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/
wsclient.go
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/
wsclient.go
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package wsclient
import (
"context"
"fmt"
"net/http"
"sync"
"time"
"github.com/gorilla/websocket"
"github.com/gsmcwhirter/go-util/v3/errors"
log "github.com/gsmcwhirter/go-util/v3/logging"
"github.com/gsmcwhirter/go-util/v3/logging/level"
"github.com/gsmcwhirter/go-util/v3/request"
"golang.org/x/sync/errgroup"
"github.com/gsmcwhirter/discord-bot-lib/v7/logging"
)
// WSClient is the api for a client that maintains an active websocket connection and hands
// off messages to be processed.
type WSClient interface {
SetGateway(string)
SetHandler(MessageHandler)
Connect(string) error
Close()
HandleRequests(context.Context) error
SendMessage(msg WSMessage)
}
type dependencies interface {
Logger() log.Logger
WSDialer() Dialer
}
type wsClient struct {
deps dependencies
gatewayURL string
conn Conn
handler MessageHandler
responses chan WSMessage
pool *sync.WaitGroup
poolTokens chan struct{}
closeLock *sync.Mutex
isClosed bool
}
// Options enables setting up a WSClient with the desired connection settings
type Options struct {
GatewayURL string
MaxConcurrentHandlers int
}
// NewWSClient creates a new WSClient
func NewWSClient(deps dependencies, options Options) WSClient {
c := &wsClient{
deps: deps,
gatewayURL: options.GatewayURL,
closeLock: &sync.Mutex{},
}
c.pool = &sync.WaitGroup{}
if options.MaxConcurrentHandlers <= 0 {
c.poolTokens = make(chan struct{}, 20)
c.responses = make(chan WSMessage, 20)
} else {
c.poolTokens = make(chan struct{}, options.MaxConcurrentHandlers)
c.responses = make(chan WSMessage, options.MaxConcurrentHandlers)
}
return c
}
func (c *wsClient) SetGateway(url string) {
c.gatewayURL = url
}
func (c *wsClient) SetHandler(handler MessageHandler) {
c.handler = handler
}
func (c *wsClient) Connect(token string) error {
var err error
ctx := request.NewRequestContext()
logger := logging.WithContext(ctx, c.deps.Logger())
dialHeader := http.Header{
"Authorization": []string{fmt.Sprintf("Bot %s", token)},
}
var dialResp *http.Response
level.Debug(logger).Message("ws client dial start",
"url", c.gatewayURL,
)
start := time.Now()
c.conn, dialResp, err = c.deps.WSDialer().Dial(c.gatewayURL, dialHeader)
level.Info(logger).Message("ws client dial complete",
"duration_ns", time.Since(start).Nanoseconds(),
"status_code", dialResp.StatusCode,
"url", c.gatewayURL,
)
if err != nil {
return err
}
if dialResp.Body != nil {
defer dialResp.Body.Close() // nolint: errcheck
}
level.Info(logger).Message("ws connected")
return nil
}
func (c *wsClient) Close() {
c.pool.Wait()
if c.conn != nil {
_ = c.conn.Close()
}
}
func (c *wsClient) gracefulClose() {
c.closeLock.Lock()
defer c.closeLock.Unlock()
if c.isClosed {
return
}
c.isClosed = true
_ = c.conn.SetReadDeadline(time.Now())
}
func (c *wsClient) HandleRequests(ctx context.Context) error {
controls, ctx := errgroup.WithContext(ctx)
controls.Go(func() error {
level.Info(c.deps.Logger()).Message("starting response handler")
return c.handleResponses(ctx)
})
controls.Go(func() error {
level.Info(c.deps.Logger()).Message("starting message reader")
return c.readMessages(ctx)
})
level.Info(c.deps.Logger()).Message("connected and listening")
err := controls.Wait()
level.Info(c.deps.Logger()).Message("shutting down")
return err
}
func (c *wsClient) handleMessageRead(ctx context.Context, msgType int, msg []byte) {
defer c.pool.Done()
select {
case <-ctx.Done():
return
default:
}
