rpc: refactor waiter-related actor code

pkg/rpcclient/actor/actor.go

@@ -25,7 +25,6 @@ import (
 // create and send transactions.
 type RPCActor interface {
 	invoker.RPCInvoke
-	RPCPollingWaiter
 
 	CalculateNetworkFee(tx *transaction.Transaction) (int64, error)
 	GetBlockCount() (uint32, error)
@@ -54,8 +53,22 @@ type SignerAccount struct {
 // action to be performed, "Make" prefix is used for methods that create
 // transactions in various ways, while "Send" prefix is used by methods that
 // directly transmit created transactions to the RPC server.
+//
+// Actor also provides a Waiter interface to wait until transaction will be
+// accepted to the chain. Depending on the underlying RPCActor functionality,
+// transaction awaiting can be performed via web-socket using RPC notifications
+// subsystem with EventWaiter, via regular RPC requests using a poll-based
+// algorithm with PollingWaiter or can not be performed if RPCActor doesn't
+// implement none of RPCEventWaiter and RPCPollingWaiter interfaces with
+// NullWaiter. ErrAwaitingNotSupported will be returned on attempt to await the
+// transaction in the latter case. Waiter uses context of the underlying RPCActor
+// and interrupts transaction awaiting process if the context is done.
+// ErrContextDone wrapped with the context's error will be returned in this case.
+// Otherwise, transaction awaiting process is ended with ValidUntilBlock acceptance
+// and ErrTxNotAccepted is returned if transaction wasn't accepted by this moment.
 type Actor struct {
 	invoker.Invoker
+	Waiter
 
 	client    RPCActor
 	opts      Options
@@ -109,6 +122,7 @@ func New(ra RPCActor, signers []SignerAccount) (*Actor, error) {
 	}
 	return &Actor{
 		Invoker:   *inv,
+		Waiter:    newWaiter(ra, version),
 		client:    ra,
 		opts:      NewDefaultOptions(),
 		signers:   signers,

pkg/rpcclient/actor/waiter.go

@@ -27,20 +27,34 @@ var (
 	// ErrContextDone is returned when Waiter context has been done in the middle
 	// of transaction awaiting process and no result was received yet.
 	ErrContextDone = errors.New("waiter context done")
+	// ErrAwaitingNotSupported is returned from Wait method if Waiter instance
+	// doesn't support transaction awaiting.
+	ErrAwaitingNotSupported = errors.New("awaiting not supported")
 )
 
 type (
+	// Waiter is an interface providing transaction awaiting functionality to Actor.
+	Waiter interface {
+		// Wait allows to wait until transaction will be accepted to the chain. It can be
+		// used as a wrapper for Send or SignAndSend and accepts transaction hash,
+		// ValidUntilBlock value and an error. It returns transaction execution result
+		// or an error if transaction wasn't accepted to the chain.
+		Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error)
+	}
 	// RPCPollingWaiter is an interface that enables transaction awaiting functionality
 	// for Actor instance based on periodical BlockCount and ApplicationLog polls.
 	RPCPollingWaiter interface {
 		// Context should return the RPC client context to be able to gracefully
 		// shut down all running processes (if so).
 		Context() context.Context
+		GetVersion() (*result.Version, error)
 		GetBlockCount() (uint32, error)
 		GetApplicationLog(hash util.Uint256, trig *trigger.Type) (*result.ApplicationLog, error)
 	}
 	// RPCEventWaiter is an interface that enables improved transaction awaiting functionality
-	// for Actor instance based on web-socket Block and ApplicationLog notifications.
+	// for Actor instance based on web-socket Block and ApplicationLog notifications. RPCEventWaiter
+	// contains RPCPollingWaiter under the hood and falls back to polling when subscription-based
+	// awaiting fails.
 	RPCEventWaiter interface {
 		RPCPollingWaiter
 
@@ -50,28 +64,73 @@ type (
 	}
 )
 
