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470 lines
12 KiB
470 lines
12 KiB
package rpcclient
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import (
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"context"
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"encoding/json"
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"fmt"
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"math"
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"net"
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"net/http"
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"sync"
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"time"
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"github.com/gorilla/websocket"
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"github.com/pkg/errors"
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metrics "github.com/rcrowley/go-metrics"
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types "github.com/tendermint/tendermint/rpc/lib/types"
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cmn "github.com/tendermint/tmlibs/common"
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)
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const (
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defaultMaxReconnectAttempts = 25
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defaultWriteWait = 0
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defaultReadWait = 0
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defaultPingPeriod = 0
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)
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// WSClient is a WebSocket client. The methods of WSClient are safe for use by
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// multiple goroutines.
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type WSClient struct {
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cmn.BaseService
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conn *websocket.Conn
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Address string // IP:PORT or /path/to/socket
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Endpoint string // /websocket/url/endpoint
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Dialer func(string, string) (net.Conn, error)
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// Time between sending a ping and receiving a pong. See
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// https://godoc.org/github.com/rcrowley/go-metrics#Timer.
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PingPongLatencyTimer metrics.Timer
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// user facing channels, closed only when the client is being stopped.
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ResultsCh chan json.RawMessage
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ErrorsCh chan error
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// Callback, which will be called each time after successful reconnect.
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onReconnect func()
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// internal channels
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send chan types.RPCRequest // user requests
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backlog chan types.RPCRequest // stores a single user request received during a conn failure
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reconnectAfter chan error // reconnect requests
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readRoutineQuit chan struct{} // a way for readRoutine to close writeRoutine
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wg sync.WaitGroup
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mtx sync.RWMutex
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sentLastPingAt time.Time
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reconnecting bool
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// Maximum reconnect attempts (0 or greater; default: 25).
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maxReconnectAttempts int
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// Time allowed to write a message to the server. 0 means block until operation succeeds.
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writeWait time.Duration
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// Time allowed to read the next message from the server. 0 means block until operation succeeds.
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readWait time.Duration
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// Send pings to server with this period. Must be less than readWait. If 0, no pings will be sent.
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pingPeriod time.Duration
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}
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// NewWSClient returns a new client. See the commentary on the func(*WSClient)
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// functions for a detailed description of how to configure ping period and
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// pong wait time. The endpoint argument must begin with a `/`.
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func NewWSClient(remoteAddr, endpoint string, options ...func(*WSClient)) *WSClient {
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addr, dialer := makeHTTPDialer(remoteAddr)
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c := &WSClient{
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Address: addr,
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Dialer: dialer,
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Endpoint: endpoint,
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PingPongLatencyTimer: metrics.NewTimer(),
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maxReconnectAttempts: defaultMaxReconnectAttempts,
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readWait: defaultReadWait,
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writeWait: defaultWriteWait,
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pingPeriod: defaultPingPeriod,
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}
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c.BaseService = *cmn.NewBaseService(nil, "WSClient", c)
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for _, option := range options {
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option(c)
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}
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return c
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}
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// MaxReconnectAttempts sets the maximum number of reconnect attempts before returning an error.
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// It should only be used in the constructor and is not Goroutine-safe.
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func MaxReconnectAttempts(max int) func(*WSClient) {
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return func(c *WSClient) {
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c.maxReconnectAttempts = max
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}
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}
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// ReadWait sets the amount of time to wait before a websocket read times out.
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// It should only be used in the constructor and is not Goroutine-safe.
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func ReadWait(readWait time.Duration) func(*WSClient) {
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return func(c *WSClient) {
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c.readWait = readWait
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}
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}
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// WriteWait sets the amount of time to wait before a websocket write times out.
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// It should only be used in the constructor and is not Goroutine-safe.
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func WriteWait(writeWait time.Duration) func(*WSClient) {
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return func(c *WSClient) {
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c.writeWait = writeWait
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}
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}
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// PingPeriod sets the duration for sending websocket pings.
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// It should only be used in the constructor - not Goroutine-safe.
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func PingPeriod(pingPeriod time.Duration) func(*WSClient) {
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return func(c *WSClient) {
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c.pingPeriod = pingPeriod
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}
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}
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// OnReconnect sets the callback, which will be called every time after
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// successful reconnect.
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func OnReconnect(cb func()) func(*WSClient) {
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return func(c *WSClient) {
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c.onReconnect = cb
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}
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}
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// String returns WS client full address.
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func (c *WSClient) String() string {
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return fmt.Sprintf("%s (%s)", c.Address, c.Endpoint)
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}
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// OnStart implements cmn.Service by dialing a server and creating read and
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// write routines.
