From 723e057d955e23852b4b3ea8a1cc5da3e72bb227 Mon Sep 17 00:00:00 2001
From: Christopher Goes <cwgoes@pluranimity.org>
Date: Sat, 7 Jul 2018 00:00:00 +0200
Subject: [PATCH] Merge pull request #1566:  Fix validator power decrease bug

* Demonstrative testcase

* Update when decreasing but still bonded

* Only update when decreasing, not when equal

* Cleanup conditional; changelog

* Clarify comments

* Simplify conditional
---
 CHANGELOG.md                     |  1 +
 x/stake/keeper/validator.go      |  7 ++++++
 x/stake/keeper/validator_test.go | 40 ++++++++++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7012336d94..4808b6db84 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -97,6 +97,7 @@ IMPROVEMENTS
 
 BUG FIXES
 * [x/slashing] \#1510 Unrevoked validators cannot un-revoke themselves
+* [x/stake] \#1567 Validators decreased in power but not unbonded are now updated in Tendermint
 * [gaia] Added self delegation for validators in the genesis creation
 * [lcd] tests now don't depend on raw json text
 * [stake] error strings lower case
diff --git a/x/stake/keeper/validator.go b/x/stake/keeper/validator.go
index 164c500492..c32b536cea 100644
--- a/x/stake/keeper/validator.go
+++ b/x/stake/keeper/validator.go
@@ -261,6 +261,13 @@ func (k Keeper) UpdateValidator(ctx sdk.Context, validator types.Validator) type
 	if updatedVal.Owner != nil { // updates to validator occurred  to be updated
 		validator = updatedVal
 	}
+	// if decreased in power but still bonded, update Tendermint validator
+	// (if updatedVal is set, the validator has changed bonding status)
+	stillBonded := oldFound && oldValidator.Status() == sdk.Bonded && updatedVal.Owner == nil
+	if stillBonded && oldValidator.PoolShares.Bonded().GT(validator.PoolShares.Bonded()) {
+		bz := k.cdc.MustMarshalBinary(validator.ABCIValidator())
+		store.Set(GetTendermintUpdatesKey(ownerAddr), bz)
+	}
 	return validator
 }
 
diff --git a/x/stake/keeper/validator_test.go b/x/stake/keeper/validator_test.go
index c4d197a36b..9ad6e12bc0 100644
--- a/x/stake/keeper/validator_test.go
+++ b/x/stake/keeper/validator_test.go
@@ -674,3 +674,43 @@ func TestGetTendermintUpdatesNotValidatorCliff(t *testing.T) {
 	require.Equal(t, validators[0].ABCIValidatorZero(), updates[0])
 	require.Equal(t, validators[2].ABCIValidator(), updates[1])
 }
+
+func TestGetTendermintUpdatesPowerDecrease(t *testing.T) {
+	ctx, _, keeper := CreateTestInput(t, false, 1000)
+
+	amts := []int64{100, 100}
+	var validators [2]types.Validator
+	for i, amt := range amts {
+		pool := keeper.GetPool(ctx)
+		validators[i] = types.NewValidator(Addrs[i], PKs[i], types.Description{})
+		validators[i], pool, _ = validators[i].AddTokensFromDel(pool, amt)
+		keeper.SetPool(ctx, pool)
+	}
+	validators[0] = keeper.UpdateValidator(ctx, validators[0])
+	validators[1] = keeper.UpdateValidator(ctx, validators[1])
+	keeper.ClearTendermintUpdates(ctx)
+	require.Equal(t, 0, len(keeper.GetTendermintUpdates(ctx)))
+
+	// check initial power
+	require.Equal(t, sdk.NewRat(100).RoundInt64(), validators[0].GetPower().RoundInt64())
+	require.Equal(t, sdk.NewRat(100).RoundInt64(), validators[1].GetPower().RoundInt64())
+
+	// test multiple value change
+	//  tendermintUpdate set: {c1, c3} -> {c1', c3'}
+	pool := keeper.GetPool(ctx)
+	validators[0], pool, _ = validators[0].RemoveDelShares(pool, sdk.NewRat(20))
+	validators[1], pool, _ = validators[1].RemoveDelShares(pool, sdk.NewRat(30))
+	keeper.SetPool(ctx, pool)
+	validators[0] = keeper.UpdateValidator(ctx, validators[0])
+	validators[1] = keeper.UpdateValidator(ctx, validators[1])
+
+	// power has changed
+	require.Equal(t, sdk.NewRat(80).RoundInt64(), validators[0].GetPower().RoundInt64())
+	require.Equal(t, sdk.NewRat(70).RoundInt64(), validators[1].GetPower().RoundInt64())
+
+	// Tendermint updates should reflect power change
+	updates := keeper.GetTendermintUpdates(ctx)
+	require.Equal(t, 2, len(updates))
+	require.Equal(t, validators[0].ABCIValidator(), updates[0])
+	require.Equal(t, validators[1].ABCIValidator(), updates[1])
+}