fix: change the initial epoch to 1

x/farming/keeper/genesis_test.go

@@ -1,6 +1,8 @@
 package keeper_test
 
 import (
+	"fmt"
+
 	tmproto "github.com/tendermint/tendermint/proto/tendermint/types"
 
 	sdk "github.com/cosmos/cosmos-sdk/types"
@@ -287,12 +289,18 @@ func (suite *KeeperTestSuite) TestExportGenesis() {
 		{
 			"HistoricalRewards",
 			func() {
-				suite.Require().Len(genState.HistoricalRewardsRecords, 2)
+				suite.Require().Len(genState.HistoricalRewardsRecords, 4)
 				for _, record := range genState.HistoricalRewardsRecords {
-					suite.Require().Equal(uint64(0), record.Epoch)
 					suite.Require().Contains([]string{denom1, denom2}, record.StakingCoinDenom)
-					suite.Require().False(record.HistoricalRewards.CumulativeUnitRewards.IsZero())
-					// TODO: need to check actual value?
+					switch record.Epoch {
+					case 0:
+						suite.Require().True(record.HistoricalRewards.CumulativeUnitRewards.IsZero())
+					case 1:
+						// TODO: need to check actual value?
+						suite.Require().False(record.HistoricalRewards.CumulativeUnitRewards.IsZero())
+					default:
+						panic(fmt.Sprintf("unexpected epoch %d", record.Epoch))
+					}
 				}
 			},
 		},
@@ -319,7 +327,7 @@ func (suite *KeeperTestSuite) TestExportGenesis() {
 			func() {
 				suite.Require().Len(genState.CurrentEpochRecords, 2)
 				for _, record := range genState.CurrentEpochRecords {
-					suite.Require().Equal(uint64(1), record.CurrentEpoch)
+					suite.Require().Equal(uint64(2), record.CurrentEpoch)
 				}
 			},
 		},

x/farming/keeper/invariants_test.go

@@ -133,22 +133,22 @@ func (suite *KeeperTestSuite) TestRemainingRewardsAmountInvariant() {
 
 	// Withdrawable rewards amount in the store > balance of rewards reserve acc.
 	// Should not be OK.
-	k.SetHistoricalRewards(ctx, denom1, 1, types.HistoricalRewards{
+	k.SetHistoricalRewards(ctx, denom1, 2, types.HistoricalRewards{
 		CumulativeUnitRewards: sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, 3)),
 	})
 	_, broken = farmingkeeper.RemainingRewardsAmountInvariant(k)(ctx)
 	suite.Require().True(broken)
 
 	// Withdrawable rewards amount in the store <= balance of rewards reserve acc.
 	// Should be OK.
-	k.SetHistoricalRewards(ctx, denom1, 1, types.HistoricalRewards{
+	k.SetHistoricalRewards(ctx, denom1, 2, types.HistoricalRewards{
 		CumulativeUnitRewards: sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, 1)),
 	})
 	_, broken = farmingkeeper.RemainingRewardsAmountInvariant(k)(ctx)
 	suite.Require().False(broken)
 
 	// Reset.
-	k.SetHistoricalRewards(ctx, denom1, 1, types.HistoricalRewards{
+	k.SetHistoricalRewards(ctx, denom1, 2, types.HistoricalRewards{
 		CumulativeUnitRewards: sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, 2)),
 	})
 	_, broken = farmingkeeper.RemainingRewardsAmountInvariant(k)(ctx)

x/farming/keeper/reward.go

@@ -38,6 +38,17 @@ func (k Keeper) DeleteHistoricalRewards(ctx sdk.Context, stakingCoinDenom string
 	store.Delete(types.GetHistoricalRewardsKey(stakingCoinDenom, epoch))
 }
 
