Add multiple options for internal locking (#14047)

8 files changed, 582 insertions, 8 deletions

diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseConfigurationOptions.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseConfigurationOptions.cs
index b481a106f..682e5019b 100644
--- a/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseConfigurationOptions.cs
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseConfigurationOptions.cs
@@ -9,4 +9,10 @@ public class DatabaseConfigurationOptions
     /// Gets or Sets the type of database jellyfin should use.
     /// </summary>
     public required string DatabaseType { get; set; }
+
+    /// <summary>
+    /// Gets or Sets the kind of locking behavior jellyfin should perform. Possible options are "NoLock", "Pessimistic", "Optimistic".
+    /// Defaults to "NoLock".
+    /// </summary>
+    public DatabaseLockingBehaviorTypes LockingBehavior { get; set; }
 }
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseLockingBehaviorTypes.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseLockingBehaviorTypes.cs
new file mode 100644
index 000000000..3b2a55802
--- /dev/null
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/DbConfiguration/DatabaseLockingBehaviorTypes.cs
@@ -0,0 +1,22 @@
+namespace Jellyfin.Database.Implementations.DbConfiguration;
+
+/// <summary>
+/// Defines all possible methods for locking database access for concurrent queries.
+/// </summary>
+public enum DatabaseLockingBehaviorTypes
+{
+    /// <summary>
+    /// Defines that no explicit application level locking for reads and writes should be done and only provider specific locking should be relied on.
+    /// </summary>
+    NoLock = 0,
+
+    /// <summary>
+    /// Defines a behavior that always blocks all reads while any one write is done.
+    /// </summary>
+    Pessimistic = 1,
+
+    /// <summary>
+    /// Defines that all writes should be attempted and when fail should be retried.
+    /// </summary>
+    Optimistic = 2
+}
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/Jellyfin.Database.Implementations.csproj b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Jellyfin.Database.Implementations.csproj
index 356f96fc9..28c4972d2 100644
--- a/src/Jellyfin.Database/Jellyfin.Database.Implementations/Jellyfin.Database.Implementations.csproj
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Jellyfin.Database.Implementations.csproj
@@ -24,6 +24,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="Polly" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Relational" />
     <PackageReference Include="Microsoft.EntityFrameworkCore.Design">
       <PrivateAssets>all</PrivateAssets>
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/JellyfinDbContext.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/JellyfinDbContext.cs
index 35ad461ec..5163bff8b 100644
--- a/src/Jellyfin.Database/Jellyfin.Database.Implementations/JellyfinDbContext.cs
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/JellyfinDbContext.cs
@@ -1,9 +1,14 @@
 using System;
+using System.Data.Common;
 using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
 using Jellyfin.Database.Implementations.Entities;
 using Jellyfin.Database.Implementations.Entities.Security;
 using Jellyfin.Database.Implementations.Interfaces;
+using Jellyfin.Database.Implementations.Locking;
 using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
 using Microsoft.Extensions.Logging;
 
 namespace Jellyfin.Database.Implementations;
@@ -15,7 +20,8 @@ namespace Jellyfin.Database.Implementations;
 /// <param name="options">The database context options.</param>
 /// <param name="logger">Logger.</param>
 /// <param name="jellyfinDatabaseProvider">The provider for the database engine specific operations.</param>
-public class JellyfinDbContext(DbContextOptions<JellyfinDbContext> options, ILogger<JellyfinDbContext> logger, IJellyfinDatabaseProvider jellyfinDatabaseProvider) : DbContext(options)
+/// <param name="entityFrameworkCoreLocking">The locking behavior.</param>
+public class JellyfinDbContext(DbContextOptions<JellyfinDbContext> options, ILogger<JellyfinDbContext> logger, IJellyfinDatabaseProvider jellyfinDatabaseProvider, IEntityFrameworkCoreLockingBehavior entityFrameworkCoreLocking) : DbContext(options)
 {
     /// <summary>
     /// Gets the <see cref="DbSet{TEntity}"/> containing the access schedules.
