From de5686509c61370ce097857dd1d68f1fb55a215b Mon Sep 17 00:00:00 2001
From: Gavin Wood <gavin@parity.io>
Date: Wed, 27 Nov 2019 18:57:03 +0000
Subject: [PATCH] Validators don't get slashed for offlineness until 10% at
once (#4232)
* Validators don't get slashed for offlineness until 10% at once
* Update frame/im-online/src/tests.rs
Co-Authored-By: Marcio Diaz <marcio.diaz@gmail.com>
* Update frame/im-online/src/tests.rs
Co-Authored-By: Marcio Diaz <marcio.diaz@gmail.com>
* Apply suggestions from code review
Co-Authored-By: joe petrowski <25483142+joepetrowski@users.noreply.github.com>
---
substrate/frame/im-online/src/lib.rs | 12 +++++++++---
substrate/frame/im-online/src/tests.rs | 11 ++++++++---
2 files changed, 17 insertions(+), 6 deletions(-)
diff --git a/substrate/frame/im-online/src/lib.rs b/substrate/frame/im-online/src/lib.rs
index 01ebde206e4..8f3361186ff 100644
--- a/substrate/frame/im-online/src/lib.rs
+++ b/substrate/frame/im-online/src/lib.rs
@@ -653,8 +653,14 @@ impl<Offender: Clone> Offence<Offender> for UnresponsivenessOffence<Offender> {
}
fn slash_fraction(offenders: u32, validator_set_count: u32) -> Perbill {
- // the formula is min((3 * (k - 1)) / n, 1) * 0.05
- let x = Perbill::from_rational_approximation(3 * (offenders - 1), validator_set_count);
- x.saturating_mul(Perbill::from_percent(5))
+ // the formula is min((3 * (k - (n / 10 + 1))) / n, 1) * 0.07
+ // basically, 10% can be offline with no slash, but after that, it linearly climbs up to 7%
+ // when 13/30 are offline (around 5% when 1/3 are offline).
+ if let Some(threshold) = offenders.checked_sub(validator_set_count / 10 + 1) {
+ let x = Perbill::from_rational_approximation(3 * threshold, validator_set_count);
+ x.saturating_mul(Perbill::from_percent(7))
+ } else {
+ Perbill::default()
+ }
}
}
diff --git a/substrate/frame/im-online/src/tests.rs b/substrate/frame/im-online/src/tests.rs
index edfdc34bc00..788956ba6e0 100644
--- a/substrate/frame/im-online/src/tests.rs
+++ b/substrate/frame/im-online/src/tests.rs
@@ -38,14 +38,19 @@ fn test_unresponsiveness_slash_fraction() {
);
assert_eq!(
- UnresponsivenessOffence::<()>::slash_fraction(3, 50),
- Perbill::from_parts(6000000), // 0.6%
+ UnresponsivenessOffence::<()>::slash_fraction(5, 50),
+ Perbill::zero(), // 0%
+ );
+
+ assert_eq!(
+ UnresponsivenessOffence::<()>::slash_fraction(7, 50),
+ Perbill::from_parts(4200000), // 0.42%
);
// One third offline should be punished around 5%.
assert_eq!(
UnresponsivenessOffence::<()>::slash_fraction(17, 50),
- Perbill::from_parts(48000000), // 4.8%
+ Perbill::from_parts(46200000), // 4.62%
);
}
--
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