Jobby.Postgres 0.1.0

Jobby

High-performance and reliable .NET library for background tasks, designed for distributed applications.

Key Features

• Scheduled tasks
• Queue-based task execution
• Transactional creation of multiple tasks
• Configurable execution order for multiple tasks
• Retry policies for failed tasks
• Proper operation in distributed applications
• Fault tolerance and component failure resilience
• High performance
• Low resource consumption on both .NET application and database sides

Usage Guide

Installation

To use Jobby, install the Jobby.Core package and a storage package (currently only PostgreSQL is supported):

dotnet package add Jobby.Core  
dotnet package add Jobby.Postgres  

For ASP.NET Core integration, also install the Jobby.AspNetCore package:

dotnet package add Jobby.AspNetCore  

Database Table Creation

Execute the SQL script to create required database tables.

Defining Background Tasks

To define a background task, implement the IJobCommand interface for the task parameters and IJobCommandHandler for the task logic:

public class SendEmailCommand : IJobCommand  
{  
    // Properties can contain any parameters to be passed to the task  
    public string Email { get; init; }  

    // Return a unique name identifying the task  
    public static string GetJobName() => "SendEmail";  

    // Return a flag indicating whether the task can be automatically restarted  
    // if the executing server is presumed to have failed.  
    // Recommended to return true only for idempotent tasks.  
    public bool CanBeRestarted() => true;  
}  

public class SendEmailCommandHandler : IJobCommandHandler<SendEmailCommand>  
{  
    // Dependency injection is supported when using Jobby.AspNetCore  
    private readonly IEmailService _emailService;  
    public SendEmailCommandHandler(IEmailService logger)  
    {  
        _logger = logger;  
    }  

    public async Task ExecuteAsync(SendEmailCommand command, JobExecutionContext ctx)  
    {  
        // Implement your task logic here  
        // command - task parameters  
        // ctx - contains cancellationToken and additional task execution info  
    }  
}  

Library Configuration

ASP.NET Core Configuration

To add Jobby to an ASP.NET Core application, use the AddJobby extension method:

var dataSource = NpgsqlDataSource.Create(databaseConnectionString);  

builder.Services.AddJobby(jobbyBuilder =>  
{  
    jobbyBuilder  
        .UsePostgresql(dataSource)  
        .UseServerSettings(new JobbyServerSettings  
        {  
            // Maximum number of concurrently executing tasks  
            MaxDegreeOfParallelism = 10,  

            // Maximum number of tasks fetched from queue per query  
            TakeToProcessingBatchSize = 10,  
        })  
        .UseDefaultRetryPolicy(new RetryPolicy  
        {  
            // Maximum number of task execution attempts  
            MaxCount = 3,  

            // Delays between retry attempts (in seconds)  
            IntervalsSeconds = [1, 2]  
        })  
        // Assemblies containing your IJobCommand and IJobCommandHandler implementations  
        .AddJobsFromAssemblies(typeof(SendEmailCommand).Assembly);  
});  

Full ASP.NET Core example: Jobby.Samples.AspNet.

Non-ASP.NET Core Configuration

For non-ASP.NET Core usage, create a JobbyServicesBuilder instance:

var jobbyBuilder = new JobbyServicesBuilder();  
jobbyBuilder  
        .UsePostgresql(dataSource)  
        // scopeFactory - your custom scope factory implementation  
        .UseExecutionScopeFactory(scopeFactory)  
        .AddJobsFromAssemblies(typeof(SendEmailCommand).Assembly);  

// Service for creating tasks  
var jobbyClient = builder.CreateJobbyClient();  

// Background task execution service  
var jobbyServer = builder.CreateJobbyServer();  
jobbyServer.StartBackgroundService(); // Start background service  
//...  
jobbyServer.SendStopSignal(); // Stop service  

Full console application example: Jobby.Samples.CliJobsSample.

