/// <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>
/// <param name="eTagOld">The ETag to be sent to the remote storage as part of the update request to make sure the content is not overwritten.</param>
/// <param name="lockInfo">Information about the lock. Null if the item is not locked.</param>
/// <returns>The new ETag returned from the remote storage.</returns>
protected async Task <string> CreateOrUpdateFileAsync(
string remoteStoragePath, IFileMetadata newInfo, FileMode mode, Stream newContentStream = null, string eTagOld = null, ServerLockInfo lockInfo = null)
{
FileInfo remoteStorageItem = new FileInfo(remoteStoragePath);
try
{
Program.VirtualDrive.RemoteStorageMonitor.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.
FileSystemItemMetadataExt itemInfo = Mapping.GetUserFileSysteItemMetadata(remoteStorageItem);
if (!(await VirtualDrive.GetETagManager(userFileSystemPath).ETagEqualsAsync(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 eTagNew = newInfo.LastWriteTime.ToUniversalTime().ToString("o");
await VirtualDrive.GetETagManager(userFileSystemPath).SetETagAsync(eTagNew);
// 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(eTagNew);
}
}
finally
{
Program.VirtualDrive.RemoteStorageMonitor.Enabled = true;
}
}
/// <summary>
/// Called when a file content changed or file/folder attributes changed in the remote storage.
/// </summary>
/// <remarks>
/// In this method we update corresponding file/folder information in user file system.
/// We also dehydrate the file if it is not blocked.
/// </remarks>
private async void ChangedAsync(object sender, FileSystemEventArgs e)
{
LogMessage(e.ChangeType.ToString(), e.FullPath);
string remoteStoragePath = e.FullPath;
try
{
// We do not want to sync MS Office temp files, etc. from remote storage.
if (!FsPath.AvoidSync(remoteStoragePath))
{
string userFileSystemPath = Mapping.ReverseMapPath(remoteStoragePath);
// Because of the on-demand population the file or folder placeholder may not exist in the user file system.
if (FsPath.Exists(userFileSystemPath))
{
FileSystemInfo remoteStorageItem = FsPath.GetFileSystemItem(remoteStoragePath);
// This check is only required because we can not prevent circular calls because of the simplicity of this example.
// In your real-life application you will not sent updates from server back to client that issued the update.
FileSystemItemMetadataExt itemInfo = Mapping.GetUserFileSysteItemMetadata(remoteStorageItem);
if (!await virtualDrive.GetETagManager(userFileSystemPath, this).ETagEqualsAsync(itemInfo))
{
await virtualDrive.ServerNotifications(userFileSystemPath, this).UpdateAsync(itemInfo);
LogMessage("Updated succesefully", userFileSystemPath);
}
}
}
}
catch (Exception ex)
{
LogError($"{e.ChangeType} failed", remoteStoragePath, null, ex);
}
}
