82 lines
1.5 KiB
Go
82 lines
1.5 KiB
Go
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// +build linux
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package fs
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import (
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"fmt"
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"os"
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"path/filepath"
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"syscall"
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"github.com/docker/libcontainer/cgroups"
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)
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// NotifyOnOOM sends signals on the returned channel when the cgroup reaches
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// its memory limit. The channel is closed when the cgroup is removed.
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func NotifyOnOOM(c *cgroups.Cgroup) (chan struct{}, error) {
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d, err := getCgroupData(c, 0)
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if err != nil {
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return nil, err
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}
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return notifyOnOOM(d)
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}
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func notifyOnOOM(d *data) (chan struct{}, error) {
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dir, err := d.path("memory")
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if err != nil {
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return nil, err
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}
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fd, _, syserr := syscall.RawSyscall(syscall.SYS_EVENTFD2, 0, syscall.FD_CLOEXEC, 0)
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if syserr != 0 {
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return nil, syserr
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}
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eventfd := os.NewFile(fd, "eventfd")
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oomControl, err := os.Open(filepath.Join(dir, "memory.oom_control"))
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if err != nil {
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eventfd.Close()
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return nil, err
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}
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var (
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eventControlPath = filepath.Join(dir, "cgroup.event_control")
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data = fmt.Sprintf("%d %d", eventfd.Fd(), oomControl.Fd())
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)
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if err := writeFile(dir, "cgroup.event_control", data); err != nil {
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eventfd.Close()
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oomControl.Close()
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return nil, err
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}
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ch := make(chan struct{})
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go func() {
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defer close(ch)
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defer eventfd.Close()
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defer oomControl.Close()
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var buf = make([]byte, 8)
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for {
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if _, err := eventfd.Read(buf); err != nil {
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return
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}
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// When a cgroup is destroyed, an event is sent to eventfd.
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// So if the control path is gone, return instead of notifying.
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if _, err := os.Lstat(eventControlPath); os.IsNotExist(err) {
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return
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}
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ch <- struct{}{}
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}
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}()
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return ch, nil
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}
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