Issue #4191 Min GzipSize

updates from review from OP.
reverted static DEFAULT_MIN_GZIP_SIZE

Signed-off-by: Greg Wilkins <gregw@webtide.com>

jetty-server/src/main/config/modules/gzip.mod

@@ -15,7 +15,7 @@ etc/jetty-gzip.xml
 
 [ini-template]
 ## Minimum content length after which gzip is enabled
-# jetty.gzip.minGzipSize=1024
+# jetty.gzip.minGzipSize=32
 
 ## Check whether a file with *.gz extension exists
 # jetty.gzip.checkGzExists=false

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

@@ -92,7 +92,7 @@ import org.eclipse.jetty.util.log.Logger;
  * </li>
  * <li>
  * Is the Response {@code Content-Length} header present, and does its
- * value meet the minimum gzip size requirements (default 1024 bytes)?
+ * value meet the minimum gzip size requirements (default 32 bytes)?
  * </li>
  * <li>
  * Is the Request {@code Accept} header present and does it contain the
@@ -154,6 +154,7 @@ public class GzipHandler extends HandlerWrapper implements GzipFactory
 {
     public static final String GZIP = "gzip";
     public static final String DEFLATE = "deflate";
+    public static final int DEFAULT_MIN_GZIP_SIZE = 32;
     public static final int BREAK_EVEN_GZIP_SIZE = 23;
     private static final Logger LOG = Log.getLogger(GzipHandler.class);
     private static final HttpField X_CE_GZIP = new PreEncodedHttpField("X-Content-Encoding", "gzip");
@@ -163,7 +164,7 @@ public class GzipHandler extends HandlerWrapper implements GzipFactory
     private int _poolCapacity = -1;
     private DeflaterPool _deflaterPool = null;
 
-    private int _minGzipSize = 1024;
+    private int _minGzipSize = DEFAULT_MIN_GZIP_SIZE;
     private int _compressionLevel = Deflater.DEFAULT_COMPRESSION;
     /**
      * @deprecated feature will be removed in Jetty 10.x, with no replacement.
@@ -949,16 +950,16 @@ public class GzipHandler extends HandlerWrapper implements GzipFactory
     /**
      * Set the minimum response size to trigger dynamic compression.
      * <p>
-     *     Sizes below 23 will result a compressed response that is larger than the
+     *     Sizes below {@link #BREAK_EVEN_GZIP_SIZE} will result a compressed response that is larger than the
      *     original data.
      * </p>
      *
-     * @param minGzipSize minimum response size in bytes (not allowed to be lower then 23)
+     * @param minGzipSize minimum response size in bytes (not allowed to be lower then {@link #BREAK_EVEN_GZIP_SIZE})
      */
     public void setMinGzipSize(int minGzipSize)
     {
         if (minGzipSize < BREAK_EVEN_GZIP_SIZE)
-            LOG.warn("minGzipSize {} is less break even size {}", minGzipSize, BREAK_EVEN_GZIP_SIZE);
+            LOG.warn("minGzipSize of {} is inefficient for short content, break even is size {}", minGzipSize, BREAK_EVEN_GZIP_SIZE);
         _minGzipSize = Math.max(0, minGzipSize);
     }
 

jetty-servlets/src/test/java/org/eclipse/jetty/server/handler/gzip/GzipContentLengthTest.java

@@ -54,7 +54,7 @@ public class GzipContentLengthTest
     private static final int LARGE = defaultHttp.getOutputBufferSize() * 8;
     private static final int MEDIUM = defaultHttp.getOutputBufferSize();
     private static final int SMALL = defaultHttp.getOutputBufferSize() / 4;
-    private static final int TINY = GzipHandler.BREAK_EVEN_GZIP_SIZE / 2;
+    private static final int TINY = GzipHandler.DEFAULT_MIN_GZIP_SIZE / 2;
     private static final boolean EXPECT_COMPRESSED = true;
 
     public static Stream<Arguments> scenarios()

jetty-servlets/src/test/java/org/eclipse/jetty/server/handler/gzip/GzipDefaultTest.java

@@ -468,7 +468,6 @@ public class GzipDefaultTest
         tester.setContentServlet(HttpContentTypeWithEncoding.class);
         tester.getGzipHandler().addIncludedMimeTypes("text/plain");
         tester.getGzipHandler().setExcludedAgentPatterns();
-        tester.getGzipHandler().setMinGzipSize(16);
         try
         {
             tester.start();

jetty-servlets/src/test/java/org/eclipse/jetty/server/handler/gzip/IncludedGzipTest.java

@@ -88,7 +88,6 @@ public class IncludedGzipTest
         tester.getContext().addServlet(org.eclipse.jetty.servlet.DefaultServlet.class, "/");
 
         GzipHandler gzipHandler = new GzipHandler();
-        gzipHandler.setMinGzipSize(16);
         tester.getContext().insertHandler(gzipHandler);
         tester.start();
     }

jetty-servlets/src/test/java/org/eclipse/jetty/servlets/GzipFilterLayeredTest.java

@@ -61,7 +61,7 @@ public class GzipFilterLayeredTest
     private static final HttpConfiguration defaultHttp = new HttpConfiguration();
     private static final int LARGE = defaultHttp.getOutputBufferSize() * 8;
     private static final int SMALL = defaultHttp.getOutputBufferSize() / 4;
-    private static final int TINY = GzipHandler.BREAK_EVEN_GZIP_SIZE / 2;
+    private static final int TINY = GzipHandler.DEFAULT_MIN_GZIP_SIZE / 2;
     private static final boolean EXPECT_COMPRESSED = true;
 
     public static Stream<Arguments> scenarios()