Added getActiveTasks() function to count how many tasks are running or suspended.

source/mijin/async/coroutine.cpp

@@ -174,6 +174,20 @@ void SimpleTaskLoop::addStoredTask(StoredTask&& storedTask) noexcept
     }
 }
 
+std::size_t SimpleTaskLoop::getActiveTasks() const noexcept
+{
+    std::size_t sum = 0;
+    for (const StoredTask& task : mijin::chain(tasks_, newTasks_))
+    {
+        const TaskStatus status = task.task ? task.task->status() : TaskStatus::FINISHED;
+        if (status == TaskStatus::SUSPENDED || status == TaskStatus::RUNNING)
+        {
+            ++sum;
+        }
+    }
+    return sum;
+}
+
 void MultiThreadedTaskLoop::transferCurrentTask(TaskLoop& otherLoop) noexcept
 {
     if (&otherLoop == this) {