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465 lines
13 KiB
465 lines
13 KiB
package client
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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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mrand "math/rand"
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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/tendermint/tendermint/libs/log"
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rpctypes "github.com/tendermint/tendermint/rpc/jsonrpc/types"
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)
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// wsOptions carries optional settings for a websocket connection.
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type wsOptions struct {
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MaxReconnectAttempts uint // maximum attempts to reconnect
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ReadWait time.Duration // deadline for any read op
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WriteWait time.Duration // deadline for any write op
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PingPeriod time.Duration // frequency with which pings are sent
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}
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// defaultWSOptions are the default websocket connection settings.
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var defaultWSOptions = wsOptions{
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MaxReconnectAttempts: 10, // first: 2 sec, last: 17 min.
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WriteWait: 10 * time.Second,
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ReadWait: 0,
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PingPeriod: 0,
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}
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// WSClient is a JSON-RPC client, which uses WebSocket for communication with
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// the remote server.
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//
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// WSClient is safe for concurrent use by multiple goroutines.
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type WSClient struct { // nolint: maligned
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Logger log.Logger
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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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// Single user facing channel to read RPCResponses from, closed only when the
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// client is being stopped.
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ResponsesCh chan rpctypes.RPCResponse
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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 rpctypes.RPCRequest // user requests
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backlog chan rpctypes.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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// Maximum reconnect attempts (0 or greater; default: 25).
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maxReconnectAttempts uint
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// Support both ws and wss protocols
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protocol string
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wg sync.WaitGroup
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mtx sync.RWMutex
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reconnecting bool
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nextReqID int
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// sentIDs map[types.JSONRPCIntID]bool // IDs of the requests currently in flight
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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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// NewWS returns a new client with default options. The endpoint argument must
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// begin with a `/`. An error is returned on invalid remote.
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func NewWS(remoteAddr, endpoint string) (*WSClient, error) {
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opts := defaultWSOptions
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parsedURL, err := newParsedURL(remoteAddr)
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if err != nil {
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return nil, err
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}
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// default to ws protocol, unless wss is explicitly specified
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if parsedURL.Scheme != protoWSS {
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parsedURL.Scheme = protoWS
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}
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dialFn, err := makeHTTPDialer(remoteAddr)
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if err != nil {
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return nil, err
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}
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c := &WSClient{
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Logger: log.NewNopLogger(),
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Address: parsedURL.GetTrimmedHostWithPath(),
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Dialer: dialFn,
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Endpoint: endpoint,
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maxReconnectAttempts: opts.MaxReconnectAttempts,
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readWait: opts.ReadWait,
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writeWait: opts.WriteWait,
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pingPeriod: opts.PingPeriod,
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protocol: parsedURL.Scheme,
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// sentIDs: make(map[types.JSONRPCIntID]bool),
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}
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return c, nil
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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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// Could only be set before Start.
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func (c *WSClient) OnReconnect(cb func()) {
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c.onReconnect = cb
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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("WSClient{%s (%s)}", c.Address, c.Endpoint)
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}
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// Start dials the specified service address and starts the I/O routines. The
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// service routines run until ctx terminates. To wait for the client to exit
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// after ctx ends, call Stop.
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func (c *WSClient) Start(ctx context.Context) error {
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if err := c.dial(); err != nil {
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return err
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}
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c.ResponsesCh = make(chan rpctypes.RPCResponse)
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c.send = make(chan rpctypes.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 rpctypes.RPCRequest, 1)
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c.startReadWriteRoutines(ctx)
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go c.reconnectRoutine(ctx)
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return nil
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}
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// Stop blocks until the client is shut down and returns nil.
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//
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// TODO(creachadair): This method exists for compatibility with the original
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// service plumbing. Give it a better name (e.g., Wait).
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func (c *WSClient) Stop() error {
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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.ResponsesCh)
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return nil
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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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// Send the given RPC request to the server. Results will be available on
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// ResponsesCh, 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 rpctypes.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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// c.mtx.Lock()
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// c.sentIDs[request.ID.(types.JSONRPCIntID)] = true
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// c.mtx.Unlock()
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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 enqueues a call request onto the Send queue. Requests are JSON encoded.
