native: support postPersist method

It should be called for NEO contract to distribute
committee bounties.

pkg/core/blockchain.go

@@ -365,6 +365,19 @@ func (bc *Blockchain) notificationDispatcher() {
 						ch <- tx
 					}
 				}
+
+				aer = event.appExecResults[aerIdx]
+				if !aer.TxHash.Equals(event.block.Hash()) {
+					panic("inconsistent application execution results")
+				}
+				for ch := range executionFeed {
+					ch <- aer
+				}
+				for i := range aer.Events {
+					for ch := range notificationFeed {
+						ch <- &aer.Events[i]
+					}
+				}
 			}
 			for ch := range blockFeed {
 				ch <- event.block
@@ -528,7 +541,7 @@ func (bc *Blockchain) GetStateRoot(height uint32) (*state.MPTRootState, error) {
 func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error {
 	cache := dao.NewCached(bc.dao)
 	writeBuf := io.NewBufBinWriter()
-	appExecResults := make([]*state.AppExecResult, 0, 1+len(block.Transactions))
+	appExecResults := make([]*state.AppExecResult, 0, 2+len(block.Transactions))
 	if err := cache.StoreAsBlock(block, writeBuf); err != nil {
 		return err
 	}
@@ -540,28 +553,12 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 	writeBuf.Reset()
 
 	if block.Index > 0 {
-		systemInterop := bc.newInteropContext(trigger.System, cache, block, nil)
+		aer, err := bc.runPersist(bc.contracts.GetPersistScript(), block, cache)
-		v := systemInterop.SpawnVM()
+		if err != nil {
-		v.LoadScriptWithFlags(bc.contracts.GetPersistScript(), smartcontract.AllowModifyStates|smartcontract.AllowCall)
+			return fmt.Errorf("onPersist failed: %w", err)
-		v.SetPriceGetter(getPrice)
-		if err := v.Run(); err != nil {
-			return fmt.Errorf("onPersist run failed: %w", err)
-		} else if _, err := systemInterop.DAO.Persist(); err != nil {
-			return fmt.Errorf("can't save onPersist changes: %w", err)
-		}
-		for i := range systemInterop.Notifications {
-			bc.handleNotification(&systemInterop.Notifications[i], cache, block, block.Hash())
-		}
-		aer := &state.AppExecResult{
-			TxHash:      block.Hash(), // application logs can be retrieved by block hash
-			Trigger:     trigger.System,
-			VMState:     v.State(),
-			GasConsumed: v.GasConsumed(),
-			Stack:       v.Estack().ToArray(),
-			Events:      systemInterop.Notifications,
 		}
 		appExecResults = append(appExecResults, aer)
-		err := cache.PutAppExecResult(aer, writeBuf)
+		err = cache.PutAppExecResult(aer, writeBuf)
 		if err != nil {
 			return fmt.Errorf("failed to store onPersist exec result: %w", err)
 		}
@@ -611,6 +608,17 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 		writeBuf.Reset()
 	}
 
+	aer, err := bc.runPersist(bc.contracts.GetPostPersistScript(), block, cache)
+	if err != nil {
+		return fmt.Errorf("postPersist failed: %w", err)
+	}
+	appExecResults = append(appExecResults, aer)
+	err = cache.PutAppExecResult(aer, writeBuf)
+	if err != nil {
+		return fmt.Errorf("failed to store postPersist exec result: %w", err)
+	}
+	writeBuf.Reset()
+
 	root := bc.dao.MPT.StateRoot()
 	var prevHash util.Uint256
 	if block.Index > 0 {
@@ -620,7 +628,7 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 		}
 		prevHash = hash.DoubleSha256(prev.GetSignedPart())
 	}
-	err := bc.AddStateRoot(&state.MPTRoot{
+	err = bc.AddStateRoot(&state.MPTRoot{
 		MPTRootBase: state.MPTRootBase{
 			Index:    block.Index,
 			PrevHash: prevHash,
@@ -664,6 +672,29 @@ func (bc *Blockchain) storeBlock(block *block.Block, txpool *mempool.Pool) error
 	return nil
 }
 
