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// Copyright 2017-2018 Parity Technologies (UK) Ltd.
// This file is part of Substrate.
// Substrate 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.
// Substrate 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 Substrate. If not, see <http://www.gnu.org/licenses/>.
//! Session manager: is told the validators and allows them to manage their session keys for the
//! consensus module.
#![cfg_attr(not(feature = "std"), no_std)]
#[cfg(test)]
extern crate substrate_primitives;
#[cfg(test)]
extern crate sr_io as runtime_io;
extern crate parity_codec as codec;
extern crate sr_primitives as primitives;
extern crate srml_consensus as consensus;
extern crate srml_system as system;
extern crate srml_timestamp as timestamp;
use primitives::traits::{As, Zero, One, Convert};
use runtime_support::dispatch::Result;
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use runtime_support::for_each_tuple;
use rstd::ops::Mul;
/// A session has changed.
/// Session has changed.
fn on_session_change(time_elapsed: T, should_reward: bool);
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macro_rules! impl_session_change {
() => (
impl<T> OnSessionChange<T> for () {
fn on_session_change(_: T, _: bool) {}
}
);
( $($t:ident)* ) => {
impl<T: Clone, $($t: OnSessionChange<T>),*> OnSessionChange<T> for ($($t,)*) {
fn on_session_change(time_elapsed: T, should_reward: bool) {
$($t::on_session_change(time_elapsed.clone(), should_reward);)*
}
}
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for_each_tuple!(impl_session_change);
pub trait Trait: timestamp::Trait {
type ConvertAccountIdToSessionKey: Convert<Self::AccountId, Self::SessionKey>;
type OnSessionChange: OnSessionChange<Self::Moment>;
type Event: From<Event<Self>> + Into<<Self as system::Trait>::Event>;
pub struct Module<T: Trait> for enum Call where origin: T::Origin {
fn deposit_event<T>() = default;
/// Sets the session key of `_validator` to `_key`. This doesn't take effect until the next
/// session.
fn set_key(origin, key: T::SessionKey) {
let who = ensure_signed(origin)?;
// set new value for next session
<NextKeyFor<T>>::insert(who, key);
}
/// Set a new session length. Won't kick in until the next session change (at current length).
fn set_length(new: <T::BlockNumber as HasCompact>::Type) {
<NextSessionLength<T>>::put(new.into());
}
/// Forces a new session.
fn force_new_session(apply_rewards: bool) -> Result {
Self::apply_force_new_session(apply_rewards)
}
fn on_finalise(n: T::BlockNumber) {
Self::check_rotate_session(n);
}
pub enum Event<T> where <T as system::Trait>::BlockNumber {
/// New session has happened. Note that the argument is the session index, not the block
/// number as the type might suggest.
NewSession(BlockNumber),
}
);
trait Store for Module<T: Trait> as Session {
/// The current set of validators.
pub Validators get(validators) config(): Vec<T::AccountId>;
/// Current length of the session.
pub SessionLength get(length) config(session_length): T::BlockNumber = T::BlockNumber::sa(1000);
/// Current index of the session.
pub CurrentIndex get(current_index) build(|_| T::BlockNumber::sa(0)): T::BlockNumber;
/// Timestamp when current session started.
pub CurrentStart get(current_start) build(|_| T::Moment::zero()): T::Moment;
/// New session is being forced is this entry exists; in which case, the boolean value is whether
/// the new session should be considered a normal rotation (rewardable) or exceptional (slashable).
pub ForcingNewSession get(forcing_new_session): Option<bool>;
/// Block at which the session length last changed.
/// The next key for a given validator.
NextKeyFor: map T::AccountId => Option<T::SessionKey>;
}
impl<T: Trait> Module<T> {
/// The number of validators currently.
pub fn validator_count() -> u32 {
<Validators<T>>::get().len() as u32 // TODO: can probably optimised
}
/// The last length change, if there was one, zero if not.
pub fn last_length_change() -> T::BlockNumber {
<LastLengthChange<T>>::get().unwrap_or_else(T::BlockNumber::zero)
}
// INTERNAL API (available to other runtime modules)
/// Forces a new session, no origin.
pub fn apply_force_new_session(apply_rewards: bool) -> Result {
<ForcingNewSession<T>>::put(apply_rewards);
Ok(())
}
/// Called by `staking::new_era()` only. `next_session` should be called after this in order to
/// update the session keys to the next validator set.
pub fn set_validators(new: &[T::AccountId]) {
<Validators<T>>::put(&new.to_vec()); // TODO: optimise.
<consensus::Module<T>>::set_authorities(
&new.iter().cloned().map(T::ConvertAccountIdToSessionKey::convert).collect::<Vec<_>>()
);
}
/// Hook to be called after transaction processing.
pub fn check_rotate_session(block_number: T::BlockNumber) {
// do this last, after the staking system has had chance to switch out the authorities for the
// new set.
// check block number and call next_session if necessary.
let is_final_block = ((block_number - Self::last_length_change()) % Self::length()).is_zero();
let (should_end_session, apply_rewards) = <ForcingNewSession<T>>::take()
.map_or((is_final_block, is_final_block), |apply_rewards| (true, apply_rewards));
Self::rotate_session(is_final_block, apply_rewards);
}
}
/// Move onto next session: register the new authority set.
pub fn rotate_session(is_final_block: bool, apply_rewards: bool) {
let now = <timestamp::Module<T>>::get();
let time_elapsed = now.clone() - Self::current_start();
let session_index = <CurrentIndex<T>>::get() + One::one();
Self::deposit_event(RawEvent::NewSession(session_index));
<CurrentStart<T>>::put(now);
let len_changed = if let Some(next_len) = <NextSessionLength<T>>::take() {
true
} else {
false
};
if len_changed || !is_final_block {
let block_number = <system::Module<T>>::block_number();
T::OnSessionChange::on_session_change(time_elapsed, apply_rewards);
// Update any changes in session keys.
