From cec7f4017d598e61865be1a37e4df8cee5f968ea Mon Sep 17 00:00:00 2001
From: Jonathan Shook <jshook@gmail.com>
Date: Mon, 13 Sep 2021 09:42:21 -0500
Subject: [PATCH] centralize ObjectCache into core templating API

---
 .../engine/api/templating/ObjectCache.java    | 27 +++++++++++++++++++
 1 file changed, 27 insertions(+)
 create mode 100644 adapters-api/src/main/java/io/nosqlbench/engine/api/templating/ObjectCache.java

diff --git a/adapters-api/src/main/java/io/nosqlbench/engine/api/templating/ObjectCache.java b/adapters-api/src/main/java/io/nosqlbench/engine/api/templating/ObjectCache.java
new file mode 100644
index 000000000..ba978afae
--- /dev/null
+++ b/adapters-api/src/main/java/io/nosqlbench/engine/api/templating/ObjectCache.java
@@ -0,0 +1,27 @@
+package io.nosqlbench.engine.api.templating;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.function.Function;
+
+/**
+ * An object cache to memoize returned objects into a concurrent hash map by name.
+ * This is meant to be used when you want to lazily initialize an instance of something
+ * by name that is likely to be re-used over the lifetime of an owning object.
+ *
+ * @param <T> The type of object.
+ */
+public class ObjectCache<T> implements Function<String,T> {
+
+    private final ConcurrentHashMap<String,T> cache = new ConcurrentHashMap<>();
+
+    private final Function<String, T> newInstanceFunction;
+
+    public ObjectCache(Function<String,T> newInstanceFunction) {
+        this.newInstanceFunction = newInstanceFunction;
+    }
+
+    @Override
+    public T apply(String name) {
+        return cache.computeIfAbsent(name, newInstanceFunction);
+    }
+}