Merge branch 'fix/98-defaultclock-volatile-timeunit' into develop

Author: remikey

CHANGELOG.md

@@ -4,7 +4,18 @@ This file lists modifications introduced by each version.
 
 ## [Unreleased]
 
-* Empty
+###  DefaultClock class modifications
+
+**Bug fixes in DefaultClock:**
+
+* The `timeUnit` field of `DefaultClock` is now also `volatile` [[issue 98]][issue: #98]
+
+  Although not impacting with the `DefaultClock`'s usage, a potential multi-threading issue was present in its 
+  implementation. Since turning `timeUnit` into `volatile` did not prove to impact performances, the fix has been 
+  applied in order to set a good coding example.  
+
+
+[issue: #98]: https://github.com/jbotsim/JBotSim/issues/98
 
 ## [1.2.0] - 2020/02/12
 

lib/jbotsim-core/src/main/java/io/jbotsim/core/DefaultClock.java

@@ -43,7 +43,7 @@ public class DefaultClock extends Clock implements Runnable {
     final Lock lock = new ReentrantLock();
     final Condition shouldRunCondition = lock.newCondition();
 
-    private int delay = 0;
+    volatile int timeUnit = 0;
 
     public DefaultClock(ClockManager manager) {
         super(manager);
@@ -53,12 +53,12 @@ public DefaultClock(ClockManager manager) {
 
     @Override
     public int getTimeUnit() {
-        return delay;
+        return timeUnit;
     }
 
     @Override
-    public void setTimeUnit(int delay) {
-        this.delay = delay;
+    public void setTimeUnit(int timeUnit) {
+        this.timeUnit = timeUnit;
     }
 
     @Override
@@ -105,8 +105,7 @@ public void run() {
                 while (!running)
                     shouldRunCondition.await();
 
-                if(delay != 0)
-                    Thread.sleep(delay);
+                sleepIfNeeded(timeUnit);
 
                 if (running)
                     manager.onClock();
@@ -119,4 +118,9 @@ public void run() {
             }
         }
     }
+
+    private void sleepIfNeeded(int delayMillis) throws InterruptedException {
+        if(delayMillis != 0)
+            Thread.sleep(delayMillis);
+    }
 }