[PATCH] for Review: BufferedReader and InputStreamReader Optimizations

[Mohan Embar <gnustuff at thisiscool dot com>]

Hi People,

No one has stepped forward with an alternative to this yet:

http://gcc.gnu.org/ml/java/2003-12/msg00208.html

...so I'm officially submitting a patch for this with the change to the
native BufferedReader.lineEnd() as per this:

http://gcc.gnu.org/ml/java/2003-12/msg00213.html

I ran this through a full "make check" in libjava for i686-pc-linux-gnu,
including the Mauve tests (thanks to Andreas Tobler for teaching me
how to do this) and the pre-patch and post-patch results are basically
the same. (The pre-patch testsuite log prints a GC warning about
repeated allocation of a very large block, but I can't imagine this
being related.)

What do you all think?

-- Mohan
http://www.thisiscool.com/
http://www.animalsong.org/

ChangeLog
2004-01-03  Mohan Embar  <gnustuff@thisiscool.com>

	* Makefile.am (nat_source_files): Added	java/io/natBufferedReader.cc.
	* Makefile.in: Rebuilt.
	* java/io/BufferedReader.java (sbuf): New field.
	(lineEnd): Removed implementation and changed to native declaration.
	(readLine): Use String.valueOf instead of new String() as per
	Per Bothner's suggestion. Use instance sbuf field instead of a
	local StringBuffer instance.
	* java/io/InputStreamReader.java (read(char[],int,int)): Pass the
	caller's buffer to refill().
	(read(void)): Pass our internal work buffer to refill if our
	input queue is empty.
	(refill): Changed return type to int. Use the specified buffer
	instead of our work buffer as per Bryce McKinlay's suggestion.
	Return the number of characters read or -1 for EOF.
	* java/io/natBufferedReader.cc (lineEnd): Native implementation
	for BufferedReader.

Index: Makefile.am
===================================================================
RCS file: /cvs/gcc/gcc/libjava/Makefile.am,v
retrieving revision 1.350
diff -u -2 -r1.350 Makefile.am
--- Makefile.am	31 Dec 2003 08:58:29 -0000	1.350
+++ Makefile.am	4 Jan 2004 01:34:32 -0000
@@ -2759,4 +2759,5 @@
 gnu/java/nio/natSelectorImpl.cc \
 gnu/java/nio/natNIOServerSocket.cc \
+java/io/natBufferedReader.cc \
 java/io/natFile.cc \
 java/io/natFileDescriptor.cc \
Index: java/io/BufferedReader.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/io/BufferedReader.java,v
retrieving revision 1.16
diff -u -2 -r1.16 BufferedReader.java
--- java/io/BufferedReader.java	28 Dec 2003 11:54:17 -0000	1.16
+++ java/io/BufferedReader.java	4 Jan 2004 01:35:08 -0000
@@ -90,4 +90,9 @@
 
   /**
+   * The line buffer for <code>readLine</code>.
+   */
+  private StringBuffer sbuf = null;
+
+  /**
     * Create a new <code>BufferedReader</code> that will read from the 
     * specified subordinate stream with a default buffer size of 8192 chars.
@@ -399,15 +404,5 @@
    * if no line terminators were found.
    */
-  private int lineEnd(int limit)
-  {
-    int i = pos;
-    for (; i < limit; i++)
-      {
-	char ch = buffer[i];
-	if (ch == '\n' || ch == '\r')
-	  break;
-      }
-    return i;
-  }
+  private native int lineEnd(int limit);
 
   /**
@@ -440,5 +435,5 @@
     if (i < limit)
       {
-	String str = new String(buffer, pos, i - pos);
+	String str = String.valueOf(buffer, pos, i - pos);
 	pos = i + 1;
 	// If the last char in the buffer is a '\r', we must remember
@@ -451,5 +446,8 @@
 	return str;
       }
-    StringBuffer sbuf = new StringBuffer(200);
+    if (sbuf == null)
+      sbuf = new StringBuffer(200);
+    else
+      sbuf.setLength(0);
     sbuf.append(buffer, pos, i - pos);
     pos = i;
Index: java/io/InputStreamReader.java
===================================================================
RCS file: /cvs/gcc/gcc/libjava/java/io/InputStreamReader.java,v
retrieving revision 1.15
diff -u -2 -r1.15 InputStreamReader.java
--- java/io/InputStreamReader.java	9 May 2003 07:10:58 -0000	1.15
+++ java/io/InputStreamReader.java	4 Jan 2004 01:35:09 -0000
@@ -232,8 +232,6 @@
 	if (wavail <= 0)
 	  {
-	    // Nothing waiting, so refill our buffer.
-	    if (! refill ())
-	      return -1;
-	    wavail = wcount - wpos;
+	    // Nothing waiting, so refill their buffer.
+	    return refill(buf, offset, length);
 	  }
 
@@ -263,7 +261,12 @@
 	if (wavail <= 0)
 	  {
-	    // Nothing waiting, so refill our buffer.
-	    if (! refill ())
+	    // Nothing waiting, so refill our internal buffer.
+	    wpos = wcount = 0;
+	    if (work == null)
+	       work = new char[100];
+	    int count = refill(work, 0, work.length);
+	    if (count == -1)
 	      return -1;
+	    wcount += count;
 	  }
 
@@ -272,13 +275,8 @@
   }
 
-  // Read more bytes and convert them into the WORK buffer.
-  // Return false on EOF.
-  private boolean refill () throws IOException
+  // Read more bytes and convert them into the specified buffer.
+  // Returns the number of converted characters or -1 on EOF.
+  private int refill(char[] buf, int offset, int length) throws IOException
   {
-    wcount = wpos = 0;
-
-    if (work == null)
-      work = new char[100];
-
     for (;;)
       {
@@ -291,16 +289,12 @@
 	in.reset ();
 	if (! r)
-	  return false;
+	  return -1;
 	converter.setInput(in.buf, in.pos, in.count);
-	int count = converter.read (work, wpos, work.length - wpos);
+	int count = converter.read(buf, offset, length);
 	in.skip(converter.inpos - in.pos);
 	if (count > 0)
-	  {
-	    wcount += count;
-	    return true;
-	  }
+	  return count;
       }
   }
-
 } // class InputStreamReader
 
Index: java/io/natBufferedReader.cc
===================================================================
--- java/io/natBufferedReader.cc	2004-01-03 19:54:04.000000000 -0600
+++ java/io/natBufferedReader.cc	2004-01-03 22:46:07.000000000 -0600
@@ -0,0 +1,29 @@
+// natBufferedReader.cc - Native part of BufferedReader class.
+
+/* Copyright (C) 1998, 1999, 2000, 2001  Free Software Foundation
+
+   This ObjectInputStream is part of libgcj.
+
+This software is copyrighted work licensed under the terms of the
+Libgcj License.  Please consult the BufferedReader "LIBGCJ_LICENSE" for
+details.  */
+
+#include <config.h>
+
+#include <gcj/cni.h>
+#include <jvm.h>
+
+#include <java/io/BufferedReader.h>
+
+jint java::io::BufferedReader::lineEnd (jint limit)
+{
+  jchar *pbuf = elements (buffer);
+  int i = pos;
+  for (; i < limit; i++)
+  {
+    jchar ch = pbuf[i];
+    if (ch == '\n' || ch == '\r')
+      break;
+  }
+  return i;
+}