Improving ConfigFilter behavior (helidon-io#8440)

Improving ConfigFilter behavior

Signed-off-by: David Kral <[email protected]>

config/config/src/main/java/io/helidon/config/ConfigItemBlueprint.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.helidon.config;
+
+import io.helidon.builder.api.Prototype;
+
+/**
+ * Configuration item policy.
+ * Contains information about the given item to improve its handling.
+ */
+@Prototype.Blueprint
+interface ConfigItemBlueprint {
+
+    /**
+     * Whether to cache this handled config item or not.
+     * If overall caching is disabled, this will not turn it on even if set to true.
+     *
+     * @return whether to cache handled config item
+     */
+    boolean cacheItem();
+
+    /**
+     * Handled config item.
+     *
+     * @return config item
+     */
+    String item();
+
+}

config/config/src/main/java/io/helidon/config/ProviderImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2017, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -312,22 +312,33 @@ void addFilter(ConfigFilter filter) {
         public String apply(Config.Key key, String stringValue) {
             if (cachingEnabled) {
                 if (!valueCache.containsKey(key)) {
-                    String value = proceedFilters(key, stringValue);
-                    valueCache.put(key, value);
+                    ConfigItem configItem = ConfigItem.builder()
+                            .cacheItem(cachingEnabled)
+                            .item(stringValue)
+                            .build();
+                    configItem = proceedFilters(key, configItem);
+                    String value = configItem.item();
+                    if (configItem.cacheItem()) {
+                        valueCache.put(key, value);
+                    }
                     return value;
                 }
                 return valueCache.get(key);
             } else {
-                return proceedFilters(key, stringValue);
+                ConfigItem configItem = ConfigItem.builder()
+                        .cacheItem(cachingEnabled)
+                        .item(stringValue)
+                        .build();
+                return proceedFilters(key, configItem).item();
             }
-
         }
 
-        private String proceedFilters(Config.Key key, String stringValue) {
+        private ConfigItem proceedFilters(Config.Key key, ConfigItem configItem) {
+            ConfigItem toReturn = configItem;
             for (Function<Config, ConfigFilter> configFilterProvider : filterProviders) {
-                stringValue = configFilterProvider.apply(config).apply(key, stringValue);
+                toReturn = configFilterProvider.apply(config).apply(key, toReturn);
             }
-            return stringValue;
+            return toReturn;
         }
 
         void enableCaching() {

config/config/src/main/java/io/helidon/config/spi/ConfigFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2017, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.helidon.config.spi;
 
 import io.helidon.config.Config;
+import io.helidon.config.ConfigItem;
 
 /**
  * Filter that can transform elementary configuration ({@code String}) values
@@ -65,6 +66,28 @@ public interface ConfigFilter {
      */
     String apply(Config.Key key, String stringValue);
 
+    /**
+     * Filters an elementary config value before it is made available to the
+     * application via the {@code Config} API. Returns {@link ConfigItem} object
+     * which contains filtered config value and specific value settings.
+     *
+     * @param key configuration {@link Config#key() key} associated with the
+     * {@code Config} node
+     * @param itemPolicy original item policy
+     * @return new item policy object with the filtered config value
+     */
+    default ConfigItem apply(Config.Key key, ConfigItem itemPolicy) {
+        String originalItem = itemPolicy.item();
+        String newItem = apply(key, originalItem);
+        if (newItem.equals(originalItem)) {
+            return itemPolicy;
+        }
+        return ConfigItem.builder()
+                .from(itemPolicy)
+                .item(newItem)
+                .build();
+    }
+
     /**
      * Initializes the filter using the {@code Config} instance which the filter
      * will affect once {@code Config.Builder.build} completes.

config/encryption/src/main/java/io/helidon/config/encryption/EncryptionFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2018, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -26,6 +26,7 @@
 
 import io.helidon.common.pki.Keys;
 import io.helidon.config.Config;
+import io.helidon.config.ConfigItem;
 import io.helidon.config.MissingValueException;
 import io.helidon.config.spi.ConfigFilter;
 
@@ -132,6 +133,19 @@ public String apply(Config.Key key, String stringValue) {
         return maybeDecode(key, stringValue);
     }
 
+    @Override
+    public ConfigItem apply(Config.Key key, ConfigItem itemPolicy) {
+        String item = apply(key, itemPolicy.item());
+        if (item.equals(itemPolicy.item())) {
+            //This was not config item handled by this filter.
+            return itemPolicy;
+        }
+        return ConfigItem.builder()
+                .cacheItem(false)
+                .item(item)
+                .build();
+    }
+
     private String maybeDecode(Config.Key key, String value) {
         Set<String> processedValues = new HashSet<>();
 

config/encryption/src/main/java/io/helidon/config/encryption/EncryptionFilterService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2021 Oracle and/or its affiliates.
+ * Copyright (c) 2018, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.helidon.config.encryption;
 
 import io.helidon.config.Config;
+import io.helidon.config.ConfigItem;
 import io.helidon.config.spi.ConfigFilter;
 
 /**
@@ -34,6 +35,14 @@ public String apply(Config.Key key, String stringValue) {
         return filter.apply(key, stringValue);
     }
 
+    @Override
+    public ConfigItem apply(Config.Key key, ConfigItem itemPolicy) {
+        if (null == filter) {
+            return itemPolicy;
+        }
+        return filter.apply(key, itemPolicy);
+    }
+
     @Override
     public void init(Config config) {
         this.filter = EncryptionFilter.fromConfig().apply(config);

config/encryption/src/test/java/io/helidon/config/encryption/AbstractSecureConfigTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018, 2021 Oracle and/or its affiliates.
+ * Copyright (c) 2018, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -27,9 +27,12 @@
 
 import static io.helidon.config.ConfigValues.simpleValue;
 import static org.hamcrest.CoreMatchers.is;
+import static org.hamcrest.CoreMatchers.not;
+import static org.hamcrest.CoreMatchers.sameInstance;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.contains;
 import static org.hamcrest.Matchers.hasSize;
+import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 /**
@@ -87,6 +90,16 @@ void testSymmetric() {
         testPassword(getConfig(), "pwd6", "");
     }
 
+    @Test
+    void testDecryptedValuesNotCached() {
+        String value1 = getConfig().get("pwd4").asString().get();
+        String value2 = getConfig().get("pwd4").asString().get();
+        assertThat(value1, is(TEST_STRING));
+        assertThat(value2, is(TEST_STRING));
+        //This is intended, since we want to verify, that the new String has been created and was not reused
+        assertThat(value1, not(sameInstance(value2)));
+    }
+
     @Test
     public void testPasswordArray() {
         ConfigValue<List<String>> passwordsOpt = getConfig().get("passwords")