IGNITE-24187 Fix code style issues in SystemDistributedConfigurationPropertyHolder (#5027)

Author: kgusakov

modules/configuration-system/build.gradle

@@ -25,6 +25,7 @@ dependencies {
 
     implementation project(':ignite-configuration-api')
     implementation project(':ignite-configuration-root')
+    implementation project(':ignite-core')
     implementation libs.auto.service.annotations
 
     testImplementation(testFixtures(project(':ignite-core')))

modules/configuration-system/src/main/java/org/apache/ignite/internal/configuration/utils/SystemDistributedConfigurationPropertyHolder.java

@@ -17,10 +17,10 @@
 
 package org.apache.ignite.internal.configuration.utils;
 
-import java.util.concurrent.CompletableFuture;
-import java.util.concurrent.atomic.AtomicReference;
-import java.util.function.BiConsumer;
+import static org.apache.ignite.internal.util.CompletableFutures.nullCompletedFuture;
+
 import java.util.function.Function;
+import java.util.function.ObjLongConsumer;
 import org.apache.ignite.internal.configuration.SystemDistributedConfiguration;
 import org.apache.ignite.internal.configuration.SystemDistributedView;
 import org.apache.ignite.internal.configuration.SystemPropertyView;
@@ -37,10 +37,10 @@ public class SystemDistributedConfigurationPropertyHolder<T> {
     private final SystemDistributedConfiguration systemDistributedConfig;
 
     /** Current value of target system distributed configuration property. */
-    private final AtomicReference<T> currentValue = new AtomicReference<>();
+    private volatile T currentValue;
 
     /** Listener, which receives (newValue, revision) on every configuration update. */
-    private final BiConsumer<T, Long> valueListener;
+    private final ObjLongConsumer<T> valueListener;
 
     /** Converter to translate {@link String} representation of property value to target type. */
     private final Function<String, T> propertyConverter;
@@ -56,7 +56,7 @@ public class SystemDistributedConfigurationPropertyHolder<T> {
      */
     public SystemDistributedConfigurationPropertyHolder(
             SystemDistributedConfiguration systemDistributedConfig,
-            BiConsumer<T, Long> valueListener,
+            ObjLongConsumer<T> valueListener,
             String propertyName,
             T defaultValue,
             Function<String, T> propertyConverter
@@ -70,7 +70,7 @@ public SystemDistributedConfigurationPropertyHolder(
         systemDistributedConfig.listen(ctx -> {
             updateSystemProperties(ctx.newValue(), ctx.storageRevision());
 
-            return CompletableFuture.completedFuture(null);
+            return nullCompletedFuture();
         });
     }
 
@@ -89,7 +89,7 @@ public void init() {
      * @return Current value.
      */
     public T currentValue() {
-        return currentValue.get();
+        return currentValue;
     }
 
     /**
@@ -103,7 +103,7 @@ private void updateSystemProperties(SystemDistributedView view, long revision) {
 
         T value = (systemPropertyView == null) ? defaultValue : propertyConverter.apply(systemPropertyView.propertyValue());
 
-        currentValue.set(value);
+        currentValue = value;
 
         if (revision != -1) {
             valueListener.accept(value, revision);

modules/configuration-system/src/test/java/org/apache/ignite/internal/configuration/utils/SystemDistributedConfigurationPropertyHolderTest.java

@@ -26,8 +26,8 @@
 
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.atomic.AtomicReference;
-import java.util.function.BiConsumer;
 import java.util.function.Function;
+import java.util.function.ObjLongConsumer;
 import org.apache.ignite.internal.configuration.SystemDistributedConfiguration;
 import org.apache.ignite.internal.configuration.testframework.ConfigurationExtension;
 import org.apache.ignite.internal.configuration.testframework.InjectConfiguration;
@@ -42,7 +42,7 @@ public class SystemDistributedConfigurationPropertyHolderTest extends BaseIgnite
 
     private static final String DEFAULT_VALUE = "defaultValue";
 
-    private static final BiConsumer<String, Long> noOpConsumer = (value, revision) -> {};
+    private static final ObjLongConsumer<String> noOpConsumer = (value, revision) -> {};
 
     @Test
     void testEmptySystemProperties(@InjectConfiguration SystemDistributedConfiguration systemConfig) {