Move AsciiLowerCaseSet to jetty-util & changes from review

Signed-off-by: Lachlan Roberts <lachlan@webtide.com>

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

@@ -21,9 +21,9 @@ package org.eclipse.jetty.server.handler.gzip;
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.EnumSet;
-import java.util.HashSet;
 import java.util.Set;
 import java.util.regex.Pattern;
+import java.util.stream.Collectors;
 import java.util.stream.Stream;
 import java.util.zip.Deflater;
 import javax.servlet.DispatcherType;
@@ -44,6 +44,7 @@ import org.eclipse.jetty.http.pathmap.PathSpecSet;
 import org.eclipse.jetty.server.HttpOutput;
 import org.eclipse.jetty.server.Request;
 import org.eclipse.jetty.server.handler.HandlerWrapper;
+import org.eclipse.jetty.util.AsciiLowerCaseSet;
 import org.eclipse.jetty.util.IncludeExclude;
 import org.eclipse.jetty.util.StringUtil;
 import org.eclipse.jetty.util.compression.CompressionPool;
@@ -172,7 +173,7 @@ public class GzipHandler extends HandlerWrapper implements GzipFactory
     // non-static, as other GzipHandler instances may have different configurations
     private final IncludeExclude<String> _methods = new IncludeExclude<>();
     private final IncludeExclude<String> _paths = new IncludeExclude<>(PathSpecSet.class);
-    private final IncludeExclude<String> _mimeTypes = new IncludeExclude<>(CaseInsensitiveSet.class);
+    private final IncludeExclude<String> _mimeTypes = new IncludeExclude<>(AsciiLowerCaseSet.class);
     private HttpField _vary = GzipHttpOutputInterceptor.VARY_ACCEPT_ENCODING;
 
     /**
@@ -780,10 +781,10 @@ public class GzipHandler extends HandlerWrapper implements GzipFactory
      */
     public void setDispatcherTypes(String... dispatchers)
     {
-        setDispatcherTypes(Stream.of(dispatchers)
+        _dispatchers = EnumSet.copyOf(Stream.of(dispatchers)
             .flatMap(s -> Stream.of(StringUtil.csvSplit(s)))
             .map(DispatcherType::valueOf)
-            .toArray(DispatcherType[]::new));
+            .collect(Collectors.toSet()));
     }
 
     /**
@@ -941,21 +942,4 @@ public class GzipHandler extends HandlerWrapper implements GzipFactory
     {
         return String.format("%s@%x{%s,min=%s,inflate=%s}", getClass().getSimpleName(), hashCode(), getState(), _minGzipSize, _inflateBufferSize);
     }
-
-    public static class CaseInsensitiveSet extends HashSet<String>
-    {
-        @Override
-        public boolean add(String s)
-        {
-            return super.add(s == null ? null : s.toLowerCase());
-        }
-
-        @Override
-        public boolean contains(Object o)
-        {
-            if (o instanceof String)
-                return super.contains(((String)o).toLowerCase());
-            return super.contains(o);
-        }
-    }
 }

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

@@ -354,6 +354,8 @@ public class GzipHttpOutputInterceptor implements HttpOutput.Interceptor
                         int off = slice.arrayOffset() + slice.position();
                         int len = slice.remaining();
                         _crc.update(array, off, len);
+                        // Ideally we would want to use the ByteBuffer API for Deflaters. However due the the ByteBuffer implementation
+                        // of the CRC32.update() it is less efficient for us to use this rather than to convert to array ourselves.
                         _deflater.setInput(array, off, len);
                         slice.position(slice.position() + len);
                         if (_last && BufferUtil.isEmpty(_content))

jetty-util/src/main/java/org/eclipse/jetty/util/AsciiLowerCaseSet.java

@@ -0,0 +1,38 @@
+//
+// ========================================================================
+// Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
+//
+// This program and the accompanying materials are made available under
+// the terms of the Eclipse Public License 2.0 which is available at
+// https://www.eclipse.org/legal/epl-2.0
+//
+// This Source Code may also be made available under the following
+// Secondary Licenses when the conditions for such availability set
+// forth in the Eclipse Public License, v. 2.0 are satisfied:
+// the Apache License v2.0 which is available at
+// https://www.apache.org/licenses/LICENSE-2.0
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+// ========================================================================
+//
+
+package org.eclipse.jetty.util;
+
+import java.util.HashSet;
+
+public class AsciiLowerCaseSet extends HashSet<String>
+{
+    @Override
+    public boolean add(String s)
+    {
+        return super.add(s == null ? null : StringUtil.asciiToLowerCase(s));
+    }
+
+    @Override
+    public boolean contains(Object o)
+    {
+        if (o instanceof String)
+            return super.contains(StringUtil.asciiToLowerCase((String)o));
+        return super.contains(o);
+    }
+}