neoneo-go/pkg/rpcclient/wsclient.go
Anna Shaleva dc3d1300dd *: replace go.uber.org/atomic with sync/atomic
Use sync/atomic everywhere and exclude go.uber.org/atomic from go.mod.
Close #2626.

Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>
2023-10-12 17:59:34 +03:00

917 lines
28 KiB
Go

package rpcclient
import (
"context"
"encoding/json"
"errors"
"fmt"
"strconv"
"sync"
"sync/atomic"
"time"
"github.com/gorilla/websocket"
"github.com/nspcc-dev/neo-go/pkg/core/block"
"github.com/nspcc-dev/neo-go/pkg/core/state"
"github.com/nspcc-dev/neo-go/pkg/core/transaction"
"github.com/nspcc-dev/neo-go/pkg/neorpc"
"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
"github.com/nspcc-dev/neo-go/pkg/neorpc/rpcevent"
)
// WSClient is a websocket-enabled RPC client that can be used with appropriate
// servers. It's supposed to be faster than Client because it has persistent
// connection to the server and at the same time it exposes some functionality
// that is only provided via websockets (like event subscription mechanism).
// WSClient is thread-safe and can be used from multiple goroutines to perform
// RPC requests.
//
// It exposes a set of Receive* methods with the same behaviour pattern that
// is caused by the fact that the client itself receives every message from the
// server via a single channel. This includes any subscriptions and any replies
// to ordinary requests at the same. The client then routes these messages to
// channels provided on subscription (passed to Receive*) or to the respective
// receivers (API callers) if it's an ordinary JSON-RPC reply. While synchronous
// API users are blocked during their calls and wake up on reply, subscription
// channels must be read from to avoid blocking the client. Failure to do so
// will make WSClient wait for the channel reader to get the event and while
// it waits every other messages (subscription-related or request replies)
// will be blocked. This also means that subscription channel must be properly
// drained after unsubscription. If CloseNotificationChannelIfFull option is on
// then the receiver channel will be closed immediately in case if a subsequent
// notification can't be sent to it, which means WSClient's operations are
// unblocking in this mode. No unsubscription is performed in this case, so it's
// still the user responsibility to unsubscribe.
//
// Any received subscription items (blocks/transactions/nofitications) are passed
// via pointers for efficiency, but the actual structures MUST NOT be changed, as
// it may affect the functionality of other notification receivers. If multiple
// subscriptions share the same receiver channel, then matching notification is
// only sent once per channel. The receiver channel will be closed by the WSClient
// immediately after MissedEvent is received from the server; no unsubscription
// is performed in this case, so it's the user responsibility to unsubscribe. It
// will also be closed on disconnection from server or on situation when it's
// impossible to send a subsequent notification to the subscriber's channel and
// CloseNotificationChannelIfFull option is on.
type WSClient struct {
Client
ws *websocket.Conn
wsOpts WSOptions
done chan struct{}
requests chan *neorpc.Request
shutdown chan struct{}
closeCalled atomic.Bool
closeErrLock sync.RWMutex
closeErr error
subscriptionsLock sync.RWMutex
subscriptions map[string]notificationReceiver
// receivers is a mapping from receiver channel to a set of corresponding subscription IDs.
// It must be accessed with subscriptionsLock taken. Its keys must be used to deliver
// notifications, if channel is not in the receivers list and corresponding subscription
// still exists, notification must not be sent.
receivers map[any][]string
respLock sync.RWMutex
respChannels map[uint64]chan *neorpc.Response
}
// WSOptions defines options for the web-socket RPC client. It contains a
// set of options for the underlying standard RPC client as far as
// WSClient-specific options. See Options documentation for more details.
type WSOptions struct {
Options
// CloseNotificationChannelIfFull allows WSClient to close a subscriber's
// receive channel in case if the channel isn't read properly and no more
// events can be pushed to it. This option, if set, allows to avoid WSClient
// blocking on a subsequent notification dispatch. However, if enabled, the
// corresponding subscription is kept even after receiver's channel closing,
// thus it's still the caller's duty to call Unsubscribe() for this
// subscription.
CloseNotificationChannelIfFull bool
}
// notificationReceiver is an interface aimed to provide WS subscriber functionality
// for different types of subscriptions.
type notificationReceiver interface {
// Comparator provides notification filtering functionality.
rpcevent.Comparator
// Receiver returns notification receiver channel.
