Advanced Usage

Graceful Shutdown (Stop)

Initiates a graceful shutdown of the task manager. It stops accepting new tasks, waits for all currently queued tasks to be completed, and then releases all managed resources. This is the recommended way to shut down your tasker instance in production environments to ensure no in-flight tasks are lost.

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/asaidimu/tasker/v2"
)

type HeavyComputeResource struct{ ID int }
func createComputeResource() (*HeavyComputeResource, error) { fmt.Printf("INFO: Creating ComputeResource\n"); return &HeavyComputeResource{ID: 1}, nil }
func destroyComputeResource(r *HeavyComputeResource) error { fmt.Printf("INFO: Destroying ComputeResource\n"); return nil }

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	config := tasker.Config[*HeavyComputeResource]{
		OnCreate:    createComputeResource,
		OnDestroy:   destroyComputeResource,
		WorkerCount: 2,
		Ctx:         ctx,
	}

	manager, err := tasker.NewTaskManager[*HeavyComputeResource, string](config)
	if err != nil {
		log.Fatalf("Error creating task manager: %v", err)
	}

	// Queue some tasks
	for i := 0; i < 5; i++ {
		taskID := i
		go func() {
			_, _ = manager.QueueTask(func(ctx context.Context, res *HeavyComputeResource) (string, error) {
				fmt.Printf("Worker %d processing Task %d\n", res.ID, taskID)
				time.Sleep(100 * time.Millisecond)
				return fmt.Sprintf("Task %d completed", taskID), nil
			})
		}()
	}

	// Allow some tasks to start, then initiate graceful shutdown
	time.Sleep(200 * time.Millisecond)
	fmt.Println("\nInitiating graceful shutdown...")
	err = manager.Stop()
	if err != nil {
		fmt.Printf("Error during graceful shutdown: %v\n", err)
	} else {
		fmt.Println("Task manager gracefully shut down.")
	}
	fmt.Printf("Final Active Workers: %d\n", manager.Stats().ActiveWorkers)
}

Immediate Shutdown (Kill)

Immediately terminates the task manager. It cancels all running tasks, drops all queued tasks, and releases resources without waiting for tasks to complete. Use Kill() for scenarios where immediate termination is required, even at the cost of losing in-flight tasks (e.g., during critical error recovery or unit testing).

package main

import (
	"context"
	"fmt"
	"log"
	"time"

	"github.com/asaidimu/tasker/v2"
)

type HeavyComputeResource struct{ ID int }
func createComputeResource() (*HeavyComputeResource, error) { fmt.Printf("INFO: Creating ComputeResource\n"); return &HeavyComputeResource{ID: 1}, nil }
func destroyComputeResource(r *HeavyComputeResource) error { fmt.Printf("INFO: Destroying ComputeResource\n"); return nil }

func main() {
	ctx, cancel := context.WithCancel(context.Background())
	config := tasker.Config[*HeavyComputeResource]{
		OnCreate:    createComputeResource,
		OnDestroy:   destroyComputeResource,
		WorkerCount: 2,
		Ctx:         ctx,
	}

	manager, err := tasker.NewTaskManager[*HeavyComputeResource, string](config)
	if err != nil {
		log.Fatalf("Error creating task manager: %v", err)
	}

	// Queue a long-running task
	go func() {
		_, _ = manager.QueueTask(func(ctx context.Context, res *HeavyComputeResource) (string, error) {
			fmt.Printf("Worker %d processing long Task...\n", res.ID)
			select {
			case <-ctx.Done():
				fmt.Printf("Task on Worker %d cancelled due to shutdown.\n", res.ID)
				return "", ctx.Err()
			case <-time.After(5 * time.Second): // Simulate long work
				return "long task completed", nil
			}
		})
	}()

	// Immediately kill the manager
	time.Sleep(50 * time.Millisecond)
	fmt.Println("\nInitiating immediate shutdown (Kill)...")
	err = manager.Kill()
	if err != nil {
		fmt.Printf("Error during immediate shutdown: %v\n", err)
	} else {
		fmt.Println("Task manager immediately shut down.")
	}
	fmt.Printf("Final Active Workers: %d\n", manager.Stats().ActiveWorkers)
	// Expect 0 active workers and the long task to be cancelled
}