DocSpace-buildtools/common/ASC.Data.Storage/Extensions.cs

/*
 *
 * (c) Copyright Ascensio System Limited 2010-2018
 *
 * This program is freeware. You can redistribute it and/or modify it under the terms of the GNU 
 * General Public License (GPL) version 3 as published by the Free Software Foundation (https://www.gnu.org/copyleft/gpl.html). 
 * In accordance with Section 7(a) of the GNU GPL its Section 15 shall be amended to the effect that 
 * Ascensio System SIA expressly excludes the warranty of non-infringement of any third-party rights.
 *
 * THIS PROGRAM IS DISTRIBUTED WITHOUT ANY WARRANTY; WITHOUT EVEN THE IMPLIED WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE. For more details, see GNU GPL at https://www.gnu.org/copyleft/gpl.html
 *
 * You can contact Ascensio System SIA by email at sales@onlyoffice.com
 *
 * The interactive user interfaces in modified source and object code versions of ONLYOFFICE must display 
 * Appropriate Legal Notices, as required under Section 5 of the GNU GPL version 3.
 *
 * Pursuant to Section 7 § 3(b) of the GNU GPL you must retain the original ONLYOFFICE logo which contains 
 * relevant author attributions when distributing the software. If the display of the logo in its graphic 
 * form is not reasonably feasible for technical reasons, you must include the words "Powered by ONLYOFFICE" 
 * in every copy of the program you distribute. 
 * Pursuant to Section 7 § 3(e) we decline to grant you any rights under trademark law for use of our trademarks.
 *
*/


using System;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

using ASC.Common;

namespace ASC.Data.Storage
{
    public static class Extensions
    {
        private const int BufferSize = 2048;//NOTE: set to 2048 to fit in minimum tcp window

        public static async Task<Stream> IronReadStreamAsync(this IDataStore store, TempStream tempStream, string domain, string path, int tryCount)
        {
            var ms = tempStream.Create();
            await IronReadToStreamAsync(store, domain, path, tryCount, ms);
            ms.Seek(0, SeekOrigin.Begin);
            return ms;
        }

        public static async Task IronReadToStreamAsync(this IDataStore store, string domain, string path, int tryCount, Stream readTo)
        {
            if (tryCount < 1) throw new ArgumentOutOfRangeException(nameof(tryCount), "Must be greater or equal 1.");
            if (!readTo.CanWrite) throw new ArgumentException("stream cannot be written", nameof(readTo));

            var tryCurrent = 0;
            var offset = 0;

            while (tryCurrent < tryCount)
            {
                try
                {
                    tryCurrent++;
                    using var stream = await store.GetReadStreamAsync(domain, path, offset);
                    var buffer = new byte[BufferSize];
                    int readed;
                    while ((readed = await stream.ReadAsync(buffer, 0, BufferSize)) > 0)
                    {
                        await readTo.WriteAsync(buffer, 0, readed);
                        offset += readed;
                    }
                    break;
                }
                catch (Exception ex)
                {
                    if (tryCurrent >= tryCount)
                    {
                        throw new IOException("Can not read stream. Tries count: " + tryCurrent + ".", ex);
                    }
                    Thread.Sleep(tryCount * 50);
                }
            }
        }
    }
}