taskgroup

A Go package for managing a group of goroutines that returns results iteratively in the order tasks are added.

Usage

Adding tasks to a taskgroup with context and limited concurrency

package main

import (
	"context"
	"fmt"
	"time"

	"github.com/weirdname404/taskgroup"
)

func taskThatUsesCtx(ctx context.Context) string {
	// something is happening that requires context ...
	time.Sleep(time.Duration(50 * time.Millisecond))
	return "taskgroup"
}

func task() string {
	// something is happening ...
	time.Sleep(time.Duration(200 * time.Millisecond))
	return "hello "
}

func main() {
	tgr := taskgroup.NewTaskGroup[string](context.TODO()).Limit(2)
	err := tgr.Add(task)
	if err != nil {
		panic(err)
	}
	err = tgr.Add(taskThatUsesCtx)
	if err != nil {
		panic(err)
	}
	// Start tasks
	res := ""
	for v := range tgr.Start() {
		res += v
	}
	err = tgr.Error()
	if err != nil {
		panic(err)
	}
	fmt.Println(res)
}

Result

hello taskgroup

Create taskgroup

// cancelling context stops all tasks in the taskgroup
ctx := context.TODO()
// 1. You must specify the type of the task results by the type parameter;
// 2. Concurrency limit is optional, but the default is NO LIMIT;
tgr := taskgroup.NewTaskGroup[string](ctx).Limit(2)

Add tasks

// adding tasks DOES NOT START them
err := tgr.Add(task)
// task may have an unsupported format, so it is better to check for errors
if err != nil {
    panic(err)
}
// you can add tasks that either require context or not
err = tgr.Add(taskThatUsesCtx)
if err != nil {
    panic(err)
}

Start taskgroup and check for errors

// Start tasks
res := ""
for v := range tgr.Start() {
    res += v
}
// at least one error stops the group;
err = tgr.Error()
if err != nil {
    panic(err)
}

Adding tasks to a taskgroup that can return an error

package main

import (
	"context"
	"errors"
	"fmt"
	"time"

	"github.com/weirdname404/taskgroup"
)

var TaskError = errors.New("Task error")

func task() string {
	return "hello "
}

func taskThatReturnsError() (string, error) {
	// something is happening ...
	time.Sleep(time.Duration(100 * time.Millisecond))
	return "", TaskError
}

func main() {
	tgr := taskgroup.NewTaskGroup[string](context.TODO()).Limit(2)
	err := tgr.Add(task)
	if err != nil {
		panic(err)
	}
	err = tgr.Add(taskThatReturnsError)
	if err != nil {
		panic(err)
	}
	// Start tasks
	res := ""
	for v := range tgr.Start() {
		res += v
	}
	err = tgr.Error()
	if err != nil {
		fmt.Printf("Taskgroup returns error - %s\n", err.Error())
	}
}

Result

Taskgroup returns error - Task error