core,native: persist native contract via VM

After native contracts are deployed, single persist script is created
and executed at the start of every block persisting.

pkg/core/blockchain.go

@@ -556,6 +556,17 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 		return err
 	}
 
+	if block.Index > 0 {
+		systemInterop := bc.newInteropContext(trigger.System, cache, block, nil)
+		v := SpawnVM(systemInterop)
+		v.LoadScriptWithFlags(bc.contracts.GetPersistScript(), smartcontract.AllowModifyStates|smartcontract.AllowCall)
+		if err := v.Run(); err != nil {
+			return errors.Wrap(err, "can't persist native contracts")
+		} else if _, err := systemInterop.DAO.Persist(); err != nil {
+			return errors.Wrap(err, "can't persist `onPersist` changes")
+		}
+	}
+
 	for _, tx := range block.Transactions {
 		if err := cache.StoreAsTransaction(tx, block.Index); err != nil {
 			return err
@@ -633,13 +644,6 @@ func (bc *Blockchain) storeBlock(block *block.Block) error {
 		}
 	}
 
-	for i := range bc.contracts.Contracts {
-		systemInterop := bc.newInteropContext(trigger.Application, cache, block, nil)
-		if err := bc.contracts.Contracts[i].OnPersist(systemInterop); err != nil {
-			return err
-		}
-	}
-
 	if bc.config.SaveStorageBatch {
 		bc.lastBatch = cache.DAO.GetBatch()
 	}

pkg/core/interop/context.go

@@ -79,7 +79,6 @@ type MethodAndPrice struct {
 type Contract interface {
 	Initialize(*Context) error
 	Metadata() *ContractMD
-	OnPersist(*Context) error
 }
 
 // ContractMD represents native contract instance.

pkg/core/native/contract.go

@@ -4,8 +4,10 @@ import (
 	"fmt"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
+	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm"
+	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/pkg/errors"
 )
 
@@ -14,6 +16,8 @@ type Contracts struct {
 	NEO       *NEO
 	GAS       *GAS
 	Contracts []interop.Contract
+	// persistScript is vm script which executes "onPersist" method of every native contract.
+	persistScript []byte
 }
 
 // ByHash returns native contract with the specified hash.
@@ -53,6 +57,20 @@ func NewContracts() *Contracts {
 	return cs
 }
 
+// GetPersistScript returns VM script calling "onPersist" method of every native contract.
+func (cs *Contracts) GetPersistScript() []byte {
+	if cs.persistScript != nil {
+		return cs.persistScript
+	}
+	w := io.NewBufBinWriter()
+	for i := range cs.Contracts {
+		md := cs.Contracts[i].Metadata()
+		emit.AppCallWithOperationAndArgs(w.BinWriter, md.Hash, "onPersist")
+	}
+	cs.persistScript = w.Bytes()
+	return cs.persistScript
+}
+
 // GetNativeInterop returns an interop getter for a given set of contracts.
 func (cs *Contracts) GetNativeInterop(ic *interop.Context) func(uint32) *vm.InteropFuncPrice {
 	return func(id uint32) *vm.InteropFuncPrice {

pkg/core/native/native_gas.go

@@ -34,12 +34,16 @@ func NewGAS() *GAS {
 	nep5.symbol = "gas"
 	nep5.decimals = 8
 	nep5.factor = GASFactor
-	nep5.onPersist = chainOnPersist(g.onPersist, g.OnPersist)
+	nep5.onPersist = chainOnPersist(nep5.OnPersist, g.OnPersist)
 	nep5.incBalance = g.increaseBalance
 	nep5.ContractID = gasContractID
 
 	g.nep5TokenNative = *nep5
 
+	onp := g.Methods["onPersist"]
+	onp.Func = getOnPersistWrapper(g.onPersist)
+	g.Methods["onPersist"] = onp
+
 	return g
 }
 

