private IMailFolder GetOrCreateLockFolder(IMailFolder parentFolderOfLockFolder, string resourceName, CancellationToken cancellationToken = default)
{
var lockFolderName = parentFolderOfLockFolder.MakeSafeFolderName(resourceName);
IMailFolder lockFolder = null;
try
{
lockFolder = parentFolderOfLockFolder.GetSubfolder(lockFolderName, cancellationToken);
}
catch
{
logger.Information("Could not get lock folder '{LockFolderName}' - maybe it does not yet exist or there was an error", lockFolderName);
}
if (lockFolder == null)
{
try
{
logger.Information("Creating new lock folder with name '{LockFolderName}'", lockFolderName);
// note: on some mail servers (Greenmail) this will throw if the folder already exists, other servers don't throw and return any existing foldre with this name (Dovecot)
lockFolder = parentFolderOfLockFolder.Create(lockFolderName, true);
}
catch
{
logger.Information("Error while creating lock folder '{LockFolderName}' - maybe it already exists or ther was an error", lockFolderName);
}
}
if (lockFolder == null)
{
throw new TeasmCompanionException($"Could not get or create lock folder '{lockFolderName}'");
}
lockFolder.Open(FolderAccess.ReadOnly);
var existingLockMessages = lockFolder.Search(SearchQuery.SubjectContains(LockMessageSubject), cancellationToken);
if (existingLockMessages.Count == 0)
{
// note: this might create duplicates if run by multiple clients; we'll remove the duplicates later
lockFolder.Append(CreateLockMimeMessage());
Thread.Sleep(1000); // give other parallel clients the chance to produce their duplicates if any; we then always choose the first one (selected by UniqueId)
}
return(lockFolder);
}