Cara membuat caching yang sangat dapat disesuaikan dalam suatu proyek dan menyelamatkan kolega dari menulis jenis kode yang sama

"Jika esensi dari pekerjaan programmer adalah untuk mengotomatiskan pekerjaan orang lain, lalu mengapa pekerjaan saya begitu sedikit terotomatisasi", saya pikir, sekali lagi menyalin semua ikatan yang diperlukan dalam proyek untuk menambahkan entitas baru ke dalam database. Dan saya memutuskan untuk menyingkirkan rutin ini menambahkan kelas template, melakukan sekaligus "baik" untuk proyek, membongkar database dari operasi baca yang tidak perlu.

Penyimpangan kecil tentang sistem yang kami kembangkan dan statusnya pada saat percobaan ini dimulai:

  • Suatu sistem di mana 90% data secara aktif diubah dan diproses (transaksi, data pribadi, agregasi yang dihitung), tetapi jarang dibaca, dan sisanya 10% sangat jarang berubah, tetapi digunakan untuk membaca di setiap kesempatan
  • Layanan hampir monolitik pada .Net Framework, di mana semua ini diterapkan
  • Nhibernate dengan pengikatan minimal, digunakan untuk mengakses basis data dan sejumlah cache berdasarkannya (langganan untuk perubahan pada entitas BO, penangan dipanggil saat komit transaksi)
  • Selusin aturan tak terucapkan "bagaimana menulis kode untuk mengakses database tanpa mematikan kinerja dengan fitur NHibernate", yang secara teratur tertangkap di Core Review
  • Basis data yang agak membosankan yang membutuhkan pengoptimalan

Sambil memikirkan situasi dengan database, muncul pemikiran: apakah akan menghapus dari beban pada database ini 10% dari permintaan yang sama (dan pada saat yang sama membuka koneksi ke database yang diperlukan untuk mereka, mengadakan transaksi terbuka dan menggunakan kode templat untuk mengakses database melalui repositori kami). Dalam hal ini, perlu dipertimbangkan:

  • Kami sudah mencoba bekerja dengan cache Nhibernate, tetapi ternyata perilakunya tidak selalu eksplisit dan dapat diprediksi.
  • Saya tidak ingin mengubah apa pun secara mendasar di platform atau infrastruktur tanpa alasan yang kuat
  • Jumlah kode tulisan tangan, seperti programmer yang malas, seharusnya berkurang, menulis ratusan baris pembungkus dan langganan untuk cache yang ada dengan tangan Anda

Contoh implementasi dari salah satu cache lama ini
/// <summary> /// Base class for caches, containing rarely changed entities. Updated by subscription to nHibernate session commits. /// </summary> /// <typeparam name="T">Type, used as a base for the cache. Sessions, containing changes to any instance of this class will cause cache refresh.</typeparam> /// <typeparam name="K">Key used for cache search.</typeparam> /// <typeparam name="V">Value, stored in cache.</typeparam> public abstract class RareChangedObjectsCache<T, K, V> : EmptySessionNotificationListener, ITransactionNotificationListener, IRareChangedObjectsCache<K, V> where T : class { [NotNull] private static readonly ILog Log = IikoBizLogManager.GetLogger(typeof(RareChangedObjectsCache<T, K, V>)); [NotNull] protected readonly ReaderWriterLockSlim LockObj = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion); [NotNull] protected readonly Dictionary<K, V> Cache = new Dictionary<K, V>(); [NotNull] protected abstract QueryOver<T> GetQuery(); [NotNull] private readonly ConcurrentDictionary<String, bool> changesByTransaction = new ConcurrentDictionary<string, bool>(); private DateTime lastRefreshTime = DateTime.MinValue; [NotNull] public HibernateSessionManager SessionManager { get; set; } /// <summary> /// Interval of automatic data renewal for cases of read access to cache. Also, cache is forcibly refreshed on any commit, changing base entities of this cache. /// </summary> public TimeSpan AutoRefreshInterval { get; set; } public void Reset() { lastRefreshTime = DateTime.MinValue; } protected void ReloadCacheIfNeeded(ISession session = null) { if (SystemTime.Now - lastRefreshTime <= AutoRefreshInterval) return; LockObj.EnterWriteLock(); try { if (SystemTime.Now - lastRefreshTime <= AutoRefreshInterval) return; IList<object> result; if (session == null) result = SessionManager.CallTransacted(s => GetQuery().GetExecutableQueryOver(s).List<object>()); else //TODO At that moment, the transaction may have been closed, so a new transaction opens implicitly result = GetQuery().GetExecutableQueryOver(session).List<object>(); Cache.Clear(); ProcessResult(result); lastRefreshTime = SystemTime.Now; } catch (Exception e) { Log.Error("Exception on cache invalidation: ", e); } finally { LockObj.ExitWriteLock(); } } protected abstract void ProcessResult(IList<object> result); public override void OnSaveOrUpdate(ISession session, object entity, Guid id, object[] currentState, object[] previousState, string[] propertyNames, IType[] types) { if (entity is T) { var transactionName = HibernateSessionManager.GetTransactionName(); if (!string.IsNullOrEmpty(transactionName)) { changesByTransaction.TryAdd(transactionName, true); } } } public override void OnDelete(ISession session, object entity, Guid id) { if (entity is T) { var transactionName = HibernateSessionManager.GetTransactionName(); if (!string.IsNullOrEmpty(transactionName)) { changesByTransaction.TryAdd(transactionName, true); } } } void ITransactionNotificationListener.AfterCommit(ISession session, string transactionName) { bool tmp; if (changesByTransaction.TryRemove(transactionName, out tmp)) Reset(); ReloadCacheIfNeeded(session); } void ITransactionNotificationListener.AfterRollback(ISession session, string transactionName) { } public bool Contains(K key) { ReloadCacheIfNeeded(); LockObj.EnterReadLock(); try { return Cache.ContainsKey(key); } finally { LockObj.ExitReadLock(); } } public virtual V TryGet(K key) { ReloadCacheIfNeeded(); LockObj.EnterReadLock(); try { return Cache.TryGetValue(key, out var value) ? value : default; } finally { LockObj.ExitReadLock(); } } protected TV GetOrAddEntry<TK, TV>(IDictionary<TK, TV> dictionary, TK key) where TV : new() { TV list; if (!dictionary.TryGetValue(key, out list)) dictionary[key] = (list = new TV()); return list; } } /// <summary> /// Caches all guest categories, grouped by organization or network they belong. /// </summary> [UsedImplicitly] public sealed class GuestCategoryCache : RareChangedObjectsCache<GuestCategory, Guid, HashSet<GuestCategory>> { private static readonly QueryOver<GuestCategory> SelectAllEntitiesQuery = QueryOver.Of<GuestCategory>() .Fetch(gc => gc.Organization).Eager .Fetch(gc => gc.Network).Eager; private readonly Dictionary<Guid, string> invertedCache = new Dictionary<Guid, string>(); public bool TryGetNetworkExternalId(Guid id, out string extId) { ReloadCacheIfNeeded(); LockObj.EnterReadLock(); try { return invertedCache.TryGetValue(id, out extId); } finally { LockObj.ExitReadLock(); } } protected override QueryOver<GuestCategory> GetQuery() { return SelectAllEntitiesQuery; } protected override void ProcessResult(IList<object> result) { invertedCache.Clear(); foreach (GuestCategory gc in result) { var orgOrNetworkId = gc.Organization?.Id ?? gc.Network.Id; GetOrAddEntry(Cache, orgOrNetworkId).Add(gc); } } } 