+// DeleteAllHistoricalRewards deletes all historical rewards for a
+// staking coin denom.
+func (k Keeper) DeleteAllHistoricalRewards(ctx sdk.Context, stakingCoinDenom string) {
+	store := ctx.KVStore(k.storeKey)
+	iter := sdk.KVStorePrefixIterator(store, types.GetHistoricalRewardsPrefix(stakingCoinDenom))
+	defer iter.Close()
+	for ; iter.Valid(); iter.Next() {
+		store.Delete(iter.Key())
+	}
+}
+
 // IterateHistoricalRewards iterates through all historical rewards
 // stored in the store and invokes callback function for each item.
 // Stops the iteration when the callback function returns true.
@@ -74,6 +85,13 @@ func (k Keeper) SetCurrentEpoch(ctx sdk.Context, stakingCoinDenom string, curren
 	store.Set(types.GetCurrentEpochKey(stakingCoinDenom), bz)
 }
 
+// DeleteCurrentEpoch deletes current epoch info for a given
+// staking coin denom.
+func (k Keeper) DeleteCurrentEpoch(ctx sdk.Context, stakingCoinDenom string) {
+	store := ctx.KVStore(k.storeKey)
+	store.Delete(types.GetCurrentEpochKey(stakingCoinDenom))
+}
+
 // IterateCurrentEpochs iterates through all current epoch infos
 // stored in the store and invokes callback function for each item.
 // Stops the iteration when the callback function returns true.
@@ -139,7 +157,10 @@ func (k Keeper) IterateOutstandingRewards(ctx sdk.Context, cb func(stakingCoinDe
 // IncreaseOutstandingRewards increases outstanding rewards for a given
 // staking coin denom by given amount.
 func (k Keeper) IncreaseOutstandingRewards(ctx sdk.Context, stakingCoinDenom string, amount sdk.DecCoins) {
-	outstanding, _ := k.GetOutstandingRewards(ctx, stakingCoinDenom)
+	outstanding, found := k.GetOutstandingRewards(ctx, stakingCoinDenom)
+	if !found {
+		panic("outstanding rewards not found")
+	}
 	outstanding.Rewards = outstanding.Rewards.Add(amount...)
 	k.SetOutstandingRewards(ctx, stakingCoinDenom, outstanding)
 }
@@ -153,12 +174,8 @@ func (k Keeper) DecreaseOutstandingRewards(ctx sdk.Context, stakingCoinDenom str
 	if !found {
 		panic("outstanding rewards not found")
 	}
-	if outstanding.Rewards.IsEqual(amount) {
-		k.DeleteOutstandingRewards(ctx, stakingCoinDenom)
-	} else {
-		outstanding.Rewards = outstanding.Rewards.Sub(amount)
-		k.SetOutstandingRewards(ctx, stakingCoinDenom, outstanding)
-	}
+	outstanding.Rewards = outstanding.Rewards.Sub(amount)
+	k.SetOutstandingRewards(ctx, stakingCoinDenom, outstanding)
 }
 
 // CalculateRewards returns rewards accumulated until endingEpoch

x/farming/keeper/reward_test.go

@@ -347,12 +347,69 @@ func (suite *KeeperTestSuite) TestHistoricalRewards() {
 		count++
 		return false
 	})
-	suite.Require().Equal(count, 3)
+	suite.Require().Equal(4, count)
 
