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             delegate.write(name.length); //assuming the len is small enough to fit into byte
  55             delegate.write(name);
  56             delegate.write(1);
  57             delegate.write(b);
  58             delegate.flush();
  59         }
  60     }
  61 
  62     @Override
  63     public void write(byte[] b, int off, int len) throws IOException {
  64         synchronized (delegate) {
  65             int i = 0;
  66             while (len > 0) {
  67                 int size = Math.min(PACKET_SIZE, len);
  68                 delegate.write(name.length); //assuming the len is small enough to fit into byte
  69                 delegate.write(name);
  70                 delegate.write(size);
  71                 delegate.write(b, off + i, size);
  72                 i += size;
  73                 len -= size;
  74             }
  75             delegate.flush();
  76         }
  77     }
  78 
  79     @Override
  80     public void flush() throws IOException {
  81         super.flush();
  82         delegate.flush();
  83     }
  84 
  85     @Override
  86     public void close() throws IOException {
  87         super.close();
  88         delegate.close();
  89     }
  90 
  91 }