saat itu udah agak capek.
- Fitur baru tidak boleh memengaruhi pengembang lain secara global, migrasi ke pendekatan baru harus terjadi dengan lancar dan lembut.

Pada saat yang sama, saya ingin memastikan bahwa menambahkan entitas baru ke mekanisme caching membutuhkan upaya minimal, kode tetap dapat dibaca dan langsung, dan ketika mengambil data dari cache, orang bisa berpikir minimal tentang kode bantu apa yang harus ditulis. Dua poin terakhir sangat memangkas kisaran opsi. Faktanya, Anda harus membuat perbedaan dengan kelas refleksi dan generik, atau beralih ke pemrograman lama yang baik.

Karena alat pengembangan utama adalah Visual Studio, tetapi saya tidak ingin menghabiskan banyak energi pada kenyataan bahwa itu bukan efek besar, saya memutuskan untuk membuat keputusan "di dahi" dengan alat paling standar dan hanya pada tahap Bukti Konsep selesai pada beberapa yang paling sering digunakan entitas - menyajikan keputusan kepada kolega di pengadilan.

Berikutnya adalah beberapa dilema moral. Apakah akan digunakan sebagai sumber, beberapa kelas tergantung dengan atribut untuk semua kesempatan (dengan gaya pemetaan Fluent Nhibernate pada steroid), atau menulis XML yang rapi dan bagus. Mengingat kemalasan adalah sahabat programmer, dan mendeskripsikan kelas dengan atribut lebih memakan waktu daripada menulis sedikit XML, saya telah memilih yang terakhir.

Intinya, apa yang saya butuhkan dari deskripsi entitas?

  • Deskripsi bidang yang di-cache
  • Kemampuan untuk menentukan sifat-sifat dimana kami akan membuat sampel dari data ini, jika perlu, kemampuan untuk mengoptimalkan sampel ini dengan menghilangkan jalur linear melalui daftar (jika Anda bermain dalam optimasi, begitu lengkap)
  • Kenyamanan tambahan apa pun untuk mendistribusikan kelas dalam folder yang berbeda dan menggunakan pengembangan yang ada dalam kode untuk mengurangi jumlahnya

Kami mendapat struktur xml ini
 <class name="GuestCategory" logicallyDeletable="true" revisioned="true" organizationNetworkBased="true" basedOn="BO.GuestCategory" > <emitBo emitMapping="true"/> <emitRepository dependsOn="guestCategoryCache">IGuestCategoryRepository</emitRepository> <field name="IsActive" type="bool"/> <field name="IsDefaultForNewGuests" type="bool"/> <field name="Name" type="string" notNull="true"/> </class> 


Dan template T4 yang menakutkan untuk menguraikannya dan menghasilkan kelas yang bervariasi, tetapi sangat dibutuhkan:

