refactor: Refactor data services.

9 files changed, 205 insertions, 96 deletions

diff --git a/BackEnd/Timeline/Services/Data/DataManager.cs b/BackEnd/Timeline/Services/Data/DataManager.cs
index d9a4491d..9de17da3 100644
--- a/BackEnd/Timeline/Services/Data/DataManager.cs
+++ b/BackEnd/Timeline/Services/Data/DataManager.cs
@@ -1,73 +1,40 @@
 using Microsoft.EntityFrameworkCore;

+using Microsoft.Extensions.Logging;

 using System;

 using System.Linq;

+using System.Threading;

 using System.Threading.Tasks;

 using Timeline.Entities;

 

 namespace Timeline.Services.Data

 {

-    /// <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 ILogger<DataManager> _logger;

         private readonly DatabaseContext _database;

         private readonly IETagGenerator _eTagGenerator;

 

-        public DataManager(DatabaseContext database, IETagGenerator eTagGenerator)

+        public DataManager(ILogger<DataManager> logger, DatabaseContext database, IETagGenerator eTagGenerator)

         {

+            _logger = logger;

             _database = database;

             _eTagGenerator = eTagGenerator;

         }

 

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

+        public async Task<string> RetainEntry(byte[] data, CancellationToken cancellationToken = default)

         {

             if (data == null)

                 throw new ArgumentNullException(nameof(data));

 

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

+            var tag = await _eTagGenerator.GenerateETagAsync(data, cancellationToken);

+

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

+            bool create;

 

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

 

             if (entity == null)

             {

+                create = true;

                 entity = new DataEntity

                 {

                     Tag = tag,

@@ -78,42 +45,54 @@ namespace Timeline.Services.Data
             }

             else

             {

+                create = false;

                 entity.Ref += 1;

             }

 

-            await _database.SaveChangesAsync();

+            await _database.SaveChangesAsync(cancellationToken);

+

+            _logger.LogInformation(create ? Resource.LogDataManagerRetainEntryCreate : Resource.LogDataManagerRetainEntryAddRefCount, tag);

 

             return tag;

         }

 

-        public async Task FreeEntry(string tag)

+        public async Task FreeEntry(string tag, CancellationToken cancellationToken = default)

         {

             if (tag == null)

                 throw new ArgumentNullException(nameof(tag));

 

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

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

 

             if (entity != null)

             {

+                bool remove;

+

                 if (entity.Ref == 1)

                 {

+                    remove = true;

                     _database.Data.Remove(entity);

                 }

                 else

                 {

+                    remove = false;

                     entity.Ref -= 1;

                 }

 

-                await _database.SaveChangesAsync();

+                await _database.SaveChangesAsync(cancellationToken);

+                _logger.LogInformation(remove ? Resource.LogDataManagerFreeEntryRemove : Resource.LogDataManagerFreeEntryDecreaseRefCount, tag);

+            }

+            else

+            {

+                _logger.LogInformation(Resource.LogDataManagerFreeEntryNotExist, tag);

             }

         }

 

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

+        public async Task<byte[]?> GetEntry(string tag, CancellationToken cancellationToken = default)

         {

             if (tag == null)

                 throw new ArgumentNullException(nameof(tag));

 

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

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

 

             if (entity is null)

                 return null;

@@ -121,18 +100,4 @@ namespace Timeline.Services.Data
             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;

-        }

-    }

 }

diff --git a/BackEnd/Timeline/Services/Data/DataManagerExtensions.cs b/BackEnd/Timeline/Services/Data/DataManagerExtensions.cs
new file mode 100644
index 00000000..64d35b9b
--- /dev/null
+++ b/BackEnd/Timeline/Services/Data/DataManagerExtensions.cs
@@ -0,0 +1,26 @@
+using System;

+using System.Threading.Tasks;

+

+namespace Timeline.Services.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)

+        {

+            if (dataManager is null)

+                throw new ArgumentNullException(nameof(dataManager));

+            if (tag is null)

+                throw new ArgumentNullException(nameof(tag));

+            if (notExistMessage is null)

+                throw new ArgumentNullException(nameof(notExistMessage));

+

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

+            if (data is null)

+                throw new DatabaseCorruptedException(string.Format(Resource.GetEntryAndCheckNotExist, tag, notExistMessage));

+            return data;

+        }

+    }

+}

diff --git a/BackEnd/Timeline/Services/Data/ETagGenerator.cs b/BackEnd/Timeline/Services/Data/ETagGenerator.cs
index 847c120b..03837dc9 100644
--- a/BackEnd/Timeline/Services/Data/ETagGenerator.cs
+++ b/BackEnd/Timeline/Services/Data/ETagGenerator.cs
@@ -1,20 +1,10 @@
 using System;

 using System.Security.Cryptography;

+using System.Threading;

 using System.Threading.Tasks;

 

 namespace Timeline.Services.Data

 {

-    public interface IETagGenerator

-    {

-        /// <summary>

-        /// Generate a etag for given source.

