use AtomicReference in DataEntry

this resolves a race-condition situation on multithreading cases

Author: HSGamer

agent/core/src/main/java/me/hsgamer/topper/agent/core/DataEntryAgent.java

@@ -7,7 +7,7 @@ default void onCreate(DataEntry<K, V> entry) {
         // EMPTY
     }
 
-    default void onUpdate(DataEntry<K, V> entry, V oldValue) {
+    default void onUpdate(DataEntry<K, V> entry, V oldValue, V newValue) {
         // EMPTY
     }
 

agent/holder/src/main/java/me/hsgamer/topper/agent/holder/AgentDataHolder.java

@@ -39,8 +39,8 @@ protected final void onCreate(DataEntry<K, V> entry) {
     }
 
     @Override
-    protected void onUpdate(DataEntry<K, V> entry, V oldValue) {
-        entryAgentList.forEach(agent -> agent.onUpdate(entry, oldValue));
+    protected void onUpdate(DataEntry<K, V> entry, V oldValue, V newValue) {
+        entryAgentList.forEach(agent -> agent.onUpdate(entry, oldValue, newValue));
     }
 
     @Override

agent/storage/src/main/java/me/hsgamer/topper/agent/storage/StorageAgent.java

@@ -111,8 +111,8 @@ public void beforeStop() {
     }
 
     @Override
-    public void onUpdate(DataEntry<K, V> entry, V oldValue) {
-        storeMap.get().put(entry.getKey(), entry.getValue());
+    public void onUpdate(DataEntry<K, V> entry, V oldValue, V newValue) {
+        storeMap.get().put(entry.getKey(), newValue);
     }
 
     @Override

core/src/main/java/me/hsgamer/topper/core/DataEntry.java

@@ -1,25 +1,26 @@
 package me.hsgamer.topper.core;
 
 import java.util.Objects;
+import java.util.concurrent.atomic.AtomicReference;
 import java.util.function.UnaryOperator;
 
 public final class DataEntry<K, V> {
     private final K key;
     private final DataHolder<K, V> holder;
-    private volatile V value;
+    private final AtomicReference<V> value;
 
     public DataEntry(K key, DataHolder<K, V> holder) {
         this.key = key;
         this.holder = holder;
-        this.value = holder.getDefaultValue();
+        this.value = new AtomicReference<>(holder.getDefaultValue());
     }
 
     public K getKey() {
         return key;
     }
 
     public V getValue() {
-        return value;
+        return value.get();
     }
 
     public void setValue(V value) {
@@ -31,14 +32,17 @@ public void setValue(UnaryOperator<V> operator) {
     }
 
     public void setValue(V value, boolean notify) {
-        if (Objects.equals(this.value, value)) return;
-        V oldValue = this.value;
-        this.value = value;
-        if (notify) holder.onUpdate(this, oldValue);
+        setValue(v -> value, notify);
     }
 
     public void setValue(UnaryOperator<V> operator, boolean notify) {
-        setValue(operator.apply(value), notify);
+        this.value.updateAndGet(oldValue -> {
+            V newValue = operator.apply(oldValue);
+            if (notify && !Objects.equals(oldValue, newValue)) {
+                holder.onUpdate(this, oldValue, newValue);
+            }
+            return newValue;
+        });
     }
 
     public DataHolder<K, V> getHolder() {

core/src/main/java/me/hsgamer/topper/core/DataHolder.java

@@ -23,7 +23,7 @@ protected void onCreate(DataEntry<K, V> entry) {
     protected void onRemove(DataEntry<K, V> entry) {
     }
 
-    protected void onUpdate(DataEntry<K, V> entry, V oldValue) {
+    protected void onUpdate(DataEntry<K, V> entry, V oldValue, V newValue) {
     }
 
     public final String getName() {

spigot/plugin/src/main/java/me/hsgamer/topper/spigot/plugin/holder/NumberTopHolder.java

@@ -93,8 +93,8 @@ public void start() {
         });
         addEntryAgent(new DataEntryAgent<UUID, Double>() {
             @Override
-            public void onUpdate(DataEntry<UUID, Double> entry, Double oldValue) {
-                Bukkit.getPluginManager().callEvent(new GenericEntryUpdateEvent(name, entry.getKey(), oldValue, entry.getValue(), true));
+            public void onUpdate(DataEntry<UUID, Double> entry, Double oldValue, Double newValue) {
+                Bukkit.getPluginManager().callEvent(new GenericEntryUpdateEvent(name, entry.getKey(), oldValue, newValue, true));
             }
         });
     }