  • Jenis "cache" dengan bidang yang sama dengan BO tetapi tidak dapat diedit
  • Menerapkan cache untuk suatu tipe dengan metode pemilihan filter
  • Registri cache untuk berlangganan mekanisme Nhibernate untuk notifikasi dan pendaftaran di DI (Spring dalam kasus kami)
  • Antarmuka untuk semua ini untuk menyembunyikan bagian dalam dan kemampuan, jika perlu, untuk mengganti kode yang dihasilkan dengan tulisan tangan dan kembali.
  • Sebagai bonus yang tidak terencana yang menyenangkan sejak awal, jika bekerja dengan entitas utama sudah siap - saya melakukan setengah langkah untuk keberuntungan, dan menambahkan pada sisi kemampuan untuk menghasilkan tipe-BO sederhana dan pemetaan untuk mereka, untuk memberi rekan kerja kesempatan untuk menambahkan kelas baru dengan setengah tendangan.

Templat itu sendiri, dari sudut pandang logis, terdiri dari dua bagian: parsing xml asli ke dalam kelas yang menggambarkan struktur kelas yang diinginkan (untuk mengurangi risiko perilaku implisit, dalam hal ini, diputuskan untuk melakukannya melalui penguraian tag yang eksplisit, dan tidak melalui pemetaan atribut.