Receiver() any
// TrySend checks whether notification passes receiver filter and sends it
// to the underlying channel if so. It is performed under subscriptions lock
// taken. nonBlocking denotes whether the receiving operation shouldn't block
// the client's operation. It returns whether notification matches the filter
// and whether the receiver channel is overflown.
TrySend(ntf Notification, nonBlocking bool) (bool, bool)
// Close closes underlying receiver channel.
Close()
}
// blockReceiver stores information about block events subscriber.
type blockReceiver struct {
filter *neorpc.BlockFilter
ch chan<- *block.Block
}
// EventID implements neorpc.Comparator interface.
func (r *blockReceiver) EventID() neorpc.EventID {
return neorpc.BlockEventID
}
// Filter implements neorpc.Comparator interface.
func (r *blockReceiver) Filter() any {
if r.filter == nil {
return nil
}
return *r.filter
}
// Receiver implements notificationReceiver interface.
func (r *blockReceiver) Receiver() any {
return r.ch
}
// TrySend implements notificationReceiver interface.
func (r *blockReceiver) TrySend(ntf Notification, nonBlocking bool) (bool, bool) {
if rpcevent.Matches(r, ntf) {
if nonBlocking {
select {
case r.ch <- ntf.Value.(*block.Block):
default:
return true, true
}
} else {
r.ch <- ntf.Value.(*block.Block)
}
return true, false
}
return false, false
}
// Close implements notificationReceiver interface.
func (r *blockReceiver) Close() {
close(r.ch)
}
// txReceiver stores information about transaction events subscriber.
type txReceiver struct {
filter *neorpc.TxFilter
ch chan<- *transaction.Transaction
}
// EventID implements neorpc.Comparator interface.
func (r *txReceiver) EventID() neorpc.EventID {
return neorpc.TransactionEventID
}
// Filter implements neorpc.Comparator interface.
func (r *txReceiver) Filter() any {
if r.filter == nil {
return nil
}
return *r.filter
}
// Receiver implements notificationReceiver interface.
func (r *txReceiver) Receiver() any {
return r.ch
}
// TrySend implements notificationReceiver interface.
func (r *txReceiver) TrySend(ntf Notification, nonBlocking bool) (bool, bool) {
if rpcevent.Matches(r, ntf) {
if nonBlocking {
select {
case r.ch <- ntf.Value.(*transaction.Transaction):
default:
return true, true
}
} else {
r.ch <- ntf.Value.(*transaction.Transaction)
}
return true, false
}
return false, false
}
// Close implements notificationReceiver interface.
func (r *txReceiver) Close() {
close(r.ch)
}
// executionNotificationReceiver stores information about execution notifications subscriber.
type executionNotificationReceiver struct {
filter *neorpc.NotificationFilter
ch chan<- *state.ContainedNotificationEvent
}
// EventID implements neorpc.Comparator interface.
func (r *executionNotificationReceiver) EventID() neorpc.EventID {
return neorpc.NotificationEventID
}
// Filter implements neorpc.Comparator interface.
func (r *executionNotificationReceiver) Filter() any {
if r.filter == nil {
return nil
}
return *r.filter
}
// Receiver implements notificationReceiver interface.
func (r *executionNotificationReceiver) Receiver() any {
return r.ch
}
// TrySend implements notificationReceiver interface.
func (r *executionNotificationReceiver) TrySend(ntf Notification, nonBlocking bool) (bool, bool) {
if rpcevent.Matches(r, ntf) {
if nonBlocking {
select {
case r.ch <- ntf.Value.(*state.ContainedNotificationEvent):
default:
return true, true
}
} else {
r.ch <- ntf.Value.(*state.ContainedNotificationEvent)
}
return true, false
}
return false, false
}
// Close implements notificationReceiver interface.
func (r *executionNotificationReceiver) Close() {
close(r.ch)
}
// executionReceiver stores information about application execution results subscriber.
type executionReceiver struct {
filter *neorpc.ExecutionFilter
ch chan<- *state.AppExecResult
}
// EventID implements neorpc.Comparator interface.