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func (c *WSClient) OnStart() error {
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err := c.dial()
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if err != nil {
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return err
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}
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c.ResultsCh = make(chan json.RawMessage)
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c.ErrorsCh = make(chan error)
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c.send = make(chan types.RPCRequest)
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// 1 additional error may come from the read/write
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// goroutine depending on which failed first.
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c.reconnectAfter = make(chan error, 1)
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// capacity for 1 request. a user won't be able to send more because the send
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// channel is unbuffered.
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c.backlog = make(chan types.RPCRequest, 1)
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c.startReadWriteRoutines()
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go c.reconnectRoutine()
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return nil
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}
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// OnStop implements cmn.Service.
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func (c *WSClient) OnStop() {}
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// Stop overrides cmn.Service#Stop. There is no other way to wait until Quit
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// channel is closed.
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func (c *WSClient) Stop() bool {
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success := c.BaseService.Stop()
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// only close user-facing channels when we can't write to them
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c.wg.Wait()
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close(c.ResultsCh)
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close(c.ErrorsCh)
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return success
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}
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// IsReconnecting returns true if the client is reconnecting right now.
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func (c *WSClient) IsReconnecting() bool {
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c.mtx.RLock()
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defer c.mtx.RUnlock()
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return c.reconnecting
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}
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// IsActive returns true if the client is running and not reconnecting.
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func (c *WSClient) IsActive() bool {
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return c.IsRunning() && !c.IsReconnecting()
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}
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// Send the given RPC request to the server. Results will be available on
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// ResultsCh, errors, if any, on ErrorsCh. Will block until send succeeds or
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// ctx.Done is closed.
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func (c *WSClient) Send(ctx context.Context, request types.RPCRequest) error {
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select {
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case c.send <- request:
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c.Logger.Info("sent a request", "req", request)
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return nil
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case <-ctx.Done():
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return ctx.Err()
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}
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}
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// Call the given method. See Send description.
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func (c *WSClient) Call(ctx context.Context, method string, params map[string]interface{}) error {
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request, err := types.MapToRequest("ws-client", method, params)
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if err != nil {
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return err
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}
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return c.Send(ctx, request)
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}
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// CallWithArrayParams the given method with params in a form of array. See
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// Send description.
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func (c *WSClient) CallWithArrayParams(ctx context.Context, method string, params []interface{}) error {
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request, err := types.ArrayToRequest("ws-client", method, params)
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if err != nil {
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return err
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}
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return c.Send(ctx, request)
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}
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///////////////////////////////////////////////////////////////////////////////
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// Private methods
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func (c *WSClient) dial() error {
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dialer := &websocket.Dialer{
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NetDial: c.Dialer,
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Proxy: http.ProxyFromEnvironment,
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}
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rHeader := http.Header{}
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conn, _, err := dialer.Dial("ws://"+c.Address+c.Endpoint, rHeader)
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if err != nil {
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return err
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}
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c.conn = conn
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return nil
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}
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// reconnect tries to redial up to maxReconnectAttempts with exponential
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// backoff.
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func (c *WSClient) reconnect() error {
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attempt := 0
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c.mtx.Lock()
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c.reconnecting = true
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c.mtx.Unlock()
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defer func() {
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c.mtx.Lock()
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c.reconnecting = false
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c.mtx.Unlock()
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}()
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for {
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c.Logger.Info("reconnecting", "attempt", attempt+1)
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d := time.Duration(math.Exp2(float64(attempt)))
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time.Sleep(d * time.Second)
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err := c.dial()
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if err != nil {
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c.Logger.Error("failed to redial", "err", err)
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} else {
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c.Logger.Info("reconnected")
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if c.onReconnect != nil {
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go c.onReconnect()
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}
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return nil
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}
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attempt++
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if attempt > c.maxReconnectAttempts {
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return errors.Wrap(err, "reached maximum reconnect attempts")
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}
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}
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}
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func (c *WSClient) startReadWriteRoutines() {
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c.wg.Add(2)
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c.readRoutineQuit = make(chan struct{})
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go c.readRoutine()
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go c.writeRoutine()
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}
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func (c *WSClient) processBacklog() error {
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select {
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case request := <-c.backlog:
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if c.writeWait > 0 {
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c.conn.SetWriteDeadline(time.Now().Add(c.writeWait))
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}
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err := c.conn.WriteJSON(request)
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if err != nil {
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c.Logger.Error("failed to resend request", "err", err)
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c.reconnectAfter <- err
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// requeue request
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c.backlog <- request
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return err
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}
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c.Logger.Info("resend a request", "req", request)
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default:
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}
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return nil
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}
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func (c *WSClient) reconnectRoutine() {
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for {
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select {
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case originalError := <-c.reconnectAfter:
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// wait until writeRoutine and readRoutine finish
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c.wg.Wait()
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err := c.reconnect()
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if err != nil {
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c.Logger.Error("failed to reconnect", "err", err, "original_err", originalError)
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c.Stop()
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return
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} else {
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// drain reconnectAfter
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LOOP:
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for {
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select {
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case <-c.reconnectAfter:
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default:
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break LOOP
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}
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}
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err = c.processBacklog()
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if err == nil {
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c.startReadWriteRoutines()
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}
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}
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case <-c.Quit:
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return
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}
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}
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}
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// The client ensures that there is at most one writer to a connection by
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// executing all writes from this goroutine.
