kouzant/execloop

Simple task execution control loop

execloop

Simple task execution engine.

Installation

To install execloop simply run go get -u github.com/kouzant/execloop

Usage

execloop is a very simple and generic execution engine with retryable tasks. In the very basics it's an oversimplified control loop constantly trying to reach a final state by executing a Plan consisting of some Tasks.

Task

A Task is an isolated unit of work. A Task can have sub-tasks which will be executed after the parent task has finished successfully. The main workload is executed in the PerformAction function surrounded by a Pre and Post action.

Your Task implementation should comply with the following interface:

type Task interface {
	Pre() error
	PerformAction() ([]Task, error)
	Post() error
	Name() string
}

Plan

One or more Tasks form a Plan and this is what is going to be executed by the scheduler. In every loop, the plan will be asked to return a set of tasks to be executed in order to reach a final state. Only when the plan will return an empty set of tasks the execution will stop.

Each time the scheduler will invoke the Create function of a plan to get a set of tasks to execute. Eventually the Create function should return an empy slice of Tasks meaning the final state has been reached.

A Plan should implement the follwing interface:

type Plan interface {
	Create() ([]Task, error)
}

Executor

Finally a plan will be executed by the scheduler. You can invoke the Run(plan Plan) error or the RunWithContext(ctx context.Context, plan Plan) error function to execute a plan. The latter will timeout after a configurable period of time.

Call executor.New(options *execloop.Options) *Executor to create a new scheduler. The Options are the following:

type Options struct {
	Logger           Logger
	SleepBetweenRuns time.Duration
	ErrorsToTolerate int
	ExecutionTimeout time.Duration
}

Use the With* functions to override the default options obtained by execloop.DefaultOptions()

Development

make to build and test

make test to run the tests

test-no-cache to run all tests with no cache

make build to build the library