feat(mongodb): Add MongoClientFactory to reuse MongoClient per connection string"

framework/src/Volo.Abp.MongoDB/Volo/Abp/MongoDB/AbpMongoDbModule.cs

@@ -8,6 +8,7 @@ using Volo.Abp.Domain;
 using Volo.Abp.Domain.Entities.Events.Distributed;
 using Volo.Abp.Domain.Repositories.MongoDB;
 using Volo.Abp.Modularity;
+using Volo.Abp.MongoDB.Clients;
 using Volo.Abp.MongoDB.DependencyInjection;
 using Volo.Abp.Uow.MongoDB;
 using Volo.Abp.MongoDB.DistributedEvents;
@@ -30,6 +31,8 @@ public class AbpMongoDbModule : AbpModule
 
     public override void ConfigureServices(ServiceConfigurationContext context)
     {
+        context.Services.AddSingleton<IMongoClientFactory, MongoClientFactory>();
+
         context.Services.TryAddTransient(
             typeof(IMongoDbContextProvider<>),
             typeof(UnitOfWorkMongoDbContextProvider<>)
@@ -61,4 +64,4 @@ public class AbpMongoDbModule : AbpModule
             options.IgnoredEventSelectors.Add<IncomingEventRecord>();
         });
     }
-}
+}

framework/src/Volo.Abp.MongoDB/Volo/Abp/MongoDB/Clients/IMongoClientFactory.cs

@@ -0,0 +1,9 @@
+using MongoDB.Driver;
+using Volo.Abp.DependencyInjection;
+
+namespace Volo.Abp.MongoDB.Clients;
+
+public interface IMongoClientFactory : ISingletonDependency
+{
+    MongoClient GetClient(string connectionString);
+}

framework/src/Volo.Abp.MongoDB/Volo/Abp/MongoDB/Clients/MongoClientFactory.cs

@@ -0,0 +1,32 @@
+using System;
+using System.Collections.Concurrent;
+using Microsoft.Extensions.Options;
+using MongoDB.Driver;
+
+namespace Volo.Abp.MongoDB.Clients;
+
+public class MongoClientFactory : IMongoClientFactory
+{
+    private readonly ConcurrentDictionary<string, MongoClient> _clients = new();
+    private readonly AbpMongoDbContextOptions Options;
+
+    public MongoClientFactory(IOptions<AbpMongoDbContextOptions> options)
+    {
+        Options = options.Value;
+    }
+
+    public MongoClient GetClient(string connectionString)
+    {
+        if (string.IsNullOrWhiteSpace(connectionString))
+        {
+            throw new ArgumentException("Connection string must not be null or empty.", nameof(connectionString));
+        }
+
+        return _clients.GetOrAdd(connectionString, cs =>
+        {
+            var mongoClientSettings = MongoClientSettings.FromUrl(new MongoUrl(cs));
+            Options.MongoClientSettingsConfigurer?.Invoke(mongoClientSettings);
+            return new MongoClient(mongoClientSettings);
+        });
+    }
+}

framework/src/Volo.Abp.MongoDB/Volo/Abp/Uow/MongoDB/UnitOfWorkMongoDbContextProvider.cs

@@ -9,6 +9,7 @@ using MongoDB.Bson;
 using MongoDB.Driver;
 using Volo.Abp.Data;
 using Volo.Abp.MongoDB;
+using Volo.Abp.MongoDB.Clients;
 using Volo.Abp.MultiTenancy;
 using Volo.Abp.Threading;
 
@@ -26,6 +27,7 @@ public class UnitOfWorkMongoDbContextProvider<TMongoDbContext> : IMongoDbContext
     protected readonly ICurrentTenant CurrentTenant;
     protected readonly AbpMongoDbContextOptions Options;
     protected readonly IMongoDbContextTypeProvider DbContextTypeProvider;
+    protected readonly IMongoClientFactory MongoClientFactory;
 
     public UnitOfWorkMongoDbContextProvider(
         IUnitOfWorkManager unitOfWorkManager,
@@ -33,13 +35,14 @@ public class UnitOfWorkMongoDbContextProvider<TMongoDbContext> : IMongoDbContext
         ICancellationTokenProvider cancellationTokenProvider,
         ICurrentTenant currentTenant,
         IOptions<AbpMongoDbContextOptions> options,
-        IMongoDbContextTypeProvider dbContextTypeProvider)
+        IMongoDbContextTypeProvider dbContextTypeProvider, IMongoClientFactory mongoClientFactory)
     {
         UnitOfWorkManager = unitOfWorkManager;
         ConnectionStringResolver = connectionStringResolver;
         CancellationTokenProvider = cancellationTokenProvider;
         CurrentTenant = currentTenant;
         DbContextTypeProvider = dbContextTypeProvider;
+        MongoClientFactory = mongoClientFactory;
         Options = options.Value;
 
