1 files changed, 50 insertions, 0 deletions
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/util/LRUMap.java b/org.eclipse.jgit/src/org/eclipse/jgit/util/LRUMap.java
new file mode 100644
index 0000000000..14f7f1f181
--- /dev/null
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/util/LRUMap.java
@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2018, Konrad Windszus <konrad_w@gmx.de> and others
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Distribution License v. 1.0 which is available at
+ * https://www.eclipse.org/org/documents/edl-v10.php.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+package org.eclipse.jgit.util;
+
+import java.util.LinkedHashMap;
+
+/**
+ * Map with only up to n entries. If a new entry is added so that the map
+ * contains more than those n entries the least-recently used entry is removed
+ * from the map.
+ *
+ * @param <K>
+ *            the type of keys maintained by this map
+ * @param <V>
+ *            the type of mapped values
+ *
+ * @since 5.4
+ */
+public class LRUMap<K, V> extends LinkedHashMap<K, V> {
+
+	private static final long serialVersionUID = 4329609127403759486L;
+
+	private final int limit;
+
+	/**
+	 * Constructs an empty map which may contain at most the given amount of
+	 * entries.
+	 *
+	 * @param initialCapacity
+	 *            the initial capacity
+	 * @param limit
+	 *            the number of entries the map should have at most
+	 */
+	public LRUMap(int initialCapacity, int limit) {
+		super(initialCapacity, 0.75f, true);
+		this.limit = limit;
+	}
+
+	@Override
+	protected boolean removeEldestEntry(java.util.Map.Entry<K, V> eldest) {
+		return size() > limit;
+	}
+}