[cp-patches] FYI: loopify scatter/gather file I/O

[Casey Marshall]

readScattering and writeGathering seem really unhappy on Darwin for
files, and calling the latter seems to return 0 too often (ie, all the
time). I don't know if this is a bug in those methods or not, but I
don't think it makes sense to use readv/writev for file I/O, when a loop
will suffice.

And, this makes Azureus extremely unhappy.

2006-09-24  Casey Marshall  <[EMAIL PROTECTED]>

        * gnu/java/nio/FileChannelImpl.java
        (read): call `read' in a loop, don't use `readScattering.'
        (write): call `write' in a loop, don't use `writeGathering.'

Committed.

### Eclipse Workspace Patch 1.0
#P classpath
Index: gnu/java/nio/FileChannelImpl.java
===================================================================
RCS file: /cvsroot/classpath/classpath/gnu/java/nio/FileChannelImpl.java,v
retrieving revision 1.17
diff -u -r1.17 FileChannelImpl.java
--- gnu/java/nio/FileChannelImpl.java   17 Sep 2006 07:31:41 -0000      1.17
+++ gnu/java/nio/FileChannelImpl.java   25 Sep 2006 06:44:06 -0000
@@ -253,7 +253,18 @@
   public long read (ByteBuffer[] dsts, int offset, int length)
     throws IOException
   {
-    return ch.readScattering(dsts, offset, length);
+    int n = offset + length;
+    long read = 0;
+    if (offset < 0 || length < 0 || n > dsts.length)
+      throw new ArrayIndexOutOfBoundsException();
+    for (int i = offset; i < n; i++)
+      {
+        int ret = read(dsts[i]);
+        if (ret == -1)
+          break;
+        read += ret;
+      }
+    return read;
   }
 
   public int write (ByteBuffer src) throws IOException
@@ -292,7 +303,13 @@
   public long write(ByteBuffer[] srcs, int offset, int length)
     throws IOException
   {
-    return ch.writeGathering(srcs, offset, length);
+    int n = offset + length;
+    long written = 0;
+    if (offset < 0 || length < 0 || n > srcs.length)
+      throw new ArrayIndexOutOfBoundsException();
+    for (int i = offset; i < n; i++)
+      written += write(srcs[i]);
+    return written;
   }
 
   public MappedByteBuffer map (FileChannel.MapMode mode,