From 03dfe3ccfd42972e5316c058d5356e394ebcf828 Mon Sep 17 00:00:00 2001
From: "Tristan B. Velloza Kildaire" <deavmi@redxen.eu>
Date: Sat, 26 Nov 2022 16:52:21 +0200
Subject: [PATCH] Removed TODO comment

Added configuration system

Introduced two modes of "sleeping" the event loop, sleep-based and yield-based (with 200ms sleep-mode as the default)

Disabled `setSleep(Duration)` for now
---
 source/eventy/config.d | 30 +++++++++++++++++++++++
 source/eventy/engine.d | 54 +++++++++++++++++++++++++++++++++---------
 2 files changed, 73 insertions(+), 11 deletions(-)
 create mode 100644 source/eventy/config.d

diff --git a/source/eventy/config.d b/source/eventy/config.d
new file mode 100644
index 0000000..05aa5c4
--- /dev/null
+++ b/source/eventy/config.d
@@ -0,0 +1,30 @@
+module eventy.config;
+
+import core.thread : Duration, dur;
+
+/**
+ * Configuration system for eventy
+ *
+ * Allows the user to specify certain
+ * tweaks to the engine
+ */
+public struct EngineSettings
+{
+    /* Agressive lock trying (can starve the loop-check) */
+    bool agressiveTryLock;
+
+    /* Hold-off mode */
+    HoldOffMode holdOffMode;
+
+    /* If `holdOffMode` is `SLEEP` then set the duration for the sleep */
+    Duration sleepTime;
+}
+
+/**
+ * 
+ */
+public enum HoldOffMode
+{
+    YIELD,
+    SLEEP
+}
\ No newline at end of file
diff --git a/source/eventy/engine.d b/source/eventy/engine.d
index 4396ce9..e7dfbec 100644
--- a/source/eventy/engine.d
+++ b/source/eventy/engine.d
@@ -3,6 +3,7 @@ module eventy.engine;
 import eventy.queues : Queue;
 import eventy.signal : Signal;
 import eventy.event : Event;
+import eventy.config;
 
 import std.container.dlist;
 import core.sync.mutex : Mutex;
@@ -94,19 +95,42 @@ public final class Engine : Thread
     private DList!(Signal) handlers;
     private Mutex handlerLock;
 
-    private Duration sleepTime;
+
+    /* Engine configuration */
+    private EngineSettings settings;
 
     private bool running;
 
     private DList!(DispatchWrapper) threadStore;
     private Mutex threadStoreLock;
 
-    this()
+    this(EngineSettings settings)
     {
         super(&run);
         queueLock = new Mutex();
         handlerLock = new Mutex();
         threadStoreLock = new Mutex();
+
+        this.settings = settings;
+    }
+
+    
+    /** 
+     * Instantiates a new Eventy engine with the default
+     * settings
+     */
+    this()
+    {
+        EngineSettings defaultSettings;
+
+        /* Yield if a lock fails (prevent potential thread starvation) */
+        defaultSettings.agressiveTryLock = false;
+
+        /* Make the event engine loop sleep (1) and for 200ms (2) (TODO: Adjust this) */
+        defaultSettings.holdOffMode = HoldOffMode.SLEEP;
+        defaultSettings.sleepTime = dur!("msecs")(200);
+
+        this(defaultSettings);
     }
 
     /**
@@ -126,7 +150,7 @@ public final class Engine : Thread
     */
     public void setSleep(Duration time)
     {
-        sleepTime = time;
+        // sleepTime = time;
     }
 
     /**
@@ -192,14 +216,22 @@ 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);
+            /* Activate hold off (dependening on the type) */
+            if(settings.holdOffMode == HoldOffMode.YIELD)
+            {
+                /* Yield to stop mutex starvation */
+                yield();
+            }
+            else if(settings.holdOffMode == HoldOffMode.SLEEP)
+            {
+                /* Sleep the thread (for given time) to stop mutex starvation */
+                sleep(settings.sleepTime);
+            }
+            else
+            {
+                /* This should never happen */
+                assert(false);
+            }
         }
     }