36a6e68169
This makes it easier to ensure the error conditions are handled well and that we don't leak watches. Fixes #703
129 lines
3.2 KiB
Go
129 lines
3.2 KiB
Go
// Copyright 2015 Google Inc. All Rights Reserved.
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//
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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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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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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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package raw
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import (
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"sync"
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"golang.org/x/exp/inotify"
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)
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// Watcher for container-related inotify events in the cgroup hierarchy.
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//
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// Implementation is thread-safe.
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type InotifyWatcher struct {
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// Underlying inotify watcher.
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watcher *inotify.Watcher
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// Containers being watched.
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containersWatched map[string]bool
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// Full cgroup paths being watched.
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cgroupsWatched map[string]bool
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// Lock for all datastructure access.
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lock sync.Mutex
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}
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func NewInotifyWatcher() (*InotifyWatcher, error) {
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w, err := inotify.NewWatcher()
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if err != nil {
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return nil, err
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}
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return &InotifyWatcher{
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watcher: w,
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containersWatched: make(map[string]bool),
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cgroupsWatched: make(map[string]bool),
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}, nil
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}
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// Add a watch to the specified directory. Returns if the container was already being watched.
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func (iw *InotifyWatcher) AddWatch(containerName, dir string) (bool, error) {
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iw.lock.Lock()
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defer iw.lock.Unlock()
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alreadyWatched := iw.containersWatched[containerName]
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// Register an inotify notification.
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if !iw.cgroupsWatched[dir] {
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err := iw.watcher.AddWatch(dir, inotify.IN_CREATE|inotify.IN_DELETE|inotify.IN_MOVE)
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if err != nil {
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return alreadyWatched, err
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}
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iw.cgroupsWatched[dir] = true
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}
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// Record our watching of the container.
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if !alreadyWatched {
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iw.containersWatched[containerName] = true
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}
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return alreadyWatched, nil
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}
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// Remove watch from the specified directory. Returns if the container was already being watched.
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func (iw *InotifyWatcher) RemoveWatch(containerName, dir string) (bool, error) {
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iw.lock.Lock()
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defer iw.lock.Unlock()
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alreadyWatched := iw.containersWatched[containerName]
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// Remove the inotify watch if it exists.
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if iw.cgroupsWatched[dir] {
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err := iw.watcher.RemoveWatch(dir)
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if err != nil {
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return alreadyWatched, nil
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}
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delete(iw.cgroupsWatched, dir)
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}
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// Record the container as no longer being watched.
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if alreadyWatched {
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delete(iw.containersWatched, containerName)
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}
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return alreadyWatched, nil
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}
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// Errors are returned on this channel.
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func (iw *InotifyWatcher) Error() chan error {
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return iw.watcher.Error
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}
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// Events are returned on this channel.
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func (iw *InotifyWatcher) Event() chan *inotify.Event {
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return iw.watcher.Event
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}
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// Closes the inotify watcher.
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func (iw *InotifyWatcher) Close() error {
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return iw.watcher.Close()
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}
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// Returns a list of:
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// - Containers being watched.
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// - Cgroup paths being watched.
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func (iw *InotifyWatcher) GetWatches() ([]string, []string) {
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return mapToSlice(iw.containersWatched), mapToSlice(iw.cgroupsWatched)
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}
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func mapToSlice(m map[string]bool) []string {
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out := make([]string, 0, len(m))
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for k := range m {
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out = append(out, k)
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}
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return out
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}
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