Expose minimum required version to cadence interface

engine/execution/computation/computer/computer_test.go

@@ -705,6 +705,7 @@ func TestBlockExecutor_ExecuteBlock(t *testing.T) {
 						},
 					),
 				),
+				fvm.WithReadVersionFromNodeVersionBeacon(false),
 			)
 
 			vm := fvm.NewVirtualMachine()
@@ -816,7 +817,9 @@ func TestBlockExecutor_ExecuteBlock(t *testing.T) {
 					runtime.Config{},
 					func(_ runtime.Config) runtime.Runtime {
 						return rt
-					})))
+					})),
+			fvm.WithReadVersionFromNodeVersionBeacon(false),
+		)
 
 		vm := fvm.NewVirtualMachine()
 
@@ -929,7 +932,9 @@ func TestBlockExecutor_ExecuteBlock(t *testing.T) {
 					runtime.Config{},
 					func(_ runtime.Config) runtime.Runtime {
 						return rt
-					})))
+					})),
+			fvm.WithReadVersionFromNodeVersionBeacon(false),
+		)
 
 		vm := fvm.NewVirtualMachine()
 

fvm/context.go

@@ -392,3 +392,12 @@ func WithEVMTracer(tracer debug.EVMTracer) Option {
 		return ctx
 	}
 }
+
+// WithReadVersionFromNodeVersionBeacon sets whether the version from the node version beacon should be read
+// this should only be disabled for testing
+func WithReadVersionFromNodeVersionBeacon(enabled bool) Option {
+	return func(ctx Context) Context {
+		ctx.ReadVersionFromNodeVersionBeacon = enabled
+		return ctx
+	}
+}

fvm/environment/derived_data_invalidator.go

@@ -25,7 +25,7 @@ func (u ContractUpdates) Any() bool {
 type DerivedDataInvalidator struct {
 	ContractUpdates
 
-	MeterParamOverridesUpdated bool
+	ExecutionParametersUpdated bool
 }
 
 var _ derived.TransactionInvalidator = DerivedDataInvalidator{}
@@ -37,16 +37,16 @@ func NewDerivedDataInvalidator(
 ) DerivedDataInvalidator {
 	return DerivedDataInvalidator{
 		ContractUpdates: contractUpdates,
-		MeterParamOverridesUpdated: meterParamOverridesUpdated(
+		ExecutionParametersUpdated: executionParametersUpdated(
 			executionSnapshot,
 			meterStateRead),
 	}
 }
 
-// meterParamOverridesUpdated returns true if the meter param overrides have been updated
+// executionParametersUpdated returns true if the meter param overrides have been updated
 // this is done by checking if the registers needed to compute the meter param overrides
 // have been touched in the execution snapshot
-func meterParamOverridesUpdated(
+func executionParametersUpdated(
 	executionSnapshot *snapshot.ExecutionSnapshot,
 	meterStateRead *snapshot.ExecutionSnapshot,
 ) bool {
@@ -73,16 +73,16 @@ func (invalidator DerivedDataInvalidator) ProgramInvalidator() derived.ProgramIn
 	return ProgramInvalidator{invalidator}
 }
 
-func (invalidator DerivedDataInvalidator) MeterParamOverridesInvalidator() derived.MeterParamOverridesInvalidator {
-	return MeterParamOverridesInvalidator{invalidator}
+func (invalidator DerivedDataInvalidator) ExecutionParametersInvalidator() derived.ExecutionParametersInvalidator {
+	return ExecutionParametersInvalidator{invalidator}
 }
 
 type ProgramInvalidator struct {
 	DerivedDataInvalidator
 }
 
 func (invalidator ProgramInvalidator) ShouldInvalidateEntries() bool {
-	return invalidator.MeterParamOverridesUpdated ||
+	return invalidator.ExecutionParametersUpdated ||
 		invalidator.ContractUpdates.Any()
 }
 