-        /// </summary>

-        /// <param name="source">The source data.</param>

-        /// <returns>The generated etag.</returns>

-        /// <exception cref="ArgumentNullException">Thrown if <paramref name="source"/> is null.</exception>

-        Task<string> Generate(byte[] source);

-    }

-

     public sealed class ETagGenerator : IETagGenerator, IDisposable

     {

         private readonly SHA1 _sha1;

@@ -25,12 +15,12 @@ namespace Timeline.Services.Data
             _sha1 = SHA1.Create();

         }

 

-        public Task<string> Generate(byte[] source)

+        public Task<string> GenerateETagAsync(byte[] source, CancellationToken cancellationToken = default)

         {

             if (source == null)

                 throw new ArgumentNullException(nameof(source));

 

-            return Task.Run(() => Convert.ToBase64String(_sha1.ComputeHash(source)));

+            return Task.Run(() => Convert.ToBase64String(_sha1.ComputeHash(source)), cancellationToken);

         }

 

         private bool _disposed; // To detect redundant calls

diff --git a/BackEnd/Timeline/Services/Data/IDataManager.cs b/BackEnd/Timeline/Services/Data/IDataManager.cs
new file mode 100644
index 00000000..6a87c1b2
--- /dev/null
+++ b/BackEnd/Timeline/Services/Data/IDataManager.cs
@@ -0,0 +1,49 @@
+using System;

+using System.Threading;

+using System.Threading.Tasks;

+

+namespace Timeline.Services.Data

+{

+    /// <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>

+        /// <param name="cancellationToken">Cancellation token.</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, CancellationToken cancellationToken = default);

+

+        /// <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>

+        /// <param name="cancellationToken">Cancellation token.</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, CancellationToken cancellationToken = default);

+

+        /// <summary>

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

+        /// </summary>

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

+        /// <param name="cancellationToken">Cancellation token.</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, CancellationToken cancellationToken = default);

+    }

+}

diff --git a/BackEnd/Timeline/Services/Data/IETagGenerator.cs b/BackEnd/Timeline/Services/Data/IETagGenerator.cs
new file mode 100644
index 00000000..fa81c449
--- /dev/null
+++ b/BackEnd/Timeline/Services/Data/IETagGenerator.cs
@@ -0,0 +1,19 @@
+using System;

+using System.Threading;

+using System.Threading.Tasks;

+

+namespace Timeline.Services.Data

+{

+    public interface IETagGenerator

+    {

+        /// <summary>

+        /// Generate a etag for given source.

+        /// </summary>

+        /// <param name="source">The source data.</param>

+        /// <param name="cancellationToken">Cancellation token.</param>

+        /// <returns>The generated etag.</returns>

+        /// <exception cref="ArgumentNullException">Thrown if <paramref name="source"/> is null.</exception>

+        /// <remarks>This function must guarantee the same result with equal given source.</remarks>

+        Task<string> GenerateETagAsync(byte[] source, CancellationToken cancellationToken = default);

+    }

+}

diff --git a/BackEnd/Timeline/Resources/Services/DataManager.Designer.cs b/BackEnd/Timeline/Services/Data/Resource.Designer.cs
index 0872059a..46b9eaf0 100644
--- a/BackEnd/Timeline/Resources/Services/DataManager.Designer.cs
+++ b/BackEnd/Timeline/Services/Data/Resource.Designer.cs
@@ -8,7 +8,7 @@
 // </auto-generated>

 //------------------------------------------------------------------------------

 

-namespace Timeline.Resources.Services {

+namespace Timeline.Services.Data {

     using System;

     

     

@@ -22,14 +22,14 @@ namespace Timeline.Resources.Services {
     [global::System.CodeDom.Compiler.GeneratedCodeAttribute("System.Resources.Tools.StronglyTypedResourceBuilder", "16.0.0.0")]

