IFileReadAsync Method

Task<IFileMetadata> ReadAsync(
	Stream output,
	long offset,
	long length,
	IFileMetadata metadata,
	ITransferDataOperationContext operationContext,
	ITransferDataResultContext resultContext,
	CancellationToken cancellationToken
)

Function ReadAsync ( 
	output As Stream,
	offset As Long,
	length As Long,
	metadata As IFileMetadata,
	operationContext As ITransferDataOperationContext,
	resultContext As ITransferDataResultContext,
	cancellationToken As CancellationToken
) As Task(Of IFileMetadata)

Task<IFileMetadata^>^ ReadAsync(
	Stream^ output, 
	long long offset, 
	long long length, 
	IFileMetadata^ metadata, 
	ITransferDataOperationContext^ operationContext, 
	ITransferDataResultContext^ resultContext, 
	CancellationToken cancellationToken
)

abstract ReadAsync : 
        output : Stream * 
        offset : int64 * 
        length : int64 * 
        metadata : IFileMetadata * 
        operationContext : ITransferDataOperationContext * 
        resultContext : ITransferDataResultContext * 
        cancellationToken : CancellationToken -> Task<IFileMetadata> 

public async Task<IFileMetadata> ReadAsync(Stream output, long offset, long length, IFileMetadata metadata, ITransferDataOperationContext operationContext, ITransferDataResultContext resultContext, CancellationToken cancellationToken)
{
    // On Windows this method has a 60 sec timeout. 
    // To process longer requests and reset the timeout timer write to the output stream or call the resultContext.ReportProgress() or resultContext.ReturnDataAsync() methods.

    Logger.LogMessage($"{nameof(IFile)}.{nameof(ReadAsync)}({offset}, {length})", UserFileSystemPath, default, operationContext, metadata);

    using (FileStream stream = new FileInfo(RemoteStoragePath).Open(FileMode.Open, FileAccess.Read, FileShare.ReadWrite | FileShare.Delete))
    {
        stream.Seek(offset, SeekOrigin.Begin);
        const int bufferSize = 0x500000; // 5Mb. Buffer size must be multiple of 4096 bytes for optimal performance.
        try
        {
            await stream.CopyToAsync(output, bufferSize, length, cancellationToken);
        }
        catch (OperationCanceledException)
        {
            // Operation was canceled by the calling Engine.StopAsync() or the operation timeout occured.
            Logger.LogDebug($"{nameof(ReadAsync)}({offset}, {length}) canceled", UserFileSystemPath, default, operationContext, metadata);
        }
    }

    // Return an updated item to the Engine.
    // In the returned data set the following fields:
    //  - Content eTag. The Engine will store it to determine if the file content should be updated.
    //  - Medatdata eTag. The Engine will store it to determine if the item metadata should be updated.
    return null;
}