From 657fb589137099794e58fbd35beb7d942b376965 Mon Sep 17 00:00:00 2001
From: crupest <crupest@outlook.com>
Date: Sun, 25 Apr 2021 21:20:04 +0800
Subject: ...

---
 BackEnd/Timeline/Services/DataManager.cs | 138 -------------------------------
 1 file changed, 138 deletions(-)
 delete mode 100644 BackEnd/Timeline/Services/DataManager.cs

(limited to 'BackEnd/Timeline/Services/DataManager.cs')

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;
-        }
-    }
-}
-- 
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