/// <summary>
/// Creates or updates folder in the remote storage.
/// </summary>
/// <param name="remoteStoragePath">Path of the folder to be created or updated in the remote storage.</param>
/// <param name="newInfo">New information about the folder, such as modification date, attributes, custom data, etc.</param>
/// <param name="mode">Specifies if a new folder should be created or existing folder should be updated.</param>
/// <param name="lockInfo">Information about the lock. Caller passes null if the item is not locked.</param>
/// <returns>New ETag returned from the remote storage.</returns>
protected async Task <string> CreateOrUpdateFolderAsync(string remoteStoragePath, IFolderBasicInfo newInfo, FileMode mode, ServerLockInfo lockInfo = null)
{
// Get ETag and lock-token here and send it to the remote storage with the new item content/info if needed.
if (mode == FileMode.Open)
{
// Get ETag.
string eTag = await ETag.GetETagAsync(UserFileSystemPath);
// Get lock-token.
string lockToken = lockInfo?.LockToken;
}
DirectoryInfo remoteStorageItem = new DirectoryInfo(remoteStoragePath);
try
{
Program.RemoteStorageMonitorInstance.Enabled = false; // Disable RemoteStorageMonitor to avoid circular calls.
remoteStorageItem.Create();
string userFileSystemPath = Mapping.ReverseMapPath(remoteStoragePath);
if (mode == FileMode.Open)
{
// Verify that the item in the remote storage is not modified since it was downloaded to the user file system.
// In your real-life application you will send the ETag to the server as part of the update request.
FileSystemItemBasicInfo itemInfo = Mapping.GetUserFileSysteItemBasicInfo(remoteStorageItem);
if (!(await ETag.ETagEqualsAsync(userFileSystemPath, itemInfo)))
{
throw new ConflictException(Modified.Server, "Item is modified in the remote storage, ETags not equal.");
}
}
// Update ETag/LastWriteTime in user file system, so the synchronyzation or remote storage monitor would not start the new update.
// This is only required to avoid circular updates because of the simplicity of this sample.
// In your real-life application you will receive a new ETag from server in the update response.
string eTag = newInfo.LastWriteTime.DateTime.ToBinary().ToString();
await ETag.SetETagAsync(userFileSystemPath, eTag);
remoteStorageItem.Attributes = newInfo.Attributes;
remoteStorageItem.CreationTimeUtc = newInfo.CreationTime.DateTime;
remoteStorageItem.LastWriteTimeUtc = newInfo.LastWriteTime.DateTime;
remoteStorageItem.LastAccessTimeUtc = newInfo.LastAccessTime.DateTime;
remoteStorageItem.LastWriteTimeUtc = newInfo.LastWriteTime.DateTime;
return(eTag);
}
finally
{
Program.RemoteStorageMonitorInstance.Enabled = true;
}
}
/// <summary>
/// Returns true if the item was created and must be synched to remote storage.
/// </summary>
/// <returns>
/// True if the item was created in the user file system and does not exists
/// in the remote storage. False otherwise.
/// </returns>
public static bool IsNew(this PlaceholderItem placeholder)
{
// ETag absence signals that the item is new.
// However, ETag file may not exists during move operation,
// additionally checking OriginalPath presence.
// Can not rely on OriginalPath only,
// because MS Office files are being deleted and re-created during transactional save.
string originalPath = placeholder.GetOriginalPath();
bool eTagFileExists = File.Exists(ETag.GetETagFilePath(placeholder.Path));
return(!eTagFileExists && string.IsNullOrEmpty(originalPath));
}
/// <summary>
/// Returns true if the remote storage ETag and user file system ETags are equal. False - otherwise.
/// </summary>
/// <param name="userFileSystemPath">User file system item.</param>
/// <param name="remoteStorageItem">Remote storage item info.</param>
/// <remarks>
/// ETag is updated on the server during every document update and is sent to client with a file.
/// During client->server update it is sent back to the remote storage together with a modified content.
/// This ensures the changes on the server are not overwritten if the document on the server is modified.
/// </remarks>
internal static async Task <bool> ETagEqualsAsync(string userFileSystemPath, FileSystemItemBasicInfo remoteStorageItem)
{
string remoteStorageETag = remoteStorageItem.ETag;
// Intstead of the real ETag we store remote storage LastWriteTime when
// creating and updating files/folders.
string userFileSystemETag = await ETag.GetETagAsync(userFileSystemPath);
if (string.IsNullOrEmpty(userFileSystemETag))
{
// No ETag associated with the file. This is a new file created in user file system.
return(false);
}
return(remoteStorageETag == userFileSystemETag);
}
/// <inheritdoc/>
public async Task GetChildrenAsync(string pattern, IOperationContext operationContext, IFolderListingResultContext resultContext)
{
// This method has a 60 sec timeout.
