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v1.go
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v1.go
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// +build linux
/*
Copyright The containerd Authors.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package v1
import (
"context"
"sync"
"github.com/containerd/cgroups"
eventstypes "github.com/containerd/containerd/api/events"
"github.com/containerd/containerd/pkg/oom"
"github.com/containerd/containerd/runtime"
"github.com/containerd/containerd/runtime/v2/shim"
"github.com/pkg/errors"
"github.com/sirupsen/logrus"
"golang.org/x/sys/unix"
)
// New returns an epoll implementation that listens to OOM events
// from a container's cgroups.
func New(publisher shim.Publisher) (oom.Watcher, error) {
fd, err := unix.EpollCreate1(unix.EPOLL_CLOEXEC)
if err != nil {
return nil, err
}
return &epoller{
fd: fd,
publisher: publisher,
set: make(map[uintptr]*item),
}, nil
}
// epoller implementation for handling OOM events from a container's cgroup
type epoller struct {
mu sync.Mutex
fd int
publisher shim.Publisher
set map[uintptr]*item
}
type item struct {
id string
cg cgroups.Cgroup
}
// Close the epoll fd
func (e *epoller) Close() error {
return unix.Close(e.fd)
}
// Run the epoll loop
func (e *epoller) Run(ctx context.Context) {
var events [128]unix.EpollEvent
for {
select {
case <-ctx.Done():
e.Close()
return
default:
n, err := unix.EpollWait(e.fd, events[:], -1)
if err != nil {
if err == unix.EINTR {
continue
}
logrus.WithError(err).Error("cgroups: epoll wait")
}
for i := 0; i < n; i++ {
e.process(ctx, uintptr(events[i].Fd))
}
}
}
}
// Add cgroups.Cgroup to the epoll monitor
func (e *epoller) Add(id string, cgx interface{}) error {
cg, ok := cgx.(cgroups.Cgroup)
if !ok {
return errors.Errorf("expected cgroups.Cgroup, got: %T", cgx)
}
e.mu.Lock()
defer e.mu.Unlock()
fd, err := cg.OOMEventFD()
if err != nil {
return err
}
e.set[fd] = &item{
id: id,
cg: cg,
}
event := unix.EpollEvent{
Fd: int32(fd),
Events: unix.EPOLLHUP | unix.EPOLLIN | unix.EPOLLERR,
}
return unix.EpollCtl(e.fd, unix.EPOLL_CTL_ADD, int(fd), &event)
}
func (e *epoller) process(ctx context.Context, fd uintptr) {
flush(fd)
e.mu.Lock()
i, ok := e.set[fd]
if !ok {
e.mu.Unlock()
return
}
e.mu.Unlock()
if i.cg.State() == cgroups.Deleted {
e.mu.Lock()
delete(e.set, fd)
e.mu.Unlock()
unix.Close(int(fd))
return
}
if err := e.publisher.Publish(ctx, runtime.TaskOOMEventTopic, &eventstypes.TaskOOM{
ContainerID: i.id,
}); err != nil {
logrus.WithError(err).Error("publish OOM event")
}
}
func flush(fd uintptr) error {
var buf [8]byte
_, err := unix.Read(int(fd), buf[:])
return err
}