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import ( "cmp" "context" "fmt" "log/slog" "net/http" "net/url" "time"
indigoxrpc "github.com/bluesky-social/indigo/xrpc" "github.com/carlmjohnson/versioninfo" "github.com/gorilla/websocket" cbg "github.com/whyrusleeping/cbor-gen")
const minHealthyConn = 30 * time.Second
type Client struct { indigoxrpc.Client Dialer websocket.Dialer Logger *slog.Logger}
var _ LexClient = (*Client)(nil)
func makeParams(p map[string]any) url.Values { params := url.Values{} for k, v := range p { if s, ok := v.([]string); ok { for _, v := range s { params.Add(k, v) } } else { params.Add(k, fmt.Sprint(v)) } } return params}
type processFn func(ctx context.Context, cr *cbg.CborReader) error
func (c *Client) LexDo(ctx context.Context, method string, inputEncoding string, endpoint string, params map[string]any, bodyData any, out any) error { switch method { case Subscription: if process, ok := out.(func(context.Context, *cbg.CborReader) error); ok { return c.LexSubscribe(ctx, endpoint, params, process) } else if process, ok := out.(processFn); ok { return c.LexSubscribe(ctx, endpoint, params, process) } else if redialer, ok := out.(Redialer); ok { return c.LexSubscribeWithRedialer(ctx, endpoint, params, redialer) } else { return fmt.Errorf("unknown output type: %T", out) } default: return c.Client.LexDo(ctx, method, inputEncoding, endpoint, params, bodyData, out) }}
func (c *Client) getHeader() http.Header { header := http.Header{} if c.UserAgent != nil { header.Set("User-Agent", *c.UserAgent) } else { header.Set("User-Agent", "extlexutil/"+versioninfo.Short()) } if c.Headers != nil { for k, v := range c.Headers { header.Set(k, v) } } return header}
func (c *Client) LexSubscribe(ctx context.Context, endpoint string, params map[string]any, process func(ctx context.Context, cr *cbg.CborReader) error) error { logger := cmp.Or(c.Logger, slog.Default().With("system", "events")) rurl, err := url.Parse(c.Host) if err != nil { return err } if rurl.Scheme == "http" { rurl.Scheme = "ws" } else { rurl.Scheme = "wss" } surl := rurl.JoinPath("/xrpc", endpoint) surl.RawQuery = makeParams(params).Encode()
header := c.getHeader()
u := surl.String() conn, resp, err := c.Dialer.DialContext(ctx, u, header) if err != nil { return fmt.Errorf("%w: %w", ErrDialFailure, err) }
logger.Debug("event subscription response", "code", resp.StatusCode, "url", u)
return c.handleConn(ctx, conn, process)}
func (c *Client) LexSubscribeWithRedialer(ctx context.Context, endpoint string, params map[string]any, redialer Redialer) error { logger := cmp.Or(c.Logger, slog.Default().With("system", "events")) rurl, err := url.Parse(c.Host) if err != nil { return err } if rurl.Scheme == "http" { rurl.Scheme = "ws" } else { rurl.Scheme = "wss" } surl := rurl.JoinPath("/xrpc", endpoint)
header := c.getHeader()
var backoff int // returns false if the retry budget is exhausted sleepBackoff := func() bool { select { case <-ctx.Done(): case <-time.After(time.Duration(5+backoff) * time.Second): } backoff++ return backoff <= 15 }
for { select { case <-ctx.Done(): return ctx.Err() default: }
surl.RawQuery = makeParams(params).Encode()
u := surl.String() conn, resp, err := c.Dialer.DialContext(ctx, u, header) if err != nil { logger.Warn("dialing failed", "err", err, "backoff", backoff) if !sleepBackoff() { return fmt.Errorf("%w: %w", ErrDialFailure, err) } continue }
logger.Debug("event subscription response", "code", resp.StatusCode, "url", u)
connectedAt := time.Now() connErr := c.handleConn(ctx, conn, redialer.Process) if connErr != nil { logger.Warn("host connection failed", "err", connErr, "backoff", backoff) }
// updates cursor updated := redialer.UpdateParams(ctx, params)
// a connection that drops immediately shouldnt reset backoff // this to avoid reconnect storms if updated || time.Since(connectedAt) >= minHealthyConn { backoff = 0 continue } if !sleepBackoff() { return fmt.Errorf("%w: %w", ErrConnFailure, connErr) } }}
func (c *Client) handleConn(ctx context.Context, conn *websocket.Conn, process func(ctx context.Context, cr *cbg.CborReader) error) error { logger := cmp.Or(c.Logger, slog.Default().With("system", "events")) ctx, cancel := context.WithCancel(ctx) defer cancel()
go func() { t := time.NewTicker(time.Second * 30) defer t.Stop() failcount := 0
for {
select { case <-t.C: if err := conn.WriteControl(websocket.PingMessage, []byte{}, time.Now().Add(time.Second*10)); err != nil { logger.Warn("failed to ping", "err", err) failcount++ if failcount >= 4 { logger.Error("too many ping fails", "count", failcount) conn.Close() return } } else { failcount = 0 // ok ping } case <-ctx.Done(): conn.Close() return } } }()
conn.SetPingHandler(func(message string) error { err := conn.WriteControl(websocket.PongMessage, []byte(message), time.Now().Add(time.Second*60)) if err == websocket.ErrCloseSent { return nil } return err })
conn.SetPongHandler(func(_ string) error { if err := conn.SetReadDeadline(time.Now().Add(time.Minute)); err != nil { logger.Error("failed to set read deadline", "err", err) }
return nil })
cr := new(cbg.CborReader)
for { select { case <-ctx.Done(): return ctx.Err() default: }
mt, rawReader, err := conn.NextReader() if err != nil { return fmt.Errorf("conn err at read: %w", err) }
if mt != websocket.BinaryMessage { return fmt.Errorf("expected binary message from subscription endpoint") }
cr.SetReader(rawReader)
if err := process(ctx, cr); err != nil { return err } }}