Add caching and improve performance

core-common/src/main/java/org/glassfish/jersey/internal/util/collection/GuardianStringKeyMultivaluedMap.java

@@ -0,0 +1,208 @@
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0, which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the
+ * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
+ * version 2 with the GNU Classpath Exception, which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ */
+
+package org.glassfish.jersey.internal.util.collection;
+
+import javax.ws.rs.core.MultivaluedMap;
+import java.util.Collection;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Objects;
+import java.util.Set;
+
+/**
+ * The {@link MultivaluedMap} wrapper that is able to set guards observing changes of values represented by a key.
+ * @param <V> The value type of the wrapped {@code MultivaluedMap}.
+ *
+ * @since 2.38
+ */
+public class GuardianStringKeyMultivaluedMap<V> implements MultivaluedMap<String, V> {
+
+    private final MultivaluedMap<String, V> inner;
+    private final Map<String, Boolean> guards = new HashMap<>();
+
+    public GuardianStringKeyMultivaluedMap(MultivaluedMap<String, V> inner) {
+        this.inner = inner;
+    }
+
+    @Override
+    public void putSingle(String key, V value) {
+        observe(key);
+        inner.putSingle(key, value);
+    }
+
+    @Override
+    public void add(String key, V value) {
+        observe(key);
+        inner.add(key, value);
+    }
+
+    @Override
+    public V getFirst(String key) {
+        return inner.getFirst(key);
+    }
+
+    @Override
+    public void addAll(String key, V... newValues) {
+        observe(key);
+        inner.addAll(key, newValues);
+    }
+
+    @Override
+    public void addAll(String key, List<V> valueList) {
+        observe(key);
+        inner.addAll(key, valueList);
+    }
+
+    @Override
+    public void addFirst(String key, V value) {
+        observe(key);
+        inner.addFirst(key, value);
+    }
+
+    @Override
+    public boolean equalsIgnoreValueOrder(MultivaluedMap<String, V> otherMap) {
+        return inner.equalsIgnoreValueOrder(otherMap);
+    }
+
+    @Override
+    public int size() {
+        return inner.size();
+    }
+
+    @Override
+    public boolean isEmpty() {
+        return inner.isEmpty();
+    }
+
+    @Override
+    public boolean containsKey(Object key) {
+        return inner.containsKey(key);
+    }
+
+    @Override
+    public boolean containsValue(Object value) {
+        return inner.containsValue(value);
+    }
+
+    @Override
+    public List<V> get(Object key) {
+        return inner.get(key);
+    }
+
+    @Override
+    public List<V> put(String key, List<V> value) {
+        observe(key);
+        return inner.put(key, value);
+    }
+
+    @Override
+    public List<V> remove(Object key) {
+        if (key != null) {
+            observe(key.toString());
+        }
+        return inner.remove(key);
+    }
+
+    @Override
+    public void putAll(Map<? extends String, ? extends List<V>> m) {
+        for (String key : m.keySet()) {
+            observe(key);
+        }
+        inner.putAll(m);
+    }
+
+    @Override
+    public void clear() {
+        observeAll();
+        inner.clear();
+    }
+
+    @Override
+    public Set<String> keySet() {
+        return inner.keySet();
+    }
+
+    @Override
+    public Collection<List<V>> values() {
+        return inner.values();
+    }
+
+    @Override
+    public Set<Entry<String, List<V>>> entrySet() {
+        return inner.entrySet();
+    }
+
+    /**
+     * Observe changes of a value represented by the key.
+     * @param key the key values to observe
+     */
+    public void setGuard(String key) {
+        guards.put(key, false);
+    }
+
+    /**
+     * Get all the guarded keys
+     * @return a {@link Set} of keys guarded.
+     */
+    public Set<String> getGuards() {
+        return guards.keySet();
+    }
+
+    /**
+     * Return true when the value represented by the key has changed. Resets any observation - the operation is not idempotent.
+     * @param key the Key observed.
+     * @return whether the value represented by the key has changed.
+     */
+    public boolean isObservedAndReset(String key) {
+        Boolean observed = guards.get(key);
+        guards.put(key, false);
+        return observed != null && observed;
+    }
+
+    private void observe(String key) {
+        for (Map.Entry<String, Boolean> guard : guards.entrySet()) {
+            if (guard.getKey().equals(key)) {
+                guard.setValue(true);
+            }
+        }
+    }
+
+    private void observeAll() {
+        for (Map.Entry<String, Boolean> guard : guards.entrySet()) {
+            guard.setValue(true);
+        }
+    }
+
+    @Override
+    public String toString() {
+        return inner.toString();
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o) return true;
+        if (o == null || getClass() != o.getClass()) return false;
+        GuardianStringKeyMultivaluedMap<?> that = (GuardianStringKeyMultivaluedMap<?>) o;
+        return inner.equals(that.inner) && guards.equals(that.guards);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(inner, guards);
+    }
+}