Enqueueing Tasks

Use the IJobbyClient service to enqueue tasks (available via DI in ASP.NET Core or from JobbyServicesBuilder otherwise).

Single Task

var command = new SendEmailCommand { Email = "some@email.com" };  

// Enqueue task for execution as soon as possible  
await jobbyClient.EnqueueCommandAsync(command);   

// Enqueue task for execution no earlier than specified time  
await jobbyClient.EnqueueCommandAsync(command, DateTime.UtcNow.AddHours(1));  

Multiple Tasks

For transactional creation of multiple tasks:

var jobs = new List<JobCreationModel>  
{  
    jobbyClient.Factory
        .Create(new SendEmailCommand { Email = "first@email.com" }),  
    
    jobbyClient.Factory
        .Create(new SendEmailCommand { Email = "second@email.com" }),  
};  

await jobbyClient.EnqueueBatchAsync(jobs);  

To enforce strict execution order:

var sequenceBuilder = jobbyClient.Factory.CreateSequenceBuilder();  

// Tasks will execute in strict order  
sequenceBuilder.Add(jobbyClient.Factory
    .Create(new SendEmailCommand { Email = "first@email.com" }));  

sequenceBuilder.Add(jobbyClient.Factory
    .Create(new SendEmailCommand { Email = "second@email.com" }));  

var jobs = sequenceBuilder.GetJobs();  

await jobbyClient.EnqueueBatchAsync(jobs);  

Using EntityFramework

For EF Core integration:

public class YourDbContext : DbContext  
{  
    // Add DbSet for JobCreationModel  
    public DbSet<JobCreationModel> Jobs { get; set; }  

    protected override void OnModelCreating(ModelBuilder modelBuilder)  
    {  
        modelBuilder.Entity<JobCreationModel>().ToTable("jobby_jobs");  
        modelBuilder.Entity<JobCreationModel>().HasKey(x => x.Id);  
        // Apply snake_case naming convention for other configurations  
    }  
}  

// Enqueue via EF  
var command = new SendEmailCommand { Email = "some@email.com" };  
var jobEntity = jobbyClient.Factory.Create(command);  
_dbContext.Jobs.Add(job);  
await _dbContext.SaveChangesAsync();  

EF Core example: Jobby.Samples.AspNet.

Scheduled Tasks

// Scheduled tasks are defined similarly to regular tasks  

public class RecurrentJobCommand : IJobCommand  
{  
    public static string GetJobName() => "SomeRecurrentJob";  
    public bool CanBeRestarted() => true;  
}  

public class RecurrentJobHandler : IJobCommandHandler<RecurrentJobCommand>  
{  
    public async Task ExecuteAsync(SendEmailCommand command, JobExecutionContext ctx)  
    {  
        // Your scheduled task logic  
    }  
}  

// Schedule task using cron expression  
// Will execute every 5 minutes  
var command = new RecurrentJobCommand();  
await jobbyClient.ScheduleRecurrentAsync(command, "*/5 * * * *");  

Retry Policy Configuration

Failed tasks can be retried according to configured policies.

A RetryPolicy defines:

• Maximum total execution attempts
• Delays between retries (in seconds)

var retryPolicy = new RetryPolicy  
{  
    // Maximum total execution attempts  
    // Value of 3 means 1 initial attempt + 2 retries  
    MaxCount = 3,  

    // Delays between retry attempts  
    // First retry after 1 second, second after 2 seconds  
    IntervalsSeconds = [1, 2]  
};  

// IntervalSeconds doesn't require all values  
// Example for 10 retries every 10 minutes:  
retryPolicy = new RetryPolicy  
{  
    MaxCount = 11,  
    IntervalsSeconds = [600]  
};  

Policies can be global or task-specific:

jobbyBuilder  
    // Default policy for all tasks  
    .UseDefaultRetryPolicy(defaultPolicy)  
    // Custom policy for SendEmailCommand  
    .UseRetryPolicyForJob<SendEmailCommand>(specialRetryPolicy);