@@ -91,7 +91,7 @@ func (invalidator ProgramInvalidator) ShouldInvalidateEntry(
 	program *derived.Program,
 	_ *snapshot.ExecutionSnapshot,
 ) bool {
-	if invalidator.MeterParamOverridesUpdated {
+	if invalidator.ExecutionParametersUpdated {
 		// if meter parameters changed we need to invalidate all programs
 		return true
 	}
@@ -124,18 +124,18 @@ func (invalidator ProgramInvalidator) ShouldInvalidateEntry(
 	return false
 }
 
-type MeterParamOverridesInvalidator struct {
+type ExecutionParametersInvalidator struct {
 	DerivedDataInvalidator
 }
 
-func (invalidator MeterParamOverridesInvalidator) ShouldInvalidateEntries() bool {
-	return invalidator.MeterParamOverridesUpdated
+func (invalidator ExecutionParametersInvalidator) ShouldInvalidateEntries() bool {
+	return invalidator.ExecutionParametersUpdated
 }
 
-func (invalidator MeterParamOverridesInvalidator) ShouldInvalidateEntry(
+func (invalidator ExecutionParametersInvalidator) ShouldInvalidateEntry(
 	_ struct{},
-	_ derived.MeterParamOverrides,
+	_ derived.StateExecutionParameters,
 	_ *snapshot.ExecutionSnapshot,
 ) bool {
-	return invalidator.MeterParamOverridesUpdated
+	return invalidator.ExecutionParametersUpdated
 }

fvm/environment/derived_data_invalidator_test.go

@@ -82,7 +82,7 @@ func TestDerivedDataProgramInvalidator(t *testing.T) {
 	})
 	t.Run("meter parameters invalidator invalidates all entries", func(t *testing.T) {
 		invalidator := environment.DerivedDataInvalidator{
-			MeterParamOverridesUpdated: true,
+			ExecutionParametersUpdated: true,
 		}.ProgramInvalidator()
 
 		require.True(t, invalidator.ShouldInvalidateEntries())
@@ -207,23 +207,23 @@ func TestDerivedDataProgramInvalidator(t *testing.T) {
 
 func TestMeterParamOverridesInvalidator(t *testing.T) {
 	invalidator := environment.DerivedDataInvalidator{}.
-		MeterParamOverridesInvalidator()
+		ExecutionParametersInvalidator()
 
 	require.False(t, invalidator.ShouldInvalidateEntries())
 	require.False(t, invalidator.ShouldInvalidateEntry(
 		struct{}{},
-		derived.MeterParamOverrides{},
+		derived.StateExecutionParameters{},
 		nil))
 
 	invalidator = environment.DerivedDataInvalidator{
 		ContractUpdates:            environment.ContractUpdates{},
-		MeterParamOverridesUpdated: true,
-	}.MeterParamOverridesInvalidator()
+		ExecutionParametersUpdated: true,
+	}.ExecutionParametersInvalidator()
 
 	require.True(t, invalidator.ShouldInvalidateEntries())
 	require.True(t, invalidator.ShouldInvalidateEntry(
 		struct{}{},
-		derived.MeterParamOverrides{},
+		derived.StateExecutionParameters{},
 		nil))
 }
 
@@ -265,7 +265,11 @@ func TestMeterParamOverridesUpdated(t *testing.T) {
 	txnState, err := blockDatabase.NewTransaction(0, state.DefaultParameters())
 	require.NoError(t, err)
 
-	computer := fvm.NewMeterParamOverridesComputer(ctx, txnState)
+	computer := fvm.NewExecutionParametersComputer(
+		ctx.Logger,
+		ctx,
+		txnState,
+	)
 
 	overrides, err := computer.Compute(txnState, struct{}{})
 	require.NoError(t, err)
@@ -300,7 +304,7 @@ func TestMeterParamOverridesUpdated(t *testing.T) {
 			environment.ContractUpdates{},
 			snapshot,
 			meterStateRead)
-		require.Equal(t, expected, invalidator.MeterParamOverridesUpdated)
+		require.Equal(t, expected, invalidator.ExecutionParametersUpdated)
 	}
 
 	executionSnapshot, err = txnState.FinalizeMainTransaction()

fvm/environment/env.go

@@ -62,6 +62,12 @@ type Environment interface {
 		error,
 	)
 