@@ -247,19 +253,41 @@ public class JellyfinDbContext(DbContextOptions<JellyfinDbContext> options, ILog
     public DbSet<TrackMetadata> TrackMetadata => Set<TrackMetadata>();*/
 
     /// <inheritdoc/>
-    public override int SaveChanges()
+    public override async Task<int> SaveChangesAsync(
+        bool acceptAllChangesOnSuccess,
+        CancellationToken cancellationToken = default)
     {
-        foreach (var saveEntity in ChangeTracker.Entries()
-                     .Where(e => e.State == EntityState.Modified)
-                     .Select(entry => entry.Entity)
-                     .OfType<IHasConcurrencyToken>())
+        HandleConcurrencyToken();
+
+        try
         {
-            saveEntity.OnSavingChanges();
+            var result = -1;
+            await entityFrameworkCoreLocking.OnSaveChangesAsync(this, async () =>
+            {
+                result = await base.SaveChangesAsync(acceptAllChangesOnSuccess, cancellationToken).ConfigureAwait(false);
+            }).ConfigureAwait(false);
+            return result;
         }
+        catch (Exception e)
+        {
+            logger.LogError(e, "Error trying to save changes.");
+            throw;
+        }
+    }
+
+    /// <inheritdoc/>
+    public override int SaveChanges(bool acceptAllChangesOnSuccess) // SaveChanges(bool) is beeing called by SaveChanges() with default to false.
+    {
+        HandleConcurrencyToken();
 
         try
         {
-            return base.SaveChanges();
+            var result = -1;
+            entityFrameworkCoreLocking.OnSaveChanges(this, () =>
+            {
+                result = base.SaveChanges(acceptAllChangesOnSuccess);
+            });
+            return result;
         }
         catch (Exception e)
         {
@@ -268,6 +296,17 @@ public class JellyfinDbContext(DbContextOptions<JellyfinDbContext> options, ILog
         }
     }
 
+    private void HandleConcurrencyToken()
+    {
+        foreach (var saveEntity in ChangeTracker.Entries()
+                     .Where(e => e.State == EntityState.Modified)
+                     .Select(entry => entry.Entity)
+                     .OfType<IHasConcurrencyToken>())
+        {
+            saveEntity.OnSavingChanges();
+        }
+    }
+
     /// <inheritdoc />
     protected override void OnModelCreating(ModelBuilder modelBuilder)
     {
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/IEntityFrameworkCoreLockingBehavior.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/IEntityFrameworkCoreLockingBehavior.cs
new file mode 100644
index 000000000..465c31212
--- /dev/null
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/IEntityFrameworkCoreLockingBehavior.cs
@@ -0,0 +1,32 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+
+namespace Jellyfin.Database.Implementations.Locking;
+
+/// <summary>
+/// Defines a jellyfin locking behavior that can be configured.
+/// </summary>
+public interface IEntityFrameworkCoreLockingBehavior
+{
+    /// <summary>
+    /// Provides access to the builder to setup any connection related locking behavior.
+    /// </summary>
+    /// <param name="optionsBuilder">The options builder.</param>
+    void Initialise(DbContextOptionsBuilder optionsBuilder);
+
+    /// <summary>
+    /// Will be invoked when changes should be saved in the current locking behavior.
+    /// </summary>
+    /// <param name="context">The database context invoking the action.</param>
+    /// <param name="saveChanges">Callback for performing the actual save changes.</param>
+    void OnSaveChanges(JellyfinDbContext context, Action saveChanges);
+
+    /// <summary>
+    /// Will be invoked when changes should be saved in the current locking behavior.
+    /// </summary>
+    /// <param name="context">The database context invoking the action.</param>
+    /// <param name="saveChanges">Callback for performing the actual save changes.</param>
+    /// <returns>A <see cref="Task"/> representing the asynchronous operation.</returns>
+    Task OnSaveChangesAsync(JellyfinDbContext context, Func<Task> saveChanges);
+}
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/NoLockBehavior.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/NoLockBehavior.cs
new file mode 100644
index 000000000..3b654f4c4
--- /dev/null
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/NoLockBehavior.cs
@@ -0,0 +1,41 @@
+using System;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.Database.Implementations.Locking;
+
+/// <summary>
+/// Default lock behavior. Defines no explicit application locking behavior.
