period to it as well.
now + period
}
} else {
offset
};
// Weight note: `estimate_next_session_rotation` has no storage reads and trivial
// computational overhead. There should be no risk to the chain having this weight value be
// zero for now. However, this value of zero was not properly calculated, and so it would be
// reasonable to come back here and properly calculate the weight of this function.
(Some(next_session), Zero::zero())
}
}
/// A trait for managing creation of new validator set.
pub trait SessionManager<ValidatorId> {
/// Plan a new session, and optionally provide the new validator set.
///
/// Even if the validator-set is the same as before, if any underlying economic conditions have
/// changed (i.e. stake-weights), the new validator set must be returned. This is necessary for
/// consensus engines making use of the session pallet to issue a validator-set change so
/// misbehavior can be provably associated with the new economic conditions as opposed to the
/// old. The returned validator set, if any, will not be applied until `new_index`. `new_index`
/// is strictly greater than from previous call.
///
/// The first session start at index 0.
///
/// `new_session(session)` is guaranteed to be called before `end_session(session-1)`. In other
/// words, a new session must always be planned before an ongoing one can be finished.
fn new_session(new_index: SessionIndex) -> Option<Vec<ValidatorId>>;
/// Same as `new_session`, but it this should only be called at genesis.
///
/// The session manager might decide to treat this in a different way. Default impl is simply
/// using [`new_session`](Self::new_session).
fn new_session_genesis(new_index: SessionIndex) -> Option<Vec<ValidatorId>> {
Self::new_session(new_index)
}
/// End the session.
///
/// Because the session pallet can queue validator set the ending session can be lower than the
/// last new session index.
fn end_session(end_index: SessionIndex);
/// Start an already planned session.
///
/// The session start to be used for validation.
fn start_session(start_index: SessionIndex);
}
impl<A> SessionManager<A> for () {
fn new_session(_: SessionIndex) -> Option<Vec<A>> {
None
}
fn start_session(_: SessionIndex) {}
fn end_session(_: SessionIndex) {}
}
/// Handler for session life cycle events.
pub trait SessionHandler<ValidatorId> {
/// All the key type ids this session handler can process.
///
/// The order must be the same as it expects them in
/// [`on_new_session`](Self::on_new_session<Ks>) and
/// [`on_genesis_session`](Self::on_genesis_session<Ks>).
const KEY_TYPE_IDS: &'static [KeyTypeId];
/// The given validator set will be used for the genesis session.
/// It is guaranteed that the given validator set will also be used
/// for the second session, therefore the first call to `on_new_session`
/// should provide the same validator set.
fn on_genesis_session<Ks: OpaqueKeys>(validators: &[(ValidatorId, Ks)]);
/// Session set has changed; act appropriately. Note that this can be called
/// before initialization of your pallet.
///
/// `changed` is true whenever any of the session keys or underlying economic
/// identities or weightings behind `validators` keys has changed. `queued_validators`
/// could change without `validators` changing. Example of possible sequent calls:
/// Session N: on_new_session(false, unchanged_validators, unchanged_queued_validators)
/// Session N + 1: on_new_session(false, unchanged_validators, new_queued_validators)
/// Session N + 2: on_new_session(true, new_queued_validators, new_queued_validators)
fn on_new_session<Ks: OpaqueKeys>(
changed: bool,
validators: &[(ValidatorId, Ks)],
queued_validators: &[(ValidatorId, Ks)],
);
/// A notification for end of the session.
///
/// Note it is triggered before any [`SessionManager::end_session`] handlers,
/// so we can still affect the validator set.
fn on_before_session_ending() {}
/// A validator got disabled. Act accordingly until a new session begins.
