110 lines
2.6 KiB
Go
110 lines
2.6 KiB
Go
// +build !windows
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/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package shim
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import (
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"os/exec"
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"sync"
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"time"
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"github.com/containerd/containerd/sys"
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runc "github.com/containerd/go-runc"
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"github.com/pkg/errors"
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)
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// ErrNoSuchProcess is returned when the process no longer exists
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var ErrNoSuchProcess = errors.New("no such process")
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const bufferSize = 2048
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// Reap should be called when the process receives an SIGCHLD. Reap will reap
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// all exited processes and close their wait channels
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func Reap() error {
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now := time.Now()
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exits, err := sys.Reap(false)
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Default.Lock()
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for c := range Default.subscribers {
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for _, e := range exits {
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c <- runc.Exit{
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Timestamp: now,
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Pid: e.Pid,
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Status: e.Status,
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}
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}
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}
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Default.Unlock()
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return err
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}
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// Default is the default monitor initialized for the package
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var Default = &Monitor{
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subscribers: make(map[chan runc.Exit]struct{}),
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}
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// Monitor monitors the underlying system for process status changes
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type Monitor struct {
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sync.Mutex
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subscribers map[chan runc.Exit]struct{}
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}
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// Start starts the command a registers the process with the reaper
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func (m *Monitor) Start(c *exec.Cmd) (chan runc.Exit, error) {
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ec := m.Subscribe()
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if err := c.Start(); err != nil {
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m.Unsubscribe(ec)
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return nil, err
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}
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return ec, nil
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}
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// Wait blocks until a process is signal as dead.
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// User should rely on the value of the exit status to determine if the
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// command was successful or not.
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func (m *Monitor) Wait(c *exec.Cmd, ec chan runc.Exit) (int, error) {
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for e := range ec {
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if e.Pid == c.Process.Pid {
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// make sure we flush all IO
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c.Wait()
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m.Unsubscribe(ec)
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return e.Status, nil
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}
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}
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// return no such process if the ec channel is closed and no more exit
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// events will be sent
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return -1, ErrNoSuchProcess
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}
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// Subscribe to process exit changes
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func (m *Monitor) Subscribe() chan runc.Exit {
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c := make(chan runc.Exit, bufferSize)
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m.Lock()
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m.subscribers[c] = struct{}{}
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m.Unlock()
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return c
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}
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// Unsubscribe to process exit changes
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func (m *Monitor) Unsubscribe(c chan runc.Exit) {
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m.Lock()
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delete(m.subscribers, c)
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close(c)
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m.Unlock()
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}
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