From 6968ef2b027d09f701abd4156f92686e17f1df41 Mon Sep 17 00:00:00 2001
From: srosse <none@none>
Date: Wed, 29 Mar 2017 10:18:35 +0200
Subject: [PATCH] OO-2657: implement the round robin algorithm with usage
statistics
---
.../nodes/gta/manager/GTAManagerImpl.java | 52 +++++++++++++------
.../nodes/gta/manager/GTAManagerTest.java | 35 ++++++++++++-
2 files changed, 70 insertions(+), 17 deletions(-)
diff --git a/src/main/java/org/olat/course/nodes/gta/manager/GTAManagerImpl.java b/src/main/java/org/olat/course/nodes/gta/manager/GTAManagerImpl.java
index bba5000030c..b1e4a902370 100644
--- a/src/main/java/org/olat/course/nodes/gta/manager/GTAManagerImpl.java
+++ b/src/main/java/org/olat/course/nodes/gta/manager/GTAManagerImpl.java
@@ -26,10 +26,12 @@ import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Date;
+import java.util.HashMap;
import java.util.HashSet;
-import java.util.Iterator;
import java.util.List;
+import java.util.Map;
import java.util.Set;
+import java.util.concurrent.atomic.AtomicInteger;
import javax.persistence.LockModeType;
import javax.persistence.Query;
@@ -889,18 +891,6 @@ public class GTAManagerImpl implements GTAManager, DeletableGroupData {
}
protected String nextSlotRoundRobin(String[] slots, List<String> usedSlots) {
- //remove previous rounds
- Set<String> usedOnce = new HashSet<>();
- for(Iterator<String> usedSlotIt=usedSlots.iterator(); usedSlotIt.hasNext(); ) {
- String usedSlot = usedSlotIt.next();
- if(usedOnce.contains(usedSlot)) {
- usedSlotIt.remove();
- } else {
- usedOnce.add(usedSlot);
- }
- }
-
- //usedSlots are cleaned and contains only current round
String nextSlot = null;
for(String slot:slots) {
if(!usedSlots.contains(slot)) {
@@ -909,11 +899,41 @@ public class GTAManagerImpl implements GTAManager, DeletableGroupData {
}
}
+ //not found an used slot
if(nextSlot == null) {
- //begin a new round
- if (slots.length > 0) {
- nextSlot = slots[0];
+ //statistics
+ Map<String,AtomicInteger> usages = new HashMap<>();
+ for(String usedSlot:usedSlots) {
+ if(usages.containsKey(usedSlot)) {
+ usages.get(usedSlot).incrementAndGet();
+ } else {
+ usages.put(usedSlot, new AtomicInteger(1));
+ }
+ }
+
+ int minimum = Integer.MAX_VALUE;
+ for(AtomicInteger slotUsage:usages.values()) {
+ minimum = Math.min(minimum, slotUsage.get());
}
+ Set<String> slotsWithMinimalUsage = new HashSet<>();
+ for(Map.Entry<String, AtomicInteger> slotUsage:usages.entrySet()) {
+ if(slotUsage.getValue().get() == minimum) {
+ slotsWithMinimalUsage.add(slotUsage.getKey());
+ }
+ }
+
+ //found the next slot with minimal usage
+ for(String slot:slots) {
+ if(slotsWithMinimalUsage.contains(slot)) {
+ nextSlot = slot;
+ break;
+ }
+ }
+ }
+
+ //security
+ if(nextSlot == null && slots.length > 0) {
+ nextSlot = slots[0];
}
return nextSlot;
}
diff --git a/src/test/java/org/olat/course/nodes/gta/manager/GTAManagerTest.java b/src/test/java/org/olat/course/nodes/gta/manager/GTAManagerTest.java
index 91eb3470a00..f96e3b4394d 100644
--- a/src/test/java/org/olat/course/nodes/gta/manager/GTAManagerTest.java
+++ b/src/test/java/org/olat/course/nodes/gta/manager/GTAManagerTest.java
@@ -600,7 +600,7 @@ public class GTAManagerTest extends OlatTestCase {
}
@Test
- public void roundsRobin() {
+ public void roundRobin_oneRound() {
String[] slots = new String[]{ "A", "B", "C" };
List<String> usedSlots = new ArrayList<>();
usedSlots.add("A");
@@ -608,7 +608,40 @@ public class GTAManagerTest extends OlatTestCase {
usedSlots.add("C");
usedSlots.add("A");
+ String nextSlot = gtaManager.nextSlotRoundRobin(slots, usedSlots);
+ Assert.assertEquals("B", nextSlot);
+ }
+
+ @Test
+ public void roundRobin_randomRound() {
+ String[] slots = new String[]{ "A", "B", "C" };
+ List<String> usedSlots = new ArrayList<>();
+ usedSlots.add("A");
+ usedSlots.add("B");
+ usedSlots.add("B");
+ usedSlots.add("B");
+ usedSlots.add("C");
+ usedSlots.add("C");
+ usedSlots.add("A");
+
String nextSlot = gtaManager.nextSlotRoundRobin(slots, usedSlots);
Assert.assertEquals("A", nextSlot);
}
+
+ @Test
+ public void roundRobin_randomRoundAlt() {
+ String[] slots = new String[]{ "A", "B", "C" };
+ List<String> usedSlots = new ArrayList<>();
+ usedSlots.add("A");
+ usedSlots.add("B");
+ usedSlots.add("B");
+ usedSlots.add("B");
+ usedSlots.add("C");
+ usedSlots.add("C");
+ usedSlots.add("A");
+ usedSlots.add("A");
+
+ String nextSlot = gtaManager.nextSlotRoundRobin(slots, usedSlots);
+ Assert.assertEquals("C", nextSlot);
+ }
}
--
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