fermentord/vendor/github.com/warthog618/go-gpiocdev/infowatcher.go

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// SPDX-FileCopyrightText: 2020 Kent Gibson <warthog618@gmail.com>
//
// SPDX-License-Identifier: MIT
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package gpiocdev
import (
"fmt"
"time"
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"github.com/warthog618/go-gpiocdev/uapi"
"golang.org/x/sys/unix"
)
type infoWatcher struct {
epfd int
// eventfd to signal watcher to shutdown
donefd int
// the handler for detected events
ch InfoChangeHandler
// closed once watcher exits
doneCh chan struct{}
abi int
}
func newInfoWatcher(fd int, ch InfoChangeHandler, abi int) (iw *infoWatcher, err error) {
var epfd, donefd int
epfd, err = unix.EpollCreate1(unix.EPOLL_CLOEXEC)
if err != nil {
return
}
defer func() {
if err != nil {
unix.Close(epfd)
}
}()
donefd, err = unix.Eventfd(0, unix.EFD_CLOEXEC)
if err != nil {
return
}
defer func() {
if err != nil {
unix.Close(donefd)
}
}()
epv := unix.EpollEvent{Events: unix.EPOLLIN, Fd: int32(donefd)}
err = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, int(donefd), &epv)
if err != nil {
return
}
epv.Fd = int32(fd)
err = unix.EpollCtl(epfd, unix.EPOLL_CTL_ADD, fd, &epv)
if err != nil {
return
}
iw = &infoWatcher{
epfd: epfd,
donefd: donefd,
ch: ch,
doneCh: make(chan struct{}),
abi: abi,
}
go iw.watch()
return
}
func (iw *infoWatcher) close() {
unix.Write(iw.donefd, []byte{1, 0, 0, 0, 0, 0, 0, 0})
<-iw.doneCh
unix.Close(iw.donefd)
}
func (iw *infoWatcher) watch() {
epollEvents := make([]unix.EpollEvent, 2)
defer close(iw.doneCh)
for {
n, err := unix.EpollWait(iw.epfd, epollEvents[:], -1)
if err != nil {
if err == unix.EBADF || err == unix.EINVAL {
// fd closed so exit
return
}
if err == unix.EINTR {
continue
}
panic(fmt.Sprintf("EpollWait unexpected error: %v", err))
}
for i := 0; i < n; i++ {
ev := epollEvents[i]
fd := ev.Fd
if fd == int32(iw.donefd) {
unix.Close(iw.epfd)
return
}
if iw.abi == 1 {
iw.readInfoChanged(fd)
} else {
iw.readInfoChangedV2(fd)
}
}
}
}
func (iw *infoWatcher) readInfoChanged(fd int32) {
lic, err := uapi.ReadLineInfoChanged(uintptr(fd))
if err != nil {
fmt.Printf("error reading line change:%s\n", err)
return
}
lice := LineInfoChangeEvent{
Info: newLineInfo(lic.Info),
Timestamp: time.Duration(lic.Timestamp),
Type: LineInfoChangeType(lic.Type),
}
iw.ch(lice)
}
func (iw *infoWatcher) readInfoChangedV2(fd int32) {
lic, err := uapi.ReadLineInfoChangedV2(uintptr(fd))
if err != nil {
fmt.Printf("error reading line change:%s\n", err)
return
}
lice := LineInfoChangeEvent{
Info: newLineInfoV2(lic.Info),
Timestamp: time.Duration(lic.Timestamp),
Type: LineInfoChangeType(lic.Type),
}
iw.ch(lice)
}