Synchronization

TagBites.IO offers two ways to keep two directories in sync: a one-time transfer, and a continuously running synchronizer.

One-time synchronization

SyncWith compares and transfers the difference between a source and a destination directory once:

var directory1 = FileSystem.Local.GetDirectory("directory1");
var directory2 = FileSystem.Local.GetDirectory("directory2");
directory1.SyncWith(directory2, FileSystemSynchronizeMode.OneWay);

Available modes (FileSystemSynchronizeMode):

Mode	Description
OneWay	Copies new/changed files from source to destination. Files removed from source are left untouched in destination.
OneWayWithRemoveNotExisting	Same as OneWay, but also removes files/directories from destination that no longer exist in source.
BothWaysUsingLastWriteTime	Propagates changes in both directions, using the last write time to resolve which side is newer.

An overload also accepts ignoredPaths to exclude specific paths from the comparison.

Continuous synchronization

FileSystemLinkSynchronizer keeps one or more source/destination pairs in sync for as long as it is enabled, re-syncing whenever a change is detected:

var synchronizer = new FileSystemLinkSynchronizer();
synchronizer.Add(FileSystem.Local.GetDirectory("C:/Photos"), ftpFileSystem.GetDirectory("photos"), FileSystemSynchronizeMode.BothWaysUsingLastWriteTime);
synchronizer.Enabled = true;

// ... later
synchronizer.Remove(FileSystem.Local.GetDirectory("C:/Photos"), ftpFileSystem.GetDirectory("photos"));
synchronizer.Dispose();

• Add/Remove register or unregister a source/destination pair with a synchronization mode. Pairs can be added before or after Enabled is set.
• Enabled starts or stops watching and syncing all registered pairs. Enabling performs an initial synchronization pass for every pair.
• Synchronized is true/false once enabled, or null while disabled.
• WaitForSync() (with optional timeout) blocks until the current synchronization pass completes.
• ForceSyncAsync() triggers an extra synchronization pass immediately, without waiting for a change notification.

Caveat: the synchronizer detects changes using the same watchers described above. For FileSystem.Local and the virtual file system this means real, OS-level change detection. For every other provider (FTP, SFTP, HTTP, ZIP, Dropbox, Google Cloud Storage, S3) it only reacts to changes made through the same FileSystem instances registered with the synchronizer - it will not notice a file someone else uploads directly to the remote server. In that case, call ForceSyncAsync() periodically (e.g. on a timer) instead of relying on change detection alone.