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// Copyright 2020 Parity Technologies (UK) Ltd.
// This file is part of Polkadot.
// Polkadot is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// Polkadot is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with Polkadot. If not, see <http://www.gnu.org/licenses/>.
//! The session info module provides information about validator sets
//! from prior sessions needed for approvals and disputes.
//!
//! See https://w3f.github.io/parachain-implementers-guide/runtime/session_info.html.
use primitives::v1::{SessionIndex, SessionInfo, ValidatorId};
use frame_support::{
decl_storage, decl_module, decl_error,
};
use crate::{configuration, paras, scheduler};
pub trait Trait:
frame_system::Trait
+ configuration::Trait
+ paras::Trait
+ scheduler::Trait
+ pallet_authority_discovery::Trait
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{
}
decl_storage! {
trait Store for Module<T: Trait> as ParaSessionInfo {
/// The earliest session for which previous session info is stored.
EarliestStoredSession get(fn earliest_stored_session): SessionIndex;
/// Session information in a rolling window.
/// Should have an entry in range `EarliestStoredSession..=CurrentSessionIndex`.
Sessions get(fn session_info): map hasher(identity) SessionIndex => Option<SessionInfo>;
}
}
decl_error! {
pub enum Error for Module<T: Trait> { }
}
decl_module! {
/// The session info module.
pub struct Module<T: Trait> for enum Call where origin: <T as frame_system::Trait>::Origin {
type Error = Error<T>;
}
}
impl<T: Trait> sp_runtime::BoundToRuntimeAppPublic for Module<T> {
type Public = ValidatorId;
}
impl<T: pallet_session::Trait + Trait> pallet_session::OneSessionHandler<T::AccountId> for Module<T> {
type Key = ValidatorId;
fn on_genesis_session<'a, I: 'a>(_validators: I)
where I: Iterator<Item=(&'a T::AccountId, Self::Key)>
{
}
fn on_new_session<'a, I: 'a>(_changed: bool, validators: I, _queued: I)
where I: Iterator<Item=(&'a T::AccountId, Self::Key)>
{
let config = <configuration::Module<T>>::config();
let dispute_period = config.dispute_period;
let n_parachains = <paras::Module<T>>::parachains().len() as u32;
// TODO: is is the same as <inclusion::Module<T>>::validators()?
let validators: Vec<_> = validators.map(|(_, key)| key).collect();
let discovery_keys = <pallet_authority_discovery::Module<T>>::authorities();
// FIXME:???
let approval_keys = Vec::new();
let validator_groups = <scheduler::Module<T>>::validator_groups();
let n_cores = n_parachains + config.parathread_cores;
let zeroth_delay_tranche_width = config.zeroth_delay_tranche_width;
let relay_vrf_modulo_samples = config.relay_vrf_modulo_samples;
// FIXME: add n_delay_tranches to config?
let n_delay_tranches = 0u32;
let no_show_slots = config.no_show_slots;
let needed_approvals = config.needed_approvals;
let new_session_index = <pallet_session::Module<T>>::current_index();
let old_earliest_stored_session = EarliestStoredSession::get();
let new_earliest_stored_session = new_session_index.checked_sub(dispute_period).unwrap_or(0);
// update `EarliestStoredSession` based on `config.dispute_period`
EarliestStoredSession::set(new_earliest_stored_session);
// remove all entries from `Sessions` from the previous value up to the new value
for idx in old_earliest_stored_session..new_earliest_stored_session {
Sessions::remove(&idx);
}
// create a new entry in `Sessions` with information about the current session
let new_session_info = SessionInfo {
validators,
discovery_keys,
approval_keys,
validator_groups,
n_cores,
zeroth_delay_tranche_width,
relay_vrf_modulo_samples,
n_delay_tranches,
no_show_slots,
needed_approvals,
};
Sessions::insert(&new_session_index, &new_session_info);
}
fn on_disabled(_i: usize) { }
}
#[cfg(test)]
mod tests {