4.Saga事务

Saga事务

Saga可以封装一系列步骤，并可以为每个步骤进行补偿操作。

//Task2会抛出异常，则会触发undotask2和undotask1
builder
    .StartWith(context => Console.WriteLine("Begin"))
    .Saga(saga => saga
        .StartWith<Task1>()
            .CompensateWith<UndoTask1>()//补偿操作
        .Then<Task2>()
            .CompensateWith<UndoTask2>()
        .Then<Task3>()
            .CompensateWith<UndoTask3>()
    )
    .Then(context => Console.WriteLine("End"));

saga事务的重试

//该案例会5s重试一次
builder
    .StartWith(context => Console.WriteLine("Begin"))
    .Saga(saga => saga
        .StartWith<Task1>()
            .CompensateWith<UndoTask1>()
        .Then<Task2>()
            .CompensateWith<UndoTask2>()
        .Then<Task3>()
            .CompensateWith<UndoTask3>()
    )
    .OnError(Models.WorkflowErrorHandling.Retry, TimeSpan.FromSeconds(5))
    .Then(context => Console.WriteLine("End"));

补偿整个saga事务

builder
    .StartWith(context => Console.WriteLine("Begin"))
        .Saga(saga => saga
            .StartWith<Task1>()
            .Then<Task2>()
            .Then<Task3>()
    )
        .CompensateWith<UndoEverything>()//补充整个saga事务
    .Then(context => Console.WriteLine("End"));

给补偿步骤传参

builder
    .StartWith<SayHello>()
        .CompensateWith<PrintMessage>(compensate => 
        {
            compensate.Input(step => step.Message, data => "undoing...");
        })