fn on_disabled(validator_index: u32);
}
#[impl_trait_for_tuples::impl_for_tuples(1, 30)]
#[tuple_types_custom_trait_bound(OneSessionHandler<AId>)]
impl<AId> SessionHandler<AId> for Tuple {
for_tuples!(
const KEY_TYPE_IDS: &'static [KeyTypeId] = &[ #( <Tuple::Key as RuntimeAppPublic>::ID ),* ];
);
fn on_genesis_session<Ks: OpaqueKeys>(validators: &[(AId, Ks)]) {
for_tuples!(
#(
let our_keys: Box<dyn Iterator<Item=_>> = Box::new(validators.iter()
.filter_map(|k|
k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID).map(|k1| (&k.0, k1))
)
);
Tuple::on_genesis_session(our_keys);
)*
)
}
fn on_new_session<Ks: OpaqueKeys>(
changed: bool,
validators: &[(AId, Ks)],
queued_validators: &[(AId, Ks)],
) {
for_tuples!(
#(
let our_keys: Box<dyn Iterator<Item=_>> = Box::new(validators.iter()
.filter_map(|k|
k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID).map(|k1| (&k.0, k1))
));
let queued_keys: Box<dyn Iterator<Item=_>> = Box::new(queued_validators.iter()
.filter_map(|k|
k.1.get::<Tuple::Key>(<Tuple::Key as RuntimeAppPublic>::ID).map(|k1| (&k.0, k1))
));
Tuple::on_new_session(changed, our_keys, queued_keys);
)*
)
}
fn on_before_session_ending() {
for_tuples!( #( Tuple::on_before_session_ending(); )* )
}
fn on_disabled(i: u32) {
for_tuples!( #( Tuple::on_disabled(i); )* )
}
}
/// `SessionHandler` for tests that use `UintAuthorityId` as `Keys`.
pub struct TestSessionHandler;
impl<AId> SessionHandler<AId> for TestSessionHandler {
const KEY_TYPE_IDS: &'static [KeyTypeId] = &[sp_runtime::key_types::DUMMY];
fn on_genesis_session<Ks: OpaqueKeys>(_: &[(AId, Ks)]) {}
fn on_new_session<Ks: OpaqueKeys>(_: bool, _: &[(AId, Ks)], _: &[(AId, Ks)]) {}
fn on_before_session_ending() {}
fn on_disabled(_: u32) {}
}
#[frame_support::pallet]
pub mod pallet {
use super::*;
use frame_support::pallet_prelude::*;
use frame_system::pallet_prelude::*;
/// The in-code storage version.
const STORAGE_VERSION: StorageVersion = StorageVersion::new(0);
#[pallet::pallet]
#[pallet::storage_version(STORAGE_VERSION)]
#[pallet::without_storage_info]
pub struct Pallet<T>(_);
#[pallet::config]
pub trait Config: frame_system::Config {
/// The overarching event type.
type RuntimeEvent: From<Event> + IsType<<Self as frame_system::Config>::RuntimeEvent>;
/// A stable ID for a validator.
type ValidatorId: Member
+ Parameter
+ MaybeSerializeDeserialize
+ MaxEncodedLen
+ TryFrom<Self::AccountId>;
/// A conversion from account ID to validator ID.
///
/// Its cost must be at most one storage read.
type ValidatorIdOf: Convert<Self::AccountId, Option<Self::ValidatorId>>;
/// Indicator for when to end the session.
type ShouldEndSession: ShouldEndSession<BlockNumberFor<Self>>;
/// Something that can predict the next session rotation. This should typically come from
/// the same logical unit that provides [`ShouldEndSession`], yet, it gives a best effort
/// estimate. It is helpful to implement [`EstimateNextNewSession`].
type NextSessionRotation: EstimateNextSessionRotation<BlockNumberFor<Self>>;
/// Handler for managing new session.
type SessionManager: SessionManager<Self::ValidatorId>;
/// Handler when a session has changed.
type SessionHandler: SessionHandler<Self::ValidatorId>;
/// The keys.
type Keys: OpaqueKeys + Member + Parameter + MaybeSerializeDeserialize;
/// Weight information for extrinsics in this pallet.
type WeightInfo: WeightInfo;
}
#[pallet::genesis_config]
#[derive(frame_support::DefaultNoBound)]
pub struct GenesisConfig<T: Config> {
/// Initial list of validator at genesis representing by their `(AccountId, ValidatorId,
/// Keys)`. These keys will be considered authorities for the first two sessions and they
/// will be valid at least until session 2
pub keys: Vec<(T::AccountId, T::ValidatorId, T::Keys)>,
/// List of (AccountId, ValidatorId, Keys) that will be registered at genesis, but not as
/// active validators. These keys are set, together with `keys`, as authority candidates
/// for future sessions (enactable from session 2 onwards)
pub non_authority_keys: Vec<(T::AccountId, T::ValidatorId, T::Keys)>,
}
#[pallet::genesis_build]
impl<T: Config> BuildGenesisConfig for GenesisConfig<T> {
fn build(&self) {
if T::SessionHandler::KEY_TYPE_IDS.len() != T::Keys::key_ids().len() {
panic!("Number of keys in session handler and session keys does not match");
}
T::SessionHandler::KEY_TYPE_IDS
.iter()
.zip(T::Keys::key_ids())
.enumerate()
.for_each(|(i, (sk, kk))| {
if sk != kk {
panic!(
"Session handler and session key expect different key type at index: {}",
i,
);
}
});
for (account, val, keys) in
self.keys.iter().chain(self.non_authority_keys.iter()).cloned()
{
Pallet::<T>::inner_set_keys(&val, keys)
.expect("genesis config must not contain duplicates; qed");
if frame_system::Pallet::<T>::inc_consumers_without_limit(&account).is_err() {
// This will leak a provider reference, however it only happens once (at
// genesis) so it's really not a big deal and we assume that the user wants to
// do this since it's the only way a non-endowed account can contain a session
// key.
