[api] Move the subscribers of coreService to serverV2 (#3073)

* move the subscribers under api to serverV2

api/coreservice.go

@@ -138,6 +138,8 @@ type (
 		TipHeight() uint64
 		// PendingNonce returns the pending nonce of an account
 		PendingNonce(address.Address) (uint64, error)
+		// ReceiveBlock broadcasts the block to api subscribers
+		ReceiveBlock(blk *block.Block) error
 	}
 
 	// coreService implements the CoreService interface
@@ -783,12 +785,6 @@ func (core *coreService) TipHeight() uint64 {
 
 // Start starts the API server
 func (core *coreService) Start(_ context.Context) error {
-	if err := core.bc.AddSubscriber(core.readCache); err != nil {
-		return errors.Wrap(err, "failed to add readCache")
-	}
-	if err := core.bc.AddSubscriber(core.chainListener); err != nil {
-		return errors.Wrap(err, "failed to add chainListener")
-	}
 	if err := core.chainListener.Start(); err != nil {
 		return errors.Wrap(err, "failed to start blockchain listener")
 	}
@@ -1618,6 +1614,11 @@ func (core *coreService) ReadContractStorage(ctx context.Context, addr address.A
 	return core.sf.ReadContractStorage(ctx, addr, key)
 }
 
+func (core *coreService) ReceiveBlock(blk *block.Block) error {
+	core.readCache.Clear()
+	return core.chainListener.ReceiveBlock(blk)
+}
+
 func (core *coreService) SimulateExecution(ctx context.Context, addr address.Address, exec *action.Execution) ([]byte, *action.Receipt, error) {
 	state, err := accountutil.AccountState(core.sf, addr)
 	if err != nil {

api/read_cache.go

@@ -7,7 +7,6 @@ import (
 	"github.com/iotexproject/go-pkgs/hash"
 	"go.uber.org/zap"
 
-	"github.com/iotexproject/iotex-core/blockchain/block"
 	"github.com/iotexproject/iotex-core/pkg/log"
 )
 
@@ -64,15 +63,3 @@ func (rc *ReadCache) Put(key hash.Hash160, value []byte) {
 func (rc *ReadCache) Clear() {
 	rc.c.Reset()
 }
-
-// ReceiveBlock receives the new block
-func (rc *ReadCache) ReceiveBlock(*block.Block) error {
-	// invalidate the cache at every new block
-	rc.c.Reset()
-	return nil
-}
-
-// Exit implements the Responder interface
-func (rc *ReadCache) Exit() {
-	rc.c.Reset()
-}

api/serverV2.go

@@ -11,6 +11,7 @@ import (
 	"github.com/iotexproject/iotex-core/action/protocol"
 	"github.com/iotexproject/iotex-core/actpool"
 	"github.com/iotexproject/iotex-core/blockchain"
+	"github.com/iotexproject/iotex-core/blockchain/block"
 	"github.com/iotexproject/iotex-core/blockchain/blockdao"
 	"github.com/iotexproject/iotex-core/blockindex"
 	"github.com/iotexproject/iotex-core/blocksync"
@@ -128,3 +129,8 @@ func (svr *ServerV2) Stop(ctx context.Context) error {
 	}
 	return nil
 }
+
+// ReceiveBlock receives the new block
+func (svr *ServerV2) ReceiveBlock(blk *block.Block) error {
+	return svr.core.ReceiveBlock(blk)
+}

chainservice/chainservice.go

@@ -379,6 +379,9 @@ func New(
 	if err != nil {
 		return nil, err
 	}
+	if err := chain.AddSubscriber(apiSvr); err != nil {
+		log.L().Warn("Failed to add subscriber: api server.", zap.Error(err))
+	}
 	accountProtocol := account.NewProtocol(rewarding.DepositGas)
 	if accountProtocol != nil {
 		if err = accountProtocol.Register(registry); err != nil {