func (r *executionReceiver) EventID() neorpc.EventID {
return neorpc.ExecutionEventID
}
// Filter implements neorpc.Comparator interface.
func (r *executionReceiver) Filter() any {
if r.filter == nil {
return nil
}
return *r.filter
}
// Receiver implements notificationReceiver interface.
func (r *executionReceiver) Receiver() any {
return r.ch
}
// TrySend implements notificationReceiver interface.
func (r *executionReceiver) TrySend(ntf Notification, nonBlocking bool) (bool, bool) {
if rpcevent.Matches(r, ntf) {
if nonBlocking {
select {
case r.ch <- ntf.Value.(*state.AppExecResult):
default:
return true, true
}
} else {
r.ch <- ntf.Value.(*state.AppExecResult)
}
return true, false
}
return false, false
}
// Close implements notificationReceiver interface.
func (r *executionReceiver) Close() {
close(r.ch)
}
// notaryRequestReceiver stores information about notary requests subscriber.
type notaryRequestReceiver struct {
filter *neorpc.TxFilter
ch chan<- *result.NotaryRequestEvent
}
// EventID implements neorpc.Comparator interface.
func (r *notaryRequestReceiver) EventID() neorpc.EventID {
return neorpc.NotaryRequestEventID
}
// Filter implements neorpc.Comparator interface.
func (r *notaryRequestReceiver) Filter() any {
if r.filter == nil {
return nil
}
return *r.filter
}
// Receiver implements notificationReceiver interface.
func (r *notaryRequestReceiver) Receiver() any {
return r.ch
}
// TrySend implements notificationReceiver interface.
func (r *notaryRequestReceiver) TrySend(ntf Notification, nonBlocking bool) (bool, bool) {
if rpcevent.Matches(r, ntf) {
if nonBlocking {
select {
case r.ch <- ntf.Value.(*result.NotaryRequestEvent):
default:
return true, true
}
} else {
r.ch <- ntf.Value.(*result.NotaryRequestEvent)
}
return true, false
}
return false, false
}
// Close implements notificationReceiver interface.
func (r *notaryRequestReceiver) Close() {
close(r.ch)
}
// Notification represents a server-generated notification for client subscriptions.
// Value can be one of *block.Block, *state.AppExecResult, *state.ContainedNotificationEvent
// *transaction.Transaction or *subscriptions.NotaryRequestEvent based on Type.
type Notification struct {
Type neorpc.EventID
Value any
}
// EventID implements Container interface and returns notification ID.
func (n Notification) EventID() neorpc.EventID {
return n.Type
}
// EventPayload implements Container interface and returns notification
// object.
func (n Notification) EventPayload() any {
return n.Value
}
// requestResponse is a combined type for request and response since we can get
// any of them here.
type requestResponse struct {
neorpc.Response
Method string `json:"method"`
RawParams []json.RawMessage `json:"params,omitempty"`
}
const (
// Message limit for receiving side.
wsReadLimit = 10 * 1024 * 1024
// Disconnection timeout.
wsPongLimit = 60 * time.Second
// Ping period for connection liveness check.
wsPingPeriod = wsPongLimit / 2
// Write deadline.
wsWriteLimit = wsPingPeriod / 2
)
// ErrNilNotificationReceiver is returned when notification receiver channel is nil.
var ErrNilNotificationReceiver = errors.New("nil notification receiver")
// ErrWSConnLost is a WSClient-specific error that will be returned for any
// requests after disconnection (including intentional ones via
// (*WSClient).Close).
var ErrWSConnLost = errors.New("connection lost")
// errConnClosedByUser is a WSClient error used iff the user calls (*WSClient).Close method by himself.
var errConnClosedByUser = errors.New("connection closed by user")
// NewWS returns a new WSClient ready to use (with established websocket
// connection). You need to use websocket URL for it like `ws://1.2.3.4/ws`.
// You should call Init method to initialize the network magic the client is
// operating on.
func NewWS(ctx context.Context, endpoint string, opts WSOptions) (*WSClient, error) {
dialer := websocket.Dialer{HandshakeTimeout: opts.DialTimeout}
ws, resp, err := dialer.DialContext(ctx, endpoint, nil)
if resp != nil && resp.Body != nil { // Can be non-nil even with error returned.
defer resp.Body.Close() // Not exactly required by websocket, but let's do this for bodyclose checker.
