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// Copyright 2018 The containerd Authors.
// Copyright 2018 The gVisor 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
//
// https://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.
// +build linux
package shim
import (
"context"
"fmt"
"sync"
"github.com/containerd/cgroups"
"github.com/containerd/containerd/events"
"github.com/containerd/containerd/runtime"
"golang.org/x/sys/unix"
)
func newOOMEpoller(publisher events.Publisher) (*epoller, 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
}
type epoller struct {
mu sync.Mutex
fd int
publisher events.Publisher
set map[uintptr]*item
}
type item struct {
id string
cg cgroups.Cgroup
}
func (e *epoller) Close() error {
return unix.Close(e.fd)
}
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 || err == unix.EAGAIN {
continue
}
// Should not happen.
panic(fmt.Errorf("cgroups: epoll wait: %w", err))
}
for i := 0; i < n; i++ {
e.process(ctx, uintptr(events[i].Fd))
}
}
}
}
func (e *epoller) add(id string, cg cgroups.Cgroup) error {
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, &TaskOOM{
ContainerID: i.id,
}); err != nil {
// Should not happen.
panic(fmt.Errorf("publish OOM event: %w", err))
}
}
func flush(fd uintptr) error {
var buf [8]byte
_, err := unix.Read(int(fd), buf[:])
return err
}
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