Kelas Struktural
 class DalClass { public string Name { get; } public bool LogicallyDeletable { get; } public string BasedOn { get; } public string DalBOType { get; } public string[] Implements { get; } public string[] Include { get; } public bool CustomConsistencyManager { get; } public List<DalField> Fields { get; } public List<DalField> ExplicitlyDefinedFields { get; } public DalGetBy[] GetBy { get; } public DalGetBy[] GetAllBy { get; } public bool GenerateInterface { get; } public DalEmitBo EmitBo { get; } public DalEmitRepository EmitRepository { get; } public DalClass(XmlElement sourceXml) { Implements = sourceXml.SelectNodes("*[local-name()='implements']") .Cast<XmlElement>() .Select(f => f.InnerText + ",") .ToArray(); Include = sourceXml.SelectNodes("*[local-name()='include']") .Cast<XmlElement>() .Select(f => f.InnerText) .ToArray(); Name = sourceXml.GetAttribute("name"); LogicallyDeletable = sourceXml.HasAttribute("logicallyDeletable"); BasedOn = sourceXml.GetAttribute("basedOn"); DalBOType = sourceXml.HasAttribute("dalBoType") ? sourceXml.GetAttribute("dalBoType") : BasedOn; CustomConsistencyManager = sourceXml.HasAttribute("customConsistencyManager") ? sourceXml.GetAttribute("customConsistencyManager") == "true" : false; Fields = sourceXml.SelectNodes("*[local-name()='field']") .Cast<XmlElement>() .Select(f => new DalField(f)) .ToList(); ExplicitlyDefinedFields = Fields.ToList(); Fields = Fields.OrderBy(f=>f.Name).ToList(); GetBy = sourceXml.SelectNodes("*[local-name()='getBy']") .Cast<XmlElement>() .Select(f => new DalGetBy(f)) .ToArray(); GetAllBy = sourceXml.SelectNodes("*[local-name()='getAllBy']") .Cast<XmlElement>() .Select(f => new DalGetBy(f)) .ToArray(); EmitBo = sourceXml.SelectNodes("*[local-name()='emitBo']") .Cast<XmlElement>() .Select(f => new DalEmitBo(f)) .SingleOrDefault(); EmitRepository = sourceXml.SelectNodes("*[local-name()='emitRepository']") .Cast<XmlElement>() .Select(f => new DalEmitRepository(f, Name)) .SingleOrDefault(); GenerateInterface = true; } public string GetIncludedNamespaces() { return string.Join("/n", Include.Select(i => "using " + i + ";")); } public string GetBoClassDefinition() { return Name + " :\n\t\tBaseEntity,\n\t\t" + (LogicallyDeletable ? "ILogicallyDeletable,\n\t\t" : string.Empty) + (Implements.Any() ? string.Join("\n\t\t", Implements) + "\n\t\t" : string.Empty) + "I" + Name; } public string GetCachedClassDefinition() { return "Cached" + Name + " :\n\t\t" + (LogicallyDeletable ? "Deletable" : string.Empty) + "CachedEntity<" + BasedOn + ">,\n\t\t" + (Implements.Any() ? string.Join("\n\t\t", Implements) + "\n\t\t" : string.Empty) + "I" + Name; } public string TryGetIsDeletedParameter() { if (LogicallyDeletable) return ",bool getDeleted"; else return String.Empty; } public string TryGetIsDeletedFilter() { if (LogicallyDeletable) return @" if (!getDeleted) entities = entities.Where(e => !e.IsDeleted); "; else return String.Empty; } public string GetFilterParameters(DalGetBy getBy) { var filters = new List<FieldDescription>(); foreach (var filter in getBy.Filters) filters.Add(new FieldDescription { TypeName = Fields.Single(f => f.Name == filter.Key).FieldType, Alias = filter.Value }); return string.Join(", ", filters.Select(f => f.TypeName + " " + f.Alias)); } private struct FieldDescription { public string TypeName; public string Alias; } } class DalField { public string Name { get; } public string FieldType { get; } public string Source { get; } public string PropertySource { get; } public bool NotNull { get; } public DalField(string name, string type) { Name = name; FieldType = type; Source = name; } public DalField(XmlElement sourceXml) { Name = sourceXml.GetAttribute("name"); FieldType = sourceXml.GetAttribute("type"); Source = sourceXml.HasAttribute("source") ? sourceXml.GetAttribute("source") : sourceXml.GetAttribute("name"); PropertySource = sourceXml.HasAttribute("propertySource") ? sourceXml.GetAttribute("propertySource") : null; NotNull = sourceXml.HasAttribute("notNull") ? sourceXml.GetAttribute("notNull") == "true" : false; } public string GetConstructorInitValueExpression() { var fieldIsArray = FieldType.EndsWith("[]"); var fieldRealType = FieldType.Replace("[]", ""); if (PropertySource!=null && fieldRealType.StartsWith("I")) fieldRealType = "Cached" + fieldRealType.Substring(1); return UpperInitial(Name) + " = source." + Source + (fieldIsArray ? ".Select(i=>new " + fieldRealType + "(i)).ToArray()" : "") + ";"; } public string GetPropertyDefinitionExpression() { return "public " + GetType() + " " + UpperInitial(Name) + (PropertySource != null ? " => " + PropertySource + ";" : " { get; private set; }"); } public string GetBOPropertyDefinitionExpression() { return "public virtual " + GetBoType() + " " + UpperInitial(Name) + " { get; set; }"; } public string GetInterfacePropertyDefinitionExpression() { return GetNullAttribute() + GetType() + " " + UpperInitial(Name) + " { get; }"; } public string GetType() { var fieldIsArray = FieldType.EndsWith("[]"); if (fieldIsArray) return "IEnumerable<" + FieldType.Replace("[]", "") + ">"; return FieldType; } public string GetBoType() { var fieldIsArray = FieldType.EndsWith("[]"); if (fieldIsArray) return "IList<" + FieldType.Replace("[]", "") + ">"; return FieldType; } private string GetNullAttribute() => TypeCanBeNull() ? NotNull ? "[NotNull] " : "[CanBeNull] " : string.Empty; private static string[] NotNullTypes = { "Guid", "DateTime", "DateTimeOffset", "bool", "int", "long", "short", "ProgramType", "GuestSubscriptionTypes", "SenderType", "ApiClientType" }; public bool TypeCanBeNull() => !NotNullTypes.Contains(FieldType); private string UpperInitial(string name) { return name[0].ToString().ToUpperInvariant() + name.Substring(1); } } class DalGetBy { public bool IsTry { get; } public string Alias { get; } public Dictionary<string, string> Filters { get; } = new Dictionary<string, string>(); public DalGetBy(XmlElement sourceXml) { IsTry = sourceXml.HasAttribute("try"); Alias = sourceXml.GetAttribute("alias"); foreach (XmlElement filterNode in sourceXml.SelectNodes("*[local-name()='field']")) Filters.Add(filterNode.GetAttribute("field"), filterNode.GetAttribute("alias")); } public string GetConditions() { return string.Join(" && ", Filters.Select(f => $"e.{f.Key} == {f.Value}")); return string.Join(" && ", Filters.Select(f => $"e.{f.Key} == {f.Value}")); } } class DalEmitBo { public string Namespace { get; } public bool EmitMapping { get; } private XmlElement sourceXml; public DalEmitBo(XmlElement sourceXml) { Namespace = sourceXml.GetAttribute("ns"); EmitMapping = sourceXml.HasAttribute("emitMapping"); this.sourceXml = sourceXml; } public string GetMapping(DalField field) { bool notNull = !field.TypeCanBeNull() || field.NotNull; var overridenXml = sourceXml.SelectNodes("*[local-name()='column']").Cast<XmlElement>().SingleOrDefault(e => e.GetAttribute("name") == field.Name); var props = overridenXml != null ? new OverridenProperties(overridenXml) : null; switch(field.FieldType) { case "string": return $"<property name=\"{field.Name}\"><column name=\"{field.Name}\" {(notNull ? "not-null=\"true\"" : string.Empty)} {(props?.SqlType !=null ? "sql-type=\"" + props.SqlType+"\"" : string.Empty)}/></property>"; case "bool": return $"<property name=\"{field.Name}\" not-null=\"true\" type=\"boolean\"><column name=\"{field.Name}\" not-null=\"true\" default=\"{props?.DefaultValue??"0"}\" sql-type=\"bit\" /></property>"; case "DateTime": return $"<property name=\"{field.Name}\" not-null=\"true\"/>"; case "DateTime?": return $"<property name=\"{field.Name}\" />"; case "ProgramType": return $"<property name=\"{field.Name}\"><column name=\"{field.Name}\" default=\"{props?.DefaultValue??"0"}\" {(notNull ? "not-null=\"true\"" : string.Empty)}/></property>"; case "Guid?": return $"<property name=\"{field.Name}\" />"; default: throw new ArgumentOutOfRangeException($"Not supported type {field.FieldType}. Edit DAL.tt to add mapping definition."); } } private class OverridenProperties { public string DefaultValue { get; } public string SqlType { get; } public OverridenProperties(XmlElement sourceXml) { DefaultValue = sourceXml.GetAttribute("default"); SqlType = sourceXml.GetAttribute("sql-type"); } } } class DalEmitRepository { public string Interface { get; } public string DependsOn { get; } public DalEmitRepository(XmlElement sourceXml, string className) { Interface = string.IsNullOrEmpty(sourceXml.InnerText) ? "IRepository<"+className+">" : sourceXml.InnerText; DependsOn = sourceXml.GetAttribute("dependsOn"); } public string GetRepositoryClassName() => Interface.Substring(1); } 