 	// Next, check if cumulative unit rewards is correct.
-	for i := uint64(0); i < 3; i++ {
+	for i := uint64(1); i <= 3; i++ {
 		historical, found := suite.keeper.GetHistoricalRewards(suite.ctx, denom1, i)
 		suite.Require().True(found)
-		suite.Require().True(decCoinsEq(sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, int64((i+1)*2))), historical.CumulativeUnitRewards))
+		suite.Require().True(decCoinsEq(sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, int64(i*2))), historical.CumulativeUnitRewards))
 	}
 }
+
+// Test if initialization and pruning of staking coin info work properly.
+func (suite *KeeperTestSuite) TestInitializeAndPruneStakingCoinInfo() {
+	suite.SetFixedAmountPlan(1, suite.addrs[4], map[string]string{denom1: "1"}, map[string]int64{denom3: 1000000})
+
+	suite.Stake(suite.addrs[0], sdk.NewCoins(sdk.NewInt64Coin(denom1, 1000000)))
+
+	suite.Require().Equal(uint64(0), suite.keeper.GetCurrentEpoch(suite.ctx, denom1))
+	_, found := suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 0)
+	suite.Require().False(found)
+	_, found = suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 1)
+	suite.Require().False(found)
+	_, found = suite.keeper.GetOutstandingRewards(suite.ctx, denom1)
+	suite.Require().False(found)
+
+	suite.AdvanceEpoch()
+
+	suite.Require().Equal(uint64(1), suite.keeper.GetCurrentEpoch(suite.ctx, denom1))
+	historical, found := suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 0)
+	suite.Require().True(found)
+	suite.Require().True(decCoinsEq(sdk.DecCoins{}, historical.CumulativeUnitRewards))
+	outstanding, found := suite.keeper.GetOutstandingRewards(suite.ctx, denom1)
+	suite.Require().True(found)
+	suite.Require().True(decCoinsEq(sdk.DecCoins{}, outstanding.Rewards))
+
+	suite.AdvanceEpoch()
+
+	suite.Require().Equal(uint64(2), suite.keeper.GetCurrentEpoch(suite.ctx, denom1))
+	historical, found = suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 1)
+	suite.Require().True(found)
+	suite.Require().True(decCoinsEq(sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, 1)), historical.CumulativeUnitRewards))
+	outstanding, found = suite.keeper.GetOutstandingRewards(suite.ctx, denom1)
+	suite.Require().True(found)
+	suite.Require().True(decCoinsEq(sdk.NewDecCoins(sdk.NewInt64DecCoin(denom3, 1000000)), outstanding.Rewards))
+	// Historical rewards for epoch 2 must not be present at this point,
+	// since current epoch is 2, and it has not ended yet.
+	_, found = suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 2)
+	suite.Require().False(found)
+
+	// Unstake most of the coins. This should not delete any info
+	// about the staking coin yet.
+	suite.Unstake(suite.addrs[0], sdk.NewCoins(sdk.NewInt64Coin(denom1, 999999)))
+	suite.Require().Equal(uint64(2), suite.keeper.GetCurrentEpoch(suite.ctx, denom1))
+	_, found = suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 1)
+	suite.Require().True(found)
+	_, found = suite.keeper.GetOutstandingRewards(suite.ctx, denom1)
+	suite.Require().True(found)
+
+	// Now unstake the rest of the coins. This should delete info
+	// about the staking coin.
+	suite.Unstake(suite.addrs[0], sdk.NewCoins(sdk.NewInt64Coin(denom1, 1)))
+	suite.Require().Equal(uint64(0), suite.keeper.GetCurrentEpoch(suite.ctx, denom1))
+	_, found = suite.keeper.GetHistoricalRewards(suite.ctx, denom1, 1)
+	suite.Require().False(found)
+	_, found = suite.keeper.GetOutstandingRewards(suite.ctx, denom1)
+	suite.Require().False(found)
+}

x/farming/keeper/staking.go

@@ -185,6 +185,11 @@ func (k Keeper) IncreaseTotalStakings(ctx sdk.Context, stakingCoinDenom string,
 	}
 	totalStaking.Amount = totalStaking.Amount.Add(amount)
 	k.SetTotalStakings(ctx, stakingCoinDenom, totalStaking)
+	if totalStaking.Amount.Equal(amount) {
+		if err := k.afterStakingCoinAdded(ctx, stakingCoinDenom); err != nil {
+			panic(err)
+		}
+	}
 }
 
