zot/pkg/scheduler/README.md

# How to submit a Generator to the scheduler

## What is a generator and how should it be implemented?
In order to create a new generator (which will generate new tasks one by one) and add it to the scheduler there are 4 methods which should be implemented:
1. ***Next() (Task, error)***
    ```
    This method should implement the logic for generating a new task.
    Basically, when this method is called by the scheduler it should return the next task until there are no more tasks to be generated.
    Also, the Task returned by this method should implement DoWork(ctx context.Context) method which should contain the logic that should be executed when this task is run by the scheduler.
    ```
2. ***IsDone() bool***
    ```
    This method should return true after the generator finished all the work and has no more tasks to generate.
    ```
3. ***IsReady() bool***
    ```
    This method should return true if the generator is ready to generate a new task and should be used when it is needed to generate tasks with some delay between.
    ```
4. ***Reset()***
    ```
    When this method is called the generator should reset to its initial state.
    After the generator is reset, it will generate new tasks as if it hadn't been used before.
    This is useful for periodic generators, because the scheduler will call this method when the generator is done and has to wait a specific interval of time for this generator to become ready to run again.
    ```

## Submit a generator
The scheduler accepts both periodic and non-periodic generators.

To submit a generator to the scheduler, ***SubmitGenerator*** should be called with the implemented generator, interval of time (which should be time.Duration(0) in case of non-periodic generator, or the interval for the periodic generator) and the priority of the tasks which will be generated by this generator as parameters.

Notes:

    - A generator should submit only tasks having the same priority
    - The priority of a task can be: LowPriority, MediumPriority or HighPriority

# How to submit a Task to the scheduler

In order to create a new task and add it to the scheduler we need to implement below methods:

1. ***DoWork(ctx context.Context) error***
```
This should contain the logic that should be executed when this task is run by the scheduler.
```
2. ***Name() string***
```
Name of the task.
```
3. ***String() string***
```
Description of the task. Used in debugging to identify executed task.
```

To submit a task to the scheduler ***SubmitTask*** should be called with the implemented task and the priority of the task as parameters.

Note:

    - A task can not be periodic. In order to add a periodic task, it can be created a generator which will generate periodically the same task.