Kode untuk templat yang dihasilkan
 <#@ template debug="false" hostspecific="true" language="C#" #> <#@ assembly name="System.Xml" #> <#@ assembly name="System.Core" #> <#@ assembly name="EnvDTE" #> <#@ import namespace="System.Xml" #> <#@ import namespace="System.Collections.Generic" #> <#@ import namespace="System.IO" #> <#@ import namespace="System.Linq" #> <#@ output extension="/" #> <# EnvDTE.DTE dte = (EnvDTE.DTE) ((IServiceProvider) this.Host) .GetService(typeof(EnvDTE.DTE)); XmlDocument doc = new XmlDocument(); doc.Load(System.IO.Path.Combine(dte.ActiveDocument.Path, "DAL.xml")); var classes = doc.SelectNodes("//*[local-name()='class']").Cast<XmlElement>().Select(classXml=>new DalClass(classXml)).ToArray(); //fields foreach(var classNode in classes) { #> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Serialization; using JetBrains.Annotations; <#=classNode.GetIncludedNamespaces()#> namespace Domain.DALV2 { public class <#=classNode.GetCachedClassDefinition()#> { public Cached<#=classNode.Name#>(<#=classNode.DalBOType#> source) : base(source) { <#=string.Join("\n\t\t\t", classNode.Fields.Where(f => f.PropertySource == null).Select(f=>f.GetConstructorInitValueExpression()))#> } <#=string.Join("\n\n\t\t", classNode.Fields.Select(f=>f.GetPropertyDefinitionExpression()))#> } } <#if (classNode.GenerateInterface){#> namespace Domain.DAL { public interface I<#=classNode.Name#> <#if (classNode.LogicallyDeletable){#> :ILogicallyDeletableReadonly <#}#> { Guid Id { get; } <#=string.Join("\n\n\t\t", classNode.Fields.Select(f=>f.GetInterfacePropertyDefinitionExpression()))#> } } <#SaveOutput("Entities//gen//"+classNode.Name+".g.cs");#> <#}#> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using System; using System.Collections.Generic; using System.Linq; using System.Runtime.Serialization; using Resto.Framework.Common; using JetBrains.Annotations; <#=classNode.GetIncludedNamespaces()#> namespace Domain.DALV2 { public partial class <#=classNode.Name#>DAL : DAL<Cached<#=classNode.Name#>, <#=classNode.BasedOn#>, <#=classNode.DalBOType#>> { internal <#=classNode.Name#>DAL(ISessionManager sessionManager, ICacheConsistencyManager<<#=classNode.BasedOn#>, <#=classNode.DalBOType#>> consistencyManager) : base(sessionManager, Repositories.<#=classNode.Name#>, consistencyManager) { } <#foreach (var getBy in classNode.GetBy){#> <#=getBy.IsTry?"[CanBeNull]":"[NotNull]"#> public Cached<#=classNode.Name#> <#=getBy.IsTry?"Try":""#>GetBy<#=getBy.Alias#>(<#=classNode.GetFilterParameters(getBy)#>) { UpdateCacheIfNeeded(); using (ConsistencyManager.GetReadLock()) { return Cache.Values.Single<#=getBy.IsTry?"OrDefault":""#>(e => <#=getBy.GetConditions()#>); } } <#}#> <#foreach (var fieldNode in classNode.GetAllBy){#> [NotNull] [ItemNotNull] public IList<Cached<#=classNode.Name#>> GetAllBy<#=fieldNode.Alias#>(<#=classNode.GetFilterParameters(fieldNode)#>) { UpdateCacheIfNeeded(); using (ConsistencyManager.GetReadLock()) { return Cache.Values.Where(e => <#=fieldNode.GetConditions()#>).ToList(); } } <#}#> [NotNull] protected override Cached<#=classNode.Name#> Convert(<#=classNode.DalBOType#> source) { return new Cached<#=classNode.Name#>(source); } } } <#SaveOutput("Repositories//gen//"+ classNode.Name+".g.cs");#> <#if(classNode.EmitBo != null){#> <?xml version="1.0" encoding="utf-8"?> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Domain" namespace="<#=classNode.EmitBo.Namespace#>"> <class name="<#=classNode.Name#>" dynamic-update="true" dynamic-insert="true"> <id name="Id"> <generator class="assigned" /> </id> <#=string.Join("\n\t\t", classNode.ExplicitlyDefinedFields.Select(f=>classNode.EmitBo.GetMapping(f)))#> <#if (classNode.LogicallyDeletable){#> <property name="IsDeleted" not-null="true" type="boolean"> <column name="IsDeleted" not-null="true" default="0" /> </property> <property name="WhenDeleted" type="DateTime" not-null="false"/> <#}#> </class> </hibernate-mapping> <#SaveOutput("..\\..\\DAL.Hibernate\\Mapping\\gen\\"+classNode.Name+".hbm.xml");#> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using System; using Common.Domain.BO.DB; using Domain.DAL; using Domain.DALV2; using JetBrains.Annotations; <#=classNode.GetIncludedNamespaces()#> namespace <#=classNode.EmitBo.Namespace#> { public partial class <#=classNode.GetBoClassDefinition()#> { [UsedImplicitly] protected <#=classNode.Name#>(){} <#=string.Join("\n\n\t\t", classNode.ExplicitlyDefinedFields.Select(f=>f.GetBOPropertyDefinitionExpression()))#> <#if (classNode.LogicallyDeletable){#> public virtual bool IsDeleted { get; set; } public virtual DateTime? WhenDeleted { get; set; } <#}#> } } <# SaveOutput("..//BO//gen//"+ classNode.Name+".g.cs"); } } #> <!