-// Wait allows to wait until transaction will be accepted to the chain. It can be
-// used as a wrapper for Send or SignAndSend and accepts transaction hash,
-// ValidUntilBlock value and an error. It returns transaction execution result
-// or an error if transaction wasn't accepted to the chain.
-func (a *Actor) Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error) {
+// NullWaiter is a Waiter stub that doesn't support transaction awaiting functionality.
+type NullWaiter struct{}
+
+// PollingWaiter is a polling-based Waiter.
+type PollingWaiter struct {
+	polling RPCPollingWaiter
+	version *result.Version
+}
+
+// EventWaiter is a websocket-based Waiter.
+type EventWaiter struct {
+	ws      RPCEventWaiter
+	polling Waiter
+}
+
+// newWaiter creates Waiter instance. It can be either websocket-based or
+// polling-base, otherwise Waiter stub is returned.
+func newWaiter(ra RPCActor, v *result.Version) Waiter {
+	if eventW, ok := ra.(RPCEventWaiter); ok {
+		return &EventWaiter{
+			ws: eventW,
+			polling: &PollingWaiter{
+				polling: eventW,
+				version: v,
+			},
+		}
+	}
+	if pollW, ok := ra.(RPCPollingWaiter); ok {
+		return &PollingWaiter{
+			polling: pollW,
+			version: v,
+		}
+	}
+	return NewNullWaiter()
+}
+
+// NewNullWaiter creates an instance of Waiter stub.
+func NewNullWaiter() NullWaiter {
+	return NullWaiter{}
+}
+
+// Wait implements Waiter interface.
+func (NullWaiter) Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error) {
+	return nil, ErrAwaitingNotSupported
+}
+
+// NewPollingWaiter creates an instance of Waiter supporting poll-based transaction awaiting.
+func NewPollingWaiter(waiter RPCPollingWaiter) (*PollingWaiter, error) {
+	v, err := waiter.GetVersion()
 	if err != nil {
 		return nil, err
 	}
-	if wsW, ok := a.client.(RPCEventWaiter); ok {
-		return a.waitWithWSWaiter(wsW, h, vub)
-	}
-	return a.waitWithSimpleWaiter(a.client, h, vub)
+	return &PollingWaiter{
+		polling: waiter,
+		version: v,
+	}, nil
 }
 
-// waitWithSimpleWaiter waits until transaction is accepted to the chain and
-// returns its execution result or an error if it's missing from chain after
-// VUB block.
-func (a *Actor) waitWithSimpleWaiter(c RPCPollingWaiter, h util.Uint256, vub uint32) (*state.AppExecResult, error) {
+// Wait implements Waiter interface.
+func (w *PollingWaiter) Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error) {
+	if err != nil {
+		return nil, err
+	}
 	var (
 		currentHeight uint32
 		failedAttempt int
-		pollTime      = time.Millisecond * time.Duration(a.GetVersion().Protocol.MillisecondsPerBlock) / 2
+		pollTime      = time.Millisecond * time.Duration(w.version.Protocol.MillisecondsPerBlock) / 2
 	)
 	if pollTime == 0 {
 		pollTime = time.Second
@@ -81,7 +140,7 @@ func (a *Actor) waitWithSimpleWaiter(c RPCPollingWaiter, h util.Uint256, vub uin
 	for {
 		select {
 		case <-timer.C:
-			blockCount, err := c.GetBlockCount()
+			blockCount, err := w.polling.GetBlockCount()
 			if err != nil {
 				failedAttempt++
 				if failedAttempt > PollingWaiterRetryCount {
@@ -94,7 +153,7 @@ func (a *Actor) waitWithSimpleWaiter(c RPCPollingWaiter, h util.Uint256, vub uin
 				currentHeight = blockCount - 1
 			}
 			t := trigger.Application
-			res, err := c.GetApplicationLog(h, &t)
+			res, err := w.polling.GetApplicationLog(h, &t)
 			if err == nil {
 				return &state.AppExecResult{
 					Container: h,
@@ -104,21 +163,35 @@ func (a *Actor) waitWithSimpleWaiter(c RPCPollingWaiter, h util.Uint256, vub uin
 			if currentHeight >= vub {
 				return nil, ErrTxNotAccepted
 			}
-
-		case <-c.Context().Done():
-			return nil, fmt.Errorf("%w: %v", ErrContextDone, c.Context().Err())
+		case <-w.polling.Context().Done():
+			return nil, fmt.Errorf("%w: %v", ErrContextDone, w.polling.Context().Err())
 		}
 	}
 }
 