         Logger = NullLogger<UnitOfWorkMongoDbContextProvider<TMongoDbContext>>.Instance;
@@ -77,12 +80,11 @@ public class UnitOfWorkMongoDbContextProvider<TMongoDbContext> : IMongoDbContext
             databaseName = ConnectionStringNameAttribute.GetConnStringName(targetDbContextType);
         }
 
-        //TODO: Create only single MongoDbClient per connection string in an application (extract MongoClientCache for example).
         var databaseApi = unitOfWork.GetOrAddDatabaseApi(
             dbContextKey,
             () => new MongoDbDatabaseApi(CreateDbContext(unitOfWork, mongoUrl, databaseName)));
 
-        return (TMongoDbContext)((MongoDbDatabaseApi) databaseApi).DbContext;
+        return (TMongoDbContext)((MongoDbDatabaseApi)databaseApi).DbContext;
     }
 
     public virtual async Task<TMongoDbContext> GetDbContextAsync(CancellationToken cancellationToken = default)
@@ -121,11 +123,10 @@ public class UnitOfWorkMongoDbContextProvider<TMongoDbContext> : IMongoDbContext
             unitOfWork.AddDatabaseApi(dbContextKey, databaseApi);
         }
 
-        return (TMongoDbContext)((MongoDbDatabaseApi) databaseApi).DbContext;
+        return (TMongoDbContext)((MongoDbDatabaseApi)databaseApi).DbContext;
     }
 
     [Obsolete("Use CreateDbContextAsync")]
-
     private TMongoDbContext CreateDbContext(IUnitOfWork unitOfWork, MongoUrl mongoUrl, string databaseName)
     {
         var client = CreateMongoClient(mongoUrl);
@@ -299,14 +300,11 @@ public class UnitOfWorkMongoDbContextProvider<TMongoDbContext> : IMongoDbContext
 
     protected virtual MongoClient CreateMongoClient(MongoUrl mongoUrl)
     {
-        var mongoClientSettings = MongoClientSettings.FromUrl(mongoUrl);
-        Options.MongoClientSettingsConfigurer?.Invoke(mongoClientSettings);
-
-        return new MongoClient(mongoClientSettings);
+        return MongoClientFactory.GetClient(mongoUrl.ToString());
     }
 
     protected virtual CancellationToken GetCancellationToken(CancellationToken preferredValue = default)
     {
         return CancellationTokenProvider.FallbackToProvider(preferredValue);
     }
-}
+}

framework/test/Volo.Abp.MongoDB.Tests/Volo/Abp/MongoDB/Clients/MongoClient_Factory_Tests.cs

@@ -0,0 +1,82 @@
+using System;
+using System.Threading.Tasks;
+using MongoDB.Driver;
+using Volo.Abp.TestApp.Testing;
+using Xunit;
+
+namespace Volo.Abp.MongoDB.Clients;
+
+[Collection(MongoTestCollection.Name)]
+public class MongoClient_Factory_Tests : MongoDbTestBase
+{
+    private readonly IMongoClientFactory _factory;
+
+    public MongoClient_Factory_Tests()
+    {
+        _factory = GetRequiredService<IMongoClientFactory>();
+    }
+
+    [Fact]
+    public void Should_Return_Same_Instance_For_Same_ConnectionString()
+    {
+        // Arrange
+        var connectionString = "mongodb://localhost:27017/my-db";
+
+        // Act
+        var client1 = _factory.GetClient(connectionString);
+        var client2 = _factory.GetClient(connectionString);
+
+        // Assert
+        Assert.Same(client1, client2);
+    }
+
+    [Fact]
+    public void Should_Return_Different_Instances_For_Different_ConnectionStrings()
+    {
+        // Arrange
+        var cs1 = "mongodb://localhost:27017/db1";
+        var cs2 = "mongodb://localhost:27017/db2";
+
+        // Act
+        var client1 = _factory.GetClient(cs1);
+        var client2 = _factory.GetClient(cs2);
+
+        // Assert
+        Assert.NotSame(client1, client2);
+    }
+
+    [Fact]
+    public void Should_Not_Throw_For_Valid_But_Unreachable_Connection()
+    {
+        // Arrange
+        var cs = "mongodb://unreachablehost:12345/any";
+
+        // Act
+        var client = _factory.GetClient(cs);
+
+        // Assert
+        Assert.NotNull(client); // Even though it's not connectable now, the instance can be created
+    }
+
+    [Fact]
+    public void Should_Be_ThreadSafe_When_Accessed_Concurrently()
+    {
+        var connectionString = "mongodb://localhost:27017/threadsafe";
+        MongoClient[] results = new MongoClient[100];
+
+        Parallel.For(0, 100, i =>
+        {
+            results[i] = _factory.GetClient(connectionString);
+        });
+
+        Assert.All(results, client => Assert.Same(results[0], client));
+    }
+    
+    [Theory]
+    [InlineData(null)]
+    [InlineData("")]
+    public void Should_Throw_If_ConnectionString_Is_Null_Or_Empty(string connectionString)
+    {
+        Assert.Throws<ArgumentException>(() => _factory.GetClient(connectionString));
+    }
+}