core-common/src/main/java/org/glassfish/jersey/internal/util/collection/LRU.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright (c) 2022 Oracle and/or its affiliates. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v. 2.0, which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * This Source Code may also be made available under the following Secondary
+ * Licenses when the conditions for such availability set forth in the
+ * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
+ * version 2 with the GNU Classpath Exception, which is available at
+ * https://www.gnu.org/software/classpath/license.html.
+ *
+ * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
+ */
+
+package org.glassfish.jersey.internal.util.collection;
+
+import org.glassfish.jersey.internal.guava.Cache;
+import org.glassfish.jersey.internal.guava.CacheBuilder;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * An abstract LRU interface wrapping an actual LRU implementation.
+ * @param <K> Key type
+ * @param <V> Value type
+ * @Since 2.38
+ */
+public abstract class LRU<K, V> {
+
+    /**
+     * Returns the value associated with {@code key} in this cache, or {@code null} if there is no
+     * cached value for {@code key}.
+     */
+    public abstract V getIfPresent(Object key);
+
+    /**
+     * Associates {@code value} with {@code key} in this cache. If the cache previously contained a
+     * value associated with {@code key}, the old value is replaced by {@code value}.
+     */
+    public abstract void put(K key, V value);
+
+    /**
+     * Create new LRU
+     * @return new LRU
+     */
+    public static <K, V> LRU<K, V> create() {
+        return LRUFactory.createLRU();
+    }
+
+    private static class LRUFactory {
+        // TODO configure via the Configuration
+        public static final int LRU_CACHE_SIZE = 128;
+        public static final long TIMEOUT = 5000L;
+        private static <K, V> LRU<K, V> createLRU() {
+            final Cache<K, V> CACHE = CacheBuilder.newBuilder()
+                    .maximumSize(LRU_CACHE_SIZE)
+                    .expireAfterAccess(TIMEOUT, TimeUnit.MILLISECONDS)
+                    .build();
+            return new LRU<K, V>() {
+                @Override
+                public V getIfPresent(Object key) {
+                    return CACHE.getIfPresent(key);
+                }
+
+                @Override
+                public void put(K key, V value) {
+                    CACHE.put(key, value);
+                }
+            };
+        }
+    }
+
+
+}

core-common/src/main/java/org/glassfish/jersey/message/internal/HeaderUtils.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2010, 2021 Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2010, 2022 Oracle and/or its affiliates. All rights reserved.
  *
  * This program and the accompanying materials are made available under the
  * terms of the Eclipse Public License v. 2.0, which is available at
@@ -102,7 +102,7 @@ public static AbstractMultivaluedMap<String, Object> createOutbound() {
      *         if the supplied header value is {@code null}.
      */
     @SuppressWarnings("unchecked")
-    private static String asString(final Object headerValue, RuntimeDelegate rd) {
+    public static String asString(final Object headerValue, RuntimeDelegate rd) {
         if (headerValue == null) {
             return null;
         }
@@ -149,7 +149,7 @@ public static String asString(final Object headerValue, Configuration configurat
      *                     will be called for before element conversion.
      * @return String view of header values.
      */
-    private static List<String> asStringList(final List<Object> headerValues, final RuntimeDelegate rd) {
+    public static List<String> asStringList(final List<Object> headerValues, final RuntimeDelegate rd) {
         if (headerValues == null || headerValues.isEmpty()) {
             return Collections.emptyList();
         }
@@ -191,7 +191,24 @@ public static MultivaluedMap<String, String> asStringHeaders(
             return null;
         }
 
-        final RuntimeDelegate rd = RuntimeDelegateDecorator.configured(configuration);
+        return asStringHeaders(headers, RuntimeDelegateDecorator.configured(configuration));
+    }
+
+    /**
+     * Returns string view of passed headers. Any modifications to the headers are visible to the view, the view also
+     * supports removal of elements. Does not support other modifications.
+     *
+     * @param headers headers.
+     * @param rd     {@link RuntimeDelegate} instance or {@code null} (in that case {@link RuntimeDelegate#getInstance()}
+     *               will be called for before conversion of elements).
+     * @return String view of headers or {@code null} if {code headers} input parameter is {@code null}.
+     */
+    public static MultivaluedMap<String, String> asStringHeaders(
+            final MultivaluedMap<String, Object> headers, RuntimeDelegate rd) {
+        if (headers == null) {
+            return null;
+        }
+
         return new AbstractMultivaluedMap<String, String>(
                 Views.mapView(headers, input -> HeaderUtils.asStringList(input, rd))
         ) {