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func (c *WSClient) Call(ctx context.Context, method string, params map[string]interface{}) error {
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req := rpctypes.NewRequest(c.nextRequestID())
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if err := req.SetMethodAndParams(method, params); err != nil {
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return err
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}
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return c.Send(ctx, req)
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}
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// Private methods
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func (c *WSClient) nextRequestID() int {
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c.mtx.Lock()
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defer c.mtx.Unlock()
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id := c.nextReqID
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c.nextReqID++
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return id
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}
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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(c.protocol+"://"+c.Address+c.Endpoint, rHeader) // nolint:bodyclose
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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(ctx context.Context) error {
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attempt := uint(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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timer := time.NewTimer(0)
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defer timer.Stop()
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for {
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// nolint:gosec // G404: Use of weak random number generator
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jitter := time.Duration(mrand.Float64() * float64(time.Second)) // 1s == (1e9 ns)
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backoffDuration := jitter + ((1 << attempt) * time.Second)
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c.Logger.Info("reconnecting", "attempt", attempt+1, "backoff_duration", backoffDuration)
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timer.Reset(backoffDuration)
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select {
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case <-ctx.Done():
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return nil
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case <-timer.C:
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}
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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 fmt.Errorf("reached maximum reconnect attempts: %w", err)
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}
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}
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}
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func (c *WSClient) startReadWriteRoutines(ctx context.Context) {
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c.wg.Add(2)
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c.readRoutineQuit = make(chan struct{})
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go c.readRoutine(ctx)
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go c.writeRoutine(ctx)
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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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if err := c.conn.SetWriteDeadline(time.Now().Add(c.writeWait)); err != nil {
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c.Logger.Error("failed to set write deadline", "err", err)
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}
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}
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if err := c.conn.WriteJSON(request); 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(ctx context.Context) {
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for {
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select {
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case <-ctx.Done():
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return
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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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if err := c.reconnect(ctx); err != nil {
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c.Logger.Error("failed to reconnect", "err", err, "original_err", originalError)
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if err = c.Stop(); err != nil {
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c.Logger.Error("failed to stop conn", "error", err)
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}
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return
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}
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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 <-ctx.Done():
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return
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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(ctx)
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}
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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(ctx context.Context) {
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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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if err := c.conn.SetWriteDeadline(time.Now().Add(c.writeWait)); err != nil {
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c.Logger.Error("failed to set write deadline", "err", err)
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}
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}
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if err := c.conn.WriteJSON(request); 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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if err := c.conn.SetWriteDeadline(time.Now().Add(c.writeWait)); err != nil {
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c.Logger.Error("failed to set write deadline", "err", err)
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}
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}
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if err := c.conn.WriteMessage(websocket.PingMessage, []byte{}); 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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case <-c.readRoutineQuit:
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return
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case <-ctx.Done():
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if err := c.conn.WriteMessage(
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websocket.CloseMessage,
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websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""),
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); err != nil {
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c.Logger.Error("failed to write message", "err", err)
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}
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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(ctx context.Context) {
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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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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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if err := c.conn.SetReadDeadline(time.Now().Add(c.readWait)); err != nil {
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c.Logger.Error("failed to set read deadline", "err", err)
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}
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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 rpctypes.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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continue
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}
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// TODO: events resulting from /subscribe do not work with ->
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// because they are implemented as responses with the subscribe request's
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// ID. According to the spec, they should be notifications (requests
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// without IDs).
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// https://github.com/tendermint/tendermint/issues/2949
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//
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// Combine a non-blocking read on BaseService.Quit with a non-blocking write on ResponsesCh to avoid blocking
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// c.wg.Wait() in c.Stop(). Note we rely on Quit being closed so that it sends unlimited Quit signals to stop
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// both readRoutine and writeRoutine
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c.Logger.Info("got response", "id", response.ID, "result", response.Result)
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select {
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case <-ctx.Done():
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return
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case c.ResponsesCh <- response:
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}
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}
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}
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// Predefined methods
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// Subscribe to a query. Note the server must have a "subscribe" route
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// defined.
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func (c *WSClient) Subscribe(ctx context.Context, query string) error {
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params := map[string]interface{}{"query": query}
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return c.Call(ctx, "subscribe", params)
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}
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// Unsubscribe from a query. Note the server must have a "unsubscribe" route
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// defined.
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func (c *WSClient) Unsubscribe(ctx context.Context, query string) error {
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params := map[string]interface{}{"query": query}
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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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