From 2ead5b3c40b78b49385648a35fdd08bba7bf21f5 Mon Sep 17 00:00:00 2001
From: DanMB <danielmillst@gmail.com>
Date: Sat, 22 Jan 2022 17:52:53 -0500
Subject: [PATCH] Object recycler

---
 .../com/volmit/iris/util/data/Recycler.java   | 175 ++++++++++++++++++
 1 file changed, 175 insertions(+)
 create mode 100644 src/main/java/com/volmit/iris/util/data/Recycler.java

diff --git a/src/main/java/com/volmit/iris/util/data/Recycler.java b/src/main/java/com/volmit/iris/util/data/Recycler.java
new file mode 100644
index 000000000..ac4218b08
--- /dev/null
+++ b/src/main/java/com/volmit/iris/util/data/Recycler.java
@@ -0,0 +1,175 @@
+package com.volmit.iris.util.data;
+
+import java.util.List;
+import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.atomic.AtomicBoolean;
+import java.util.function.Supplier;
+
+public class Recycler<T> {
+    private final List<RecycledObject<T>> pool;
+    private final Supplier<T> factory;
+
+    public Recycler(Supplier<T> factory)
+    {
+        pool = new CopyOnWriteArrayList<>();
+        this.factory = factory;
+    }
+
+    public int getFreeObjects()
+    {
+        int m = 0;
+        RecycledObject<T> o;
+        for (RecycledObject<T> tRecycledObject : pool) {
+            o = tRecycledObject;
+
+            if (!o.isUsed()) {
+                m++;
+            }
+        }
+
+        return m;
+    }
+
+    public int getUsedOjects()
+    {
+        int m = 0;
+        RecycledObject<T> o;
+        for (RecycledObject<T> tRecycledObject : pool) {
+            o = tRecycledObject;
+
+            if (o.isUsed()) {
+                m++;
+            }
+        }
+
+        return m;
+    }
+
+    public void dealloc(T t)
+    {
+        RecycledObject<T> o;
+
+        for (RecycledObject<T> tRecycledObject : pool) {
+            o = tRecycledObject;
+            if (o.isUsed() && System.identityHashCode(t) == System.identityHashCode(o.getObject())) {
+                o.dealloc();
+                return;
+            }
+        }
+    }
+
+    public T alloc()
+    {
+        RecycledObject<T> o;
+
+        for (RecycledObject<T> tRecycledObject : pool) {
+            o = tRecycledObject;
+            if (o.alloc()) {
+                return o.getObject();
+            }
+        }
+
+        expand();
+
+        return alloc();
+    }
+
+    public boolean contract()
+    {
+        return contract(Math.max(getFreeObjects() / 2, Runtime.getRuntime().availableProcessors()));
+    }
+
+    public boolean contract(int maxFree)
+    {
+        int remove = getFreeObjects() - maxFree;
+
+        if(remove > 0)
+        {
+            RecycledObject<T> o;
+
+            for(int i = pool.size()-1; i > 0; i--)
+            {
+                o = pool.get(i);
+                if(!o.isUsed())
+                {
+                    pool.remove(i);
+                    remove--;
+
+                    if(remove <= 0)
+                    {
+                        return true;
+                    }
+                }
+            }
+        }
+
+        return false;
+    }
+
+    public void expand()
+    {
+        if(pool.isEmpty())
+        {
+            expand(Runtime.getRuntime().availableProcessors());
+            return;
+        }
+
+        expand(getUsedOjects() + Runtime.getRuntime().availableProcessors());
+    }
+
+    public void expand(int by)
+    {
+        for(int i = 0; i < by; i++)
+        {
+            pool.add(new RecycledObject<>(factory.get()));
+        }
+    }
+
+    public int size()
+    {
+        return pool.size();
+    }
+
+    public void deallocAll()
+    {
+        pool.clear();
+    }
+
+    public static class RecycledObject<T>
+    {
+        private final T object;
+        private final AtomicBoolean used;
+
+        public RecycledObject(T object)
+        {
+            this.object = object;
+            used = new AtomicBoolean(false);
+        }
+
+        public T getObject()
+        {
+            return object;
+        }
+
+        public boolean isUsed()
+        {
+            return used.get();
+        }
+
+        public void dealloc()
+        {
+            used.set(false);
+        }
+
+        public boolean alloc()
+        {
+            if(used.get())
+            {
+                return false;
+            }
+
+            used.set(true);
+            return true;
+        }
+    }
+}