Remove stale expiries in AdvanceTimeTo

vms/platformvm/txs/executor/state_changes.go

@@ -183,6 +183,30 @@ func AdvanceTimeTo(
 		changes.SetFeeState(feeState)
 	}
 
+	// Remove all expiries whose timestamp now implies they can never be
+	// re-issued.
+	//
+	// The expiry timestamp is the time at which it is no longer valid, so any
+	// expiry with a timestamp less than or equal to the new chain time can be
+	// removed.
+	//
+	// Ref: https://github.com/avalanche-foundation/ACPs/tree/main/ACPs/77-reinventing-subnets#registersubnetvalidatortx
+	expiryIterator, err := parentState.GetExpiryIterator()
+	if err != nil {
+		return false, err
+	}
+	defer expiryIterator.Release()
+
+	newChainTimeUnix := uint64(newChainTime.Unix())
+	for expiryIterator.Next() {
+		expiry := expiryIterator.Value()
+		if expiry.Timestamp > newChainTimeUnix {
+			break
+		}
+
+		changes.DeleteExpiry(expiry)
+	}
+
 	changes.SetTimestamp(newChainTime)
 	return changed, changes.Apply(parentState)
 }

vms/platformvm/txs/executor/state_changes_test.go

@@ -9,9 +9,12 @@ import (
 
 	"github.com/stretchr/testify/require"
 
+	"github.com/ava-labs/avalanchego/ids"
 	"github.com/ava-labs/avalanchego/upgrade/upgradetest"
+	"github.com/ava-labs/avalanchego/utils/iterator"
 	"github.com/ava-labs/avalanchego/vms/components/gas"
 	"github.com/ava-labs/avalanchego/vms/platformvm/config"
+	"github.com/ava-labs/avalanchego/vms/platformvm/genesis/genesistest"
 	"github.com/ava-labs/avalanchego/vms/platformvm/state"
 	"github.com/ava-labs/avalanchego/vms/platformvm/state/statetest"
 )
@@ -98,3 +101,110 @@ func TestAdvanceTimeTo_UpdatesFeeState(t *testing.T) {
 		})
 	}
 }
+
+func TestAdvanceTimeTo_RemovesStaleExpiries(t *testing.T) {
+	var (
+		currentTime = genesistest.DefaultValidatorStartTime
+		newTime     = currentTime.Add(3 * time.Second)
+		newTimeUnix = uint64(newTime.Unix())
+	)
+
+	tests := []struct {
+		name             string
+		initialExpiries  []state.ExpiryEntry
+		expectedExpiries []state.ExpiryEntry
+	}{
+		{
+			name: "no expiries",
+		},
+		{
+			name: "unexpired expiry",
+			initialExpiries: []state.ExpiryEntry{
+				{
+					Timestamp:    newTimeUnix + 1,
+					ValidationID: ids.ID{1},
+				},
+			},
+			expectedExpiries: []state.ExpiryEntry{
+				{
+					Timestamp:    newTimeUnix + 1,
+					ValidationID: ids.ID{1},
+				},
+			},
+		},
+		{
+			name: "unexpired expiry at new time",
+			initialExpiries: []state.ExpiryEntry{
+				{
+					Timestamp:    newTimeUnix,
+					ValidationID: ids.GenerateTestID(),
+				},
+			},
+		},
+		{
+			name: "unexpired expiry at previous time",
+			initialExpiries: []state.ExpiryEntry{
+				{
+					Timestamp:    newTimeUnix - 1,
+					ValidationID: ids.GenerateTestID(),
+				},
+			},
+		},
+		{
+			name: "limit expiries removed",
+			initialExpiries: []state.ExpiryEntry{
+				{
+					Timestamp:    newTimeUnix,
+					ValidationID: ids.GenerateTestID(),
+				},
+				{
+					Timestamp:    newTimeUnix + 1,
+					ValidationID: ids.ID{1},
+				},
+			},
+			expectedExpiries: []state.ExpiryEntry{
+				{
+					Timestamp:    newTimeUnix + 1,
+					ValidationID: ids.ID{1},
+				},
+			},
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			var (
+				require = require.New(t)
+				s       = statetest.New(t, statetest.Config{})
+			)
+
+			// Ensure the invariant that [newTime <= nextStakerChangeTime] on
+			// AdvanceTimeTo is maintained.
+			nextStakerChangeTime, err := state.GetNextStakerChangeTime(s)
+			require.NoError(err)
+			require.False(newTime.After(nextStakerChangeTime))
+
+			for _, expiry := range test.initialExpiries {
+				s.PutExpiry(expiry)
+			}
+
+			validatorsModified, err := AdvanceTimeTo(
+				&Backend{
+					Config: &config.Config{
+						UpgradeConfig: upgradetest.GetConfig(upgradetest.Latest),
+					},
+				},
+				s,
+				newTime,
+			)
+			require.NoError(err)
+			require.False(validatorsModified)
+
+			expiryIterator, err := s.GetExpiryIterator()
+			require.NoError(err)
+			require.Equal(
+				test.expectedExpiries,
+				iterator.ToSlice(expiryIterator),
+			)
+		})
+	}
+}