Redo Handler renaming (#9318)

* Redo Handler renaming

Wrapper to Singleton
BaseWrapper to Wrapper

* Updates from review

documentation/jetty-documentation/src/main/java/org/eclipse/jetty/docs/programming/server/http/HTTPServerDocs.java

@@ -583,7 +583,7 @@ public boolean process(Request request, Response response, Callback callback)
         }
 
         // tag::handlerFilter[]
-        class FilterHandler extends Handler.BaseWrapper
+        class FilterHandler extends Handler.Wrapper
         {
             @Override
             public boolean process(Request request, Response response, Callback callback) throws Exception

jetty-core/jetty-fcgi/jetty-fcgi-proxy/src/test/java/org/eclipse/jetty/fcgi/proxy/FastCGIProxyHandlerTest.java

@@ -208,7 +208,7 @@ public boolean process(Request request, Response response, Callback callback)
         fcgiHandler.setOriginalQueryAttribute(queryAttribute);
 
         proxyContext.stop();
-        proxyContext.insertHandler(new Handler.BaseWrapper()
+        proxyContext.insertHandler(new Handler.Wrapper()
         {
             @Override
             public boolean process(Request request, Response response, Callback callback) throws Exception

jetty-core/jetty-rewrite/src/main/java/org/eclipse/jetty/rewrite/handler/RewriteHandler.java

@@ -37,7 +37,7 @@
  * {@link PatternRule} subclasses), via regular expression matching (using
  * {@link RegexRule} subclasses), or by a custom implementation of {@code Rule}.</p>
  */
-public class RewriteHandler extends Handler.BaseWrapper
+public class RewriteHandler extends Handler.Wrapper
 {
     private final RuleContainer _rules;
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/Handler.java

@@ -226,7 +226,7 @@ static void setAsParent(Container parent, Handler handler)
         {
             if (parent instanceof Collection collection)
                 collection.addHandler(handler);
-            else if (parent instanceof Wrapper wrapper)
+            else if (parent instanceof Singleton wrapper)
                 wrapper.setHandler(handler);
             else if (parent != null)
                 throw new IllegalArgumentException("Unknown parent type: " + parent);
@@ -256,16 +256,18 @@ default void setHandlers(Handler... handlers)
 
     /**
      * <p>A {@link Handler.Container} that can contain a single other {@code Handler}.</p>
-     * @see BaseWrapper for an implementation of {@link Wrapper}.
+     * <p>This is "singleton" in the sense of {@link Collections#singleton(Object)} and not
+     * in the sense of the singleton pattern of a single instance per JVM.</p>
+     * @see Wrapper for an implementation of {@link Singleton}.
      */
-    interface Wrapper extends Container
+    interface Singleton extends Container
     {
         Handler getHandler();
 
         /**
          * Set the nested handler.
          * Implementations should check for loops, set the server and update any {@link ContainerLifeCycle} beans, all
-         * of which can be done by using the utility method {@link #updateHandler(Wrapper, Handler)}
+         * of which can be done by using the utility method {@link #updateHandler(Singleton, Handler)}
          * @param handler The handler to set.
          */
         void setHandler(Handler handler);
@@ -286,12 +288,12 @@ default List<Handler> getHandlers()
             return (next == null) ? Collections.emptyList() : Collections.singletonList(next);
         }
 
-        default void insertHandler(Wrapper handler)
+        default void insertHandler(Singleton handler)
         {
-            Wrapper tail = handler;
-            while (tail.getHandler() instanceof BaseWrapper)
+            Singleton tail = handler;
+            while (tail.getHandler() instanceof Wrapper)
             {
-                tail = (BaseWrapper)tail.getHandler();
+                tail = (Wrapper)tail.getHandler();
             }
             if (tail.getHandler() != null)
                 throw new IllegalArgumentException("bad tail of inserted wrapper chain");
@@ -301,12 +303,12 @@ default void insertHandler(Wrapper handler)
         }
 
         /**
-         * @return The tail {@link Wrapper} of a chain of {@link Wrapper}s
+         * @return The tail {@link Singleton} of a chain of {@link Singleton}s
          */
-        default Wrapper getTail()
+        default Singleton getTail()
         {
-            Wrapper tail = this;
-            while (tail.getHandler() instanceof Wrapper wrapped)
+            Singleton tail = this;
+            while (tail.getHandler() instanceof Singleton wrapped)
                 tail = wrapped;
             return tail;
         }
@@ -322,7 +324,7 @@ default Wrapper getTail()
          * @param handler The handle to set
          * @return The set handler.
          */
-        static Handler updateHandler(Wrapper wrapper, Handler handler)
+        static Handler updateHandler(Singleton wrapper, Handler handler)
         {
             // check state
             Server server = wrapper.getServer();
@@ -561,31 +563,31 @@ public static <T extends Handler.Container> T findContainerOf(Handler.Container
     }
 