reqCtx := request.NewRequestContextFrom(ctx)
mT := MessageType(msgType)
mC := make([]byte, len(msg))
copy(mC, msg)
logger := logging.WithContext(reqCtx, c.deps.Logger())
wsMsg := WSMessage{Ctx: reqCtx, MessageType: mT, MessageContents: mC}
level.Info(logger).Message("received message",
"ws_msg_type", mT,
"ws_msg_len", len(mC),
)
level.Debug(logger).Message("waiting for worker token")
c.poolTokens <- struct{}{}
level.Info(logger).Message("worker token acquired")
c.handleRequest(wsMsg)
}
func (c *wsClient) doReads(ctx context.Context) error {
defer level.Info(c.deps.Logger()).Message("websocket reader done")
for {
select {
case <-ctx.Done():
return ctx.Err()
default:
}
msgType, msg, err := c.conn.ReadMessage()
if err != nil {
level.Error(c.deps.Logger()).Err("read error", err,
"ws_msg_type", msgType,
"ws_content", msg,
)
return errors.Wrap(err, "read error")
}
c.pool.Add(1)
go c.handleMessageRead(ctx, msgType, msg)
}
}
func (c *wsClient) readMessages(ctx context.Context) error {
defer level.Info(c.deps.Logger()).Message("readMessages shutdown complete")
reader, ctx := errgroup.WithContext(ctx)
reader.Go(func() error {
return c.doReads(ctx)
})
// watches for close message
reader.Go(func() error {
<-ctx.Done()
level.Info(c.deps.Logger()).Message("readMessages shutting down")
c.gracefulClose()
return ctx.Err()
})
return reader.Wait()
}
func (c *wsClient) handleRequest(req WSMessage) {
logger := logging.WithContext(req.Ctx, c.deps.Logger())
defer func() {
<-c.poolTokens
level.Info(logger).Message("released worker token")
}()
select {
case <-req.Ctx.Done():
level.Info(logger).Message("handleRequest received interrupt -- shutting down")
return
default:
level.Info(logger).Message("handleRequest dispatching request")
c.handler.HandleRequest(req, c.responses)
}
}
func (c *wsClient) processResponse(resp WSMessage) {
logger := logging.WithContext(resp.Ctx, c.deps.Logger())
level.Debug(logger).Message("starting sending message",
"ws_msg_type", resp.MessageType,
"ws_msg_len", len(resp.MessageContents),
)
start := time.Now()
err := c.conn.WriteMessage(int(resp.MessageType), resp.MessageContents)
level.Info(logger).Message("done sending message",
"elapsed_ns", time.Since(start).Nanoseconds(),
"ws_msg_type", resp.MessageType,
"ws_msg_len", len(resp.MessageContents),
)
if err != nil {
level.Error(logger).Err("error sending message", err)
}
}
func (c *wsClient) handleResponses(ctx context.Context) error {
defer func() {
level.Info(c.deps.Logger()).Message("handleResponses shutdown complete")
}()
for {
select {
case <-ctx.Done(): // time to stop
level.Info(c.deps.Logger()).Message("handleResponses shutting down")
defer func() {
level.Info(c.deps.Logger()).Message("gracefully closing the socket")
err := c.conn.WriteMessage(websocket.CloseMessage, websocket.FormatCloseMessage(websocket.CloseNormalClosure, ""))
if err != nil {
level.Error(c.deps.Logger()).Err("Unable to write websocket close message", err)
return
}
level.Info(c.deps.Logger()).Message("close message sent")
}()
// drain the remaining response queue
deadline := time.After(5 * time.Second)
DRAIN_LOOP:
for {
select {
case _, ok := <-c.responses:
if !ok {
close(c.responses)
break DRAIN_LOOP
}
case <-deadline:
break DRAIN_LOOP
}
}
return ctx.Err()
case resp := <-c.responses: // handle pending responses
c.processResponse(resp)
}
}
}
func (c *wsClient) SendMessage(msg WSMessage) {
logger := logging.WithContext(msg.Ctx, c.deps.Logger())
level.Debug(logger).Message("adding message to response queue",
"ws_msg_type", msg.MessageType,
"ws_msg_len", len(msg.MessageContents),
)
c.responses <- msg
}