Extract concurrent identity hashmap into separate class

1 files changed, 39 insertions, 0 deletions

diff --git a/container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/SimpleConcurrentIdentityHashMap.java b/container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/SimpleConcurrentIdentityHashMap.java
new file mode 100644
index 00000000000..52142e534ba
--- /dev/null
+++ b/container-core/src/main/java/com/yahoo/jdisc/http/server/jetty/SimpleConcurrentIdentityHashMap.java
@@ -0,0 +1,39 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.jdisc.http.server.jetty;
+
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
+
+/**
+ * A simplified {@link ConcurrentMap} using reference-equality to compare keys (similarly to {@link java.util.IdentityHashMap})
+ *
+ * @author bjorncs
+ */
+class SimpleConcurrentIdentityHashMap<K, V> {
+
+    private final ConcurrentMap<IdentityKey<K>, V> wrappedMap = new ConcurrentHashMap<>();
+
+    V get(K key) { return wrappedMap.get(IdentityKey.of(key)); }
+
+    V remove(K key) { return wrappedMap.remove(IdentityKey.of(key)); }
+
+    void put(K key, V value) { wrappedMap.put(IdentityKey.of(key), value); }
+
+    private static class IdentityKey<K> {
+        final K instance;
+
+        IdentityKey(K instance) { this.instance = instance; }
+
+        static <K> IdentityKey<K> of(K instance) { return new IdentityKey<>(instance); }
+
+        @Override public int hashCode() { return System.identityHashCode(instance); }
+
+        @Override
+        public boolean equals(Object obj) {
+            if (this == obj) return true;
+            if (!(obj instanceof IdentityKey<?>)) return false;
+            IdentityKey<?> other = (IdentityKey<?>) obj;
+            return this.instance == other.instance;
+        }
+    }
+}