Self::validators().iter().enumerate().for_each(|(i, v)| {
if let Some(n) = <NextKeyFor<T>>::take(v) {
<consensus::Module<T>>::set_authority(i as u32, &n);
}
});
}
/// Get the time that should have elapsed over a session if everything was working perfectly.
pub fn ideal_session_duration() -> T::Moment {
let block_period: T::Moment = <timestamp::Module<T>>::block_period();
let session_length: T::BlockNumber = Self::length();
Mul::<T::BlockNumber>::mul(block_period, session_length)
}
/// Number of blocks remaining in this session, not counting this one. If the session is
/// due to rotate at the end of this block, then it will return 0. If the just began, then
/// it will return `Self::length() - 1`.
pub fn blocks_remaining() -> T::BlockNumber {
let length = Self::length();
let length_minus_1 = length - One::one();
let block_number = <system::Module<T>>::block_number();
length_minus_1 - (block_number - Self::last_length_change() + length_minus_1) % length
}
}
#[cfg(test)]
mod tests {
use super::*;
use runtime_io::with_externalities;
use substrate_primitives::{H256, Blake2Hasher};
use primitives::traits::BlakeTwo256;
use primitives::testing::{Digest, DigestItem, Header, UintAuthorityId, ConvertUintAuthorityId};
impl_outer_origin!{
pub enum Origin for Test {}
}
pub struct Test;
impl consensus::Trait for Test {
const NOTE_OFFLINE_POSITION: u32 = 1;
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type Log = DigestItem;
type InherentOfflineReport = ();
type Index = u64;
type BlockNumber = u64;
type Hash = H256;
type Digest = Digest;
type AccountId = u64;
type Header = Header;
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type Log = DigestItem;
impl timestamp::Trait for Test {
const TIMESTAMP_SET_POSITION: u32 = 0;
type Moment = u64;
type OnTimestampSet = ();
type ConvertAccountIdToSessionKey = ConvertUintAuthorityId;
type OnSessionChange = ();
}
type System = system::Module<Test>;
type Consensus = consensus::Module<Test>;
type Session = Module<Test>;
fn new_test_ext() -> runtime_io::TestExternalities<Blake2Hasher> {
let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
authorities: vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)],
}.build_storage().unwrap().0);
t.extend(timestamp::GenesisConfig::<Test>{
period: 5,
}.build_storage().unwrap().0);
t.extend(GenesisConfig::<Test>{
session_length: 2,
validators: vec![1, 2, 3],
}.build_storage().unwrap().0);
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runtime_io::TestExternalities::new(t)
}
#[test]
fn simple_setup_should_work() {
with_externalities(&mut new_test_ext(), || {
assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1).into(), UintAuthorityId(2).into(), UintAuthorityId(3).into()]);
assert_eq!(Session::length(), 2);
assert_eq!(Session::validators(), vec![1, 2, 3]);
});
}
#[test]
fn should_work_with_early_exit() {
with_externalities(&mut new_test_ext(), || {
System::set_block_number(1);
assert_ok!(Session::set_length(10.into()));
assert_eq!(Session::blocks_remaining(), 1);
System::set_block_number(2);
assert_eq!(Session::blocks_remaining(), 0);
System::set_block_number(7);
assert_eq!(Session::current_index(), 1);
assert_eq!(Session::blocks_remaining(), 5);
System::set_block_number(8);
assert_eq!(Session::current_index(), 2);
assert_eq!(Session::blocks_remaining(), 9);
System::set_block_number(17);
assert_eq!(Session::current_index(), 2);
assert_eq!(Session::blocks_remaining(), 0);
System::set_block_number(18);
assert_eq!(Session::current_index(), 3);
});
}
#[test]
fn session_length_change_should_work() {
with_externalities(&mut new_test_ext(), || {
// Block 1: Change to length 3; no visible change.
System::set_block_number(1);
assert_ok!(Session::set_length(3.into()));
assert_eq!(Session::length(), 2);
assert_eq!(Session::current_index(), 0);
// Block 2: Length now changed to 3. Index incremented.
System::set_block_number(2);
assert_ok!(Session::set_length(3.into()));
assert_eq!(Session::length(), 3);
assert_eq!(Session::current_index(), 1);
// Block 3: Length now changed to 3. Index incremented.
System::set_block_number(3);
assert_eq!(Session::length(), 3);
assert_eq!(Session::current_index(), 1);
// Block 4: Change to length 2; no visible change.
System::set_block_number(4);
assert_ok!(Session::set_length(2.into()));
assert_eq!(Session::length(), 3);
assert_eq!(Session::current_index(), 1);
// Block 5: Length now changed to 2. Index incremented.
System::set_block_number(5);
assert_eq!(Session::length(), 2);
assert_eq!(Session::current_index(), 2);
// Block 6: No change.
System::set_block_number(6);
assert_eq!(Session::length(), 2);
assert_eq!(Session::current_index(), 2);
// Block 7: Next index.
System::set_block_number(7);
assert_eq!(Session::length(), 2);
assert_eq!(Session::current_index(), 3);
});
}
#[test]
fn session_change_should_work() {
with_externalities(&mut new_test_ext(), || {
// Block 1: No change
System::set_block_number(1);
assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
// Block 2: Session rollover, but no change.
System::set_block_number(2);
assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
// Block 3: Set new key for validator 2; no visible change.
System::set_block_number(3);
assert_ok!(Session::set_key(Origin::signed(2), UintAuthorityId(5)));
assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
// Block 4: Session rollover, authority 2 changes.
System::set_block_number(4);
assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(5), UintAuthorityId(3)]);