89 lines
2.1 KiB
Go
89 lines
2.1 KiB
Go
// +build linux
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package libcontainer
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import (
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"fmt"
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"io/ioutil"
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"os"
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"path/filepath"
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"syscall"
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)
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const oomCgroupName = "memory"
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type PressureLevel uint
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const (
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LowPressure PressureLevel = iota
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MediumPressure
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CriticalPressure
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)
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func registerMemoryEvent(cgDir string, evName string, arg string) (<-chan struct{}, error) {
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evFile, err := os.Open(filepath.Join(cgDir, evName))
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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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evFile.Close()
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return nil, syserr
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}
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eventfd := os.NewFile(fd, "eventfd")
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eventControlPath := filepath.Join(cgDir, "cgroup.event_control")
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data := fmt.Sprintf("%d %d %s", eventfd.Fd(), evFile.Fd(), arg)
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if err := ioutil.WriteFile(eventControlPath, []byte(data), 0700); err != nil {
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eventfd.Close()
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evFile.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 func() {
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close(ch)
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eventfd.Close()
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evFile.Close()
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}()
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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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// notifyOnOOM returns channel on which you can expect event about OOM,
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// if process died without OOM this channel will be closed.
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func notifyOnOOM(paths map[string]string) (<-chan struct{}, error) {
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dir := paths[oomCgroupName]
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if dir == "" {
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return nil, fmt.Errorf("path %q missing", oomCgroupName)
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}
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return registerMemoryEvent(dir, "memory.oom_control", "")
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}
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func notifyMemoryPressure(paths map[string]string, level PressureLevel) (<-chan struct{}, error) {
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dir := paths[oomCgroupName]
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if dir == "" {
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return nil, fmt.Errorf("path %q missing", oomCgroupName)
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}
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if level > CriticalPressure {
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return nil, fmt.Errorf("invalid pressure level %d", level)
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}
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levelStr := []string{"low", "medium", "critical"}[level]
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return registerMemoryEvent(dir, "memory.pressure_level", levelStr)
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}
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