Add task pool, minor changes

- Add task pool to smooth impact when list in config is pretty long
- Update dependencies
- Update config

vendor/github.com/alitto/pond/group.go

@@ -0,0 +1,106 @@
+package pond
+
+import (
+	"context"
+	"sync"
+)
+
+// TaskGroup represents a group of related tasks
+type TaskGroup struct {
+	pool      *WorkerPool
+	waitGroup sync.WaitGroup
+}
+
+// Submit adds a task to this group and sends it to the worker pool to be executed
+func (g *TaskGroup) Submit(task func()) {
+	g.waitGroup.Add(1)
+
+	g.pool.Submit(func() {
+		defer g.waitGroup.Done()
+
+		task()
+	})
+}
+
+// Wait waits until all the tasks in this group have completed
+func (g *TaskGroup) Wait() {
+
+	// Wait for all tasks to complete
+	g.waitGroup.Wait()
+}
+
+// TaskGroupWithContext represents a group of related tasks associated to a context
+type TaskGroupWithContext struct {
+	TaskGroup
+	ctx    context.Context
+	cancel context.CancelFunc
+
+	errSync struct {
+		once  sync.Once
+		guard sync.RWMutex
+	}
+	err error
+}
+
+// Submit adds a task to this group and sends it to the worker pool to be executed
+func (g *TaskGroupWithContext) Submit(task func() error) {
+	g.waitGroup.Add(1)
+
+	g.pool.Submit(func() {
+		defer g.waitGroup.Done()
+
+		// If context has already been cancelled, skip task execution
+		select {
+		case <-g.ctx.Done():
+			return
+		default:
+		}
+
+		// don't actually ignore errors
+		err := task()
+		if err != nil {
+			g.setError(err)
+		}
+	})
+}
+
+// Wait blocks until either all the tasks submitted to this group have completed,
+// one of them returned a non-nil error or the context associated to this group
+// was canceled.
+func (g *TaskGroupWithContext) Wait() error {
+
+	// Wait for all tasks to complete
+	tasksCompleted := make(chan struct{})
+	go func() {
+		g.waitGroup.Wait()
+		tasksCompleted <- struct{}{}
+	}()
+
+	select {
+	case <-tasksCompleted:
+		// If context was provided, cancel it to signal all running tasks to stop
+		g.cancel()
+	case <-g.ctx.Done():
+		g.setError(g.ctx.Err())
+	}
+
+	return g.getError()
+}
+
+func (g *TaskGroupWithContext) getError() error {
+	g.errSync.guard.RLock()
+	err := g.err
+	g.errSync.guard.RUnlock()
+	return err
+}
+
+func (g *TaskGroupWithContext) setError(err error) {
+	g.errSync.once.Do(func() {
+		g.errSync.guard.Lock()
+		g.err = err
+		g.errSync.guard.Unlock()
+
+		// Cancel execution of any pending task in this group
+		g.cancel()
+	})
+}