annotations/Azaion.Common/Database/DbFactory.cs

using System.Data.SQLite;
using System.Diagnostics;
using System.IO;
using Azaion.Common.DTO;
using Azaion.Common.DTO.Config;
using LinqToDB;
using LinqToDB.DataProvider.SQLite;
using LinqToDB.Mapping;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;

namespace Azaion.Common.Database;

public interface IDbFactory
{
    Task<T> Run<T>(Func<AnnotationsDb, Task<T>> func);
    Task Run(Func<AnnotationsDb, Task> func);
    void SaveToDisk();
}

public class DbFactory : IDbFactory
{
    private readonly AnnotationConfig _annConfig;

    private string MemoryConnStr => "Data Source=:memory:";
    private readonly SQLiteConnection _memoryConnection;
    private readonly DataOptions _memoryDataOptions;

    private string FileConnStr   => $"Data Source={_annConfig.AnnotationsDbFile}";
    private readonly SQLiteConnection _fileConnection;
    private readonly DataOptions _fileDataOptions;

    public DbFactory(IOptions<AnnotationConfig> annConfig, ILogger<DbFactory> logger)
    {
        _annConfig = annConfig.Value;

        _memoryConnection = new SQLiteConnection(MemoryConnStr);
        _memoryConnection.Open();
        _memoryDataOptions = new DataOptions()
            .UseDataProvider(SQLiteTools.GetDataProvider())
            .UseConnection(_memoryConnection)
            .UseMappingSchema(AnnotationsDbSchemaHolder.MappingSchema);
        _ = _memoryDataOptions.UseTracing(TraceLevel.Info, t => logger.LogInformation(t.SqlText));


        _fileConnection = new SQLiteConnection(FileConnStr);
        _fileDataOptions = new DataOptions()
            .UseDataProvider(SQLiteTools.GetDataProvider())
            .UseConnection(_fileConnection)
            .UseMappingSchema(AnnotationsDbSchemaHolder.MappingSchema);
        _ = _fileDataOptions.UseTracing(TraceLevel.Info, t => logger.LogInformation(t.SqlText));

        if (!File.Exists(_annConfig.AnnotationsDbFile))
            CreateDb();
        _fileConnection.Open();
        _fileConnection.BackupDatabase(_memoryConnection, "main", "main", -1, null, -1);
    }

    private void CreateDb()
    {
        SQLiteConnection.CreateFile(_annConfig.AnnotationsDbFile);
        using var db = new AnnotationsDb(_fileDataOptions);
        db.CreateTable<Annotation>();
        db.CreateTable<AnnotationName>();
        db.CreateTable<Detection>();
    }

    public async Task<T> Run<T>(Func<AnnotationsDb, Task<T>> func)
    {
        await using var db = new AnnotationsDb(_memoryDataOptions);
        return await func(db);
    }

    public async Task Run(Func<AnnotationsDb, Task> func)
    {
        await using var db = new AnnotationsDb(_memoryDataOptions);
        await func(db);
    }

    public void SaveToDisk()
    {
        _memoryConnection.BackupDatabase(_fileConnection, "main", "main", -1, null, -1);
    }
}

public static class AnnotationsDbSchemaHolder
{
    public static readonly MappingSchema MappingSchema;

    static AnnotationsDbSchemaHolder()
    {
        MappingSchema = new MappingSchema();
        var builder = new FluentMappingBuilder(MappingSchema);

        builder.Entity<Annotation>()
            .HasTableName(Constants.ANNOTATIONS_TABLENAME)
            .HasPrimaryKey(x => x.Name)
            .Association(a => a.Detections, (a, d) => a.Name == d.AnnotationName);

        builder.Entity<Detection>()
            .HasTableName(Constants.DETECTIONS_TABLENAME);

        builder.Entity<AnnotationName>()
            .HasTableName(Constants.ANNOTATIONS_QUEUE_TABLENAME);

        builder.Build();
    }
}