-- The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. --> <objects xmlns="http://www.springframework.net" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:db="http://www.springframework.net/database" xsi:schemaLocation="http://www.springframework.net http://www.springframework.net/xsd/spring-objects.xsd"> <# foreach(var classNode in classes.Where(c => !c.CustomConsistencyManager)) { #> <object id="<#=LowerInitial(classNode.Name)#>CacheManager" type="Domain.DALV2.TransactionSubscribedManager<<#=classNode.BasedOn#>, <#=classNode.DalBOType#>>, Domain" singleton="true"> </object> <#}#> <object id="dalGeneratedListeners" type="System.Collections.Generic.List<Common.Hibernate.DAL.ISessionNotificationListener>, mscorlib"> <constructor-arg> <list element-type="Common.Hibernate.DAL.ISessionNotificationListener, Common.Hibernate"> <# foreach(var classNode in classes) { #> <ref object="<#=LowerInitial(classNode.Name)#>CacheManager"/> <#}#> </list> </constructor-arg> </object> </objects> <#SaveOutput("..//Config//DALSpringDefinitions.g.xml");#> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using Common; using Common.Domain.DAL; using Domain.BO; using Domain.DALV2; using Spring.Context.Support; using JetBrains.Annotations; <#=string.Join("\n", classes.Select(c=>c.GetIncludedNamespaces()).Where(s=>!string.IsNullOrEmpty(s)))#> namespace Domain.DAL { public partial class DALs { private static readonly SafeLazy<DALs> instance = new SafeLazy<DALs>(() => new DALs()); private DALs() { var sessionManager = (ISessionManager)ContextRegistry.GetContext().GetObject("sessionManager"); <# foreach(var classNode in classes){ #> this.<#=LowerInitial(classNode.Name)#> = new <#=classNode.Name#>DAL(sessionManager, (ICacheConsistencyManager<<#=classNode.BasedOn#>, <#=classNode.DalBOType#>>)ContextRegistry.GetContext().GetObject("<#=LowerInitial(classNode.Name)#>CacheManager")); <# } #> } <# foreach(var classNode in classes) { #> [NotNull] private readonly <#=classNode.Name#>DAL <#=LowerInitial(classNode.Name)#>; [NotNull] public static <#=classNode.Name#>DAL <#=classNode.Name#> => instance.Value.<#=LowerInitial(classNode.Name)#>; <#}#> public static void ResetAll() => instance.Value.ResetAllImpl(); private void ResetAllImpl() { <#foreach(var classNode in classes){#> this.<#=LowerInitial(classNode.Name)#>.Reset(); <#}#> } } } <#SaveOutput("DALs.g.cs");#> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using JetBrains.Annotations; namespace Domain.DAL { public partial interface IRepositoryFactory { <#foreach(var classNode in classes.Where(c => c.EmitRepository != null)){#> [NotNull] <#=classNode.EmitRepository.Interface#> <#=classNode.Name#> { get; } <#}#> } } <#SaveOutput("IRepositoryFactory.g.cs");#> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using JetBrains.Annotations; namespace Domain.DAL { public static partial class Repositories { <#foreach(var classNode in classes.Where(c => c.EmitRepository != null)){#> [NotNull] public static <#=classNode.EmitRepository.Interface#> <#=classNode.Name#> => Instance.Value.<#=classNode.Name#>; <#}#> } } <#SaveOutput("Repositories.g.cs");#> /* The file was generated automatically and should not be edited manually. For any changes edit DAL.xml or DAL.tt. */ using Common.Domain.DAL; using Common.Hibernate.DAL; using DAL.Hibernate.Cache.CachingProviders; using Domain.BO; using Domain.DAL; using Domain.DAL.Cache; using Domain.SaveManager; using System; using System.Collections.Generic; using JetBrains.Annotations; using Engine.Main; <#=string.Join("\n", classes.Select(c=>c.GetIncludedNamespaces()).Where(s=>!string.IsNullOrEmpty(s)))#> namespace DAL.Hibernate.DAL { public partial class RepositoryFactory : IRepositoryFactory { public void Init([NotNull] IOrganizationsByNetworkCache organizationsByNetworkCache, [NotNull] INetworkCache networkCache, [NotNull] ITransactionSaveManager transactionSaveManager, [NotNull] ILoginEntryDataProvider loginEntryDataProvider, ListenerNotifier listenerNotifier) { <#foreach(var classNode in classes.Where(c => c.EmitRepository != null)){#> this.<#=classNode.Name#> = new <#=classNode.EmitRepository.GetRepositoryClassName()#>(<#=classNode.EmitRepository.DependsOn#>); <#}#> } <#foreach(var classNode in classes.Where(c => c.EmitRepository != null)){#> [NotNull] public <#=classNode.EmitRepository.Interface#> <#=classNode.Name#> { get; private set; } <#}#> } } <#SaveOutput("..\\..\\DAL.Hibernate\\DAL\\RepositoryFactory.g.cs");#> <#+ private string LowerInitial(string name) { return name[0].ToString().ToLowerInvariant() + name.Substring(1); } private string UpperInitial(string name) { return name[0].ToString().ToUpperInvariant() + name.Substring(1); } void SaveOutput(string outputFileName) { string templateDirectory = Path.GetDirectoryName(Host.TemplateFile); string outputFilePath = Path.Combine(templateDirectory, outputFileName); File.WriteAllText(outputFilePath, this.GenerationEnvironment.ToString()); this.GenerationEnvironment.Remove(0, this.GenerationEnvironment.Length); } #> 


