taskmanager

README

taskmanager

Basic handler of long-running Goroutines.

Authors

• Christophe Lambin

License

This project is licensed under the MIT License - see the LICENSE.md file for details.

Documentation

Overview

Package taskmanager provides a basic way to start multiple long-running Goroutines.

Example

package main

import (
	"context"
	"github.com/clambin/go-common/taskmanager"
	"github.com/clambin/go-common/taskmanager/httpserver"
	"github.com/clambin/go-common/taskmanager/prometheus"
	"net/http"
	"os"
	"os/signal"
)

func main() {
	m := taskmanager.New()

	// Add a Goroutine. We use TaskFunc to convert a func to a Task
	// without having to declare a struct that adheres to the Task interface.
	_ = m.Add(taskmanager.TaskFunc(func(ctx context.Context) error {
		<-ctx.Done()
		return ctx.Err()
	}))

	// Add an HTTP Server.
	r := http.NewServeMux()
	r.HandleFunc("/test", func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("hello"))
	})
	_ = m.Add(httpserver.New(":8080", r))

	// Add a Prometheus server
	_ = m.Add(prometheus.New(prometheus.WithAddr(":9092")))

	// Run until the program is interrupted.
	ctx, done := signal.NotifyContext(context.Background(), os.Interrupt)
	defer done()

	// Start the task manager. This will run until the context is marked as done.
	if err := m.Run(ctx); err != nil {
		panic(err)
	}
}

Index

• Variables
• type Manager
  • func New(tasks ...Task) *Manager
  • func (m *Manager) Add(task ...Task) error
  • func (m *Manager) Run(ctx context.Context) error
• type Task
• type TaskFunc
  • func (f TaskFunc) Run(ctx context.Context) error

Examples

• Package

Variables

var ErrAlreadyRunning = errors.New("task manager already running")

ErrAlreadyRunning indicates the Manager is already running and the requested function cannot be performed.

Types

type Manager

type Manager struct {
	// contains filtered or unexported fields
}

Manager groups a number of Task instances

func New

func New(tasks ...Task) *Manager

New returns a Manager for the specified Task objects.

func (*Manager) Add

func (m *Manager) Add(task ...Task) error

Add adds a Task to the Manager. This can only be done when the Manager is not running. Otherwise, it returns ErrAlreadyRunning.

func (*Manager) Run

func (m *Manager) Run(ctx context.Context) error

Run starts the different Task objects as separate Goroutines and waits for the context to be marked as Done. It then stops all Tasks and returns any returned errors.

If any Task returns an error before the context is marked as Done, Run will stop all Goroutines and return the error of the failing Task.

Only one instance of a Manager can run at a single time. If Run is called while the Manager is already running, Run returns ErrAlreadyRunning.

type Task

type Task interface {
	Run(ctx context.Context) error
}

Task is the interface that any taskmanager task must adhere to. It consists of a single Run method. The task should run until the provided context is marked as Done, or a fatal error occurs.

type TaskFunc

type TaskFunc func(ctx context.Context) error

The TaskFunc type is an adapter to allow the use of ordinary functions as a Task. If f is a function with the appropriate signature, TaskFunc(f) is a Task that calls f.

func (TaskFunc) Run

func (f TaskFunc) Run(ctx context.Context) error

Run calls f(ctx).