...

1 files changed, 0 insertions, 138 deletions

diff --git a/BackEnd/Timeline/Services/DataManager.cs b/BackEnd/Timeline/Services/DataManager.cs
deleted file mode 100644
index b43b80f9..00000000
--- a/BackEnd/Timeline/Services/DataManager.cs
+++ /dev/null
@@ -1,138 +0,0 @@
-using Microsoft.EntityFrameworkCore;

-using System;

-using System.Linq;

-using System.Threading.Tasks;

-using Timeline.Entities;

-

-namespace Timeline.Services

-{

-    /// <summary>

-    /// A data manager controlling data.

-    /// </summary>

-    /// <remarks>

-    /// Identical data will be saved as one copy and return the same tag.

-    /// Every data has a ref count. When data is retained, ref count increase.

-    /// When data is freed, ref count decease. If ref count is decreased

-    /// to 0, the data entry will be destroyed and no longer occupy space.

-    /// </remarks>

-    public interface IDataManager

-    {

-        /// <summary>

-        /// Saves the data to a new entry if it does not exist, 

-        /// increases its ref count and returns a tag to the entry.

-        /// </summary>

-        /// <param name="data">The data. Can't be null.</param>

-        /// <returns>The tag of the created entry.</returns>

-        /// <exception cref="ArgumentNullException">Thrown when <paramref name="data"/> is null.</exception>

-        public Task<string> RetainEntry(byte[] data);

-

-        /// <summary>

-        /// Decrease the the ref count of the entry.

-        /// Remove it if ref count is zero.

-        /// </summary>

-        /// <param name="tag">The tag of the entry.</param>

-        /// <exception cref="ArgumentNullException">Thrown when <paramref name="tag"/> is null.</exception>

-        /// <remarks>

-        /// It's no-op if entry with tag does not exist.

-        /// </remarks>

-        public Task FreeEntry(string tag);

-

-        /// <summary>

-        /// Retrieve the entry with given tag. If not exist, returns null.

-        /// </summary>

-        /// <param name="tag">The tag of the entry.</param>

-        /// <returns>The data of the entry. If not exist, returns null.</returns>

-        /// <exception cref="ArgumentNullException">Thrown when <paramref name="tag"/> is null.</exception>

-        public Task<byte[]?> GetEntry(string tag);

-    }

-

-    public class DataManager : IDataManager

-    {

-        private readonly DatabaseContext _database;

-        private readonly IETagGenerator _eTagGenerator;

-

-        public DataManager(DatabaseContext database, IETagGenerator eTagGenerator)

-        {

-            _database = database;

-            _eTagGenerator = eTagGenerator;

-        }

-

-        public async Task<string> RetainEntry(byte[] data)

-        {

-            if (data == null)

-                throw new ArgumentNullException(nameof(data));

-

-            var tag = await _eTagGenerator.Generate(data);

-

-            var entity = await _database.Data.Where(d => d.Tag == tag).SingleOrDefaultAsync();

-

-            if (entity == null)

-            {

-                entity = new DataEntity

-                {

-                    Tag = tag,

-                    Data = data,

-                    Ref = 1

-                };

-                _database.Data.Add(entity);

-            }

-            else

-            {

-                entity.Ref += 1;

-            }

-

-            await _database.SaveChangesAsync();

-

-            return tag;

-        }

-

-        public async Task FreeEntry(string tag)

-        {

-            if (tag == null)

-                throw new ArgumentNullException(nameof(tag));

-

-            var entity = await _database.Data.Where(d => d.Tag == tag).SingleOrDefaultAsync();

-

-            if (entity != null)

-            {

-                if (entity.Ref == 1)

-                {

-                    _database.Data.Remove(entity);

-                }

-                else

-                {

-                    entity.Ref -= 1;

-                }

-

-                await _database.SaveChangesAsync();

-            }

-        }

-

-        public async Task<byte[]?> GetEntry(string tag)

-        {

-            if (tag == null)

-                throw new ArgumentNullException(nameof(tag));

-

-            var entity = await _database.Data.Where(d => d.Tag == tag).Select(d => new { d.Data }).SingleOrDefaultAsync();

-

-            if (entity is null)

-                return null;

-

-            return entity.Data;

-        }

-    }

-

-    public static class DataManagerExtensions

-    {

-        /// <summary>

-        /// Try to get an entry and throw <see cref="DatabaseCorruptedException"/> if not exist.

-        /// </summary>

-        public static async Task<byte[]> GetEntryAndCheck(this IDataManager dataManager, string tag, string notExistMessage)

-        {

-            var data = await dataManager.GetEntry(tag);

-            if (data is null)

-                throw new DatabaseCorruptedException($"Can't get data of tag {tag}. {notExistMessage}");

-            return data;

-        }

-    }

-}