+func (bc *Blockchain) runPersist(script []byte, block *block.Block, cache *dao.Cached) (*state.AppExecResult, error) {
+	systemInterop := bc.newInteropContext(trigger.System, cache, block, nil)
+	v := systemInterop.SpawnVM()
+	v.LoadScriptWithFlags(script, smartcontract.AllowModifyStates|smartcontract.AllowCall)
+	v.SetPriceGetter(getPrice)
+	if err := v.Run(); err != nil {
+		return nil, fmt.Errorf("VM has failed: %w", err)
+	} else if _, err := systemInterop.DAO.Persist(); err != nil {
+		return nil, fmt.Errorf("can't save changes: %w", err)
+	}
+	for i := range systemInterop.Notifications {
+		bc.handleNotification(&systemInterop.Notifications[i], cache, block, block.Hash())
+	}
+	return &state.AppExecResult{
+		TxHash:      block.Hash(), // application logs can be retrieved by block hash
+		Trigger:     trigger.System,
+		VMState:     v.State(),
+		GasConsumed: v.GasConsumed(),
+		Stack:       v.Estack().ToArray(),
+		Events:      systemInterop.Notifications,
+	}, nil
+}
+
 func (bc *Blockchain) handleNotification(note *state.NotificationEvent, d *dao.Cached, b *block.Block, h util.Uint256) {
 	if note.Name != "transfer" && note.Name != "Transfer" {
 		return

pkg/core/blockchain_test.go

@@ -588,7 +588,7 @@ func TestSubscriptions(t *testing.T) {
 	require.NoError(t, err)
 	require.Eventually(t, func() bool { return len(blockCh) != 0 }, time.Second, 10*time.Millisecond)
 	assert.Len(t, notificationCh, 1) // validator bounty
-	assert.Len(t, executionCh, 1)
+	assert.Len(t, executionCh, 2)
 	assert.Empty(t, txCh)
 
 	b := <-blockCh
@@ -597,6 +597,8 @@ func TestSubscriptions(t *testing.T) {
 
 	aer := <-executionCh
 	assert.Equal(t, b.Hash(), aer.TxHash)
+	aer = <-executionCh
+	assert.Equal(t, b.Hash(), aer.TxHash)
 
 	notif := <-notificationCh
 	require.Equal(t, bc.UtilityTokenHash(), notif.ScriptHash)
@@ -669,11 +671,15 @@ func TestSubscriptions(t *testing.T) {
 	}
 	assert.Empty(t, txCh)
 	assert.Len(t, notificationCh, 1)
-	assert.Empty(t, executionCh)
+	assert.Len(t, executionCh, 1)
 
 	notif = <-notificationCh
 	require.Equal(t, bc.UtilityTokenHash(), notif.ScriptHash)
 
+	exec = <-executionCh
+	require.Equal(t, b.Hash(), exec.TxHash)
+	require.Equal(t, exec.VMState, vm.HaltState)
+
 	bc.UnsubscribeFromBlocks(blockCh)
 	bc.UnsubscribeFromTransactions(txCh)
 	bc.UnsubscribeFromNotifications(notificationCh)

pkg/core/helper_test.go

@@ -177,7 +177,7 @@ func TestCreateBasicChain(t *testing.T) {
 	priv0 := testchain.PrivateKeyByID(0)
 	priv0ScriptHash := priv0.GetScriptHash()
 
-	require.Equal(t, big.NewInt(0), bc.GetUtilityTokenBalance(priv0ScriptHash))
+	require.Equal(t, big.NewInt(2500_0000), bc.GetUtilityTokenBalance(priv0ScriptHash)) // gas bounty
 	// Move some NEO to one simple account.
 	txMoveNeo := newNEP5Transfer(neoHash, neoOwner, priv0ScriptHash, neoAmount)
 	txMoveNeo.ValidUntilBlock = validUntilBlock

pkg/core/native/contract.go

@@ -1,8 +1,11 @@
 package native
 
 import (
+	"errors"
+
 	"github.com/nspcc-dev/neo-go/pkg/core/interop"
 	"github.com/nspcc-dev/neo-go/pkg/io"
+	"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/emit"
 	"github.com/nspcc-dev/neo-go/pkg/vm/opcode"
@@ -16,6 +19,8 @@ type Contracts struct {
 	Contracts []interop.Contract
 	// persistScript is vm script which executes "onPersist" method of every native contract.
 	persistScript []byte
+	// postPersistScript is vm script which executes "postPersist" method of every native contract.
+	postPersistScript []byte
 }
 