}
if err != nil {
if resp != nil && resp.Body != nil {
var srvErr neorpc.HeaderAndError
dec := json.NewDecoder(resp.Body)
decErr := dec.Decode(&srvErr)
if decErr == nil && srvErr.Error != nil {
err = srvErr.Error
}
}
return nil, err
}
wsc := &WSClient{
Client: Client{},
ws: ws,
wsOpts: opts,
shutdown: make(chan struct{}),
done: make(chan struct{}),
respChannels: make(map[uint64]chan *neorpc.Response),
requests: make(chan *neorpc.Request),
subscriptions: make(map[string]notificationReceiver),
receivers: make(map[any][]string),
}
err = initClient(ctx, &wsc.Client, endpoint, opts.Options)
if err != nil {
return nil, err
}
wsc.Client.cli = nil
go wsc.wsReader()
go wsc.wsWriter()
wsc.requestF = wsc.makeWsRequest
return wsc, nil
}
// Close closes connection to the remote side rendering this client instance
// unusable.
func (c *WSClient) Close() {
if c.closeCalled.CompareAndSwap(false, true) {
c.setCloseErr(errConnClosedByUser)
// Closing shutdown channel sends a signal to wsWriter to break out of the
// loop. In doing so it does ws.Close() closing the network connection
// which in turn makes wsReader receive an err from ws.ReadJSON() and also
// break out of the loop closing c.done channel in its shutdown sequence.
close(c.shutdown)
// Call to cancel will send signal to all users of Context().
c.Client.ctxCancel()
}
<-c.done
}
func (c *WSClient) wsReader() {
c.ws.SetReadLimit(wsReadLimit)
c.ws.SetPongHandler(func(string) error {
err := c.ws.SetReadDeadline(time.Now().Add(wsPongLimit))
if err != nil {
c.setCloseErr(fmt.Errorf("failed to set pong read deadline: %w", err))
}
return err
})
var connCloseErr error
readloop:
for {
rr := new(requestResponse)
err := c.ws.SetReadDeadline(time.Now().Add(wsPongLimit))
if err != nil {
connCloseErr = fmt.Errorf("failed to set response read deadline: %w", err)
break readloop
}
err = c.ws.ReadJSON(rr)
if err != nil {
// Timeout/connection loss/malformed response.
connCloseErr = fmt.Errorf("failed to read JSON response (timeout/connection loss/malformed response): %w", err)
break readloop
}
if rr.ID == nil && rr.Method != "" {
event, err := neorpc.GetEventIDFromString(rr.Method)
if err != nil {
// Bad event received.
connCloseErr = fmt.Errorf("failed to perse event ID from string %s: %w", rr.Method, err)
break readloop
}
if event != neorpc.MissedEventID && len(rr.RawParams) != 1 {
// Bad event received.
connCloseErr = fmt.Errorf("bad event received: %s / %d", event, len(rr.RawParams))
break readloop
}
ntf := Notification{Type: event}
switch event {
case neorpc.BlockEventID:
sr, err := c.stateRootInHeader()
if err != nil {
// Client is not initialized.
connCloseErr = fmt.Errorf("failed to fetch StateRootInHeader: %w", err)
break readloop
}
ntf.Value = block.New(sr)
case neorpc.TransactionEventID:
ntf.Value = &transaction.Transaction{}
case neorpc.NotificationEventID:
ntf.Value = new(state.ContainedNotificationEvent)
case neorpc.ExecutionEventID:
ntf.Value = new(state.AppExecResult)
case neorpc.NotaryRequestEventID:
ntf.Value = new(result.NotaryRequestEvent)
case neorpc.MissedEventID:
// No value.
default:
// Bad event received.
connCloseErr = fmt.Errorf("unknown event received: %d", event)
break readloop
}
if event != neorpc.MissedEventID {
err = json.Unmarshal(rr.RawParams[0], ntf.Value)
if err != nil {
// Bad event received.
connCloseErr = fmt.Errorf("failed to unmarshal event of type %s from JSON: %w", event, err)
break readloop
}
}
c.notifySubscribers(ntf)
} else if rr.ID != nil && (rr.Error != nil || rr.Result != nil) {
id, err := strconv.ParseUint(string(rr.ID), 10, 64)
if err != nil {
connCloseErr = fmt.Errorf("failed to retrieve response ID from string %s: %w", string(rr.ID), err)
break readloop // Malformed response (invalid response ID).