Dan di mana tanpa sejumlah kode generik yang rumit untuk berlangganan membuat perubahan pada database, memperbarui cache sesuai permintaan, dan kesenangan hidup lainnya. Di sini generik ternyata cukup untuk menutup semua kasus penggunaan, ditambah dengan yang sudah digunakan

Kode umum untuk mengakses data
  public abstract class DAL<T, TBase, TCachedBo> where T : CachedEntity<TBase> where TBase : class, IEntity where TCachedBo : class, IIdEntity<Guid> { [NotNull] private readonly ILog log; [NotNull] protected readonly ISessionManager SessionManager; [NotNull] protected readonly IReadonlyRepository<TBase> BaseRepository; [NotNull] protected readonly ICacheConsistencyManager<TBase, TCachedBo> ConsistencyManager; [NotNull] protected Dictionary<Guid, T> Cache = new Dictionary<Guid, T>(); protected DAL([NotNull] ISessionManager sessionManager, [NotNull] IReadonlyRepository<TBase> baseRepository, [NotNull] ICacheConsistencyManager<TBase, TCachedBo> consistencyManager) { this.SessionManager = sessionManager; this.BaseRepository = baseRepository; this.ConsistencyManager = consistencyManager; log = LogManager.GetLogger(GetType()); } [CanBeNull] public T TryGetById(Guid id) { UpdateCacheIfNeeded(); using (ConsistencyManager.GetReadLock()) { return Cache.GetOrDefault(id); } } [NotNull] public T GetById(Guid id) { UpdateCacheIfNeeded(); using (ConsistencyManager.GetReadLock()) { return ValidateEntityFound(Cache.GetOrDefault(id), "{0} with id {1} not found", null, typeof(T), id); } } [NotNull] public TBase GetEntity([NotNull] ISession session, Guid id) { return BaseRepository.GetById(session, id); } [NotNull] public TBase GetEntity([NotNull] ISession session, [NotNull] T e) { return BaseRepository.GetById(session, e.Id); } [NotNull] public HashSet<T> GetByIds([NotNull] HashSet<Guid> ids) { UpdateCacheIfNeeded(); using (ConsistencyManager.GetReadLock()) { return ids .Select(id => Cache.GetOrDefault(id)) .ToHashSet(); } } public void Reset() { ConsistencyManager.Reset(); } protected abstract T Convert(TCachedBo source); protected void UpdateCacheIfNeeded() { if (!ConsistencyManager.UpdateRequired) return; log.Debug($"{typeof(T).Name} DAL: Update required, getting writeLock"); using (var updateScope = ConsistencyManager.GetWriteLock()) { if (updateScope.UpdateRequired ?? ConsistencyManager.UpdateRequired) SessionManager.RunTransacted(session => { try { var updatedEntities = updateScope.GetUpdatedEntities(BaseRepository, session); foreach (var updatedEntity in updatedEntities) if (updatedEntity.Value != null) Cache[updatedEntity.Key] = Convert(updatedEntity.Value); else Cache.Remove(updatedEntity.Key); Reindex(); } catch (Exception) { ConsistencyManager.Reset(); throw; } }); } } /// <summary> /// Reevaluate specific indexes, used for search in cached entities. Called after cache has been updated. /// </summary> protected virtual void Reindex() { } [NotNull] protected T1 ValidateEntityFound<T1>([CanBeNull] T1 entity, [NotNull] string errorMessage, [NotNull] string frontMessage, [NotNull] params object[] p) { if (entity == null) throw new DataAccessException(Util.GetMessage(errorMessage, p), Util.GetMessage(frontMessage, p)); return entity; } } 



Menarik, menurut saya, ternyata kelas memantau konsistensi cache dan mengelola pembaruannya, tempat utama di mana saya harus berpikir tentang menerapkan kunci sehingga semuanya optimal dan minimal memblokir, tetapi pada saat yang sama dilindungi