 // ByHash returns native contract with the specified hash.
@@ -71,3 +76,33 @@ func (cs *Contracts) GetPersistScript() []byte {
 	cs.persistScript = w.Bytes()
 	return cs.persistScript
 }
+
+// GetPostPersistScript returns VM script calling "postPersist" method of some native contracts.
+func (cs *Contracts) GetPostPersistScript() []byte {
+	if cs.postPersistScript != nil {
+		return cs.postPersistScript
+	}
+	w := io.NewBufBinWriter()
+	for i := range cs.Contracts {
+		md := cs.Contracts[i].Metadata()
+		// Not every contract is persisted:
+		// https://github.com/neo-project/neo/blob/master/src/neo/Ledger/Blockchain.cs#L103
+		if md.ContractID == policyContractID || md.ContractID == gasContractID {
+			continue
+		}
+		emit.Int(w.BinWriter, 0)
+		emit.Opcode(w.BinWriter, opcode.NEWARRAY)
+		emit.String(w.BinWriter, "postPersist")
+		emit.AppCall(w.BinWriter, md.Hash)
+		emit.Opcode(w.BinWriter, opcode.DROP)
+	}
+	cs.postPersistScript = w.Bytes()
+	return cs.postPersistScript
+}
+
+func postPersistBase(ic *interop.Context) error {
+	if ic.Trigger != trigger.System {
+		return errors.New("'postPersist' should be trigered by system")
+	}
+	return nil
+}

pkg/core/native/native_neo.go

@@ -90,6 +90,7 @@ func NewNEO() *NEO {
 	nep5.decimals = 0
 	nep5.factor = 1
 	nep5.onPersist = chainOnPersist(nep5.OnPersist, n.OnPersist)
+	nep5.postPersist = chainOnPersist(nep5.postPersist, n.PostPersist)
 	nep5.incBalance = n.increaseBalance
 	nep5.ContractID = neoContractID
 
@@ -103,6 +104,10 @@ func NewNEO() *NEO {
 	onp.Func = getOnPersistWrapper(n.onPersist)
 	n.Methods["onPersist"] = onp
 
+	pp := n.Methods["postPersist"]
+	pp.Func = getOnPersistWrapper(n.postPersist)
+	n.Methods["postPersist"] = pp
+
 	desc := newDescriptor("unclaimedGas", smartcontract.IntegerType,
 		manifest.NewParameter("account", smartcontract.Hash160Type),
 		manifest.NewParameter("end", smartcontract.IntegerType))
@@ -226,7 +231,11 @@ func (n *NEO) OnPersist(ic *interop.Context) error {
 			return err
 		}
 	}
+	return nil
+}
 
+// PostPersist implements Contract interface.
+func (n *NEO) PostPersist(ic *interop.Context) error {
 	gas, err := n.GetGASPerBlock(ic, ic.Block.Index)
 	if err != nil {
 		return err

pkg/core/native/native_nep5.go

@@ -35,6 +35,7 @@ type nep5TokenNative struct {
 	decimals    int64
 	factor      int64
 	onPersist   func(*interop.Context) error
+	postPersist func(*interop.Context) error
 	incBalance  func(*interop.Context, util.Uint160, *state.StorageItem, *big.Int) error
 }
 
@@ -84,6 +85,10 @@ func newNEP5Native(name string) *nep5TokenNative {
 	md = newMethodAndPrice(getOnPersistWrapper(n.OnPersist), 0, smartcontract.AllowModifyStates)
 	n.AddMethod(md, desc, false)
 
