Move to typical go project layout, fix golangci-lint warnings, update deps

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

@@ -6,7 +6,7 @@ import (
 )
 
 // worker represents a worker goroutine
-func worker(context context.Context, waitGroup *sync.WaitGroup, firstTask func(), tasks <-chan func(), taskExecutor func(func(), bool)) {
+func worker(context context.Context, waitGroup *sync.WaitGroup, firstTask func(), tasks <-chan func(), taskExecutor func(func(), bool), taskWaitGroup *sync.WaitGroup) {
 
 	// If provided, execute the first task immediately, before listening to the tasks channel
 	if firstTask != nil {
@@ -20,16 +20,43 @@ func worker(context context.Context, waitGroup *sync.WaitGroup, firstTask func()
 	for {
 		select {
 		case <-context.Done():
-			// Pool context was cancelled, exit
+			// Pool context was cancelled, empty tasks channel and exit
+			drainTasks(tasks, taskWaitGroup)
 			return
 		case task, ok := <-tasks:
-			if task == nil || !ok {
-				// We have received a signal to exit
+			// Prioritize context.Done statement (https://stackoverflow.com/questions/46200343/force-priority-of-go-select-statement)
+			select {
+			case <-context.Done():
+				if task != nil && ok {
+					// We have received a task, ignore it
+					taskWaitGroup.Done()
+				}
+				// Pool context was cancelled, empty tasks channel and exit
+				drainTasks(tasks, taskWaitGroup)
 				return
-			}
+			default:
+				if task == nil || !ok {
+					// We have received a signal to exit
+					return
+				}
 
-			// We have received a task, execute it
-			taskExecutor(task, false)
+				// We have received a task, execute it
+				taskExecutor(task, false)
+			}
+		}
+	}
+}
+
+// drainPendingTasks discards queued tasks and decrements the corresponding wait group
+func drainTasks(tasks <-chan func(), tasksWaitGroup *sync.WaitGroup) {
+	for {
+		select {
+		case task, ok := <-tasks:
+			if task != nil && ok {
+				tasksWaitGroup.Done()
+			}
+		default:
+			return
 		}
 	}
 }