[refactor] share empty read-only byte-buffer

Author: kares

src/main/java/org/jruby/ext/openssl/SSLSocket.java

@@ -141,14 +141,15 @@ private static CallSite callSite(final CallSite[] sites, final CallSiteIndex ind
         return sites[ index.ordinal() ];
     }
 
+    private static final ByteBuffer EMPTY_DATA = ByteBuffer.allocate(0).asReadOnlyBuffer();
+
     private SSLContext sslContext;
     private SSLEngine engine;
     private RubyIO io;
 
     private ByteBuffer appReadData;
     private ByteBuffer netReadData;
     private ByteBuffer netWriteData;
-    private final ByteBuffer dummy = ByteBuffer.allocate(0); // could be static
 
     private boolean initialHandshake = false;
     private transient long initializeTime;
@@ -623,7 +624,7 @@ private IRubyObject doHandshake(final boolean blocking, final boolean exception)
 
     private void doWrap(final boolean blocking) throws IOException {
         netWriteData.clear();
-        SSLEngineResult result = engine.wrap(dummy, netWriteData);
+        SSLEngineResult result = engine.wrap(EMPTY_DATA.duplicate(), netWriteData);
         netWriteData.flip();
         handshakeStatus = result.getHandshakeStatus();
         status = result.getStatus();
@@ -820,7 +821,7 @@ private void doShutdown() throws IOException {
         }
         netWriteData.clear();
         try {
-            engine.wrap(dummy, netWriteData); // send close (after sslEngine.closeOutbound)
+            engine.wrap(EMPTY_DATA.duplicate(), netWriteData); // send close (after sslEngine.closeOutbound)
         }
         catch (SSLException e) {
             debug(getRuntime(), "SSLSocket.doShutdown", e);