Add CloseShieldChannel to close-shielded NIO Channels

- Only convert set to array if required
- Extract constant
- Use the simple class name for CloseShieldChannel in toString()

Author: garydgregory

src/changes/changes.xml

@@ -66,7 +66,7 @@ The <action> type attribute can be add,update,fix,remove.
       <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add org.apache.commons.io.file.PathUtils.getPath(String, String).</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add org.apache.commons.io.channels.ByteArraySeekableByteChannel.</action>
       <action dev="ggregory" type="add"                due-to="Gary Gregory">Add IOIterable.asIterable().</action>
-      <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add CloseShieldChannel to close-shielded NIO Channels.</action>
+      <action dev="pkarwasz" type="add"                due-to="Piotr P. Karwasz">Add CloseShieldChannel to close-shielded NIO Channels #786.</action>
       <!-- UPDATE -->
       <action type="update" dev="ggregory"             due-to="Gary Gregory, Dependabot">Bump org.apache.commons:commons-parent from 85 to 88 #774, #783.</action>
       <action type="update" dev="ggregory"             due-to="Gary Gregory">[test] Bump commons-codec:commons-codec from 1.18.0 to 1.19.0.</action>

src/main/java/org/apache/commons/io/channels/CloseShieldChannel.java

@@ -37,19 +37,16 @@
  */
 public final class CloseShieldChannel {
 
-    private static Class<?>[] collectChannelInterfaces(final Class<?> type) {
-        final Set<Class<?>> out = new LinkedHashSet<>();
-        collectChannelInterfaces(type, out);
-        return out.toArray(new Class<?>[0]);
-    }
+    private static final Class<?>[] EMPTY = {};
 
-    private static void collectChannelInterfaces(final Class<?> type, final Set<Class<?>> out) {
+    private static Set<Class<?>> collectChannelInterfaces(final Class<?> type, final Set<Class<?>> out) {
         // Visit interfaces
         for (final Class<?> iface : type.getInterfaces()) {
             if (Channel.class.isAssignableFrom(iface) && out.add(iface)) {
                 collectChannelInterfaces(iface, out);
             }
         }
+        return out;
     }
 
     /**
@@ -63,18 +60,14 @@ private static void collectChannelInterfaces(final Class<?> type, final Set<Clas
     public static <T extends Channel> T wrap(final T channel) {
         Objects.requireNonNull(channel, "channel");
         // Fast path: already our shield
-        if (Proxy.isProxyClass(channel.getClass())) {
-            if (Proxy.getInvocationHandler(channel) instanceof CloseShieldChannelHandler) {
-                return channel;
-            }
+        if (Proxy.isProxyClass(channel.getClass()) && Proxy.getInvocationHandler(channel) instanceof CloseShieldChannelHandler) {
+            return channel;
         }
         // Collect only Channel sub-interfaces.
-        Class<?>[] ifaces = collectChannelInterfaces(channel.getClass());
-        if (ifaces.length == 0) {
-            ifaces = new Class<?>[] { Channel.class }; // fallback to root surface
-        }
+        final Set<Class<?>> set = collectChannelInterfaces(channel.getClass(), new LinkedHashSet<>());
+        // fallback to root surface
         return (T) Proxy.newProxyInstance(channel.getClass().getClassLoader(), // use delegate's loader
-                ifaces, new CloseShieldChannelHandler(channel));
+                set.isEmpty() ? new Class<?>[] { Channel.class } : set.toArray(EMPTY), new CloseShieldChannelHandler(channel));
     }
 
     private CloseShieldChannel() {

src/main/java/org/apache/commons/io/channels/CloseShieldChannelHandler.java

@@ -103,7 +103,7 @@ public Object invoke(final Object proxy, final Method method, final Object[] arg
     private Object invokeObjectMethod(final Object proxy, final Method method, final Object[] args) {
         switch (method.getName()) {
         case "toString":
-            return "CloseShield(" + delegate + ")";
+            return "CloseShieldChannel(" + delegate + ")";
         case "hashCode":
             return Objects.hashCode(delegate);
         case "equals": {