From 217688767ada061ba9981dfa6370c5a1c8112103 Mon Sep 17 00:00:00 2001
From: "Tristan B. Kildaire" <deavmi@redxen.eu>
Date: Tue, 7 Sep 2021 14:05:31 +0200
Subject: [PATCH] Added yield to stop starving the mutex on our side. They (API
 users) could of course still starve it on their side, so they should use
 functions not to rapidly else event-loop gets no time to dispatch events they
 add.

---
 source/eventy/engine.d | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/source/eventy/engine.d b/source/eventy/engine.d
index 570ca9e..6ec302a 100644
--- a/source/eventy/engine.d
+++ b/source/eventy/engine.d
@@ -6,7 +6,7 @@ import eventy.event : Event;
 
 import std.container.dlist;
 import core.sync.mutex : Mutex;
-import core.thread : Thread;
+import core.thread : Thread, dur, Duration;
 
 
 import std.stdio;
@@ -33,6 +33,9 @@ unittest
     Event eTest = new Event(1);
     engine.push(eTest);
 
+    Thread.sleep(dur!("seconds")(2));
+    engine.push(eTest);
+
     writeln("naai");
 }
 
@@ -56,6 +59,8 @@ public final class Engine : Thread
     private DList!(Signal) handlers;
     private Mutex handlerLock;
 
+    private Duration sleepTime;
+
     this()
     {
         super(&run);
@@ -63,6 +68,26 @@ public final class Engine : Thread
         handlerLock = new Mutex();
     }
 
+    /**
+    * Set the event loop sleep time
+    *
+    * The load average will sky rocket if it is 0,
+    * which is just because it is calculated on how
+    * full the run queue is, length but also over time
+    * and even just one task continousy in it will
+    * make the average high
+    *
+    * Reason why it's always runnable is the process
+    * (the "thread") is a tight loop with no sleeps
+    * that would dequeue it from the run queue and/or
+    * no I/O system calls that would put it into the
+    * waiting queue
+    */
+    public void setSleep(Duration time)
+    {
+        sleepTime = time;
+    }
+
     public void addSignalHandler(Signal e)
     {
          /* Lock the signal-set */
@@ -109,7 +134,14 @@ public final class Engine : Thread
             /* Unlock the queue set */
             queueLock.unlock();
 
+            /* Yield to stop mutex starvation */
+            yield();
+
             /* TODO: Add yield to stop mutex starvation on a single thread */
+
+            /* Sleep the thread */
+            // sleepTime = dur!("seconds")(0);
+            // sleep(sleepTime);
         }
     }