}
ch := c.getResponseChannel(id)
if ch == nil {
connCloseErr = fmt.Errorf("unknown response channel for response %d", id)
break readloop // Unknown response (unexpected response ID).
}
ch <- &rr.Response
} else {
// Malformed response, neither valid request, nor valid response.
connCloseErr = fmt.Errorf("malformed response")
break readloop
}
}
if connCloseErr != nil {
c.setCloseErr(connCloseErr)
}
close(c.done)
c.respLock.Lock()
for _, ch := range c.respChannels {
close(ch)
}
c.respChannels = nil
c.respLock.Unlock()
c.subscriptionsLock.Lock()
for rcvrCh, ids := range c.receivers {
c.dropSubCh(rcvrCh, ids[0], true)
}
c.subscriptionsLock.Unlock()
c.Client.ctxCancel()
}
// dropSubCh closes corresponding subscriber's channel and removes it from the
// receivers map. The channel is still being kept in
// the subscribers map as technically the server-side subscription still exists
// and the user is responsible for unsubscription. This method must be called
// under subscriptionsLock taken. It's the caller's duty to ensure dropSubCh
// will be called once per channel, otherwise panic will occur.
func (c *WSClient) dropSubCh(rcvrCh any, id string, ignoreCloseNotificationChannelIfFull bool) {
if ignoreCloseNotificationChannelIfFull || c.wsOpts.CloseNotificationChannelIfFull {
c.subscriptions[id].Close()
delete(c.receivers, rcvrCh)
}
}
func (c *WSClient) wsWriter() {
pingTicker := time.NewTicker(wsPingPeriod)
defer c.ws.Close()
defer pingTicker.Stop()
var connCloseErr error
writeloop:
for {
select {
case <-c.shutdown:
return
case <-c.done:
return
case req, ok := <-c.requests:
if !ok {
return
}
if err := c.ws.SetWriteDeadline(time.Now().Add(c.opts.RequestTimeout)); err != nil {
connCloseErr = fmt.Errorf("failed to set request write deadline: %w", err)
break writeloop
}
if err := c.ws.WriteJSON(req); err != nil {
connCloseErr = fmt.Errorf("failed to write JSON request (%s / %d): %w", req.Method, len(req.Params), err)
break writeloop
}
case <-pingTicker.C:
if err := c.ws.SetWriteDeadline(time.Now().Add(wsWriteLimit)); err != nil {
connCloseErr = fmt.Errorf("failed to set ping write deadline: %w", err)
break writeloop
}
if err := c.ws.WriteMessage(websocket.PingMessage, []byte{}); err != nil {
connCloseErr = fmt.Errorf("failed to write ping message: %w", err)
break writeloop
}
}
}
if connCloseErr != nil {
c.setCloseErr(connCloseErr)
}
}
func (c *WSClient) notifySubscribers(ntf Notification) {
if ntf.Type == neorpc.MissedEventID {
c.subscriptionsLock.Lock()
for rcvr, ids := range c.receivers {
c.subscriptions[ids[0]].Close()
delete(c.receivers, rcvr)
}
c.subscriptionsLock.Unlock()
return
}
c.subscriptionsLock.Lock()
for rcvrCh, ids := range c.receivers {
for _, id := range ids {
ok, dropCh := c.subscriptions[id].TrySend(ntf, c.wsOpts.CloseNotificationChannelIfFull)
if dropCh {
c.dropSubCh(rcvrCh, id, false)
break // strictly single drop per channel
}
if ok {
break // strictly one notification per channel
}
}
}
c.subscriptionsLock.Unlock()
}
func (c *WSClient) unregisterRespChannel(id uint64) {
c.respLock.Lock()
defer c.respLock.Unlock()
if ch, ok := c.respChannels[id]; ok {
delete(c.respChannels, id)
close(ch)
}
}
func (c *WSClient) getResponseChannel(id uint64) chan *neorpc.Response {
c.respLock.RLock()
defer c.respLock.RUnlock()
return c.respChannels[id]
}
func (c *WSClient) makeWsRequest(r *neorpc.Request) (*neorpc.Response, error) {
ch := make(chan *neorpc.Response)
c.respLock.Lock()
select {
case <-c.done:
c.respLock.Unlock()
return nil, fmt.Errorf("%w: before registering response channel", ErrWSConnLost)
default:
c.respChannels[r.ID] = ch
c.respLock.Unlock()
}
select {
case <-c.done:
return nil, fmt.Errorf("%w: before sending the request", ErrWSConnLost)