frame_system::Pallet::<T>::inc_providers(&account);
}
}
let initial_validators_0 =
T::SessionManager::new_session_genesis(0).unwrap_or_else(|| {
frame_support::print(
"No initial validator provided by `SessionManager`, use \
session config keys to generate initial validator set.",
);
self.keys.iter().map(|x| x.1.clone()).collect()
});
let initial_validators_1 = T::SessionManager::new_session_genesis(1)
.unwrap_or_else(|| initial_validators_0.clone());
let queued_keys: Vec<_> = initial_validators_1
.into_iter()
.filter_map(|v| Pallet::<T>::load_keys(&v).map(|k| (v, k)))
.collect();
// Tell everyone about the genesis session keys
T::SessionHandler::on_genesis_session::<T::Keys>(&queued_keys);
Validators::<T>::put(initial_validators_0);
QueuedKeys::<T>::put(queued_keys);
T::SessionManager::start_session(0);
}
}
/// The current set of validators.
#[pallet::storage]
pub type Validators<T: Config> = StorageValue<_, Vec<T::ValidatorId>, ValueQuery>;
/// Current index of the session.
#[pallet::storage]
pub type CurrentIndex<T> = StorageValue<_, SessionIndex, ValueQuery>;
/// True if the underlying economic identities or weighting behind the validators
/// has changed in the queued validator set.
#[pallet::storage]
pub type QueuedChanged<T> = StorageValue<_, bool, ValueQuery>;
/// The queued keys for the next session. When the next session begins, these keys
/// will be used to determine the validator's session keys.
#[pallet::storage]
pub type QueuedKeys<T: Config> = StorageValue<_, Vec<(T::ValidatorId, T::Keys)>, ValueQuery>;
/// Indices of disabled validators.
///
/// The vec is always kept sorted so that we can find whether a given validator is
/// disabled using binary search. It gets cleared when `on_session_ending` returns
/// a new set of identities.
#[pallet::storage]
pub type DisabledValidators<T> = StorageValue<_, Vec<u32>, ValueQuery>;
/// The next session keys for a validator.
#[pallet::storage]
pub type NextKeys<T: Config> =
StorageMap<_, Twox64Concat, T::ValidatorId, T::Keys, OptionQuery>;
/// The owner of a key. The key is the `KeyTypeId` + the encoded key.
#[pallet::storage]
pub type KeyOwner<T: Config> =
StorageMap<_, Twox64Concat, (KeyTypeId, Vec<u8>), T::ValidatorId, OptionQuery>;
#[pallet::event]
#[pallet::generate_deposit(pub(super) fn deposit_event)]
pub enum Event {
/// New session has happened. Note that the argument is the session index, not the
/// block number as the type might suggest.
NewSession { session_index: SessionIndex },
}
/// Error for the session pallet.
#[pallet::error]
pub enum Error<T> {
/// Invalid ownership proof.
InvalidProof,
/// No associated validator ID for account.
NoAssociatedValidatorId,
/// Registered duplicate key.
DuplicatedKey,
/// No keys are associated with this account.
NoKeys,
/// Key setting account is not live, so it's impossible to associate keys.
NoAccount,
}
#[pallet::hooks]
impl<T: Config> Hooks<BlockNumberFor<T>> for Pallet<T> {
/// Called when a block is initialized. Will rotate session if it is the last
/// block of the current session.
fn on_initialize(n: BlockNumberFor<T>) -> Weight {
if T::ShouldEndSession::should_end_session(n) {
Self::rotate_session();
T::BlockWeights::get().max_block
} else {
// NOTE: the non-database part of the weight for `should_end_session(n)` is
// included as weight for empty block, the database part is expected to be in
// cache.
