mirror of
https://github.com/nspcc-dev/neo-go.git
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f5b1bd3978
Try to subscribe for headers firstly, and then if RPC server doesn't have this ability, fallback to block subscriptions to manage transaction awaiting. Close #3260. Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>
400 lines
13 KiB
Go
400 lines
13 KiB
Go
package waiter
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import (
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"context"
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"errors"
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"fmt"
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"strings"
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"time"
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"github.com/nspcc-dev/neo-go/pkg/core/block"
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"github.com/nspcc-dev/neo-go/pkg/core/state"
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"github.com/nspcc-dev/neo-go/pkg/neorpc"
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"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
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"github.com/nspcc-dev/neo-go/pkg/smartcontract/trigger"
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"github.com/nspcc-dev/neo-go/pkg/util"
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)
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// PollingBasedRetryCount is a threshold for a number of subsequent failed
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// attempts to get block count from the RPC server for PollingBased. If it fails
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// to retrieve block count PollingBasedRetryCount times in a raw then transaction
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// awaiting attempt considered to be failed and an error is returned.
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const PollingBasedRetryCount = 3
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var (
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// ErrTxNotAccepted is returned when transaction wasn't accepted to the chain
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// even after ValidUntilBlock block persist.
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ErrTxNotAccepted = errors.New("transaction was not accepted to chain")
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// ErrContextDone is returned when Waiter context has been done in the middle
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// of transaction awaiting process and no result was received yet.
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ErrContextDone = errors.New("waiter context done")
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// ErrAwaitingNotSupported is returned from Wait method if Waiter instance
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// doesn't support transaction awaiting.
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ErrAwaitingNotSupported = errors.New("awaiting not supported")
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// ErrMissedEvent is returned when RPCEventBased closes receiver channel
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// which happens if missed event was received from the RPC server.
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ErrMissedEvent = errors.New("some event was missed")
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)
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type (
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// Waiter is an interface providing transaction awaiting functionality.
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Waiter interface {
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// Wait allows to wait until transaction will be accepted to the chain. It can be
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// used as a wrapper for Send or SignAndSend and accepts transaction hash,
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// ValidUntilBlock value and an error. It returns transaction execution result
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// or an error if transaction wasn't accepted to the chain. Notice that "already
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// exists" err value is not treated as an error by this routine because it
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// means that the transactions given might be already accepted or soon going
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// to be accepted. Such transaction can be waited for in a usual way, potentially
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// with positive result, so that's what will happen.
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Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error)
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// WaitAny waits until at least one of the specified transactions will be accepted
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// to the chain until vub (including). It returns execution result of this
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// transaction or an error if none of the transactions was accepted to the chain.
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// It uses underlying RPCPollingBased or RPCEventBased context to interrupt
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// awaiting process, but additional ctx can be passed as an argument for the same
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// purpose.
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WaitAny(ctx context.Context, vub uint32, hashes ...util.Uint256) (*state.AppExecResult, error)
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}
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// RPCPollingBased is an interface that enables transaction awaiting functionality
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// based on periodical BlockCount and ApplicationLog polls.
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RPCPollingBased interface {
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// Context should return the RPC client context to be able to gracefully
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// shut down all running processes (if so).
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Context() context.Context
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GetVersion() (*result.Version, error)
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GetBlockCount() (uint32, error)
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GetApplicationLog(hash util.Uint256, trig *trigger.Type) (*result.ApplicationLog, error)
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}
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// RPCEventBased is an interface that enables improved transaction awaiting functionality
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// based on web-socket Block and ApplicationLog notifications. RPCEventBased
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// contains RPCPollingBased under the hood and falls back to polling when subscription-based
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// awaiting fails.
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RPCEventBased interface {
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RPCPollingBased
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ReceiveHeadersOfAddedBlocks(flt *neorpc.BlockFilter, rcvr chan<- *block.Header) (string, error)
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ReceiveBlocks(flt *neorpc.BlockFilter, rcvr chan<- *block.Block) (string, error)
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ReceiveExecutions(flt *neorpc.ExecutionFilter, rcvr chan<- *state.AppExecResult) (string, error)
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Unsubscribe(id string) error
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}
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)
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// Null is a Waiter stub that doesn't support transaction awaiting functionality.
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type Null struct{}
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// PollingBased is a polling-based Waiter.
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type PollingBased struct {
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polling RPCPollingBased
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version *result.Version
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}
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// EventBased is a websocket-based Waiter.
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type EventBased struct {
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ws RPCEventBased
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polling Waiter
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}
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// errIsAlreadyExists is a temporary helper until we have #2248 solved. Both C#
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// and Go nodes return this string (possibly among other data).
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func errIsAlreadyExists(err error) bool {
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return strings.Contains(strings.ToLower(err.Error()), "already exists")
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}
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// New creates Waiter instance. It can be either websocket-based or
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// polling-base, otherwise Waiter stub is returned. As a first argument
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// it accepts RPCEventBased implementation, RPCPollingBased implementation
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// or not an implementation of these two interfaces. It returns websocket-based
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// waiter, polling-based waiter or a stub correspondingly.
