1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package jdk.jshell.execution;
  26 
  27 import java.io.IOException;
  28 import java.io.OutputStream;
  29 import java.io.UnsupportedEncodingException;
  30 
  31 /**
  32  * Packetize an OutputStream, dividing it into named channels.
  33  *
  34  * @author Jan Lahoda
  35  */
  36 class MultiplexingOutputStream extends OutputStream {
  37 
  38     private static final int PACKET_SIZE = 127;
  39     private final byte[] name;
  40     private final OutputStream delegate;
  41 
  42     MultiplexingOutputStream(String name, OutputStream delegate) {
  43         try {
  44             this.name = name.getBytes("UTF-8");
  45             this.delegate = delegate;
  46         } catch (UnsupportedEncodingException ex) {
  47             throw new IllegalStateException(ex); //should not happen
  48         }
  49     }
  50 
  51     @Override
  52     public void write(int b) throws IOException {
  53         synchronized (delegate) {
  54             byte[] data = new byte[name.length + 1 + 1 + 1];
  55             data[0] = (byte) name.length; //assuming the len is small enough to fit into byte
  56             System.arraycopy(name, 0, data, 1, name.length);
  57             data[name.length + 1] = 1;
  58             data[name.length + 2] = (byte) b;
  59             delegate.write(data);
  60             delegate.flush();
  61         }
  62     }
  63 
  64     @Override
  65     public void write(byte[] b, int off, int len) throws IOException {
  66         synchronized (delegate) {
  67             int i = 0;
  68             while (len > 0) {
  69                 int size = Math.min(PACKET_SIZE, len);
  70                 byte[] data = new byte[name.length + 1 + size + 1];
  71                 data[0] = (byte) name.length; //assuming the len is small enough to fit into byte
  72                 System.arraycopy(name, 0, data, 1, name.length);
  73                 data[name.length + 1] = (byte) size;
  74                 System.arraycopy(b, off + i, data, name.length + 2, size);
  75                 delegate.write(data);
  76                 i += size;
  77                 len -= size;
  78             }
  79             delegate.flush();
  80         }
  81     }
  82 
  83     @Override
  84     public void flush() throws IOException {
  85         super.flush();
  86         delegate.flush();
  87     }
  88 
  89     @Override
  90     public void close() throws IOException {
  91         super.close();
  92         delegate.close();
  93     }
  94 
  95 }