-// waitWithWSWaiter waits until transaction is accepted to the chain and returns
-// its execution result or an error if it's missing from chain after VUB block.
-// It uses optimized web-socket waiter if possible.
-func (a *Actor) waitWithWSWaiter(c RPCEventWaiter, h util.Uint256, vub uint32) (res *state.AppExecResult, waitErr error) {
+// NewEventWaiter creates an instance of Waiter supporting websocket event-based transaction awaiting.
+// EventWaiter contains PollingWaiter under the hood and falls back to polling when subscription-based
+// awaiting fails.
+func NewEventWaiter(waiter RPCEventWaiter) (*EventWaiter, error) {
+	polling, err := NewPollingWaiter(waiter)
+	if err != nil {
+		return nil, err
+	}
+	return &EventWaiter{
+		ws:      waiter,
+		polling: polling,
+	}, nil
+}
+
+// Wait implements Waiter interface.
+func (w *EventWaiter) Wait(h util.Uint256, vub uint32, err error) (res *state.AppExecResult, waitErr error) {
+	if err != nil {
+		return nil, err
+	}
 	var wsWaitErr error
 	defer func() {
 		if wsWaitErr != nil {
-			res, waitErr = a.waitWithSimpleWaiter(c, h, vub)
+			res, waitErr = w.polling.Wait(h, vub, nil)
 			if waitErr != nil {
 				waitErr = fmt.Errorf("WS waiter error: %w, simple waiter error: %v", wsWaitErr, waitErr)
 			}
@@ -139,13 +212,13 @@ func (a *Actor) waitWithWSWaiter(c RPCEventWaiter, h util.Uint256, vub uint32) (
 	}()
 	// Execution event follows the block event, thus wait until the block next to the VUB to be sure.
 	since := vub + 1
-	blocksID, err := c.SubscribeForNewBlocksWithChan(nil, &since, nil, rcvr)
+	blocksID, err := w.ws.SubscribeForNewBlocksWithChan(nil, &since, nil, rcvr)
 	if err != nil {
 		wsWaitErr = fmt.Errorf("failed to subscribe for new blocks: %w", err)
 		return
 	}
 	defer func() {
-		err = c.Unsubscribe(blocksID)
+		err = w.ws.Unsubscribe(blocksID)
 		if err != nil {
 			errFmt := "failed to unsubscribe from blocks (id: %s): %v"
 			errArgs := []interface{}{blocksID, err}
@@ -156,13 +229,13 @@ func (a *Actor) waitWithWSWaiter(c RPCEventWaiter, h util.Uint256, vub uint32) (
 			waitErr = fmt.Errorf(errFmt, errArgs...)
 		}
 	}()
-	txsID, err := c.SubscribeForTransactionExecutionsWithChan(nil, &h, rcvr)
+	txsID, err := w.ws.SubscribeForTransactionExecutionsWithChan(nil, &h, rcvr)
 	if err != nil {
 		wsWaitErr = fmt.Errorf("failed to subscribe for execution results: %w", err)
 		return
 	}
 	defer func() {
-		err = c.Unsubscribe(txsID)
+		err = w.ws.Unsubscribe(txsID)
 		if err != nil {
 			errFmt := "failed to unsubscribe from transactions (id: %s): %v"
 			errArgs := []interface{}{txsID, err}
@@ -189,8 +262,8 @@ func (a *Actor) waitWithWSWaiter(c RPCEventWaiter, h util.Uint256, vub uint32) (
 				wsWaitErr = errors.New("some event was missed")
 				return
 			}
-		case <-c.Context().Done():
-			waitErr = fmt.Errorf("%w: %v", ErrContextDone, c.Context().Err())
+		case <-w.ws.Context().Done():
+			waitErr = fmt.Errorf("%w: %v", ErrContextDone, w.ws.Context().Err())
 			return
 		}
 	}