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func New(base any, v *result.Version) Waiter {
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if eventW, ok := base.(RPCEventBased); ok {
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return &EventBased{
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ws: eventW,
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polling: &PollingBased{
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polling: eventW,
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version: v,
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},
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}
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}
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if pollW, ok := base.(RPCPollingBased); ok {
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return &PollingBased{
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polling: pollW,
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version: v,
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}
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}
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return NewNull()
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}
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// NewNull creates an instance of Waiter stub.
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func NewNull() Null {
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return Null{}
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}
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// Wait implements Waiter interface.
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func (Null) Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error) {
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return nil, ErrAwaitingNotSupported
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}
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// WaitAny implements Waiter interface.
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func (Null) WaitAny(ctx context.Context, vub uint32, hashes ...util.Uint256) (*state.AppExecResult, error) {
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return nil, ErrAwaitingNotSupported
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}
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// NewPollingBased creates an instance of Waiter supporting poll-based transaction awaiting.
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func NewPollingBased(waiter RPCPollingBased) (*PollingBased, error) {
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v, err := waiter.GetVersion()
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if err != nil {
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return nil, err
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}
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return &PollingBased{
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polling: waiter,
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version: v,
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}, nil
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}
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// Wait implements Waiter interface.
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func (w *PollingBased) Wait(h util.Uint256, vub uint32, err error) (*state.AppExecResult, error) {
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if err != nil && !errIsAlreadyExists(err) {
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return nil, err
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}
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return w.WaitAny(context.TODO(), vub, h)
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}
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// WaitAny implements Waiter interface.
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func (w *PollingBased) WaitAny(ctx context.Context, vub uint32, hashes ...util.Uint256) (*state.AppExecResult, error) {
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var (
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currentHeight uint32
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failedAttempt int
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pollTime = time.Millisecond * time.Duration(w.version.Protocol.MillisecondsPerBlock) / 2
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)
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if pollTime == 0 {
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pollTime = time.Second
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}
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timer := time.NewTicker(pollTime)
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defer timer.Stop()
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for {
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select {
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case <-timer.C:
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blockCount, err := w.polling.GetBlockCount()
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if err != nil {
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failedAttempt++
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if failedAttempt > PollingBasedRetryCount {
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return nil, fmt.Errorf("failed to retrieve block count: %w", err)
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}
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continue
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}
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failedAttempt = 0
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if blockCount-1 > currentHeight {
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currentHeight = blockCount - 1
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}
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t := trigger.Application
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for _, h := range hashes {
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res, err := w.polling.GetApplicationLog(h, &t)
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if err == nil {
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return &state.AppExecResult{
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Container: res.Container,
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Execution: res.Executions[0],
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}, nil
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}
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}
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if currentHeight >= vub {
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return nil, ErrTxNotAccepted
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}
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case <-w.polling.Context().Done():
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return nil, fmt.Errorf("%w: %v", ErrContextDone, w.polling.Context().Err()) //nolint:errorlint // errorlint: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors
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case <-ctx.Done():
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return nil, fmt.Errorf("%w: %v", ErrContextDone, ctx.Err()) //nolint:errorlint // errorlint: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors
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}
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}
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}
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// NewEventBased creates an instance of Waiter supporting websocket event-based transaction awaiting.
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// EventBased contains PollingBased under the hood and falls back to polling when subscription-based
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// awaiting fails.
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func NewEventBased(waiter RPCEventBased) (*EventBased, error) {
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polling, err := NewPollingBased(waiter)
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if err != nil {
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return nil, err
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}
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return &EventBased{
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ws: waiter,
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polling: polling,
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}, nil
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}
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// Wait implements Waiter interface.
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func (w *EventBased) Wait(h util.Uint256, vub uint32, err error) (res *state.AppExecResult, waitErr error) {
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if err != nil && !errIsAlreadyExists(err) {
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return nil, err
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}
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return w.WaitAny(context.TODO(), vub, h)
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}
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// WaitAny implements Waiter interface.
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func (w *EventBased) WaitAny(ctx context.Context, vub uint32, hashes ...util.Uint256) (res *state.AppExecResult, waitErr error) {
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var (
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wsWaitErr error
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waitersActive int
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hRcvr = make(chan *block.Header, 2)
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bRcvr = make(chan *block.Block, 2)
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aerRcvr = make(chan *state.AppExecResult, len(hashes))
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unsubErrs = make(chan error)
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exit = make(chan struct{})
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)
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// Execution event preceded the block event, thus wait until the VUB-th block to be sure.
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since := vub
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blocksID, err := w.ws.ReceiveHeadersOfAddedBlocks(&neorpc.BlockFilter{Since: &since}, hRcvr)
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if err != nil {
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// Falling back to block-based subscription.
