/// <summary>
/// Adds a File watcher under the specified integration name and directory.
/// Allows a callback to be registered for when any file Create/Delete/Rename/Modify occurs.
/// </summary>
/// <param name="integrationName">Name of the registration. Used later to remove the file watcher.</param>
/// <param name="directory">Directory to watch.</param>
/// <param name="actionCallback">Callback for when any Create/Delete/Rename/Modify event occurs (All data about the event is lost). Wont occur more than once every second</param>
public void AddFileWatcher(string integrationName, string directory, IntegrationFilesModifiedDelegate actionCallback)
{
// Create 2 entries.
// First one is to map an integration name to a directory. This makes it so we can deregister by integration name
// Second one is to store the actual file watcher data that we need to dispose of later.
this.FileWatcherCache.Set(integrationName, directory);
this.FileWatcherCache.GetOrCreate(directory, (entry) => this.CreateFileWatcherForIntegration(entry, integrationName, directory, actionCallback));
}
private FileWatcherData CreateFileWatcherForIntegration(ICacheEntry cacheEntry, string integrationName, string directory, IntegrationFilesModifiedDelegate callback)
{
var fileWatcher = new FileSystemWatcher(directory)
{
NotifyFilter = NotifyFilters.Attributes | NotifyFilters.FileName | NotifyFilters.LastWrite,
IncludeSubdirectories = false,
EnableRaisingEvents = true
};
// Add observables for each of the event types.
// Each of them just returns a boolean because we need a shared return type from the observable.
// We only care that *something* changed, we don't care what actually changed.
var changedFileObserable = Observable.FromEventPattern <FileSystemEventHandler, FileSystemEventArgs>(h => fileWatcher.Changed += h, h => fileWatcher.Changed -= h)
.Select(x => true);
var createdFileObserable = Observable.FromEventPattern <FileSystemEventHandler, FileSystemEventArgs>(h => fileWatcher.Created += h, h => fileWatcher.Created -= h)
.Select(x => true);
var deletedFileObserable = Observable.FromEventPattern <FileSystemEventHandler, FileSystemEventArgs>(h => fileWatcher.Deleted += h, h => fileWatcher.Deleted -= h)
.Select(x => true);
var renamedFileObserable = Observable.FromEventPattern <RenamedEventHandler, RenamedEventArgs>(h => fileWatcher.Renamed += h, h => fileWatcher.Renamed -= h)
.Select(x => true);
// Merge all the different file watcher events into 1 observable
// This allows us to throttle all the events coming through so we don't get more than 1 per second.
var fileWatcherSubscription = Observable.Merge(changedFileObserable, createdFileObserable, deletedFileObserable, renamedFileObserable)
.Throttle(TimeSpan.FromSeconds(1))
.Subscribe(_ => callback?.Invoke(directory, integrationName));
cacheEntry.RegisterPostEvictionCallback(this.OnCacheEntryEvicted);
this.ApplicationLifetime.ApplicationStopping.Register(() => this.RemoveFileWatcher(integrationName));
return(new FileWatcherData(fileWatcher, fileWatcherSubscription));
}
