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Process plugins found before the ones watched

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Currently, the method `pluginwatcher.traversePluginDir` descends into
a directory adding filesystem watchers and creating synthetic `create`
events when it finds sockets files. However, a race condition might
happen when a recently-added watcher observes a `delete` event in a
socket file before `pluginwatcher.traversePlugindir` itself notices
this file.

This patch changes this behavior by registering watchers on
directories, enqueueing and processing `create` events from sockets
found, and only then processing the events from the registered watchers.
This commit is contained in:
Fabio Bertinatto
2019-03-11 13:05:07 +01:00
parent 90fbbee129
commit 817c9ca953
3 changed files with 43 additions and 29 deletions
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45
pkg/kubelet/util/pluginwatcher/plugin_watcher.go
View File

@@ -102,9 +102,24 @@ func (w *Watcher) Start() error {
}
w.fsWatcher = fsWatcher
// Traverse plugin dir and add filesystem watchers before starting the plugin processing goroutine.
if err := w.traversePluginDir(w.path); err != nil {
w.Stop()
return fmt.Errorf("failed to traverse plugin socket path %q, err: %v", w.path, err)
}
// Traverse deprecated plugin dir, if specified.
if len(w.deprecatedPath) != 0 {
if err := w.traversePluginDir(w.deprecatedPath); err != nil {
w.Stop()
return fmt.Errorf("failed to traverse deprecated plugin socket path %q, err: %v", w.deprecatedPath, err)
}
}
w.wg.Add(1)
go func(fsWatcher *fsnotify.Watcher) {
defer w.wg.Done()
for {
select {
case event := <-fsWatcher.Events:
@@ -139,20 +154,6 @@ func (w *Watcher) Start() error {
}
}(fsWatcher)
// Traverse plugin dir after starting the plugin processing goroutine
if err := w.traversePluginDir(w.path); err != nil {
w.Stop()
return fmt.Errorf("failed to traverse plugin socket path %q, err: %v", w.path, err)
}
// Traverse deprecated plugin dir, if specified.
if len(w.deprecatedPath) != 0 {
if err := w.traversePluginDir(w.deprecatedPath); err != nil {
w.Stop()
return fmt.Errorf("failed to traverse deprecated plugin socket path %q, err: %v", w.deprecatedPath, err)
}
}
return nil
}
@@ -211,14 +212,14 @@ func (w *Watcher) traversePluginDir(dir string) error {
return fmt.Errorf("failed to watch %s, err: %v", path, err)
}
case mode&os.ModeSocket != 0:
w.wg.Add(1)
go func() {
defer w.wg.Done()
w.fsWatcher.Events <- fsnotify.Event{
Name: path,
Op: fsnotify.Create,
}
}()
event := fsnotify.Event{
Name: path,
Op: fsnotify.Create,
}
//TODO: Handle errors by taking corrective measures
if err := w.handleCreateEvent(event); err != nil {
klog.Errorf("error %v when handling create event: %s", err, event)
}
default:
klog.V(5).Infof("Ignoring file %s with mode %v", path, mode)
}