Weight::zero()
}
}
}
#[pallet::call]
impl<T: Config> Pallet<T> {
/// Sets the session key(s) of the function caller to `keys`.
/// Allows an account to set its session key prior to becoming a validator.
/// This doesn't take effect until the next session.
///
/// The dispatch origin of this function must be signed.
///
/// ## Complexity
/// - `O(1)`. Actual cost depends on the number of length of `T::Keys::key_ids()` which is
/// fixed.
#[pallet::call_index(0)]
#[pallet::weight(T::WeightInfo::set_keys())]
pub fn set_keys(origin: OriginFor<T>, keys: T::Keys, proof: Vec<u8>) -> DispatchResult {
let who = ensure_signed(origin)?;
ensure!(keys.ownership_proof_is_valid(&proof), Error::<T>::InvalidProof);
Self::do_set_keys(&who, keys)?;
Ok(())
}
/// Removes any session key(s) of the function caller.
///
/// This doesn't take effect until the next session.
///
/// The dispatch origin of this function must be Signed and the account must be either be
/// convertible to a validator ID using the chain's typical addressing system (this usually
/// means being a controller account) or directly convertible into a validator ID (which
/// usually means being a stash account).
///
/// ## Complexity
/// - `O(1)` in number of key types. Actual cost depends on the number of length of
/// `T::Keys::key_ids()` which is fixed.
#[pallet::call_index(1)]
#[pallet::weight(T::WeightInfo::purge_keys())]
pub fn purge_keys(origin: OriginFor<T>) -> DispatchResult {
let who = ensure_signed(origin)?;
Self::do_purge_keys(&who)?;
Ok(())
}
}
}
impl<T: Config> Pallet<T> {
/// Public function to access the current set of validators.
pub fn validators() -> Vec<T::ValidatorId> {
Validators::<T>::get()
}
/// Public function to access the current session index.
pub fn current_index() -> SessionIndex {
CurrentIndex::<T>::get()
}
/// Public function to access the queued keys.
pub fn queued_keys() -> Vec<(T::ValidatorId, T::Keys)> {
QueuedKeys::<T>::get()
}
/// Public function to access the disabled validators.
pub fn disabled_validators() -> Vec<u32> {
DisabledValidators::<T>::get()
}
/// Move on to next session. Register new validator set and session keys. Changes to the
/// validator set have a session of delay to take effect. This allows for equivocation
/// punishment after a fork.
pub fn rotate_session() {
let session_index = CurrentIndex::<T>::get();
log::trace!(target: "runtime::session", "rotating session {:?}", session_index);
let changed = QueuedChanged::<T>::get();
// Inform the session handlers that a session is going to end.
T::SessionHandler::on_before_session_ending();
T::SessionManager::end_session(session_index);
// Get queued session keys and validators.
let session_keys = QueuedKeys::<T>::get();
let validators =
session_keys.iter().map(|(validator, _)| validator.clone()).collect::<Vec<_>>();
Validators::<T>::put(&validators);
if changed {
// reset disabled validators if active set was changed
DisabledValidators::<T>::take();
}
// Increment session index.
let session_index = session_index + 1;
CurrentIndex::<T>::put(session_index);
T::SessionManager::start_session(session_index);
// Get next validator set.
let maybe_next_validators = T::SessionManager::new_session(session_index + 1);
let (next_validators, next_identities_changed) =
if let Some(validators) = maybe_next_validators {
// NOTE: as per the documentation on `OnSessionEnding`, we consider
// the validator set as having changed even if the validators are the
// same as before, as underlying economic conditions may have changed.
(validators, true)
} else {
(Validators::<T>::get(), false)
};
// Queue next session keys.
let (queued_amalgamated, next_changed) = {
// until we are certain there has been a change, iterate the prior
// validators along with the current and check for changes
let mut changed = next_identities_changed;
let mut now_session_keys = session_keys.iter();
let mut check_next_changed = |keys: &T::Keys| {
if changed {
return;
}
// since a new validator set always leads to `changed` starting
// as true, we can ensure that `now_session_keys` and `next_validators`
// have the same length. this function is called once per iteration.
if let Some((_, old_keys)) = now_session_keys.next() {
if old_keys != keys {
changed = true;
}
}
};
let queued_amalgamated = next_validators
.into_iter()
.filter_map(|a| {
let k = Self::load_keys(&a)?;
check_next_changed(&k);
Some((a, k))
})
.collect::<Vec<_>>();
(queued_amalgamated, changed)
};
QueuedKeys::<T>::put(queued_amalgamated.clone());
QueuedChanged::<T>::put(next_changed);
// Record that this happened.