+	// GetCurrentVersionBoundary executes the getCurrentVersionBoundary function on the NodeVersionBeacon contract.
+	// the function will return the version boundary (version, block height) that is currently in effect.
+	// the version boundary currently in effect is the highest one not above the current block height.
+	// if there is no existing version boundary lower than the current block height, the function will return version 0 and block height 0.
+	GetCurrentVersionBoundary() (cadence.Value, error)
+
 	// AccountInfo
 	GetAccount(address flow.Address) (*flow.Account, error)
 	GetAccountKeys(address flow.Address) ([]flow.AccountPublicKey, error)

fvm/environment/facade_env.go

@@ -38,6 +38,7 @@ type facadeEnvironment struct {
 	ValueStore
 
 	*SystemContracts
+	MinimumCadenceRequiredVersion
 
 	UUIDGenerator
 	AccountLocalIDGenerator
@@ -107,6 +108,9 @@ func newFacadeEnvironment(
 		),
 
 		SystemContracts: systemContracts,
+		MinimumCadenceRequiredVersion: NewMinimumCadenceRequiredVersion(
+			txnState,
+		),
 
 		UUIDGenerator: NewUUIDGenerator(
 			tracer,

fvm/environment/minimum_required_version.go

@@ -0,0 +1,99 @@
+package environment
+
+import (
+	"github.com/coreos/go-semver/semver"
+
+	"github.com/onflow/flow-go/fvm/storage/state"
+)
+
+// MinimumCadenceRequiredVersion returns the minimum required cadence version for the current environment
+// in semver format.
+type MinimumCadenceRequiredVersion interface {
+	MinimumRequiredVersion() (string, error)
+}
+
+type minimumCadenceRequiredVersion struct {
+	txnPreparer state.NestedTransactionPreparer
+}
+
+func NewMinimumCadenceRequiredVersion(
+	txnPreparer state.NestedTransactionPreparer,
+) MinimumCadenceRequiredVersion {
+	return minimumCadenceRequiredVersion{
+		txnPreparer: txnPreparer,
+	}
+}
+
+// MinimumRequiredVersion The returned cadence version can be used by cadence runtime for supporting feature flag.
+// The feature flag in cadence allows ENs to produce consistent results even if running with
+// different cadence versions at the same height, which is useful for rolling out cadence
+// upgrade without all ENs restarting all together.
+// For instance, we would like to grade cadence from v1 to v3, where v3 has a new cadence feature.
+// We first make a cadence v2 that has feature flag only turned on when the MinimumRequiredVersion()
+// method returns v2 or above.
+// So cadence v2 with the feature flag turned off will produce the same result as v1 which doesn't have the feature.
+// And cadence v2 with the feature flag turned on will also produce the same result as v3 which has the feature.
+// The feature flag allows us to roll out cadence v2 to all ENs which was running v1.
+// And we use the MinimumRequiredVersion to control when the feature flag should be switched from off to on.
+// And the switching should happen at the same height for all ENs.
+//
+// The height-based switch over can be done by using VersionBeacon, however, the VersionBeacon only
+// defines the flow-go version, not cadence version.
+// So we first read the current minimum required flow-go version from the VersionBeacon control,
+// and map it to the cadence version to be used by cadence to decide feature flag status.
+//
+// For instance, let’s say all ENs are running flow-go v0.37.0 with cadence v1.
+// We first create a version mapping entry for flow-go v0.37.1 to cadence v2, and roll out v0.37.1 to all ENs.
+// v0.37.1 ENs will produce the same result as v0.37.0 ENs, because the current version beacon still returns v0.37.0,
+// which maps zero cadence version, and cadence will keep the feature flag off.
+//
+// After all ENs have upgraded to v0.37.1, we send out a version beacon to switch to v0.37.1 at a future height,
+// let’s say height 1000.
+// Then what happens is that:
+//  1. ENs running v0.37.0 will crash after height 999, until upgrade to higher version
+//  2. ENs running v0.37.1 will execute with cadence v2 with feature flag off up until height 999, and from height 1000,
+//     the feature flag will be on, which means all v0.37.1 ENs will again produce consistent results for blocks above 1000.
+//
+// After height 1000 have been sealed, we can roll out v0.37.2 to all ENs with cadence v3, and it will produce the consistent
+// result as v0.37.1.
+func (c minimumCadenceRequiredVersion) MinimumRequiredVersion() (string, error) {
+	executionParameters := c.txnPreparer.ExecutionParameters()
+
+	// map the minimum required flow-go version to a minimum required cadence version
+	cadenceVersion := mapToCadenceVersion(executionParameters.ExecutionVersion, minimumFvmToMinimumCadenceVersionMapping)
+
+	return cadenceVersion.String(), nil
+}
+
+func mapToCadenceVersion(flowGoVersion semver.Version, versionMapping FlowGoToCadenceVersionMapping) semver.Version {
+	if versionGreaterThanOrEqualTo(flowGoVersion, versionMapping.FlowGoVersion) {
+		return versionMapping.CadenceVersion
+	} else {
+		return semver.Version{}
+	}
+}
+
+func versionGreaterThanOrEqualTo(version semver.Version, other semver.Version) bool {
+	return version.Compare(other) >= 0
+}
+
+type FlowGoToCadenceVersionMapping struct {
+	FlowGoVersion  semver.Version
+	CadenceVersion semver.Version
+}
+
+// This could also be a map, but ist not needed because we only expect one entry at a give time
+// we won't be fixing 2 separate issues at 2 separate version with one deploy.
+var minimumFvmToMinimumCadenceVersionMapping = FlowGoToCadenceVersionMapping{
+	// Leaving this example in, so it's easier to understand
+	//
+	//	FlowGoVersion:  *semver.New("0.37.0"),
+	//	CadenceVersion: *semver.New("1.0.0"),
+	//
+}
+
+func SetFVMToCadenceVersionMappingForTestingOnly(mapping FlowGoToCadenceVersionMapping) {
+	minimumFvmToMinimumCadenceVersionMapping = mapping
+}
+
+var _ MinimumCadenceRequiredVersion = (*minimumCadenceRequiredVersion)(nil)

