use closeOnError pattern

internal/epoll/poller.go

@@ -27,37 +27,42 @@ type Poller struct {
 	flushEvent *eventFd
 }
 
-func New() (*Poller, error) {
+func New() (_ *Poller, err error) {
+	closeFDOnError := func(fd int) {
+		if err != nil {
+			unix.Close(fd)
+		}
+	}
+	closeEventFDOnError := func(e *eventFd) {
+		if err != nil {
+			e.close()
+		}
+	}
+
 	epollFd, err := unix.EpollCreate1(unix.EPOLL_CLOEXEC)
 	if err != nil {
 		return nil, fmt.Errorf("create epoll fd: %v", err)
 	}
+	defer closeFDOnError(epollFd)
 
 	p := &Poller{epollFd: epollFd}
 	p.closeEvent, err = newEventFd()
 	if err != nil {
-		unix.Close(epollFd)
 		return nil, err
 	}
+	defer closeEventFDOnError(p.closeEvent)
 
 	p.flushEvent, err = newEventFd()
 	if err != nil {
-		p.closeEvent.close()
-		unix.Close(epollFd)
 		return nil, err
 	}
+	defer closeEventFDOnError(p.flushEvent)
 
 	if err := p.Add(p.closeEvent.raw, 0); err != nil {
-		unix.Close(epollFd)
-		p.closeEvent.close()
-		p.flushEvent.close()
 		return nil, fmt.Errorf("add close eventfd: %w", err)
 	}
 
 	if err := p.Add(p.flushEvent.raw, 0); err != nil {
-		unix.Close(epollFd)
-		p.closeEvent.close()
-		p.flushEvent.close()
 		return nil, fmt.Errorf("add flush eventfd: %w", err)
 	}