+/// </summary>
+public class NoLockBehavior : IEntityFrameworkCoreLockingBehavior
+{
+    private readonly ILogger<NoLockBehavior> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="NoLockBehavior"/> class.
+    /// </summary>
+    /// <param name="logger">The Application logger.</param>
+    public NoLockBehavior(ILogger<NoLockBehavior> logger)
+    {
+        _logger = logger;
+    }
+
+    /// <inheritdoc/>
+    public void OnSaveChanges(JellyfinDbContext context, Action saveChanges)
+    {
+        saveChanges();
+    }
+
+    /// <inheritdoc/>
+    public void Initialise(DbContextOptionsBuilder optionsBuilder)
+    {
+        _logger.LogInformation("The database locking mode has been set to: NoLock.");
+    }
+
+    /// <inheritdoc/>
+    public async Task OnSaveChangesAsync(JellyfinDbContext context, Func<Task> saveChanges)
+    {
+        await saveChanges().ConfigureAwait(false);
+    }
+}
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/OptimisticLockBehavior.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/OptimisticLockBehavior.cs
new file mode 100644
index 000000000..9395b2e2d
--- /dev/null
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/OptimisticLockBehavior.cs
@@ -0,0 +1,137 @@
+using System;
+using System.Data.Common;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.Extensions.Logging;
+using Polly;
+
+namespace Jellyfin.Database.Implementations.Locking;
+
+/// <summary>
+/// Defines a locking mechanism that will retry any write operation for a few times.
+/// </summary>
+public class OptimisticLockBehavior : IEntityFrameworkCoreLockingBehavior
+{
+    private readonly Policy _writePolicy;
+    private readonly AsyncPolicy _writeAsyncPolicy;
+    private readonly ILogger<OptimisticLockBehavior> _logger;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="OptimisticLockBehavior"/> class.
+    /// </summary>
+    /// <param name="logger">The application logger.</param>
+    public OptimisticLockBehavior(ILogger<OptimisticLockBehavior> logger)
+    {
+        TimeSpan[] sleepDurations = [
+            TimeSpan.FromMilliseconds(50),
+            TimeSpan.FromMilliseconds(50),
+            TimeSpan.FromMilliseconds(250),
+            TimeSpan.FromMilliseconds(150),
+            TimeSpan.FromMilliseconds(500),
+            TimeSpan.FromMilliseconds(500),
+            TimeSpan.FromSeconds(3)
+        ];
+        _logger = logger;
+        _writePolicy = Policy.HandleInner<Exception>(e => e.Message.Contains("database is locked", StringComparison.InvariantCultureIgnoreCase)).WaitAndRetry(sleepDurations, RetryHandle);
+        _writeAsyncPolicy = Policy.HandleInner<Exception>(e => e.Message.Contains("database is locked", StringComparison.InvariantCultureIgnoreCase)).WaitAndRetryAsync(sleepDurations, RetryHandle);
+
+        void RetryHandle(Exception exception, TimeSpan timespan, int retryNo, Context context)
+        {
+            if (retryNo < sleepDurations.Length)
+            {
+                _logger.LogWarning("Operation failed retry {RetryNo}", retryNo);
+            }
+            else
+            {
+                _logger.LogError(exception, "Operation failed retry {RetryNo}", retryNo);
+            }
+        }
+    }
+
+    /// <inheritdoc/>
+    public void Initialise(DbContextOptionsBuilder optionsBuilder)
+    {
+        _logger.LogInformation("The database locking mode has been set to: Optimistic.");
+        optionsBuilder.AddInterceptors(new RetryInterceptor(_writeAsyncPolicy, _writePolicy));
+        optionsBuilder.AddInterceptors(new TransactionLockingInterceptor(_writeAsyncPolicy, _writePolicy));
+    }
+
+    /// <inheritdoc/>
+    public void OnSaveChanges(JellyfinDbContext context, Action saveChanges)
+    {
+        _writePolicy.ExecuteAndCapture(saveChanges);
+    }
+
+    /// <inheritdoc/>
+    public async Task OnSaveChangesAsync(JellyfinDbContext context, Func<Task> saveChanges)
+    {
+        await _writeAsyncPolicy.ExecuteAndCaptureAsync(saveChanges).ConfigureAwait(false);
+    }
+
+    private sealed class TransactionLockingInterceptor : DbTransactionInterceptor
+    {
+        private readonly AsyncPolicy _asyncRetryPolicy;
+        private readonly Policy _retryPolicy;
+
+        public TransactionLockingInterceptor(AsyncPolicy asyncRetryPolicy, Policy retryPolicy)
+        {
+            _asyncRetryPolicy = asyncRetryPolicy;