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if errors.Is(err, neorpc.ErrInvalidParams) {
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blocksID, err = w.ws.ReceiveBlocks(&neorpc.BlockFilter{Since: &since}, bRcvr)
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}
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}
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if err != nil {
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wsWaitErr = fmt.Errorf("failed to subscribe for new blocks/headers: %w", err)
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} else {
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waitersActive++
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go func() {
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<-exit
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err = w.ws.Unsubscribe(blocksID)
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if err != nil {
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unsubErrs <- fmt.Errorf("failed to unsubscribe from blocks/headers (id: %s): %w", blocksID, err)
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return
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}
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unsubErrs <- nil
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}()
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}
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if wsWaitErr == nil {
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trig := trigger.Application
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for _, h := range hashes {
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txsID, err := w.ws.ReceiveExecutions(&neorpc.ExecutionFilter{Container: &h}, aerRcvr)
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if err != nil {
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wsWaitErr = fmt.Errorf("failed to subscribe for execution results: %w", err)
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break
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}
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waitersActive++
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go func() {
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<-exit
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err = w.ws.Unsubscribe(txsID)
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if err != nil {
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unsubErrs <- fmt.Errorf("failed to unsubscribe from transactions (id: %s): %w", txsID, err)
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return
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}
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unsubErrs <- nil
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}()
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// There is a potential race between subscription and acceptance, so
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// do a polling check once _after_ the subscription.
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appLog, err := w.ws.GetApplicationLog(h, &trig)
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if err == nil {
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res = &state.AppExecResult{
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Container: appLog.Container,
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Execution: appLog.Executions[0],
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}
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break // We have the result, no need for other subscriptions.
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}
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}
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}
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if wsWaitErr == nil && res == nil {
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select {
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case _, ok := <-hRcvr:
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if !ok {
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// We're toast, retry with non-ws client.
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hRcvr = nil
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bRcvr = nil
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aerRcvr = nil
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wsWaitErr = ErrMissedEvent
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break
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}
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waitErr = ErrTxNotAccepted
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case _, ok := <-bRcvr:
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if !ok {
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// We're toast, retry with non-ws client.
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hRcvr = nil
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bRcvr = nil
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aerRcvr = nil
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wsWaitErr = ErrMissedEvent
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break
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}
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waitErr = ErrTxNotAccepted
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case aer, ok := <-aerRcvr:
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if !ok {
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// We're toast, retry with non-ws client.
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hRcvr = nil
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bRcvr = nil
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aerRcvr = nil
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wsWaitErr = ErrMissedEvent
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break
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}
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res = aer
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case <-w.ws.Context().Done():
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waitErr = fmt.Errorf("%w: %v", ErrContextDone, w.ws.Context().Err()) //nolint:errorlint // errorlint: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors
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case <-ctx.Done():
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waitErr = fmt.Errorf("%w: %v", ErrContextDone, ctx.Err()) //nolint:errorlint // errorlint: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors
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}
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}
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close(exit)
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if waitersActive > 0 {
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// Drain receivers to avoid other notification receivers blocking.
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drainLoop:
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for {
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select {
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case _, ok := <-hRcvr:
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if !ok { // Missed event means both channels are closed.
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hRcvr = nil
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bRcvr = nil
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aerRcvr = nil
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}
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case _, ok := <-bRcvr:
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if !ok { // Missed event means both channels are closed.
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hRcvr = nil
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bRcvr = nil
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aerRcvr = nil
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}
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case _, ok := <-aerRcvr:
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if !ok { // Missed event means both channels are closed.
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hRcvr = nil
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bRcvr = nil
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aerRcvr = nil
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}
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case unsubErr := <-unsubErrs:
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if unsubErr != nil {
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errFmt := "unsubscription error: %v"
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errArgs := []any{unsubErr}
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if waitErr != nil {
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errFmt = "%w; " + errFmt
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errArgs = append([]any{waitErr}, errArgs...)
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}
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waitErr = fmt.Errorf(errFmt, errArgs...)
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}
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waitersActive--
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// Wait until all receiver channels finish their work.
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if waitersActive == 0 {
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break drainLoop
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}
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}
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}
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}
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if hRcvr != nil {
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close(hRcvr)
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}
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if bRcvr != nil {
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close(bRcvr)
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}
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if aerRcvr != nil {
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close(aerRcvr)
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}
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close(unsubErrs)
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// Rollback to a poll-based waiter if needed.
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if wsWaitErr != nil && waitErr == nil {
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res, waitErr = w.polling.WaitAny(ctx, vub, hashes...)
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if waitErr != nil {
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// Wrap the poll-based error, it's more important.
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waitErr = fmt.Errorf("event-based error: %v; poll-based waiter error: %w", wsWaitErr, waitErr) //nolint:errorlint // errorlint: non-wrapping format verb for fmt.Errorf. Use `%w` to format errors
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}
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}
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return
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}
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