Sebenarnya implementasi
  [UsedImplicitly] public class TransactionSubscribedManager<TBase, TCachedBo> : EmptySessionNotificationListener, ICacheConsistencyManager<TBase, TCachedBo>, ITransactionNotificationListener where TBase : class, IEntity where TCachedBo : class, IIdEntity<Guid> { public bool UpdateRequired => needFullUpdate || !entitiesToUpdate.IsEmpty; [NotNull] protected readonly ReaderWriterLockSlim LockObj = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion); [NotNull] private readonly ConcurrentDictionary<string, ConcurrentBag<Guid>> changesByTransaction = new ConcurrentDictionary<string, ConcurrentBag<Guid>>(); [NotNull] protected ConcurrentBag<Guid> entitiesToUpdate = new ConcurrentBag<Guid>(); protected bool needFullUpdate = true; public virtual CacheWriteLockScope<TBase, TCachedBo> GetWriteLock() { try { LockObj.EnterWriteLock(); if (needFullUpdate) { needFullUpdate = false; return new CacheWriteLockScope<TBase, TCachedBo>(LockObj); } return new IdBasedCacheWriteLockScope<TBase, TCachedBo>(LockObj, ChangedEntitiesIdsProvider); } catch (Exception) { LockObj.ExitWriteLock(); throw; } } protected ICollection<Guid> ChangedEntitiesIdsProvider() { var ids = new List<Guid>(); var newBag = new ConcurrentBag<Guid>(); var oldBag = Interlocked.Exchange(ref entitiesToUpdate, newBag); while (oldBag.TryTake(out var id)) ids.Add(id); return ids; } public CacheReadLockScope GetReadLock() { return new CacheReadLockScope(LockObj); } public override void OnSaveOrUpdate(ISession session, object entity, Guid id, object[] currentState, object[] previousState, string[] propertyNames, IType[] types) { if (entity is TBase) { var transactionName = HibernateSessionManager.GetTransactionName(); if (!string.IsNullOrEmpty(transactionName)) { if (changesByTransaction.TryAdd(transactionName, new ConcurrentBag<Guid>() { id })) return; changesByTransaction.TryGetValue(transactionName, out var transactionChangedEntities); // ReSharper disable once PossibleNullReferenceException // R# does not have attributes telling that value in dictionary is not null. But we know it. transactionChangedEntities.Add(id); } } } public override void OnDelete(ISession session, object entity, Guid id) { if (entity is TBase) { var transactionName = HibernateSessionManager.GetTransactionName(); if (string.IsNullOrEmpty(transactionName)) return; if (changesByTransaction.TryAdd(transactionName, new ConcurrentBag<Guid>() { id })) return; changesByTransaction.TryGetValue(transactionName, out var transactionChangedEntities); // ReSharper disable once PossibleNullReferenceException // R# does not have attributes telling that value in dictionary is not null. But we know it. transactionChangedEntities.Add(id); } } public void Reset() { needFullUpdate = true; } void ITransactionNotificationListener.AfterCommit(ISession session, string transactionName) { if (changesByTransaction.TryRemove(transactionName, out var transactionChangedEntities) && !transactionChangedEntities.IsEmpty) while (transactionChangedEntities.TryTake(out var id)) entitiesToUpdate.Add(id); } void ITransactionNotificationListener.AfterRollback(ISession session, string transactionName) { changesByTransaction.TryRemove(transactionName, out _); } } 

  public class IdBasedCacheWriteLockScope<TBase, TCachedBo> : CacheWriteLockScope<TBase, TCachedBo> where TBase : class, IEntity where TCachedBo : class, IIdEntity<Guid> { [NotNull] private readonly ICollection<Guid> changedEntitiesIds; public override bool? UpdateRequired => changedEntitiesIds.Any(); public IdBasedCacheWriteLockScope([NotNull] ReaderWriterLockSlim lockObj, [NotNull] Func<ICollection<Guid>> changedEntitiesIdsProvider) : base(lockObj) { changedEntitiesIds = changedEntitiesIdsProvider() ?? throw new InvalidOperationException(nameof(changedEntitiesIdsProvider)); } public override IDictionary<Guid, TCachedBo> GetUpdatedEntities(IReadonlyRepository<TBase> repository, ISession session) { var entities = repository.GetByIds(session, changedEntitiesIds, true).ToDictionary(e => e.Id, be => be as TCachedBo); foreach (var id in changedEntitiesIds.Where(i => !entities.ContainsKey(i))) entities.Add(id, null); return entities; } } 


Tiang menarik yang terungkap selama pengembangan dan ekspansi dalam pertempuran:

  • Hanya saja Anda tidak dapat menarik dan menyimpan entitas terkait dengan tautan langsung di antara mereka. Kalau tidak, ketika kita memodifikasi salah satu entitas, salinan yang ketinggalan zaman tetap berada di objek yang mereferensikannya. Alih-alih membuat logika rumit membatalkan koneksi seperti itu, kami memutuskan saat mengakses oleh properti untuk selalu mendapatkan informasi terbaru dari cache
  • , , ( , , , ). ,
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Source: https://habr.com/ru/post/id453382/


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