     [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]

     [global::System.Runtime.CompilerServices.CompilerGeneratedAttribute()]

-    internal class DataManager {

+    internal class Resource {

         

         private static global::System.Resources.ResourceManager resourceMan;

         

         private static global::System.Globalization.CultureInfo resourceCulture;

         

         [global::System.Diagnostics.CodeAnalysis.SuppressMessageAttribute("Microsoft.Performance", "CA1811:AvoidUncalledPrivateCode")]

-        internal DataManager() {

+        internal Resource() {

         }

         

         /// <summary>

@@ -39,7 +39,7 @@ namespace Timeline.Resources.Services {
         internal static global::System.Resources.ResourceManager ResourceManager {

             get {

                 if (object.ReferenceEquals(resourceMan, null)) {

-                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Timeline.Resources.Services.DataManager", typeof(DataManager).Assembly);

+                    global::System.Resources.ResourceManager temp = new global::System.Resources.ResourceManager("Timeline.Services.Data.Resource", typeof(Resource).Assembly);

                     resourceMan = temp;

                 }

                 return resourceMan;

@@ -61,11 +61,56 @@ namespace Timeline.Resources.Services {
         }

         

         /// <summary>

-        ///   Looks up a localized string similar to Entry with given tag does not exist..

+        ///   Looks up a localized string similar to Can&apos;t get data entry of tag {0}. {1}.

         /// </summary>

-        internal static string ExceptionEntryNotExist {

+        internal static string GetEntryAndCheckNotExist {

             get {

-                return ResourceManager.GetString("ExceptionEntryNotExist", resourceCulture);

+                return ResourceManager.GetString("GetEntryAndCheckNotExist", resourceCulture);

+            }

+        }

+        

+        /// <summary>

+        ///   Looks up a localized string similar to Decrease ref count of existing entry with tag {0}..

+        /// </summary>

+        internal static string LogDataManagerFreeEntryDecreaseRefCount {

+            get {

+                return ResourceManager.GetString("LogDataManagerFreeEntryDecreaseRefCount", resourceCulture);

+            }

+        }

+        

+        /// <summary>

+        ///   Looks up a localized string similar to Attempt to free an entry that does not exist with tag {0}..

+        /// </summary>

+        internal static string LogDataManagerFreeEntryNotExist {

+            get {

+                return ResourceManager.GetString("LogDataManagerFreeEntryNotExist", resourceCulture);

+            }

+        }

+        

+        /// <summary>

+        ///   Looks up a localized string similar to Remove a entry with tag {0}..

+        /// </summary>

+        internal static string LogDataManagerFreeEntryRemove {

+            get {

+                return ResourceManager.GetString("LogDataManagerFreeEntryRemove", resourceCulture);

+            }

+        }

+        

+        /// <summary>

+        ///   Looks up a localized string similar to Add ref count of existing entry with tag {0}..

+        /// </summary>

+        internal static string LogDataManagerRetainEntryAddRefCount {

+            get {

+                return ResourceManager.GetString("LogDataManagerRetainEntryAddRefCount", resourceCulture);

+            }

+        }

+        

+        /// <summary>

+        ///   Looks up a localized string similar to Create a new entry with tag {0}..

+        /// </summary>

+        internal static string LogDataManagerRetainEntryCreate {

+            get {

+                return ResourceManager.GetString("LogDataManagerRetainEntryCreate", resourceCulture);

             }

         }

     }

diff --git a/BackEnd/Timeline/Resources/Services/DataManager.resx b/BackEnd/Timeline/Services/Data/Resource.resx
index 688e0e96..6783efae 100644
--- a/BackEnd/Timeline/Resources/Services/DataManager.resx
+++ b/BackEnd/Timeline/Services/Data/Resource.resx
@@ -117,7 +117,22 @@
   <resheader name="writer">