 // DecreaseTotalStakings decreases total stakings for given staking coin denom
@@ -196,6 +201,9 @@ func (k Keeper) DecreaseTotalStakings(ctx sdk.Context, stakingCoinDenom string,
 	}
 	if totalStaking.Amount.Equal(amount) {
 		k.DeleteTotalStakings(ctx, stakingCoinDenom)
+		if err := k.afterStakingCoinRemoved(ctx, stakingCoinDenom); err != nil {
+			panic(err)
+		}
 	} else {
 		totalStaking.Amount = totalStaking.Amount.Sub(amount)
 		k.SetTotalStakings(ctx, stakingCoinDenom, totalStaking)
@@ -235,6 +243,25 @@ func (k Keeper) ReleaseStakingCoins(ctx sdk.Context, farmerAcc sdk.AccAddress, u
 	return nil
 }
 
+// afterStakingCoinAdded is called after a new staking coin denom appeared
+// during ProcessQueuedCoins.
+func (k Keeper) afterStakingCoinAdded(ctx sdk.Context, stakingCoinDenom string) error {
+	k.SetHistoricalRewards(ctx, stakingCoinDenom, 0, types.HistoricalRewards{CumulativeUnitRewards: sdk.DecCoins{}})
+	k.SetCurrentEpoch(ctx, stakingCoinDenom, 1)
+	k.SetOutstandingRewards(ctx, stakingCoinDenom, types.OutstandingRewards{Rewards: sdk.DecCoins{}})
+	return nil
+}
+
+// afterStakingCoinRemoved is called after a staking coin denom got removed
+// during Unstake.
+func (k Keeper) afterStakingCoinRemoved(ctx sdk.Context, stakingCoinDenom string) error {
+	// TODO: send remaining outstanding rewards to the fee pool
+	k.DeleteOutstandingRewards(ctx, stakingCoinDenom)
+	k.DeleteAllHistoricalRewards(ctx, stakingCoinDenom)
+	k.DeleteCurrentEpoch(ctx, stakingCoinDenom)
+	return nil
+}
+
 // Stake stores staking coins to queued coins, and it will be processed in the next epoch.
 func (k Keeper) Stake(ctx sdk.Context, farmerAcc sdk.AccAddress, amount sdk.Coins) error {
 	if err := k.ReserveStakingCoins(ctx, farmerAcc, amount); err != nil {
@@ -350,13 +377,12 @@ func (k Keeper) ProcessQueuedCoins(ctx sdk.Context) {
 		}
 
 		k.DeleteQueuedStaking(ctx, stakingCoinDenom, farmerAcc)
+		k.IncreaseTotalStakings(ctx, stakingCoinDenom, queuedStaking.Amount)
 		k.SetStaking(ctx, stakingCoinDenom, farmerAcc, types.Staking{
 			Amount:        staking.Amount.Add(queuedStaking.Amount),
 			StartingEpoch: k.GetCurrentEpoch(ctx, stakingCoinDenom),
 		})
 
-		k.IncreaseTotalStakings(ctx, stakingCoinDenom, queuedStaking.Amount)
-
 		return false
 	})
 }

x/farming/types/keys.go

@@ -87,6 +87,12 @@ func GetHistoricalRewardsKey(stakingCoinDenom string, epoch uint64) []byte {
 	return append(append(HistoricalRewardsKeyPrefix, LengthPrefixString(stakingCoinDenom)...), sdk.Uint64ToBigEndian(epoch)...)
 }
 
+// GetHistoricalRewardsPrefix returns a key prefix used to iterate
+// historical rewards by a staking coin denom.
+func GetHistoricalRewardsPrefix(stakingCoinDenom string) []byte {
+	return append(HistoricalRewardsKeyPrefix, LengthPrefixString(stakingCoinDenom)...)
+}
+
 // GetCurrentEpochKey returns a key for a current epoch info.
 func GetCurrentEpochKey(stakingCoinDenom string) []byte {
 	return append(CurrentEpochKeyPrefix, []byte(stakingCoinDenom)...)