// To process longer requests and reset the timout timer call one of the following:
// - resultContext.ReturnChildren() method.
// - resultContext.ReportProgress() method.
Logger.LogMessage($"IFolder.GetChildrenAsync({pattern})", UserFileSystemPath);
IEnumerable <FileSystemItemBasicInfo> children = await new UserFolder(UserFileSystemPath).EnumerateChildrenAsync(pattern);
// Filtering existing files/folders. This is only required to avoid extra errors in the log.
List <IFileSystemItemBasicInfo> newChildren = new List <IFileSystemItemBasicInfo>();
foreach (IFileSystemItemBasicInfo child in children)
{
string userFileSystemItemPath = Path.Combine(UserFileSystemPath, child.Name);
if (!FsPath.Exists(userFileSystemItemPath))
{
Logger.LogMessage("Creating", child.Name);
newChildren.Add(child);
}
}
// To signal that the children enumeration is completed
// always call ReturnChildren(), even if the folder is empty.
resultContext.ReturnChildren(newChildren.ToArray(), newChildren.Count());
// Save ETags and set "locked by another user" icon.
foreach (FileSystemItemBasicInfo child in children)
{
string userFileSystemItemPath = Path.Combine(UserFileSystemPath, child.Name);
// Create ETags.
// ETags must correspond with a server file/folder, NOT with a client placeholder.
// It should NOT be moved/deleted/updated when a placeholder in the user file system is moved/deleted/updated.
// It should be moved/deleted when a file/folder in the remote storage is moved/deleted.
ETag.SetETagAsync(userFileSystemItemPath, child.ETag);
// Set the lock icon and read-only attribute, to indicate that the item is locked by another user.
new UserFileSystemRawItem(userFileSystemItemPath).SetLockedByAnotherUserAsync(child.LockedByAnotherUser);
}
}
/// <summary>
/// Creates or updates file in the remote storage.
/// </summary>
/// <param name="remoteStoragePath">Path of the file to be created or updated in the remote storage.</param>
/// <param name="newInfo">New information about the file, such as modification date, attributes, custom data, etc.</param>
/// <param name="mode">Specifies if a new file should be created or existing file should be updated.</param>
/// <param name="newContentStream">New file content or null if the file content is not modified.</param>
/// <returns>New ETag returned from the remote storage.</returns>
protected async Task <string> CreateOrUpdateFileAsync(string remoteStoragePath, IFileBasicInfo newInfo, FileMode mode, Stream newContentStream = null)
{
// Get ETag and lock-token here and send it to the remote storage with the new item content/info if needed.
if (mode == FileMode.Open)
{
// Get ETag.
string eTag = await ETag.GetETagAsync(UserFileSystemPath);
// Get lock-token.
string lockToken = Lock?.LockToken;
}
FileInfo remoteStorageItem = new FileInfo(remoteStoragePath);
try
{
Program.RemoteStorageMonitorInstance.Enabled = false; // Disable RemoteStorageMonitor to avoid circular calls.
// If another thread is trying to sync the same file, this call will fail in other threads.
// In your implementation you must lock your remote storage file, or block it for reading and writing by other means.
await using (FileStream remoteStorageStream = remoteStorageItem.Open(mode, FileAccess.Write, FileShare.None))
{
string userFileSystemPath = Mapping.ReverseMapPath(remoteStoragePath);
if (mode == FileMode.Open)
{
// Verify that the item in the remote storage is not modified since it was downloaded to the user file system.
// In your real-life application you will send the ETag to the server as part of the update request.
FileSystemItemBasicInfo itemInfo = Mapping.GetUserFileSysteItemBasicInfo(remoteStorageItem);
if (!(await ETag.ETagEqualsAsync(userFileSystemPath, itemInfo)))
{
throw new ConflictException(Modified.Server, "Item is modified in the remote storage, ETags not equal.");
}
}
// Update ETag/LastWriteTime in user file system, so the synchronyzation or remote storage monitor would not start the new update.
// This is only required to avoid circular updates because of the simplicity of this sample.
// In your real-life application you will receive a new ETag from the server in the update response
// and return it from this method.
string eTag = newInfo.LastWriteTime.ToBinary().ToString();
await ETag.SetETagAsync(userFileSystemPath, eTag);
// Update remote storage file content.
if (newContentStream != null)
{
await newContentStream.CopyToAsync(remoteStorageStream);
remoteStorageStream.SetLength(newContentStream.Length);
}
// Update remote storage file basic info.
WindowsFileSystemItem.SetFileInformation(
remoteStorageStream.SafeFileHandle,
newInfo.Attributes,
newInfo.CreationTime,
newInfo.LastWriteTime,
newInfo.LastAccessTime,
newInfo.LastWriteTime);
return(eTag);
}
}
finally
{
Program.RemoteStorageMonitorInstance.Enabled = true;
}
}