Add Excess Deposit Flag to allow Validator Balances more than 32 ETH (#2625)

* add flags and code

* adding tests

* gaz

* Update shared/featureconfig/config.go

Co-Authored-By: Preston Van Loon <preston@prysmaticlabs.com>

beacon-chain/core/validators/BUILD.bazel

@@ -9,6 +9,7 @@ go_library(
         "//beacon-chain/core/helpers:go_default_library",
         "//proto/beacon/p2p/v1:go_default_library",
         "//shared/bytesutil:go_default_library",
+        "//shared/featureconfig:go_default_library",
         "//shared/params:go_default_library",
         "//shared/sliceutil:go_default_library",
         "@com_github_sirupsen_logrus//:go_default_library",
@@ -24,6 +25,7 @@ go_test(
         "//beacon-chain/core/state/stateutils:go_default_library",
         "//proto/beacon/p2p/v1:go_default_library",
         "//shared/bitutil:go_default_library",
+        "//shared/featureconfig:go_default_library",
         "//shared/params:go_default_library",
     ],
 )

beacon-chain/core/validators/validator.go

@@ -12,6 +12,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
 	"github.com/prysmaticlabs/prysm/shared/bytesutil"
+	"github.com/prysmaticlabs/prysm/shared/featureconfig"
 	"github.com/prysmaticlabs/prysm/shared/params"
 	"github.com/prysmaticlabs/prysm/shared/sliceutil"
 	"github.com/sirupsen/logrus"
@@ -137,7 +138,12 @@ func ProcessDeposit(
 				withdrawalCredentials,
 			)
 		}
-		state.ValidatorBalances[existingValidatorIdx] += amount
+		newBalance := state.ValidatorBalances[existingValidatorIdx] + amount
+		state.ValidatorBalances[existingValidatorIdx] = newBalance
+
+		if !featureconfig.FeatureConfig().EnableExcessDeposits && newBalance > params.BeaconConfig().MaxDepositAmount {
+			state.ValidatorBalances[existingValidatorIdx] = params.BeaconConfig().MaxDepositAmount
+		}
 	}
 	state.DepositIndex++
 

beacon-chain/core/validators/validator_test.go

@@ -11,6 +11,7 @@ import (
 	"github.com/prysmaticlabs/prysm/beacon-chain/core/state/stateutils"
 	pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
 	"github.com/prysmaticlabs/prysm/shared/bitutil"
+	"github.com/prysmaticlabs/prysm/shared/featureconfig"
 	"github.com/prysmaticlabs/prysm/shared/params"
 )
 
@@ -362,6 +363,90 @@ func TestProcessDeposit_PublicKeyDoesNotExistAndEmptyValidator(t *testing.T) {
 	}
 }
 