+            _retryPolicy = retryPolicy;
+        }
+
+        public override InterceptionResult<DbTransaction> TransactionStarting(DbConnection connection, TransactionStartingEventData eventData, InterceptionResult<DbTransaction> result)
+        {
+            return InterceptionResult<DbTransaction>.SuppressWithResult(_retryPolicy.Execute(() => connection.BeginTransaction(eventData.IsolationLevel)));
+        }
+
+        public override async ValueTask<InterceptionResult<DbTransaction>> TransactionStartingAsync(DbConnection connection, TransactionStartingEventData eventData, InterceptionResult<DbTransaction> result, CancellationToken cancellationToken = default)
+        {
+            return InterceptionResult<DbTransaction>.SuppressWithResult(await _asyncRetryPolicy.ExecuteAsync(async () => await connection.BeginTransactionAsync(eventData.IsolationLevel, cancellationToken).ConfigureAwait(false)).ConfigureAwait(false));
+        }
+    }
+
+    private sealed class RetryInterceptor : DbCommandInterceptor
+    {
+        private readonly AsyncPolicy _asyncRetryPolicy;
+        private readonly Policy _retryPolicy;
+
+        public RetryInterceptor(AsyncPolicy asyncRetryPolicy, Policy retryPolicy)
+        {
+            _asyncRetryPolicy = asyncRetryPolicy;
+            _retryPolicy = retryPolicy;
+        }
+
+        public override InterceptionResult<int> NonQueryExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<int> result)
+        {
+            return InterceptionResult<int>.SuppressWithResult(_retryPolicy.Execute(command.ExecuteNonQuery));
+        }
+
+        public override async ValueTask<InterceptionResult<int>> NonQueryExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<int> result, CancellationToken cancellationToken = default)
+        {
+            return InterceptionResult<int>.SuppressWithResult(await _asyncRetryPolicy.ExecuteAsync(async () => await command.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false)).ConfigureAwait(false));
+        }
+
+        public override InterceptionResult<object> ScalarExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<object> result)
+        {
+            return InterceptionResult<object>.SuppressWithResult(_retryPolicy.Execute(() => command.ExecuteScalar()!));
+        }
+
+        public override async ValueTask<InterceptionResult<object>> ScalarExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<object> result, CancellationToken cancellationToken = default)
+        {
+            return InterceptionResult<object>.SuppressWithResult((await _asyncRetryPolicy.ExecuteAsync(async () => await command.ExecuteScalarAsync(cancellationToken).ConfigureAwait(false)!).ConfigureAwait(false))!);
+        }
+
+        public override InterceptionResult<DbDataReader> ReaderExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result)
+        {
+            return InterceptionResult<DbDataReader>.SuppressWithResult(_retryPolicy.Execute(command.ExecuteReader));
+        }
+
+        public override async ValueTask<InterceptionResult<DbDataReader>> ReaderExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result, CancellationToken cancellationToken = default)
+        {
+            return InterceptionResult<DbDataReader>.SuppressWithResult(await _asyncRetryPolicy.ExecuteAsync(async () => await command.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false)).ConfigureAwait(false));
+        }
+    }
+}
diff --git a/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/PessimisticLockBehavior.cs b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/PessimisticLockBehavior.cs
new file mode 100644
index 000000000..2d6bc6902
--- /dev/null
+++ b/src/Jellyfin.Database/Jellyfin.Database.Implementations/Locking/PessimisticLockBehavior.cs
@@ -0,0 +1,296 @@
+#pragma warning disable MT1013 // Releasing lock without guarantee of execution
+#pragma warning disable MT1012 // Acquiring lock without guarantee of releasing
+
+using System;
+using System.Data;
+using System.Data.Common;
+using System.Runtime.CompilerServices;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.EntityFrameworkCore.Diagnostics;
+using Microsoft.Extensions.Logging;
+
+namespace Jellyfin.Database.Implementations.Locking;
+
+/// <summary>
+/// A locking behavior that will always block any operation while a write is requested. Mimicks the old SqliteRepository behavior.
