Fix ConcurrentModificationException in ExpiringUserSecurityContextCache

bundles/org.openhab.core.io.rest.auth/src/main/java/org/openhab/core/io/rest/auth/internal/ExpiringUserSecurityContextCache.java

@@ -12,6 +12,7 @@
  */
 package org.openhab.core.io.rest.auth.internal;
 
+import java.util.HashSet;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
@@ -28,8 +29,8 @@
  */
 @NonNullByDefault
 public class ExpiringUserSecurityContextCache {
-    private static final int MAX_SIZE = 10;
-    private static final int CLEANUP_FREQUENCY = 10;
+    static final int MAX_SIZE = 10;
+    static final int CLEANUP_FREQUENCY = 10;
 
     private final long keepPeriod;
     private final Map<String, Entry> entryMap;
@@ -50,7 +51,7 @@ protected boolean removeEldestEntry(Map.@Nullable Entry<String, Entry> eldest) {
     synchronized @Nullable UserSecurityContext get(String key) {
         calls++;
         if (calls >= CLEANUP_FREQUENCY) {
-            entryMap.keySet().forEach(k -> getEntry(k));
+            new HashSet<>(entryMap.keySet()).forEach(k -> getEntry(k));
             calls = 0;
         }
         Entry entry = getEntry(key);

bundles/org.openhab.core.io.rest.auth/src/test/java/org/openhab/core/io/rest/auth/internal/ExpiringUserSecurityContextCacheTest.java

@@ -0,0 +1,132 @@
+/**
+ * Copyright (c) 2010-2021 Contributors to the openHAB project
+ *
+ * See the NOTICE file(s) distributed with this work for additional
+ * information.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ */
+package org.openhab.core.io.rest.auth.internal;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.openhab.core.io.rest.auth.internal.ExpiringUserSecurityContextCache.*;
+
+import java.time.Duration;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.eclipse.jdt.annotation.NonNullByDefault;
+import org.junit.jupiter.api.Test;
+import org.openhab.core.auth.Authentication;
+import org.openhab.core.auth.GenericUser;
+
+/**
+ * Tests {@link ExpiringUserSecurityContextCache}.
+ *
+ * @author Wouter Born - Initial contribution
+ */
+@NonNullByDefault
+public class ExpiringUserSecurityContextCacheTest {
+
+    private static final Duration ONE_HOUR = Duration.ofHours(1);
+
+    private ExpiringUserSecurityContextCache createCache(Duration expirationDuration) {
+        return new ExpiringUserSecurityContextCache(expirationDuration.toMillis());
+    }
+
+    private Map<String, UserSecurityContext> createValues(int count) {
+        Map<String, UserSecurityContext> map = new LinkedHashMap<>();
+        for (int i = 0; i < count; i++) {
+            String userName = "user" + i;
+            UserSecurityContext userSecurityContext = new UserSecurityContext(new GenericUser(userName),
+                    new Authentication(userName), userName + " token");
+            map.put("key" + i, userSecurityContext);
+        }
+        return map;
+    }
+
+    private void addValues(ExpiringUserSecurityContextCache cache, Map<String, UserSecurityContext> values) {
+        values.entrySet().stream().forEach(entry -> cache.put(entry.getKey(), entry.getValue()));
+    }
+
+    private void assertValuesAreCached(Map<String, UserSecurityContext> values,
+            ExpiringUserSecurityContextCache cache) {
+        for (Entry<String, UserSecurityContext> entry : values.entrySet()) {
+            assertThat(cache.get(entry.getKey()), is(entry.getValue()));
+        }
+    }
+
+    private void assertValuesAreNotCached(Map<String, UserSecurityContext> values,
+            ExpiringUserSecurityContextCache cache) {
+        for (Entry<String, UserSecurityContext> entry : values.entrySet()) {
+            assertThat(cache.get(entry.getKey()), is(nullValue()));
+        }
+    }
+
+    @Test
+    public void cachedValuesAreReturned() {
+        ExpiringUserSecurityContextCache cache = createCache(ONE_HOUR);
+        Map<String, UserSecurityContext> values = createValues(MAX_SIZE);
+        addValues(cache, values);
+        assertValuesAreCached(values, cache);
+    }
+
+    @Test
+    public void nonCachedValuesAreNotReturned() {
+        ExpiringUserSecurityContextCache cache = createCache(ONE_HOUR);
+        Map<String, UserSecurityContext> values = createValues(MAX_SIZE);
+        assertValuesAreNotCached(values, cache);
+    }
+
+    @Test
+    public void clearedValuesAreNotReturned() {
+        ExpiringUserSecurityContextCache cache = createCache(ONE_HOUR);
+        Map<String, UserSecurityContext> values = createValues(MAX_SIZE);
+        addValues(cache, values);
+        cache.clear();
+        assertValuesAreNotCached(values, cache);
+    }
+
+    @Test
+    public void eldestEntriesAreRemovedWhenMaxSizeIsExceeded() {
+        ExpiringUserSecurityContextCache cache = createCache(ONE_HOUR);
+        int removed = 20;
+        Map<String, UserSecurityContext> values = createValues(MAX_SIZE + removed);
+        addValues(cache, values);
+
+        Map<String, UserSecurityContext> removedValues = new LinkedHashMap<>();
+        Map<String, UserSecurityContext> cachedValues = new LinkedHashMap<>();
+
+        int i = 0;
+        for (Entry<String, UserSecurityContext> entry : values.entrySet()) {
+            if (i < removed) {
+                removedValues.put(entry.getKey(), entry.getValue());
+            } else {
+                cachedValues.put(entry.getKey(), entry.getValue());
+            }
+            i++;
+        }
+
+        assertValuesAreNotCached(removedValues, cache);
+        assertValuesAreCached(cachedValues, cache);
+    }
+
+    @Test
+    public void expiredEntriesAreRemoved() {
+        ExpiringUserSecurityContextCache cache = createCache(Duration.ZERO);
+        Map<String, UserSecurityContext> values = createValues(MAX_SIZE);
+        addValues(cache, values);
+
+        for (int i = 0; i < CLEANUP_FREQUENCY; i++) {
+            cache.get("key");
+        }
+
+        assertValuesAreNotCached(values, cache);
+    }
+}