case c.requests <- r:
}
select {
case <-c.done:
return nil, fmt.Errorf("%w: while waiting for the response", ErrWSConnLost)
case resp, ok := <-ch:
if !ok {
return nil, fmt.Errorf("%w: while waiting for the response", ErrWSConnLost)
}
c.unregisterRespChannel(r.ID)
return resp, nil
}
}
func (c *WSClient) performSubscription(params []any, rcvr notificationReceiver) (string, error) {
var resp string
if err := c.performRequest("subscribe", params, &resp); err != nil {
return "", err
}
c.subscriptionsLock.Lock()
defer c.subscriptionsLock.Unlock()
c.subscriptions[resp] = rcvr
ch := rcvr.Receiver()
c.receivers[ch] = append(c.receivers[ch], resp)
return resp, nil
}
// ReceiveBlocks registers provided channel as a receiver for the new block events.
// Events can be filtered by the given BlockFilter, nil value doesn't add any filter.
// See WSClient comments for generic Receive* behaviour details.
func (c *WSClient) ReceiveBlocks(flt *neorpc.BlockFilter, rcvr chan<- *block.Block) (string, error) {
if rcvr == nil {
return "", ErrNilNotificationReceiver
}
params := []any{"block_added"}
if flt != nil {
flt = flt.Copy()
params = append(params, *flt)
}
r := &blockReceiver{
filter: flt,
ch: rcvr,
}
return c.performSubscription(params, r)
}
// ReceiveTransactions registers provided channel as a receiver for new transaction
// events. Events can be filtered by the given TxFilter, nil value doesn't add any
// filter. See WSClient comments for generic Receive* behaviour details.
func (c *WSClient) ReceiveTransactions(flt *neorpc.TxFilter, rcvr chan<- *transaction.Transaction) (string, error) {
if rcvr == nil {
return "", ErrNilNotificationReceiver
}
params := []any{"transaction_added"}
if flt != nil {
flt = flt.Copy()
params = append(params, *flt)
}
r := &txReceiver{
filter: flt,
ch: rcvr,
}
return c.performSubscription(params, r)
}
// ReceiveExecutionNotifications registers provided channel as a receiver for execution
// events. Events can be filtered by the given NotificationFilter, nil value doesn't add
// any filter. See WSClient comments for generic Receive* behaviour details.
func (c *WSClient) ReceiveExecutionNotifications(flt *neorpc.NotificationFilter, rcvr chan<- *state.ContainedNotificationEvent) (string, error) {
if rcvr == nil {
return "", ErrNilNotificationReceiver
}
params := []any{"notification_from_execution"}
if flt != nil {
flt = flt.Copy()
params = append(params, *flt)
}
r := &executionNotificationReceiver{
filter: flt,
ch: rcvr,
}
return c.performSubscription(params, r)
}
// ReceiveExecutions registers provided channel as a receiver for
// application execution result events generated during transaction execution.
// Events can be filtered by the given ExecutionFilter, nil value doesn't add any filter.
// See WSClient comments for generic Receive* behaviour details.
func (c *WSClient) ReceiveExecutions(flt *neorpc.ExecutionFilter, rcvr chan<- *state.AppExecResult) (string, error) {
if rcvr == nil {
return "", ErrNilNotificationReceiver
}
params := []any{"transaction_executed"}
if flt != nil {
if flt.State != nil {
if *flt.State != "HALT" && *flt.State != "FAULT" {
return "", errors.New("bad state parameter")
}
}
flt = flt.Copy()
params = append(params, *flt)
}
r := &executionReceiver{
filter: flt,
ch: rcvr,
}
return c.performSubscription(params, r)
}
// ReceiveNotaryRequests registers provided channel as a receiver for notary request
// payload addition or removal events. Events can be filtered by the given TxFilter
// where sender corresponds to notary request sender (the second fallback transaction
// signer) and signer corresponds to main transaction signers. nil value doesn't add
// any filter. See WSClient comments for generic Receive* behaviour details.