+/// </summary>
+public class PessimisticLockBehavior : IEntityFrameworkCoreLockingBehavior
+{
+    private readonly ILogger<PessimisticLockBehavior> _logger;
+    private readonly ILoggerFactory _loggerFactory;
+
+    /// <summary>
+    /// Initializes a new instance of the <see cref="PessimisticLockBehavior"/> class.
+    /// </summary>
+    /// <param name="logger">The application logger.</param>
+    /// <param name="loggerFactory">The logger factory.</param>
+    public PessimisticLockBehavior(ILogger<PessimisticLockBehavior> logger, ILoggerFactory loggerFactory)
+    {
+        _logger = logger;
+        _loggerFactory = loggerFactory;
+    }
+
+    private static ReaderWriterLockSlim DatabaseLock { get; } = new(LockRecursionPolicy.SupportsRecursion);
+
+    /// <inheritdoc/>
+    public void OnSaveChanges(JellyfinDbContext context, Action saveChanges)
+    {
+        using (DbLock.EnterWrite(_logger))
+        {
+            saveChanges();
+        }
+    }
+
+    /// <inheritdoc/>
+    public void Initialise(DbContextOptionsBuilder optionsBuilder)
+    {
+        _logger.LogInformation("The database locking mode has been set to: Pessimistic.");
+        optionsBuilder.AddInterceptors(new CommandLockingInterceptor(_loggerFactory.CreateLogger<CommandLockingInterceptor>()));
+        optionsBuilder.AddInterceptors(new TransactionLockingInterceptor(_loggerFactory.CreateLogger<TransactionLockingInterceptor>()));
+    }
+
+    /// <inheritdoc/>
+    public async Task OnSaveChangesAsync(JellyfinDbContext context, Func<Task> saveChanges)
+    {
+        using (DbLock.EnterWrite(_logger))
+        {
+            await saveChanges().ConfigureAwait(false);
+        }
+    }
+
+    private sealed class TransactionLockingInterceptor : DbTransactionInterceptor
+    {
+        private readonly ILogger _logger;
+
+        public TransactionLockingInterceptor(ILogger logger)
+        {
+            _logger = logger;
+        }
+
+        public override InterceptionResult<DbTransaction> TransactionStarting(DbConnection connection, TransactionStartingEventData eventData, InterceptionResult<DbTransaction> result)
+        {
+            DbLock.BeginWriteLock(_logger);
+
+            return base.TransactionStarting(connection, eventData, result);
+        }
+
+        public override ValueTask<InterceptionResult<DbTransaction>> TransactionStartingAsync(DbConnection connection, TransactionStartingEventData eventData, InterceptionResult<DbTransaction> result, CancellationToken cancellationToken = default)
+        {
+            DbLock.BeginWriteLock(_logger);
+
+            return base.TransactionStartingAsync(connection, eventData, result, cancellationToken);
+        }
+
+        public override void TransactionCommitted(DbTransaction transaction, TransactionEndEventData eventData)
+        {
+            DbLock.EndWriteLock(_logger);
+
+            base.TransactionCommitted(transaction, eventData);
+        }
+
+        public override Task TransactionCommittedAsync(DbTransaction transaction, TransactionEndEventData eventData, CancellationToken cancellationToken = default)
+        {
+            DbLock.EndWriteLock(_logger);
+
+            return base.TransactionCommittedAsync(transaction, eventData, cancellationToken);
+        }
+
+        public override void TransactionFailed(DbTransaction transaction, TransactionErrorEventData eventData)
+        {
+            DbLock.EndWriteLock(_logger);
+
+            base.TransactionFailed(transaction, eventData);
+        }
+
+        public override Task TransactionFailedAsync(DbTransaction transaction, TransactionErrorEventData eventData, CancellationToken cancellationToken = default)
+        {
+            DbLock.EndWriteLock(_logger);
+
+            return base.TransactionFailedAsync(transaction, eventData, cancellationToken);
+        }
+
+        public override void TransactionRolledBack(DbTransaction transaction, TransactionEndEventData eventData)
+        {
+            DbLock.EndWriteLock(_logger);
+
+            base.TransactionRolledBack(transaction, eventData);
+        }
+
+        public override Task TransactionRolledBackAsync(DbTransaction transaction, TransactionEndEventData eventData, CancellationToken cancellationToken = default)
+        {
+            DbLock.EndWriteLock(_logger);
+
+            return base.TransactionRolledBackAsync(transaction, eventData, cancellationToken);
+        }
+    }
+
+    /// <summary>
+    /// Adds strict read/write locking.