+func TestProcessDepositFlag_NotEnabled(t *testing.T) {
+	registry := []*pb.Validator{
+		{
+			Pubkey:                      []byte{1, 2, 3},
+			WithdrawalCredentialsHash32: []byte{2},
+		},
+		{
+			Pubkey:                      []byte{4, 5, 6},
+			WithdrawalCredentialsHash32: []byte{1},
+		},
+	}
+	balances := []uint64{0, 32e9}
+	beaconState := &pb.BeaconState{
+		Slot:              params.BeaconConfig().SlotsPerEpoch,
+		ValidatorBalances: balances,
+		ValidatorRegistry: registry,
+	}
+	pubkey := []byte{4, 5, 6}
+	deposit := uint64(32e9)
+	proofOfPossession := []byte{}
+	withdrawalCredentials := []byte{1}
+
+	newState, err := ProcessDeposit(
+		beaconState,
+		stateutils.ValidatorIndexMap(beaconState),
+		pubkey,
+		deposit,
+		proofOfPossession,
+		withdrawalCredentials,
+	)
+	if err != nil {
+		t.Fatalf("Process deposit failed: %v", err)
+	}
+	if newState.ValidatorBalances[1] != 32e9 {
+		t.Errorf("Balances have been updated despite flag being not applied: %d", newState.ValidatorBalances[1])
+	}
+}
+
+func TestProcessDepositFlag_Enabled(t *testing.T) {
+	featureconfig.InitFeatureConfig(&featureconfig.FeatureFlagConfig{
+		EnableExcessDeposits: true,
+	})
+
+	registry := []*pb.Validator{
+		{
+			Pubkey:                      []byte{1, 2, 3},
+			WithdrawalCredentialsHash32: []byte{2},
+		},
+		{
+			Pubkey:                      []byte{4, 5, 6},
+			WithdrawalCredentialsHash32: []byte{1},
+		},
+	}
+	balances := []uint64{0, 32e9}
+	beaconState := &pb.BeaconState{
+		Slot:              params.BeaconConfig().SlotsPerEpoch,
+		ValidatorBalances: balances,
+		ValidatorRegistry: registry,
+	}
+	pubkey := []byte{4, 5, 6}
+	deposit := uint64(32e9)
+	proofOfPossession := []byte{}
+	withdrawalCredentials := []byte{1}
+
+	newState, err := ProcessDeposit(
+		beaconState,
+		stateutils.ValidatorIndexMap(beaconState),
+		pubkey,
+		deposit,
+		proofOfPossession,
+		withdrawalCredentials,
+	)
+	if err != nil {
+		t.Fatalf("Process deposit failed: %v", err)
+	}
+	if newState.ValidatorBalances[1] != 64e9 {
+		t.Errorf("Balances have been updated despite flag being not applied: %d", newState.ValidatorBalances[1])
+	}
+	// Un-setting flag
+	featureconfig.InitFeatureConfig(&featureconfig.FeatureFlagConfig{
+		EnableExcessDeposits: false,
+	})
+}
+
 func TestActivateValidatorGenesis_OK(t *testing.T) {
 	state := &pb.BeaconState{
 		ValidatorRegistry: []*pb.Validator{

shared/featureconfig/config.go

@@ -33,6 +33,7 @@ type FeatureFlagConfig struct {
 	DisableGossipSub              bool // DisableGossipSub in p2p messaging.
 	EnableCommitteesCache         bool // EnableCommitteesCache for state transition.
 	CacheTreeHash                 bool // CacheTreeHash determent whether tree hashes will be cached.
+  EnableExcessDeposits             bool // EnableExcessDeposits in validator balances.
 }
 
 var featureConfig *FeatureFlagConfig
@@ -82,6 +83,10 @@ func ConfigureBeaconFeatures(ctx *cli.Context) {
 		log.Info("Disabled gossipsub, using floodsub")
 		cfg.DisableGossipSub = true
 	}
+	if ctx.GlobalBool(EnableExcessDepositsFlag.Name) {
+		log.Info("Enabled excess deposits")
+		cfg.EnableExcessDeposits = true
+	}
 	InitFeatureConfig(cfg)
 }
 

shared/featureconfig/flags.go

@@ -45,6 +45,12 @@ var (
 		Name:  "disable-gossip-sub",
 		Usage: "Disable gossip sub messaging and use floodsub messaging",
 	}
+	// EnableExcessDepositsFlag enables a validator to have total amount deposited as more than the
+	// max deposit amount.
+	EnableExcessDepositsFlag = cli.BoolFlag{
+		Name:  "enables-excess-deposit",
+		Usage: "Enables balances more than max deposit amount for a validator",
+	}
 )
 
 // ValidatorFlags contains a list of all the feature flags that apply to the validator client.
@@ -60,4 +66,5 @@ var BeaconChainFlags = []cli.Flag{
 	DisableHistoricalStatePruningFlag,
 	DisableGossipSubFlag,
 	CacheTreeHashFlag,
+	EnableExcessDepositsFlag,
 }