     /**
-     * An implementation of {@link Wrapper}, which is a {@link Handler.Container} that wraps a single other {@link Handler}.
+     * An implementation of {@link Singleton}, which is a {@link Handler.Container} that wraps a single other {@link Handler}.
      */
-    class BaseWrapper extends AbstractContainer implements Wrapper
+    class Wrapper extends AbstractContainer implements Singleton
     {
         private Handler _handler;
 
-        public BaseWrapper()
+        public Wrapper()
         {
             this(null);
         }
 
-        public BaseWrapper(boolean dynamic)
+        public Wrapper(boolean dynamic)
         {
             this(dynamic, null);
         }
 
-        public BaseWrapper(Handler handler)
+        public Wrapper(Handler handler)
         {
             this(false, handler);
         }
 
-        public BaseWrapper(boolean dynamic, Handler handler)
+        public Wrapper(boolean dynamic, Handler handler)
         {
             super(dynamic);
-            _handler = handler == null ? null : Wrapper.updateHandler(this, handler);
+            _handler = handler == null ? null : Singleton.updateHandler(this, handler);
         }
 
         @Override
@@ -599,7 +601,7 @@ public void setHandler(Handler handler)
         {
             if (!isDynamic() && isStarted())
                 throw new IllegalStateException(getState());
-            _handler = Wrapper.updateHandler(this, handler);
+            _handler = Singleton.updateHandler(this, handler);
         }
 
         @Override

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/Server.java

@@ -68,7 +68,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class Server extends Handler.BaseWrapper implements Attributes
+public class Server extends Handler.Wrapper implements Attributes
 {
     private static final Logger LOG = LoggerFactory.getLogger(Server.class);
     private static final String __serverInfo = "jetty/" + Server.getVersion();

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/AbstractLatencyRecordingHandler.java

@@ -28,7 +28,7 @@
  * (obtained from {@link HttpStream#getNanoTime()}) until the stream completion event has been handled by
  * {@link HttpStream#succeeded()} or {@link HttpStream#failed(Throwable)}.</p>
  */
-public abstract class AbstractLatencyRecordingHandler extends Handler.BaseWrapper
+public abstract class AbstractLatencyRecordingHandler extends Handler.Wrapper
 {
     private static final Logger LOG = LoggerFactory.getLogger(AbstractLatencyRecordingHandler.class);
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/BufferedResponseHandler.java

@@ -53,7 +53,7 @@
  * generated can also be unbounded.
  * </p>
  */
-public class BufferedResponseHandler extends Handler.BaseWrapper
+public class BufferedResponseHandler extends Handler.Wrapper
 {
     public static final String BUFFER_SIZE_ATTRIBUTE_NAME = BufferedResponseHandler.class.getName() + ".buffer-size";
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ConnectHandler.java

@@ -55,7 +55,7 @@
 /**
  * <p>Implementation of a {@link Handler} that supports HTTP CONNECT.</p>
  */
-public class ConnectHandler extends Handler.BaseWrapper
+public class ConnectHandler extends Handler.Wrapper
 {
     private static final Logger LOG = LoggerFactory.getLogger(ConnectHandler.class);
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ContextHandler.java

@@ -63,7 +63,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class ContextHandler extends Handler.BaseWrapper implements Attributes, Graceful, AliasCheck
+public class ContextHandler extends Handler.Wrapper implements Attributes, Graceful, AliasCheck
 {
     // TODO where should the alias checking go?
     // TODO add protected paths to ServletContextHandler?

