Basic support for datagram messaging. Hope I haven't fucked

anything up!


git-svn-id: svn+ssh://src.earth.threerings.net/narya/trunk@5090 542714f4-19e9-0310-aa3c-eee0fc999fb1

src/java/com/threerings/io/ByteBufferOutputStream.java

@@ -0,0 +1,102 @@
+//
+// $Id$
+
+package com.threerings.io;
+
+import java.io.OutputStream;
+
+import java.nio.BufferOverflowException;
+import java.nio.ByteBuffer;
+
+/**
+ * Stores output in an {@link ByteBuffer} that grows automatically to accommodate the data.
+ */
+public class ByteBufferOutputStream extends OutputStream
+{
+    /**
+     * Creates a new byte buffer output stream.
+     */
+    public ByteBufferOutputStream ()
+    {
+        _buffer = ByteBuffer.allocate(INITIAL_BUFFER_SIZE);
+    }
+
+    /**
+     * Returns a reference to the underlying buffer.
+     */
+    public ByteBuffer getBuffer ()
+    {
+        return _buffer;
+    }
+
+    /**
+     * Flips and returns the buffer.  The returned buffer will have a position of zero and a limit
+     * equal to the number of bytes written.  Call {@link #reset} to reset the buffer before
+     * writing again.
+     */
+    public ByteBuffer flip ()
+    {
+        _buffer.flip();
+        return _buffer;
+    }
+
+    /**
+     * Resets our internal buffer.
+     */
+    public void reset ()
+    {
+        _buffer.clear();
+    }
+
+    @Override // documentation inherited
+    public void write (int b)
+    {
+        try {
+            _buffer.put((byte)b);
+        } catch (BufferOverflowException boe) {
+            expand(1);
+            _buffer.put((byte)b);
+        }
+    }
+
+    @Override // documentation inherited
+    public void write (byte[] b, int off, int len)
+    {
+        // sanity check the arguments
+        if ((off < 0) || (off > b.length) || (len < 0) ||
+            ((off + len) > b.length) || ((off + len) < 0)) {
+            throw new IndexOutOfBoundsException();
+        } else if (len == 0) {
+            return;
+        }
+
+        try {
+            _buffer.put(b, off, len);
+        } catch (BufferOverflowException boe) {
+            expand(len);
+            _buffer.put(b, off, len);
+        }
+    }
+
+    /**
+     * Expands our buffer to accomodate the specified capacity.
+     */
+    protected final void expand (int needed)
+    {
+        int ocapacity = _buffer.capacity();
+        int ncapacity = _buffer.position() + needed;
+        if (ncapacity > ocapacity) {
+            // increase the buffer size in large increments
+            ncapacity = Math.max(ocapacity << 1, ncapacity);
+            ByteBuffer newbuf = ByteBuffer.allocate(ncapacity);
+            newbuf.put((ByteBuffer)_buffer.flip());
+            _buffer = newbuf;
+        }
+    }
+
+    /** The buffer in which we store our frame data. */
+    protected ByteBuffer _buffer;
+
+    /** The default initial size of the internal buffer. */
+    protected static final int INITIAL_BUFFER_SIZE = 32;
+}