Self::deposit_event(Event::NewSession { session_index });
// Tell everyone about the new session keys.
T::SessionHandler::on_new_session::<T::Keys>(changed, &session_keys, &queued_amalgamated);
}
/// Disable the validator of index `i`, returns `false` if the validator was already disabled.
pub fn disable_index(i: u32) -> bool {
if i >= Validators::<T>::decode_len().unwrap_or(0) as u32 {
return false
}
DisabledValidators::<T>::mutate(|disabled| {
if let Err(index) = disabled.binary_search(&i) {
disabled.insert(index, i);
T::SessionHandler::on_disabled(i);
return true
}
false
})
}
/// Disable the validator identified by `c`. (If using with the staking pallet,
/// this would be their *stash* account.)
///
/// Returns `false` either if the validator could not be found or it was already
/// disabled.
pub fn disable(c: &T::ValidatorId) -> bool {
Validators::<T>::get()
.iter()
.position(|i| i == c)
.map(|i| Self::disable_index(i as u32))
.unwrap_or(false)
}
/// Upgrade the key type from some old type to a new type. Supports adding
/// and removing key types.
///
/// This function should be used with extreme care and only during an
/// `on_runtime_upgrade` block. Misuse of this function can put your blockchain
/// into an unrecoverable state.
///
/// Care should be taken that the raw versions of the
/// added keys are unique for every `ValidatorId, KeyTypeId` combination.
/// This is an invariant that the session pallet typically maintains internally.
///
/// As the actual values of the keys are typically not known at runtime upgrade,
/// it's recommended to initialize the keys to a (unique) dummy value with the expectation
/// that all validators should invoke `set_keys` before those keys are actually
/// required.
pub fn upgrade_keys<Old, F>(upgrade: F)
where
Old: OpaqueKeys + Member + Decode,
F: Fn(T::ValidatorId, Old) -> T::Keys,
{
let old_ids = Old::key_ids();
let new_ids = T::Keys::key_ids();
// Translate NextKeys, and key ownership relations at the same time.
NextKeys::<T>::translate::<Old, _>(|val, old_keys| {
// Clear all key ownership relations. Typically the overlap should
// stay the same, but no guarantees by the upgrade function.
for i in old_ids.iter() {
Self::clear_key_owner(*i, old_keys.get_raw(*i));
}
let new_keys = upgrade(val.clone(), old_keys);
// And now set the new ones.
for i in new_ids.iter() {
Self::put_key_owner(*i, new_keys.get_raw(*i), &val);
}
Some(new_keys)
});
let _ = QueuedKeys::<T>::translate::<Vec<(T::ValidatorId, Old)>, _>(|k| {
k.map(|k| {
k.into_iter()
.map(|(val, old_keys)| (val.clone(), upgrade(val, old_keys)))
.collect::<Vec<_>>()
})
});
}
/// Perform the set_key operation, checking for duplicates. Does not set `Changed`.
///
/// This ensures that the reference counter in system is incremented appropriately and as such
/// must accept an account ID, rather than a validator ID.
fn do_set_keys(account: &T::AccountId, keys: T::Keys) -> DispatchResult {
let who = T::ValidatorIdOf::convert(account.clone())
.ok_or(Error::<T>::NoAssociatedValidatorId)?;
ensure!(frame_system::Pallet::<T>::can_inc_consumer(account), Error::<T>::NoAccount);
let old_keys = Self::inner_set_keys(&who, keys)?;
if old_keys.is_none() {
let assertion = frame_system::Pallet::<T>::inc_consumers(account).is_ok();
debug_assert!(assertion, "can_inc_consumer() returned true; no change since; qed");
}
Ok(())
}
/// Perform the set_key operation, checking for duplicates. Does not set `Changed`.
///
/// The old keys for this validator are returned, or `None` if there were none.