func (c *WSClient) ReceiveNotaryRequests(flt *neorpc.TxFilter, rcvr chan<- *result.NotaryRequestEvent) (string, error) {
if rcvr == nil {
return "", ErrNilNotificationReceiver
}
params := []any{"notary_request_event"}
if flt != nil {
flt = flt.Copy()
params = append(params, *flt)
}
r := &notaryRequestReceiver{
filter: flt,
ch: rcvr,
}
return c.performSubscription(params, r)
}
// Unsubscribe removes subscription for the given event stream. It will return an
// error in case if there's no subscription with the provided ID. Call to Unsubscribe
// doesn't block notifications receive process for given subscriber, thus, ensure
// that subscriber channel is properly drained while unsubscription is being
// performed. Failing to do so will cause WSClient to block even regular requests.
// You may probably need to run unsubscription process in a separate
// routine (in parallel with notification receiver routine) to avoid Client's
// notification dispatcher blocking.
func (c *WSClient) Unsubscribe(id string) error {
return c.performUnsubscription(id)
}
// UnsubscribeAll removes all active subscriptions of the current client. It copies
// the list of subscribers in order not to hold the lock for the whole execution
// time and tries to unsubscribe from us many feeds as possible returning the
// chunk of unsubscription errors afterwards. Call to UnsubscribeAll doesn't block
// notifications receive process for given subscribers, thus, ensure that subscribers
// channels are properly drained while unsubscription is being performed. Failing to
// do so will cause WSClient to block even regular requests. You may probably need
// to run unsubscription process in a separate routine (in parallel with notification
// receiver routines) to avoid Client's notification dispatcher blocking.
func (c *WSClient) UnsubscribeAll() error {
c.subscriptionsLock.Lock()
subs := make([]string, 0, len(c.subscriptions))
for id := range c.subscriptions {
subs = append(subs, id)
}
c.subscriptionsLock.Unlock()
var resErr error
for _, id := range subs {
err := c.performUnsubscription(id)
if err != nil {
errFmt := "failed to unsubscribe from feed %d: %v"
errArgs := []any{err}
if resErr != nil {
errFmt = "%w; " + errFmt
errArgs = append([]any{resErr}, errArgs...)
}
resErr = fmt.Errorf(errFmt, errArgs...)
}
}
return resErr
}
// performUnsubscription is internal method that removes subscription with the given
// ID from the list of subscriptions and receivers. It takes the subscriptions lock
// after WS RPC unsubscription request is completed. Until then the subscriber channel
// may still receive WS notifications.
func (c *WSClient) performUnsubscription(id string) error {
var resp bool
if err := c.performRequest("unsubscribe", []any{id}, &resp); err != nil {
return err
}
if !resp {
return errors.New("unsubscribe method returned false result")
}
c.subscriptionsLock.Lock()
defer c.subscriptionsLock.Unlock()
rcvr, ok := c.subscriptions[id]
if !ok {
return errors.New("no subscription with this ID")
}
ch := rcvr.Receiver()
ids := c.receivers[ch]
for i, rcvrID := range ids {
if rcvrID == id {
ids = append(ids[:i], ids[i+1:]...)
break
}
}
if len(ids) == 0 {
delete(c.receivers, ch)
} else {
c.receivers[ch] = ids
}
delete(c.subscriptions, id)
return nil
}
// setCloseErr is a thread-safe method setting closeErr in case if it's not yet set.
func (c *WSClient) setCloseErr(err error) {
c.closeErrLock.Lock()
defer c.closeErrLock.Unlock()
if c.closeErr == nil {
c.closeErr = err
}
}
// GetError returns the reason of WS connection closing. It returns nil in case if connection
// was closed by the use via Close() method calling.
func (c *WSClient) GetError() error {
c.closeErrLock.RLock()
defer c.closeErrLock.RUnlock()
if c.closeErr != nil && errors.Is(c.closeErr, errConnClosedByUser) {
return nil
}
return c.closeErr
}
// Context returns WSClient Cancel context that will be terminated on Client shutdown.
func (c *WSClient) Context() context.Context {
return c.Client.ctx
}