fvm/environment/minimum_required_version_test.go

@@ -0,0 +1,63 @@
+package environment
+
+import (
+	"testing"
+
+	"github.com/coreos/go-semver/semver"
+	"github.com/stretchr/testify/require"
+)
+
+func Test_MapToCadenceVersion(t *testing.T) {
+	flowV0 := semver.Version{}
+	cadenceV0 := semver.Version{}
+	flowV1 := semver.Version{
+		Major: 0,
+		Minor: 37,
+		Patch: 0,
+	}
+	cadenceV1 := semver.Version{
+		Major: 1,
+		Minor: 0,
+		Patch: 0,
+	}
+
+	mapping := FlowGoToCadenceVersionMapping{
+		FlowGoVersion:  flowV1,
+		CadenceVersion: cadenceV1,
+	}
+
+	t.Run("no mapping, v0", func(t *testing.T) {
+		version := mapToCadenceVersion(flowV0, FlowGoToCadenceVersionMapping{})
+
+		require.Equal(t, cadenceV0, version)
+	})
+
+	t.Run("v0", func(t *testing.T) {
+		version := mapToCadenceVersion(flowV0, mapping)
+
+		require.Equal(t, semver.Version{}, version)
+	})
+	t.Run("v1 - delta", func(t *testing.T) {
+
+		v := flowV1
+		v.Patch -= 1
+
+		version := mapToCadenceVersion(v, mapping)
+
+		require.Equal(t, cadenceV0, version)
+	})
+	t.Run("v1", func(t *testing.T) {
+		version := mapToCadenceVersion(flowV1, mapping)
+
+		require.Equal(t, cadenceV1, version)
+	})
+	t.Run("v1 + delta", func(t *testing.T) {
+
+		v := flowV1
+		v.BumpPatch()
+
+		version := mapToCadenceVersion(v, mapping)
+
+		require.Equal(t, cadenceV1, version)
+	})
+}