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/DebugHandler.java

@@ -35,7 +35,7 @@
  * and the current thread name is updated with information that will link
  * to the details in that output.
  */
-public class DebugHandler extends Handler.BaseWrapper implements Connection.Listener
+public class DebugHandler extends Handler.Wrapper implements Connection.Listener
 {
     private final DateCache _date = new DateCache("HH:mm:ss", Locale.US);
     private OutputStream _out;

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/DelayedHandler.java

@@ -36,7 +36,7 @@
 import org.eclipse.jetty.util.Fields;
 import org.eclipse.jetty.util.StringUtil;
 
-public class DelayedHandler extends Handler.BaseWrapper
+public class DelayedHandler extends Handler.Wrapper
 {
     @Override
     public boolean process(Request request, Response response, Callback callback) throws Exception

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/GracefulHandler.java

@@ -28,7 +28,7 @@
 /**
  * Handler to track active requests and allow them to gracefully complete.
  */
-public class GracefulHandler extends Handler.BaseWrapper implements Graceful
+public class GracefulHandler extends Handler.Wrapper implements Graceful
 {
     private static final Logger LOG = LoggerFactory.getLogger(GracefulHandler.class);
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/HotSwapHandler.java

@@ -23,7 +23,7 @@
 /**
  * A <code>HandlerContainer</code> that allows a hot swap of a wrapped handler.
  */
-public class HotSwapHandler extends Handler.AbstractContainer implements Handler.Wrapper
+public class HotSwapHandler extends Handler.AbstractContainer implements Handler.Singleton
 {
     // TODO unit tests
 
@@ -51,7 +51,7 @@ public Handler getHandler()
     public void setHandler(Handler handler)
     {
         // check state
-        Server server1 = ((Wrapper)this).getServer();
+        Server server1 = ((Singleton)this).getServer();
         if (server1 != null && server1.isStarted() && handler != null &&
             server1.getInvocationType() != Invocable.combine(server1.getInvocationType(), handler.getInvocationType()))
             throw new IllegalArgumentException("Cannot change invocation type of started server");

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/IdleTimeoutHandler.java

@@ -31,7 +31,7 @@
  *   </Set>
  * </pre>
  */
-public class IdleTimeoutHandler extends Handler.BaseWrapper
+public class IdleTimeoutHandler extends Handler.Wrapper
 {
     private long _idleTimeoutMs = 1000;
     private boolean _applyToAsync = false;

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/InetAccessHandler.java

@@ -41,7 +41,7 @@
  * the forwarded for headers, as this cannot be as easily forged.
  * </p>
  */
-public class InetAccessHandler extends Handler.BaseWrapper
+public class InetAccessHandler extends Handler.Wrapper
 {
     // TODO replace this handler with a general conditional handler wrapper.
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ProxiedRequestHandler.java

@@ -23,7 +23,7 @@
 import org.eclipse.jetty.util.Callback;
 import org.eclipse.jetty.util.HostPort;
 
-public class ProxiedRequestHandler extends Handler.BaseWrapper
+public class ProxiedRequestHandler extends Handler.Wrapper
 {
     @Override
     public boolean process(Request request, Response response, Callback callback) throws Exception

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ResourceHandler.java

@@ -53,7 +53,7 @@
  *  - request ranges
  *  - a way to configure caching or not
  */
-public class ResourceHandler extends Handler.BaseWrapper
+public class ResourceHandler extends Handler.Wrapper
 {
     private final ResourceService _resourceService;
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/SecuredRedirectHandler.java

@@ -35,7 +35,7 @@
  * {@link HttpConfiguration#getSecurePort()}
  * </p>
  */
-public class SecuredRedirectHandler extends Handler.BaseWrapper
+public class SecuredRedirectHandler extends Handler.Wrapper
 {
     /**
      * The redirect code to send in response.

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ShutdownHandler.java

@@ -76,7 +76,7 @@
  * }
  * }</pre>
  */
-public class ShutdownHandler extends Handler.BaseWrapper
+public class ShutdownHandler extends Handler.Wrapper
 {
     private static final Logger LOG = LoggerFactory.getLogger(ShutdownHandler.class);
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/StatisticsHandler.java

@@ -37,7 +37,7 @@
 import org.eclipse.jetty.util.statistic.CounterStatistic;
 import org.eclipse.jetty.util.statistic.SampleStatistic;
 
-public class StatisticsHandler extends Handler.BaseWrapper
+public class StatisticsHandler extends Handler.Wrapper
 {
     private final Set<String> _connectionStats = ConcurrentHashMap.newKeySet();
     private final CounterStatistic _requestStats = new CounterStatistic();

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/ThreadLimitHandler.java

@@ -67,7 +67,7 @@
  * a thread is available.
  * <p>This is a simpler alternative to DosFilter</p>
  */
-public class ThreadLimitHandler extends Handler.BaseWrapper
+public class ThreadLimitHandler extends Handler.Wrapper
 {
     private static final Logger LOG = LoggerFactory.getLogger(ThreadLimitHandler.class);
 