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func (c *WSClient) writeRoutine() {
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var ticker *time.Ticker
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if c.pingPeriod > 0 {
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// ticker with a predefined period
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ticker = time.NewTicker(c.pingPeriod)
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} else {
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// ticker that never fires
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ticker = &time.Ticker{C: make(<-chan time.Time)}
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}
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defer func() {
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ticker.Stop()
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c.conn.Close()
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c.wg.Done()
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}()
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for {
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select {
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case request := <-c.send:
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if c.writeWait > 0 {
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c.conn.SetWriteDeadline(time.Now().Add(c.writeWait))
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}
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err := c.conn.WriteJSON(request)
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if err != nil {
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c.Logger.Error("failed to send request", "err", err)
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c.reconnectAfter <- err
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// add request to the backlog, so we don't lose it
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c.backlog <- request
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return
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}
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case <-ticker.C:
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if c.writeWait > 0 {
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c.conn.SetWriteDeadline(time.Now().Add(c.writeWait))
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}
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err := c.conn.WriteMessage(websocket.PingMessage, []byte{})
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if err != nil {
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c.Logger.Error("failed to write ping", "err", err)
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c.reconnectAfter <- err
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return
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}
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c.mtx.Lock()
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c.sentLastPingAt = time.Now()
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c.mtx.Unlock()
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c.Logger.Debug("sent ping")
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case <-c.readRoutineQuit:
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return
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case <-c.Quit:
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c.conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
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return
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}
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}
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}
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// The client ensures that there is at most one reader to a connection by
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// executing all reads from this goroutine.
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func (c *WSClient) readRoutine() {
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defer func() {
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c.conn.Close()
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c.wg.Done()
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}()
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c.conn.SetPongHandler(func(string) error {
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// gather latency stats
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c.mtx.RLock()
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t := c.sentLastPingAt
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c.mtx.RUnlock()
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c.PingPongLatencyTimer.UpdateSince(t)
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c.Logger.Debug("got pong")
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return nil
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})
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for {
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// reset deadline for every message type (control or data)
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if c.readWait > 0 {
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c.conn.SetReadDeadline(time.Now().Add(c.readWait))
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}
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_, data, err := c.conn.ReadMessage()
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if err != nil {
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if !websocket.IsUnexpectedCloseError(err, websocket.CloseNormalClosure) {
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return
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}
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c.Logger.Error("failed to read response", "err", err)
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close(c.readRoutineQuit)
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c.reconnectAfter <- err
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return
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}
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var response types.RPCResponse
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err = json.Unmarshal(data, &response)
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if err != nil {
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c.Logger.Error("failed to parse response", "err", err, "data", string(data))
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c.ErrorsCh <- err
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continue
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}
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if response.Error != nil {
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c.ErrorsCh <- response.Error
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continue
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}
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c.Logger.Info("got response", "resp", response.Result)
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c.ResultsCh <- *response.Result
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}
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}
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///////////////////////////////////////////////////////////////////////////////
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// Predefined methods
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// Subscribe to an event. Note the server must have a "subscribe" route
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// defined.
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func (c *WSClient) Subscribe(ctx context.Context, eventType string) error {
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params := map[string]interface{}{"event": eventType}
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return c.Call(ctx, "subscribe", params)
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}
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// Unsubscribe from an event. Note the server must have a "unsubscribe" route
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// defined.
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func (c *WSClient) Unsubscribe(ctx context.Context, eventType string) error {
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params := map[string]interface{}{"event": eventType}
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return c.Call(ctx, "unsubscribe", params)
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}
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// UnsubscribeAll from all. Note the server must have a "unsubscribe_all" route
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// defined.
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func (c *WSClient) UnsubscribeAll(ctx context.Context) error {
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params := map[string]interface{}{}
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return c.Call(ctx, "unsubscribe_all", params)
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}
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