Reduce lambda allocations in ReadWriteMap

Author: tomcashman

core/src/main/java/org/mini2Dx/miniscript/core/util/ReadWriteMap.java

@@ -30,6 +30,24 @@ protected Set<Entry<K, V>> initialValue() {
 			return new HashSet<>();
 		}
 	};
+	private final ThreadLocal<ToSetConsumer<K>> keyConsumer = new ThreadLocal<ToSetConsumer<K>>() {
+		@Override
+		protected ToSetConsumer<K> initialValue() {
+			return new ToSetConsumer<K>();
+		}
+	};
+	private final ThreadLocal<ToCollectionConsumer<V>> valueConsumer = new ThreadLocal<ToCollectionConsumer<V>>() {
+		@Override
+		protected ToCollectionConsumer<V> initialValue() {
+			return new ToCollectionConsumer<V>();
+		}
+	};
+	private final ThreadLocal<ToSetConsumer<Entry<K, V>>> entryConsumer = new ThreadLocal<ToSetConsumer<Entry<K, V>>>() {
+		@Override
+		protected ToSetConsumer<Entry<K, V>> initialValue() {
+			return new ToSetConsumer<Entry<K, V>>();
+		}
+	};
 
 	@Override
 	public int size() {
@@ -105,9 +123,9 @@ public Set<K> keySet() {
 		try {
 			result.clear();
 			//addAll allocates arrays unnecessarily
-			internalMap.keySet().forEach((key) -> {
-				result.add(key);
-			});
+			final ToSetConsumer<K> consumer = keyConsumer.get();
+			consumer.setSet(result);
+			internalMap.keySet().forEach(consumer);
 		} finally {
 			lock.unlockRead();
 		}
@@ -121,9 +139,9 @@ public Collection<V> values() {
 		try {
 			result.clear();
 			//addAll allocates arrays unnecessarily
-			internalMap.values().forEach((val) -> {
-				result.add(val);
-			});
+			final ToCollectionConsumer<V> consumer = valueConsumer.get();
+			consumer.setCollection(result);
+			internalMap.values().forEach(consumer);
 		} finally {
 			lock.unlockRead();
 		}
@@ -137,9 +155,9 @@ public Set<Entry<K, V>> entrySet() {
 		try {
 			result.clear();
 			//addAll allocates arrays unnecessarily
-			internalMap.entrySet().forEach((entry) -> {
-				result.add(entry);
-			});
+			final ToSetConsumer<Entry<K, V>> consumer = entryConsumer.get();
+			consumer.setSet(result);
+			internalMap.entrySet().forEach(consumer);
 		} finally {
 			lock.unlockRead();
 		}

core/src/main/java/org/mini2Dx/miniscript/core/util/ToCollectionConsumer.java

@@ -0,0 +1,20 @@
+/**
+ * Copyright 2021 Viridian Software Ltd.
+ */
+package org.mini2Dx.miniscript.core.util;
+
+import java.util.Collection;
+import java.util.function.Consumer;
+
+public class ToCollectionConsumer<T> implements Consumer<T> {
+	private Collection<T> collection;
+
+	@Override
+	public void accept(T t) {
+		collection.add(t);
+	}
+
+	public void setCollection(Collection<T> list) {
+		this.collection = list;
+	}
+}

core/src/main/java/org/mini2Dx/miniscript/core/util/ToSetConsumer.java

@@ -0,0 +1,20 @@
+/**
+ * Copyright 2021 Viridian Software Ltd.
+ */
+package org.mini2Dx.miniscript.core.util;
+
+import java.util.Set;
+import java.util.function.Consumer;
+
+public class ToSetConsumer<T> implements Consumer<T> {
+	private Set<T> set;
+
+	@Override
+	public void accept(T t) {
+		set.add(t);
+	}
+
+	public void setSet(Set<T> list) {
+		this.set = list;
+	}
+}