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/TryPathsHandler.java

@@ -65,7 +65,7 @@
  * under the names specified by {@link #setOriginalPathAttribute(String)}
  * and {@link #setOriginalQueryAttribute(String)}.</p>
  */
-public class TryPathsHandler extends Handler.BaseWrapper
+public class TryPathsHandler extends Handler.Wrapper
 {
     private String originalPathAttribute;
     private String originalQueryAttribute;

jetty-core/jetty-server/src/main/java/org/eclipse/jetty/server/handler/gzip/GzipHandler.java

@@ -37,7 +37,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-public class GzipHandler extends Handler.BaseWrapper implements GzipFactory
+public class GzipHandler extends Handler.Wrapper implements GzipFactory
 {
     public static final String GZIP_HANDLER_ETAGS = "o.e.j.s.h.gzip.GzipHandler.etag";
     public static final String GZIP = "gzip";

jetty-core/jetty-server/src/test/java/org/eclipse/jetty/server/HttpServerTestBase.java

@@ -1825,7 +1825,7 @@ public Content.Chunk read()
     public void testProcessingAfterCompletion() throws Exception
     {
         AtomicReference<String> result = new AtomicReference<>();
-        Handler.Wrapper wrapper = new Handler.BaseWrapper()
+        Handler.Singleton wrapper = new Handler.Wrapper()
         {
             @Override
             public boolean process(Request request, Response response, Callback callback) throws Exception

jetty-core/jetty-server/src/test/java/org/eclipse/jetty/server/handler/ContextHandlerCollectionTest.java

@@ -320,7 +320,7 @@ public void testFindContainer()
 
         ContextHandler contextB = new ContextHandler("/b");
         IsHandledHandler handlerB = new IsHandledHandler("B");
-        Handler.Wrapper wrapperB = new Handler.BaseWrapper();
+        Handler.Singleton wrapperB = new Handler.Wrapper();
         wrapperB.setHandler(handlerB);
         contextB.setHandler(wrapperB);
 
@@ -334,16 +334,16 @@ public void testFindContainer()
         collection.addHandler(contextB);
         collection.addHandler(contextC);
 
-        Handler.Wrapper wrapper = new Handler.BaseWrapper();
+        Handler.Singleton wrapper = new Handler.Wrapper();
         wrapper.setHandler(collection);
         server.setHandler(wrapper);
 
-        assertEquals(wrapper, Handler.AbstractContainer.findContainerOf(server, Handler.BaseWrapper.class, handlerA));
+        assertEquals(wrapper, Handler.AbstractContainer.findContainerOf(server, Handler.Wrapper.class, handlerA));
         assertEquals(contextA, Handler.AbstractContainer.findContainerOf(server, ContextHandler.class, handlerA));
         assertEquals(contextB, Handler.AbstractContainer.findContainerOf(server, ContextHandler.class, handlerB));
-        assertEquals(wrapper, Handler.AbstractContainer.findContainerOf(server, Handler.BaseWrapper.class, handlerB));
-        assertEquals(contextB, Handler.AbstractContainer.findContainerOf(collection, Handler.BaseWrapper.class, handlerB));
-        assertEquals(wrapperB, Handler.AbstractContainer.findContainerOf(contextB, Handler.BaseWrapper.class, handlerB));
+        assertEquals(wrapper, Handler.AbstractContainer.findContainerOf(server, Handler.Wrapper.class, handlerB));
+        assertEquals(contextB, Handler.AbstractContainer.findContainerOf(collection, Handler.Wrapper.class, handlerB));
+        assertEquals(wrapperB, Handler.AbstractContainer.findContainerOf(contextB, Handler.Wrapper.class, handlerB));
     }
 
     @Test
@@ -407,7 +407,7 @@ public void testWrappedContext() throws Exception
         assertThat(response, containsString("Wrapped: right"));
     }
 
-    private static final class WrappedHandler extends Handler.BaseWrapper
+    private static final class WrappedHandler extends Handler.Wrapper
     {
         private final String tag;
 

jetty-core/jetty-server/src/test/java/org/eclipse/jetty/server/handler/ContextHandlerTest.java

@@ -658,7 +658,7 @@ public void testSetHandlerLoopSelf()
     public void testSetHandlerLoopDeepWrapper()
     {
         ContextHandler contextHandlerA = new ContextHandler();
-        Handler.Wrapper handlerWrapper = new Handler.BaseWrapper();
+        Handler.Singleton handlerWrapper = new Handler.Wrapper();
         contextHandlerA.setHandler(handlerWrapper);
         assertThrows(IllegalStateException.class, () -> handlerWrapper.setHandler(contextHandlerA));
     }