121 lines
2.7 KiB
Go
121 lines
2.7 KiB
Go
package monitor
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import (
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"io"
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"sync"
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"syscall"
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"github.com/Sirupsen/logrus"
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"github.com/docker/containerkit/epoll"
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)
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type Monitorable interface {
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FD() int
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// Remove returns true if the monitorable should be removed
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// from the event monitor under the lock of when the event was received
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Remove() bool
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}
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type Flusher interface {
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Flush() error
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}
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// New returns a new process monitor that emits events whenever the
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// state of the fd refering to a process changes
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func New() (*Monitor, error) {
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fd, err := epoll.EpollCreate1(0)
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if err != nil {
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return nil, err
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}
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return &Monitor{
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epollFd: fd,
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receivers: make(map[int]Monitorable),
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events: make(chan Monitorable, 1024),
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}, nil
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}
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type Monitor struct {
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m sync.Mutex
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receivers map[int]Monitorable
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events chan Monitorable
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epollFd int
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}
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// Events returns a chan that receives a Monitorable when it's FD changes state
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func (m *Monitor) Events() chan Monitorable {
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return m.events
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}
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// Add adds a process to the list of the one being monitored
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func (m *Monitor) Add(ma Monitorable) error {
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m.m.Lock()
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defer m.m.Unlock()
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fd := ma.FD()
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event := syscall.EpollEvent{
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Fd: int32(fd),
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Events: syscall.EPOLLHUP,
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}
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if err := epoll.EpollCtl(m.epollFd, syscall.EPOLL_CTL_ADD, fd, &event); err != nil {
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return err
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}
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m.receivers[fd] = ma
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return nil
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}
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// Remove deletes the Monitorable type from the monitor so that
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// no other events are generated
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func (m *Monitor) Remove(ma Monitorable) error {
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m.m.Lock()
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defer m.m.Unlock()
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return m.remove(ma)
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}
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func (m *Monitor) remove(ma Monitorable) error {
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fd := ma.FD()
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delete(m.receivers, fd)
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return syscall.EpollCtl(m.epollFd, syscall.EPOLL_CTL_DEL, fd, &syscall.EpollEvent{
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Events: syscall.EPOLLHUP,
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Fd: int32(fd),
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})
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}
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// Close cleans up resources allocated to the Monitor
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func (m *Monitor) Close() error {
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return syscall.Close(m.epollFd)
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}
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func (m *Monitor) Run() {
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var events [128]syscall.EpollEvent
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for {
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n, err := epoll.EpollWait(m.epollFd, events[:], -1)
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if err != nil {
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if err == syscall.EINTR {
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continue
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}
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logrus.WithField("error", err).Fatal("shim: epoll wait")
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}
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for i := 0; i < n; i++ {
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fd := int(events[i].Fd)
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m.m.Lock()
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r := m.receivers[fd]
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if f, ok := r.(Flusher); ok {
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if err := f.Flush(); err != nil {
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logrus.WithField("error", err).Fatal("shim: flush event FD")
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}
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}
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if r.Remove() {
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if err := m.remove(r); err != nil {
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logrus.WithField("error", err).Fatal("shim: remove event FD")
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}
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}
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if f, ok := r.(io.Closer); ok {
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if err := f.Close(); err != nil {
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logrus.WithField("error", err).Fatal("shim: close event FD")
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}
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}
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m.m.Unlock()
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m.events <- r
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}
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}
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}
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