Merge pull request #23 from Draczech/bytebuddyCaching

Reusing ConfigView instances when possible

build.gradle

@@ -25,8 +25,8 @@ java {
 def junitJupiterVersion = '5.8.1'
 
 dependencies {
-  api "com.typesafe:config:1.4.1"
-  implementation 'net.bytebuddy:byte-buddy:1.12.1'
+  api "com.typesafe:config:1.4.2"
+  implementation 'net.bytebuddy:byte-buddy:1.12.14'
   testImplementation("org.junit.jupiter:junit-jupiter-api:${junitJupiterVersion}")
   testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:${junitJupiterVersion}")
 }

src/main/java/cz/datadriven/utils/config/view/ConfigViewFactory.java

@@ -18,7 +18,10 @@
 import com.typesafe.config.Config;
 import java.lang.reflect.InvocationTargetException;
 import java.lang.reflect.Method;
+import java.util.Map;
+import java.util.Objects;
 import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.stream.Collectors;
 import net.bytebuddy.ByteBuddy;
 import net.bytebuddy.ClassFileVersion;
@@ -35,11 +38,40 @@ private ConfigViewFactory() {
     // no-op
   }
 
+  private static class ViewProxyKey<T> {
+    Class<T> viewClass;
+    Config rawConfig;
+
+    public ViewProxyKey(Class<T> configViewClass, Config config) {
+      this.viewClass = configViewClass;
+      this.rawConfig = config;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+      if (this == o) {
+        return true;
+      }
+      if (!(o instanceof ViewProxyKey)) {
+        return false;
+      }
+      ViewProxyKey<?> that = (ViewProxyKey<?>) o;
+      return viewClass.equals(that.viewClass) && rawConfig.equals(that.rawConfig);
+    }
+
+    @Override
+    public int hashCode() {
+      return Objects.hash(viewClass, rawConfig);
+    }
+  }
+
   private static final Set<TypeDescription> ANNOTATION_TYPE_DESCRIPTORS =
       ConfigViewProxy.ANNOTATIONS.stream()
           .map(TypeDescription.ForLoadedType::of)
           .collect(Collectors.toSet());
 
+  private static final Map<ViewProxyKey<?>, Object> VIEW_PROXY_MAP = new ConcurrentHashMap<>();
+
   /**
    * Create config view from a given config.
    *
@@ -54,7 +86,7 @@ public static <T> T create(Class<T> configViewClass, Config config, String baseP
   }
 
   /**
-   * Create config view from a given config.
+   * Create config view from a given config or return already cached instance.
    *
    * @param configViewClass class to materialize view into
    * @param config config to create view from
@@ -68,14 +100,37 @@ public static <T> T create(Class<T> configViewClass, Config config) {
               "Can not instantiate ConfigView for class [%s]. Did you forget @ConfigView annotation?",
               configViewClass));
     }
+
+    ViewProxyKey<T> proxyKey = new ViewProxyKey<>(configViewClass, config);
+
+    Object proxiedView =
+        VIEW_PROXY_MAP.computeIfAbsent(
+            proxyKey,
+            viewProxyKey -> {
+              final ConfigViewProxy proxy =
+                  new ConfigViewProxy(new ConfigViewProxy.Factory(config));
+              return instantiateView(configViewClass, proxy);
+            });
+
+    return configViewClass.cast(proxiedView);
+  }
+
+  /**
+   * Instatiates given class using provided invocation handler for respective method calls.
+   *
+   * @param configViewClass Class annotated with 'ConfigView' annotation.
+   * @param proxy interceptor for methods providing configuration properties.
+   * @return New instance of given class providing configuration properties by selected methods.
+   * @param <T> Class to instantiate.
+   */
+  private static <T> T instantiateView(Class<T> configViewClass, ConfigViewProxy proxy) {
     try {
       return new ByteBuddy(ClassFileVersion.JAVA_V8)
           .subclass(configViewClass)
           .method(
               ElementMatchers.isAnnotatedWith(ANNOTATION_TYPE_DESCRIPTORS::contains)
                   .or(ElementMatchers.isDeclaredBy(RawConfigAware.class)))
-          .intercept(
-              InvocationHandlerAdapter.of(new ConfigViewProxy(new ConfigViewProxy.Factory(config))))
+          .intercept(InvocationHandlerAdapter.of(proxy))
           .make()
           .load(
               ConfigViewFactory.class.getClassLoader(),

src/main/java/cz/datadriven/utils/config/view/ConfigViewProxy.java

@@ -172,7 +172,6 @@ public Object invoke(Object proxy, Method method, Object[] args) {
       return factory.getConfig();
     } else {
       throw new UnsupportedOperationException("Not implemented");
-      //      return methodProxy.invokeSuper(obj, args);
     }
   }
 
@@ -200,12 +199,12 @@ private Optional<Annotation> getInstrumentAnnotation(Method method) {
         Arrays.stream(method.getDeclaredAnnotations())
             .filter(a -> ANNOTATIONS.contains(a.annotationType()))
             .collect(Collectors.toList());
-    if (annotations.size() == 0) {
+    if (annotations.isEmpty()) {
       return Optional.empty();
     } else if (annotations.size() == 1) {
       return Optional.of(annotations.get(0));
     } else {
-      throw new RuntimeException(
+      throw new IllegalArgumentException(
           "Method [ " + method + " ] has more than one instrument annotation.");
     }
   }

src/test/java/cz/datadriven/utils/config/view/ConfigViewTest.java

@@ -167,9 +167,7 @@ void testWrapNonAnnotatedClass() {
     final Config config = ConfigFactory.empty();
     assertThrows(
         IllegalArgumentException.class,
-        () -> {
-          ConfigViewFactory.create(NonAnnotatedTestConfigView.class, config);
-        });
+        () -> ConfigViewFactory.create(NonAnnotatedTestConfigView.class, config));
   }
 
   @Test
@@ -194,4 +192,16 @@ void testQuotedKeyWithDotInAMap() {
     Assertions.assertEquals(20, mapConfig.data().get("quoted-apple"));
     Assertions.assertEquals(30, mapConfig.data().get("dotted.apple"));
   }
+
+  @Test
+  void sameClassTest() {
+    final Config config =
+        ConfigFactory.empty()
+            .withValue("first", ConfigValueFactory.fromAnyRef("first_value"))
+            .withValue("second", ConfigValueFactory.fromAnyRef("second_value"));
+    final TestConfigView wrap = ConfigViewFactory.create(TestConfigView.class, config);
+    final TestConfigView anotherWrap = ConfigViewFactory.create(TestConfigView.class, config);
+    assertEquals(wrap.getClass(), anotherWrap.getClass());
+    assertEquals(wrap, anotherWrap);
+  }
 }