[cp-patches] RFC: Try to reduce char[] copying in jlr.Proxy

[Ian Rogers]

Hi,

the attached patch is trying to continue Andrew's good work and reduce 
the amount of redundant array copying, in this case in jlr.Proxy. There 
is a TODO in that we have no back door to turn a char[] in to a String 
without copying.

Thanks,
Ian
Index: java/lang/reflect/Proxy.java
===================================================================
RCS file: /sources/classpath/classpath/java/lang/reflect/Proxy.java,v
retrieving revision 1.30
diff -u -r1.30 Proxy.java
--- java/lang/reflect/Proxy.java        16 Mar 2008 22:04:51 -0000      1.30
+++ java/lang/reflect/Proxy.java        29 Aug 2008 11:01:45 -0000
@@ -1402,7 +1402,12 @@
     {
       String utf8 = toUtf8(str);
       int len = utf8.length();
-      return poolIndex("\1" + (char) (len >> 8) + (char) (len & 0xff) + utf8);
+      CPStringBuilder buf = new CPStringBuilder(len+3);
+      buf.append('\1');
+      buf.append((char) (len >> 8));
+      buf.append((char) (len & 0xff));
+      buf.append(utf8);
+      return poolIndex(buf.toString());
     }
 
     /**
@@ -1416,7 +1421,7 @@
     {
       char index = utf8Info(name);
       char[] c = {7, (char) (index >> 8), (char) (index & 0xff)};
-      return poolIndex(new String(c));
+      return poolIndex(stringFromCharArray(c));
     }
 
     /**
@@ -1452,7 +1457,7 @@
       char[] c = {(char) (structure + 8),
                   (char) (cindex >> 8), (char) (cindex & 0xff),
                   (char) (ntindex >> 8), (char) (ntindex & 0xff)};
-      return poolIndex(new String(c));
+      return poolIndex(stringFromCharArray(c));
     }
 
     /**
@@ -1469,7 +1474,7 @@
       char tindex = utf8Info(type);
       char[] c = {12, (char) (nindex >> 8), (char) (nindex & 0xff),
                   (char) (tindex >> 8), (char) (tindex & 0xff)};
-      return poolIndex(new String(c));
+      return poolIndex(stringFromCharArray(c));
     }
 
     /**
@@ -1541,5 +1546,19 @@
         }
       return (char) i.intValue();
     }
+
+    /**
+     * Return a String wrapping the char array avoiding copying the char array
+     * if possible
+     *
+     * @param c the char array
+     * @return the String
+     */
+    private String stringFromCharArray(char[] c)
+    {
+      // TODO: we need some back door like VMCPStringBuilder to avoid copying
+      //       the character array in this situation
+      return new String(c);
+    }
   } // class ClassFactory
 }