Add the timer function to TaskManager

We need a timer function in the operating or test environment.
This function is delegate called repeatedly or after a certain time.

source/agora/common/Task.d

@@ -19,6 +19,13 @@ module agora.common.Task;
 
 import core.time;
 
+/// Whether the timer periodic type
+public enum Periodic : bool
+{
+    No,
+    Yes
+}
+
 /// Exposes primitives to run tasks through Vibe.d
 public class TaskManager
 {
@@ -51,4 +58,30 @@ public class TaskManager
         static import vibe.core.core;
         vibe.core.core.sleep(dur);
     }
+
+    /***************************************************************************
+
+        Run an asynchronous task after a given time.
+
+        The task will first run after the given `timeout`, and
+        can either repeat or run only once (the default).
+        Use the `setTimer` vibe.d's
+
+        Params:
+            timeout = Determines the minimum amount of time that elapses before
+                the timer fires.
+            dg = This delegate will be called when the timer fires.
+            periodic = Speficies if the timer fires repeatedly or only once.
+
+    ***************************************************************************/
+
+    public void timer (Duration timeout, void delegate() dg,
+        Periodic periodic = Periodic.No)
+    {
+        assert(dg !is null, "Cannot call this delegate if null");
+
+        static import vibe.core.core;
+        vibe.core.core.setTimer(timeout, dg, periodic);
+    }
 }
+

source/agora/test/Base.d

@@ -264,6 +264,28 @@ public class LocalRestTaskManager : TaskManager
     {
         geod24.LocalRest.sleep(dur);
     }
+
+    /***************************************************************************
+
+        Run an asynchronous task after a given time in LocalRest's
+
+        The task will first run after the given `timeout`, and
+        can either repeat or run only once (the default).
+        Works similarly to Vibe.d's `setTimer`.
+
+        Params:
+            timeout = Determines the minimum amount of time that elapses before
+                the timer fires.
+            dg = This delegate will be called when the timer fires.
+            periodic = Speficies if the timer fires repeatedly or only once.
+
+    ***************************************************************************/
+
+    public override void timer (Duration timeout, void delegate() dg,
+        Periodic periodic = Periodic.No)
+    {
+        geod24.LocalRest.setTimer(timeout, dg, periodic);
+    }
 }
 
 /// A ban manager with a fake clock for reliable unittesting