+    /// </summary>
+    private sealed class CommandLockingInterceptor : DbCommandInterceptor
+    {
+        private readonly ILogger _logger;
+
+        public CommandLockingInterceptor(ILogger logger)
+        {
+            _logger = logger;
+        }
+
+        public override InterceptionResult<int> NonQueryExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<int> result)
+        {
+            using (DbLock.EnterWrite(_logger, command))
+            {
+                return InterceptionResult<int>.SuppressWithResult(command.ExecuteNonQuery());
+            }
+        }
+
+        public override async ValueTask<InterceptionResult<int>> NonQueryExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<int> result, CancellationToken cancellationToken = default)
+        {
+            using (DbLock.EnterWrite(_logger, command))
+            {
+                return InterceptionResult<int>.SuppressWithResult(await command.ExecuteNonQueryAsync(cancellationToken).ConfigureAwait(false));
+            }
+        }
+
+        public override InterceptionResult<object> ScalarExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<object> result)
+        {
+            using (DbLock.EnterRead(_logger))
+            {
+                return InterceptionResult<object>.SuppressWithResult(command.ExecuteScalar()!);
+            }
+        }
+
+        public override async ValueTask<InterceptionResult<object>> ScalarExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<object> result, CancellationToken cancellationToken = default)
+        {
+            using (DbLock.EnterRead(_logger))
+            {
+                return InterceptionResult<object>.SuppressWithResult((await command.ExecuteScalarAsync(cancellationToken).ConfigureAwait(false))!);
+            }
+        }
+
+        public override InterceptionResult<DbDataReader> ReaderExecuting(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result)
+        {
+            using (DbLock.EnterRead(_logger))
+            {
+                return InterceptionResult<DbDataReader>.SuppressWithResult(command.ExecuteReader()!);
+            }
+        }
+
+        public override async ValueTask<InterceptionResult<DbDataReader>> ReaderExecutingAsync(DbCommand command, CommandEventData eventData, InterceptionResult<DbDataReader> result, CancellationToken cancellationToken = default)
+        {
+            using (DbLock.EnterRead(_logger))
+            {
+                return InterceptionResult<DbDataReader>.SuppressWithResult(await command.ExecuteReaderAsync(cancellationToken).ConfigureAwait(false));
+            }
+        }
+    }
+
+    private sealed class DbLock : IDisposable
+    {
+        private readonly Action? _action;
+        private bool _disposed;
+
+        private static readonly IDisposable _noLock = new DbLock(null) { _disposed = true };
+        private static (string Command, Guid Id, DateTimeOffset QueryDate, bool Printed) _blockQuery;
+
+        public DbLock(Action? action = null)
+        {
+            _action = action;
+        }
+
+#pragma warning disable IDISP015 // Member should not return created and cached instance
+        public static IDisposable EnterWrite(ILogger logger, IDbCommand? command = null, [CallerMemberName] string? callerMemberName = null, [CallerLineNumber] int? callerNo = null)
+#pragma warning restore IDISP015 // Member should not return created and cached instance
+        {
+            logger.LogTrace("Enter Write for {Caller}:{Line}", callerMemberName, callerNo);
+            if (DatabaseLock.IsWriteLockHeld)
+            {
+                logger.LogTrace("Write Held {Caller}:{Line}", callerMemberName, callerNo);
