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Separate inotify handling into its own object.
This makes it easier to ensure the error conditions are handled well and that we don't leak watches. Fixes #703
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,128 @@ | ||
| // Copyright 2015 Google Inc. All Rights Reserved. | ||
| // | ||
| // 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. | ||
|
|
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| package raw | ||
|
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| import ( | ||
| "sync" | ||
|
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| "golang.org/x/exp/inotify" | ||
| ) | ||
|
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| // Watcher for container-related inotify events in the cgroup hierarchy. | ||
| // | ||
| // Implementation is thread-safe. | ||
| type InotifyWatcher struct { | ||
| // Underlying inotify watcher. | ||
| watcher *inotify.Watcher | ||
|
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| // Containers being watched. | ||
| containersWatched map[string]bool | ||
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| // Full cgroup paths being watched. | ||
| cgroupsWatched map[string]bool | ||
|
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| // Lock for all datastructure access. | ||
| lock sync.Mutex | ||
| } | ||
|
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| func NewInotifyWatcher() (*InotifyWatcher, error) { | ||
| w, err := inotify.NewWatcher() | ||
| if err != nil { | ||
| return nil, err | ||
| } | ||
|
|
||
| return &InotifyWatcher{ | ||
| watcher: w, | ||
| containersWatched: make(map[string]bool), | ||
| cgroupsWatched: make(map[string]bool), | ||
| }, nil | ||
| } | ||
|
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| // Add a watch to the specified directory. Returns if the container was already being watched. | ||
| func (iw *InotifyWatcher) AddWatch(containerName, dir string) (bool, error) { | ||
| iw.lock.Lock() | ||
| defer iw.lock.Unlock() | ||
|
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| alreadyWatched := iw.containersWatched[containerName] | ||
|
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| // Register an inotify notification. | ||
| if !iw.cgroupsWatched[dir] { | ||
| err := iw.watcher.AddWatch(dir, inotify.IN_CREATE|inotify.IN_DELETE|inotify.IN_MOVE) | ||
| if err != nil { | ||
| return alreadyWatched, err | ||
| } | ||
| iw.cgroupsWatched[dir] = true | ||
| } | ||
|
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| // Record our watching of the container. | ||
| if !alreadyWatched { | ||
| iw.containersWatched[containerName] = true | ||
| } | ||
| return alreadyWatched, nil | ||
| } | ||
|
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| // Remove watch from the specified directory. Returns if the container was already being watched. | ||
| func (iw *InotifyWatcher) RemoveWatch(containerName, dir string) (bool, error) { | ||
| iw.lock.Lock() | ||
| defer iw.lock.Unlock() | ||
|
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| alreadyWatched := iw.containersWatched[containerName] | ||
|
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| // Remove the inotify watch if it exists. | ||
| if iw.cgroupsWatched[dir] { | ||
| err := iw.watcher.RemoveWatch(dir) | ||
| if err != nil { | ||
| return alreadyWatched, nil | ||
| } | ||
| delete(iw.cgroupsWatched, dir) | ||
| } | ||
|
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| // Record the container as no longer being watched. | ||
| if alreadyWatched { | ||
| delete(iw.containersWatched, containerName) | ||
| } | ||
|
|
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| return alreadyWatched, nil | ||
| } | ||
|
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| // Errors are returned on this channel. | ||
| func (iw *InotifyWatcher) Error() chan error { | ||
| return iw.watcher.Error | ||
| } | ||
|
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| // Events are returned on this channel. | ||
| func (iw *InotifyWatcher) Event() chan *inotify.Event { | ||
| return iw.watcher.Event | ||
| } | ||
|
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| // Closes the inotify watcher. | ||
| func (iw *InotifyWatcher) Close() error { | ||
| return iw.watcher.Close() | ||
| } | ||
|
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| // Returns a list of: | ||
| // - Containers being watched. | ||
| // - Cgroup paths being watched. | ||
| func (iw *InotifyWatcher) GetWatches() ([]string, []string) { | ||
| return mapToSlice(iw.containersWatched), mapToSlice(iw.cgroupsWatched) | ||
| } | ||
|
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| func mapToSlice(m map[string]bool) []string { | ||
| out := make([]string, 0, len(m)) | ||
| for k := range m { | ||
| out = append(out, k) | ||
| } | ||
| return out | ||
| } |