Function startKeepalive

mcp/shared.go:593–626

startKeepalive starts the keepalive mechanism for a session. It assigns the cancel function to the provided cancelPtr and starts a goroutine that sends ping messages at the specified interval. logger must be non-nil; ping failures (which terminate the keepalive loop and close the session) are repor

(session keepaliveSession, interval time.Duration, cancelPtr *context.CancelFunc, logger *slog.Logger)

// logger must be non-nil; ping failures (which terminate the keepalive loop and
// close the session) are reported via logger so they are not silently dropped.
func startKeepalive(session keepaliveSession, interval time.Duration, cancelPtr *context.CancelFunc, logger *slog.Logger) {
	ctx, cancel := context.WithCancel(context.Background())
	// Assign cancel function before starting goroutine to avoid race condition.
	// We cannot return it because the caller may need to cancel during the
	// window between goroutine scheduling and function return.
	*cancelPtr = cancel

	go func() {
		ticker := time.NewTicker(interval)
		defer ticker.Stop()

		for {
			select {
			case <-ctx.Done():
				return
			case <-ticker.C:
				pingCtx, pingCancel := context.WithTimeout(context.Background(), interval/2)
				err := session.Ping(pingCtx, nil)
				pingCancel()
				if err != nil {
					if errors.Is(err, jsonrpc2.ErrMethodNotFound) {
						// Peer doesn't support ping, stop the keepalive process.
						return
					}
					// Ping failed; log it before closing the session so the
					// failure is observable to operators. See #218.
					logger.Error("keepalive ping failed; closing session", "error", err)
					_ = session.Close()
					return
				}
			}
		}
	}()
}