/// <summary>
/// Executes a single change on the file system and updates the cache.
/// Does not commit or persist in any other way.
/// </summary>
/// <param name="change">The change to execute on the file system.</param>
private void Execute(AbstractChange change)
{
// Execute changes
DisableFileSystemEvents();
change.ExecuteChanges(FileSystemAdaptee);
EnableFileSystemEvents();
// Update cache
if (change is FileModifiedChange)
{
var mod = (FileModifiedChange)change;
_cache.Update(mod.AssociatedPath);
}
else if (change is ItemsCreatedChange)
{
var created = (ItemsCreatedChange)change;
foreach (var creation in created.Items)
{
_cache.Update(creation.GetAssociatedPath());
}
}
else if (change is ItemsDeletedChange)
{
var deleted = (ItemsDeletedChange)change;
foreach (var deletion in deleted.Items)
{
_cache.Delete(deletion);
}
}
}
/// <summary>
/// Attempts to version the given change in this file- and version control system. If a
/// conflict occurs we return it to be handled by the caller.
/// </summary>
/// <param name="change">The change to persist.</param>
/// <returns>A conflict if the merge failed, null otherwise.</returns>
public Conflict? Save(AbstractChange change)
{
try
{
// Execute the change on the file system
Execute(change);
// Commit the change
var version = new List<AbstractChange> { change };
PersistVersion(version);
// Push to server
var conflicts = PushToServer();
if (conflicts.Count > 1) throw new InvalidOperationException("Too many conflicts. Aborting.");
else if (conflicts.Count == 1) return conflicts[0];
else return null;
}
catch (Exception)
{
// If we hit an exception when pushing to server we simply ignore it
// and avoid incrementing the version - the changes will be pushed once
// the server is back on track
return null;
}
}