pkg/core/native/native_neo.go

@@ -68,12 +68,16 @@ func NewNEO() *NEO {
 	nep5.symbol = "neo"
 	nep5.decimals = 0
 	nep5.factor = 1
-	nep5.onPersist = chainOnPersist(n.onPersist, n.OnPersist)
+	nep5.onPersist = chainOnPersist(nep5.OnPersist, n.OnPersist)
 	nep5.incBalance = n.increaseBalance
 	nep5.ContractID = neoContractID
 
 	n.nep5TokenNative = *nep5
 
+	onp := n.Methods["onPersist"]
+	onp.Func = getOnPersistWrapper(n.onPersist)
+	n.Methods["onPersist"] = onp
+
 	desc := newDescriptor("unclaimedGas", smartcontract.IntegerType,
 		manifest.NewParameter("account", smartcontract.Hash160Type),
 		manifest.NewParameter("end", smartcontract.IntegerType))

pkg/core/native/native_nep5.go

@@ -10,6 +10,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/util"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 )
@@ -77,6 +78,10 @@ func newNEP5Native(name string) *nep5TokenNative {
 	md = newMethodAndPrice(n.Transfer, 1, smartcontract.AllowModifyStates)
 	n.AddMethod(md, desc, false)
 
+	desc = newDescriptor("onPersist", smartcontract.BoolType)
+	md = newMethodAndPrice(getOnPersistWrapper(n.OnPersist), 0, smartcontract.AllowModifyStates)
+	n.AddMethod(md, desc, false)
+
 	n.AddEvent("Transfer", desc.Parameters...)
 
 	return n
@@ -250,7 +255,10 @@ func (c *nep5TokenNative) addTokens(ic *interop.Context, h util.Uint160, amount
 }
 
 func (c *nep5TokenNative) OnPersist(ic *interop.Context) error {
-	return c.onPersist(ic)
+	if ic.Trigger != trigger.System {
+		return errors.New("onPersist should be triggerred by system")
+	}
+	return nil
 }
 
 func newDescriptor(name string, ret smartcontract.ParamType, ps ...manifest.Parameter) *manifest.Method {
@@ -311,3 +319,9 @@ func (s nep5ScriptHash) GetEntryScriptHash() util.Uint160 {
 func (s nep5ScriptHash) GetCurrentScriptHash() util.Uint160 {
 	return s.currentScriptHash
 }
+
+func getOnPersistWrapper(f func(ic *interop.Context) error) interop.Method {
+	return func(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
+		return stackitem.NewBool(f(ic) == nil)
+	}
+}

pkg/core/native_contract_test.go

@@ -1,7 +1,6 @@
 package core
 
 import (
-	"errors"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
@@ -10,6 +9,7 @@ import (
 	"github.com/nspcc-dev/neo-go/pkg/io"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
 	"github.com/nspcc-dev/neo-go/pkg/smartcontract/manifest"
+	"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
 	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
 	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
 	"github.com/stretchr/testify/require"
@@ -28,12 +28,15 @@ func (tn *testNative) Metadata() *interop.ContractMD {
 	return &tn.meta
 }
 
-func (tn *testNative) OnPersist(ic *interop.Context) error {
+func (tn *testNative) OnPersist(ic *interop.Context, _ []stackitem.Item) stackitem.Item {
+	if ic.Trigger != trigger.System {
+		panic("invalid trigger")
+	}
 	select {
 	case tn.blocks <- ic.Block.Index:
-		return nil
+		return stackitem.NewBool(true)
 	default:
-		return errors.New("error on persist")
+		return stackitem.NewBool(false)
 	}
 }
 
@@ -64,6 +67,10 @@ func newTestNative() *testNative {
 	}
 	tn.meta.AddMethod(md, desc, true)
 
+	desc = &manifest.Method{Name: "onPersist", ReturnType: smartcontract.BoolType}
+	md = &interop.MethodAndPrice{Func: tn.OnPersist, RequiredFlags: smartcontract.AllowModifyStates}
+	tn.meta.AddMethod(md, desc, false)
+
 	return tn
 }