/// <summary>
/// Inits the guard with the action to be performed once
/// disposal takes place.
/// </summary>
/// <param name="item">Encapsulates the locking information.</param>
/// <param name="repository">The repository that issued the lock.</param>
/// <exception cref="ArgumentNullException">If any of the parameters
/// is a null reference.</exception>
public ResourceLockGuard(LockItem item, IResourceLockRepository repository)
{
Ensure.ArgumentNotNull(item, "item");
Ensure.ArgumentNotNull(repository, "repository");
Item = item;
Repository = repository;
}
/// <summary>
/// Inits the guard with the action to be performed once
/// disposal takes place.
/// </summary>
/// <param name="item">Encapsulates the locking information.</param>
/// <param name="repository">The repository that issued the lock.</param>
/// <exception cref="ArgumentNullException">If any of the parameters
/// is a null reference.</exception>
public ResourceLockGuard(LockItem item, IResourceLockRepository repository)
{
Ensure.ArgumentNotNull(item, "item");
Ensure.ArgumentNotNull(repository, "repository");
Item = item;
Repository = repository;
}
/// <summary>
/// Gets a read lock on all parent folders of a given resource, and rolls back the resources
/// if the locking fails.
/// </summary>
/// <param name="repository">The repository that manages locked resources.</param>
/// <param name="resourceId">The resource to be locked.</param>
/// <param name="isWriteLock">Whether to acquire a read or write lock for the resource itself.</param>
/// <param name="parentFolderIds">Ids of the resource's parent folders, which are being locked one
/// by one. The list should be ordered, with the first item being the immediate parent of the locked
/// resource, and the last one the topmost folder to be locked.</param>
/// <returns>A guard which releases the resource and all folders once it is being disposed.</returns>
public static ResourceLockGuard GetResourceChainLock(this IResourceLockRepository repository, string resourceId,
bool isWriteLock, List <string> parentFolderIds)
{
LockItem lockItem = isWriteLock ? repository.TryGetWriteLock(resourceId) : repository.TryGetReadLock(resourceId);
//we couldn't get a lock on the resource itself
if (!lockItem.IsEnabled)
{
return(new ResourceLockGuard(lockItem, repository));
}
//get read locks for all parent folders
List <LockItem> folderLocks = new List <LockItem>();
LockItem folderLock = null;
foreach (string folderId in parentFolderIds)
{
//lock parent folders, one by one for read access (prevents deletion)
folderLock = repository.TryGetReadLock(folderId);
if (!folderLock.IsEnabled)
{
break;
}
folderLocks.Add(folderLock);
}
if (folderLock != null && !folderLock.IsEnabled)
{
//roll back all locks...
repository.ReleaseLock(lockItem);
folderLocks.ForEach(li => repository.ReleaseLock(li));
//...and return a dummy lock
return(new ResourceLockGuard(LockItem.CreateDenied(resourceId), repository));
}
return(new ResourceLockGuard(lockItem, repository)
{
SecondaryLocks = folderLocks
});
}
