models2: Added log character updates.

internal/task/task.go

@@ -0,0 +1,84 @@
+package task
+
+import (
+	"context"
+	"sync"
+	"time"
+)
+
+var globalCtx, globalCancel = context.WithCancel(context.Background())
+
+// A Task is a wrapper around a function that offers scheduling
+// and syncronization.
+type Task struct {
+	mutex        sync.Mutex
+	ctx          context.Context
+	ctxCancel    context.CancelFunc
+	waitDuration time.Duration
+	scheduled    bool
+	callback     func() error
+}
+
+// Context gets the task's context.
+func (task *Task) Context() context.Context {
+	return task.ctx
+}
+
+// Stop stops a task. This should not be done to stop a single run,
+// but as a way to cancel it forever.
+func (task *Task) Stop() {
+	task.ctxCancel()
+}
+
+// Schedule schedules a task for later execution.
+func (task *Task) Schedule() {
+	// Don't if the context is closed.
+	select {
+	case <-task.Context().Done():
+		return
+	default:
+	}
+
+	task.mutex.Lock()
+	if task.scheduled {
+		task.mutex.Unlock()
+		return
+	}
+	task.scheduled = true
+	task.mutex.Unlock()
+
+	go func() {
+		<-time.After(task.waitDuration)
+
+		// Mark as no longer scheduled
+		task.mutex.Lock()
+		task.scheduled = false
+		task.mutex.Unlock()
+
+		// Don't if the task is cancelled
+		select {
+		case <-task.Context().Done():
+			return
+		default:
+		}
+
+		task.callback()
+	}()
+}
+
+// New makes a new task with the callback.
+func New(waitDuration time.Duration, callback func() error) *Task {
+	ctx, ctxCancel := context.WithCancel(globalCtx)
+
+	return &Task{
+		callback:     callback,
+		ctx:          ctx,
+		ctxCancel:    ctxCancel,
+		waitDuration: waitDuration,
+	}
+}
+
+// StopAll stops all tasks.
+func StopAll() {
+	globalCancel()
+}