+	desc = newDescriptor("postPersist", smartcontract.VoidType)
+	md = newMethodAndPrice(getOnPersistWrapper(postPersistBase), 0, smartcontract.AllowModifyStates)
+	n.AddMethod(md, desc, false)
+
 	n.AddEvent("Transfer", desc.Parameters...)
 
 	return n

pkg/core/native/policy.go

@@ -124,6 +124,10 @@ func newPolicy() *Policy {
 	desc = newDescriptor("onPersist", smartcontract.VoidType)
 	md = newMethodAndPrice(getOnPersistWrapper(p.OnPersist), 0, smartcontract.AllowModifyStates)
 	p.AddMethod(md, desc, false)
+
+	desc = newDescriptor("postPersist", smartcontract.VoidType)
+	md = newMethodAndPrice(getOnPersistWrapper(postPersistBase), 0, smartcontract.AllowModifyStates)
+	p.AddMethod(md, desc, false)
 	return p
 }
 

pkg/core/native_neo_test.go

@@ -212,16 +212,16 @@ func TestNEO_CommitteeBountyOnPersist(t *testing.T) {
 		hs[i] = testchain.PrivateKeyByID(i).GetScriptHash()
 	}
 
-	bs := make(map[int]int64)
+	const singleBounty = 25000000
+	bs := map[int]int64{0: singleBounty}
 	checkBalances := func() {
 		for i := 0; i < testchain.CommitteeSize(); i++ {
-			require.EqualValues(t, bs[i], bc.GetUtilityTokenBalance(hs[i]).Int64())
+			require.EqualValues(t, bs[i], bc.GetUtilityTokenBalance(hs[i]).Int64(), i)
 		}
 	}
-
 	for i := 0; i < testchain.CommitteeSize()*2; i++ {
 		require.NoError(t, bc.AddBlock(bc.newBlock()))
-		bs[(i+1)%testchain.CommitteeSize()] += 25000000
+		bs[(i+1)%testchain.CommitteeSize()] += singleBounty
 		checkBalances()
 	}
 }

pkg/rpc/server/server_test.go

@@ -1075,7 +1075,7 @@ func checkNep5Balances(t *testing.T, e *executor, acc interface{}) {
 			},
 			{
 				Asset:       e.chain.UtilityTokenHash(),
-				Amount:      "799.34495030",
+				Amount:      "799.59495030",
 				LastUpdated: 7,
 			}},
 		Address: testchain.PrivateKeyByID(0).GetScriptHash().StringLE(),
@@ -1132,6 +1132,9 @@ func checkNep5TransfersAux(t *testing.T, e *executor, acc interface{}, sent, rcv
 	txReceiveNEO := blockReceiveGAS.Transactions[0]
 	txReceiveGAS := blockReceiveGAS.Transactions[1]
 
+	blockGASBounty0, err := e.chain.GetBlock(e.chain.GetHeaderHash(0))
+	require.NoError(t, err)
+
 	// These are laid out here explicitly for 2 purposes:
 	//  * to be able to reference any particular event for paging
 	//  * to check chain events consistency
@@ -1260,6 +1263,14 @@ func checkNep5TransfersAux(t *testing.T, e *executor, acc interface{}, sent, rcv
 				NotifyIndex: 0,
 				TxHash:      txReceiveNEO.Hash(),
 			},
+			{
+				Timestamp: blockGASBounty0.Timestamp,
+				Asset:     e.chain.UtilityTokenHash(),
+				Address:   "",
+				Amount:    "0.25000000",
+				Index:     0,
+				TxHash:    blockGASBounty0.Hash(),
+			},
 		},
 		Address: testchain.PrivateKeyByID(0).Address(),
 	}

pkg/rpc/server/subscription_test.go

@@ -120,6 +120,13 @@ func TestSubscriptions(t *testing.T) {
 			}
 		}
 		resp = getNotification(t, respMsgs)
+		require.Equal(t, response.ExecutionEventID, resp.Event)
+		for {
+			resp = getNotification(t, respMsgs)
+			if resp.Event != response.NotificationEventID {
+				break
+			}
+		}
 		require.Equal(t, response.BlockEventID, resp.Event)
 	}