///
/// This does not ensure that the reference counter in system is incremented appropriately, it
/// must be done by the caller or the keys will be leaked in storage.
fn inner_set_keys(
who: &T::ValidatorId,
keys: T::Keys,
) -> Result<Option<T::Keys>, DispatchError> {
let old_keys = Self::load_keys(who);
for id in T::Keys::key_ids() {
let key = keys.get_raw(*id);
// ensure keys are without duplication.
ensure!(
Self::key_owner(*id, key).map_or(true, |owner| &owner == who),
Error::<T>::DuplicatedKey,
);
}
for id in T::Keys::key_ids() {
let key = keys.get_raw(*id);
if let Some(old) = old_keys.as_ref().map(|k| k.get_raw(*id)) {
if key == old {
continue
}
Self::clear_key_owner(*id, old);
}
Self::put_key_owner(*id, key, who);
}
Self::put_keys(who, &keys);
Ok(old_keys)
}
fn do_purge_keys(account: &T::AccountId) -> DispatchResult {
let who = T::ValidatorIdOf::convert(account.clone())
// `purge_keys` may not have a controller-stash pair any more. If so then we expect the
// stash account to be passed in directly and convert that to a `ValidatorId` using the
// `TryFrom` trait if supported.
.or_else(|| T::ValidatorId::try_from(account.clone()).ok())
.ok_or(Error::<T>::NoAssociatedValidatorId)?;
let old_keys = Self::take_keys(&who).ok_or(Error::<T>::NoKeys)?;
for id in T::Keys::key_ids() {
let key_data = old_keys.get_raw(*id);
Self::clear_key_owner(*id, key_data);
}
frame_system::Pallet::<T>::dec_consumers(account);
Ok(())
}
fn load_keys(v: &T::ValidatorId) -> Option<T::Keys> {
NextKeys::<T>::get(v)
}
fn take_keys(v: &T::ValidatorId) -> Option<T::Keys> {
NextKeys::<T>::take(v)
}
fn put_keys(v: &T::ValidatorId, keys: &T::Keys) {
NextKeys::<T>::insert(v, keys);
}
/// Query the owner of a session key by returning the owner's validator ID.
pub fn key_owner(id: KeyTypeId, key_data: &[u8]) -> Option<T::ValidatorId> {
KeyOwner::<T>::get((id, key_data))
}
fn put_key_owner(id: KeyTypeId, key_data: &[u8], v: &T::ValidatorId) {
KeyOwner::<T>::insert((id, key_data), v)
}
fn clear_key_owner(id: KeyTypeId, key_data: &[u8]) {
KeyOwner::<T>::remove((id, key_data));
}
}
impl<T: Config> ValidatorRegistration<T::ValidatorId> for Pallet<T> {
fn is_registered(id: &T::ValidatorId) -> bool {
Self::load_keys(id).is_some()
}
}
impl<T: Config> ValidatorSet<T::AccountId> for Pallet<T> {
type ValidatorId = T::ValidatorId;
type ValidatorIdOf = T::ValidatorIdOf;
fn session_index() -> sp_staking::SessionIndex {
CurrentIndex::<T>::get()
}
fn validators() -> Vec<Self::ValidatorId> {
Validators::<T>::get()
}
}
impl<T: Config> EstimateNextNewSession<BlockNumberFor<T>> for Pallet<T> {
fn average_session_length() -> BlockNumberFor<T> {
T::NextSessionRotation::average_session_length()
}
/// This session pallet always calls new_session and next_session at the same time, hence we
/// do a simple proxy and pass the function to next rotation.
fn estimate_next_new_session(now: BlockNumberFor<T>) -> (Option<BlockNumberFor<T>>, Weight) {
T::NextSessionRotation::estimate_next_session_rotation(now)
}
}
impl<T: Config> frame_support::traits::DisabledValidators for Pallet<T> {
fn is_disabled(index: u32) -> bool {
DisabledValidators::<T>::get().binary_search(&index).is_ok()
}
fn disabled_validators() -> Vec<u32> {
DisabledValidators::<T>::get()
}
}
/// Wraps the author-scraping logic for consensus engines that can recover
/// the canonical index of an author. This then transforms it into the
/// registering account-ID of that session key index.
pub struct FindAccountFromAuthorIndex<T, Inner>(core::marker::PhantomData<(T, Inner)>);
impl<T: Config, Inner: FindAuthor<u32>> FindAuthor<T::ValidatorId>
for FindAccountFromAuthorIndex<T, Inner>
{
fn find_author<'a, I>(digests: I) -> Option<T::ValidatorId>
where
I: 'a + IntoIterator<Item = (ConsensusEngineId, &'a [u8])>,
{
let i = Inner::find_author(digests)?;
let validators = Validators::<T>::get();
validators.get(i as usize).cloned()
}
}