+                return _noLock;
+            }
+
+            BeginWriteLock(logger, command, callerMemberName, callerNo);
+            return new DbLock(() =>
+            {
+                EndWriteLock(logger, callerMemberName, callerNo);
+            });
+        }
+
+#pragma warning disable IDISP015 // Member should not return created and cached instance
+        public static IDisposable EnterRead(ILogger logger, [CallerMemberName] string? callerMemberName = null, [CallerLineNumber] int? callerNo = null)
+#pragma warning restore IDISP015 // Member should not return created and cached instance
+        {
+            logger.LogTrace("Enter Read {Caller}:{Line}", callerMemberName, callerNo);
+            if (DatabaseLock.IsWriteLockHeld)
+            {
+                logger.LogTrace("Write Held {Caller}:{Line}", callerMemberName, callerNo);
+                return _noLock;
+            }
+
+            BeginReadLock(logger, callerMemberName, callerNo);
+            return new DbLock(() =>
+            {
+                ExitReadLock(logger, callerMemberName, callerNo);
+            });
+        }
+
+        public static void BeginWriteLock(ILogger logger, IDbCommand? command = null, [CallerMemberName] string? callerMemberName = null, [CallerLineNumber] int? callerNo = null)
+        {
+            logger.LogTrace("Aquire Write {Caller}:{Line}", callerMemberName, callerNo);
+            if (!DatabaseLock.TryEnterWriteLock(TimeSpan.FromMilliseconds(1000)))
+            {
+                var blockingQuery = _blockQuery;
+                if (!blockingQuery.Printed)
+                {
+                    _blockQuery = (blockingQuery.Command, blockingQuery.Id, blockingQuery.QueryDate, true);
+                    logger.LogInformation("QueryLock: {Id} --- {Query}", blockingQuery.Id, blockingQuery.Command);
+                }
+
+                logger.LogInformation("Query congestion detected: '{Id}' since '{Date}'", blockingQuery.Id, blockingQuery.QueryDate);
+
+                DatabaseLock.EnterWriteLock();
+
+                logger.LogInformation("Query congestion cleared: '{Id}' for '{Date}'", blockingQuery.Id, DateTimeOffset.Now - blockingQuery.QueryDate);
+            }
+
+            _blockQuery = (command?.CommandText ?? "Transaction", Guid.NewGuid(), DateTimeOffset.Now, false);
+
+            logger.LogTrace("Write Aquired {Caller}:{Line}", callerMemberName, callerNo);
+        }
+
+        public static void BeginReadLock(ILogger logger, [CallerMemberName] string? callerMemberName = null, [CallerLineNumber] int? callerNo = null)
+        {
+            logger.LogTrace("Aquire Write {Caller}:{Line}", callerMemberName, callerNo);
+            DatabaseLock.EnterReadLock();
+            logger.LogTrace("Read Aquired {Caller}:{Line}", callerMemberName, callerNo);
+        }
+
+        public static void EndWriteLock(ILogger logger, [CallerMemberName] string? callerMemberName = null, [CallerLineNumber] int? callerNo = null)
+        {
+            logger.LogTrace("Release Write {Caller}:{Line}", callerMemberName, callerNo);
+            DatabaseLock.ExitWriteLock();
+        }
+
+        public static void ExitReadLock(ILogger logger, [CallerMemberName] string? callerMemberName = null, [CallerLineNumber] int? callerNo = null)
+        {
+            logger.LogTrace("Release Read {Caller}:{Line}", callerMemberName, callerNo);
+            DatabaseLock.ExitReadLock();
+        }
+
+        public void Dispose()
+        {
+            if (_disposed)
+            {
+                return;
+            }
+
+            _disposed = true;
+            if (_action is not null)
+            {
+                _action();
+            }
+        }
+    }
+}