     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>

   </resheader>

-  <data name="ExceptionEntryNotExist" xml:space="preserve">

-    <value>Entry with given tag does not exist.</value>

+  <data name="GetEntryAndCheckNotExist" xml:space="preserve">

+    <value>Can't get data entry of tag {0}. {1}</value>

+  </data>

+  <data name="LogDataManagerFreeEntryDecreaseRefCount" xml:space="preserve">

+    <value>Decrease ref count of existing entry with tag {0}.</value>

+  </data>

+  <data name="LogDataManagerFreeEntryNotExist" xml:space="preserve">

+    <value>Attempt to free an entry that does not exist with tag {0}.</value>

+  </data>

+  <data name="LogDataManagerFreeEntryRemove" xml:space="preserve">

+    <value>Remove a entry with tag {0}.</value>

+  </data>

+  <data name="LogDataManagerRetainEntryAddRefCount" xml:space="preserve">

+    <value>Add ref count of existing entry with tag {0}.</value>

+  </data>

+  <data name="LogDataManagerRetainEntryCreate" xml:space="preserve">

+    <value>Create a new entry with tag {0}.</value>

   </data>

 </root>
\ No newline at end of file
diff --git a/BackEnd/Timeline/Services/User/UserAvatarService.cs b/BackEnd/Timeline/Services/User/UserAvatarService.cs
index 0a4b7438..a92df3cb 100644
--- a/BackEnd/Timeline/Services/User/UserAvatarService.cs
+++ b/BackEnd/Timeline/Services/User/UserAvatarService.cs
@@ -95,7 +95,7 @@ namespace Timeline.Services.User
             if (_cacheData == null || File.GetLastWriteTime(path) > _cacheDigest!.LastModified)

             {

                 var data = await File.ReadAllBytesAsync(path);

-                _cacheDigest = new CacheableDataDigest(await _eTagGenerator.Generate(data), File.GetLastWriteTime(path));

+                _cacheDigest = new CacheableDataDigest(await _eTagGenerator.GenerateETagAsync(data), File.GetLastWriteTime(path));

                 Image.Identify(data, out var format);

                 _cacheData = new ByteData(data, format.DefaultMimeType);

             }

diff --git a/BackEnd/Timeline/Timeline.csproj b/BackEnd/Timeline/Timeline.csproj
index 47713284..6a74d0c0 100644
--- a/BackEnd/Timeline/Timeline.csproj
+++ b/BackEnd/Timeline/Timeline.csproj
@@ -123,11 +123,6 @@
             <AutoGen>True</AutoGen>

             <DependentUpon>Validator.resx</DependentUpon>

         </Compile>

-        <Compile Update="Resources\Services\DataManager.Designer.cs">

-            <DesignTime>True</DesignTime>

-            <AutoGen>True</AutoGen>

-            <DependentUpon>DataManager.resx</DependentUpon>

-        </Compile>

         <Compile Update="Resources\Services\TimelineService.Designer.cs">

             <DesignTime>True</DesignTime>

             <AutoGen>True</AutoGen>

@@ -148,6 +143,11 @@
             <AutoGen>True</AutoGen>

             <DependentUpon>UserTokenService.resx</DependentUpon>

         </Compile>

+        <Compile Update="Services\Data\Resource.Designer.cs">

+          <DesignTime>True</DesignTime>

+          <AutoGen>True</AutoGen>

+          <DependentUpon>Resource.resx</DependentUpon>

+        </Compile>

         <Compile Update="Services\Imaging\Resource.Designer.cs">

           <DesignTime>True</DesignTime>

           <AutoGen>True</AutoGen>

@@ -237,10 +237,6 @@
             <Generator>ResXFileCodeGenerator</Generator>

             <LastGenOutput>Validator.Designer.cs</LastGenOutput>

         </EmbeddedResource>

-        <EmbeddedResource Update="Resources\Services\DataManager.resx">

-            <Generator>ResXFileCodeGenerator</Generator>

-            <LastGenOutput>DataManager.Designer.cs</LastGenOutput>

-        </EmbeddedResource>

         <EmbeddedResource Update="Resources\Services\TimelineService.resx">

             <Generator>ResXFileCodeGenerator</Generator>

             <LastGenOutput>TimelineService.Designer.cs</LastGenOutput>

@@ -257,6 +253,10 @@
             <Generator>ResXFileCodeGenerator</Generator>

             <LastGenOutput>UserTokenService.Designer.cs</LastGenOutput>

         </EmbeddedResource>

+        <EmbeddedResource Update="Services\Data\Resource.resx">

+          <Generator>ResXFileCodeGenerator</Generator>

+          <LastGenOutput>Resource.Designer.cs</LastGenOutput>

+        </EmbeddedResource>

         <EmbeddedResource Update="Services\Imaging\Resource.resx">

           <Generator>ResXFileCodeGenerator</Generator>

           <LastGenOutput>Resource.Designer.cs</LastGenOutput>