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 */
25package jdk.jshell.execution;
26
27import java.io.IOException;
28import java.io.OutputStream;
29import java.io.UnsupportedEncodingException;
30
31/**
32 * Packetize an OutputStream, dividing it into named channels.
33 *
34 * @author Jan Lahoda
35 */
36class 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        write(new byte[] {(byte) b});
54    }
55
56    @Override
57    public void write(byte[] b, int off, int len) throws IOException {
58        synchronized (delegate) {
59            int i = 0;
60            while (len > 0) {
61                int size = Math.min(PACKET_SIZE, len);
62                byte[] data = new byte[name.length + 1 + size + 1];
63                data[0] = (byte) name.length; //assuming the len is small enough to fit into byte
64                System.arraycopy(name, 0, data, 1, name.length);
65                data[name.length + 1] = (byte) size;
66                System.arraycopy(b, off + i, data, name.length + 2, size);
67                delegate.write(data);
68                i += size;
69                len -= size;
70            }
71            delegate.flush();
72        }
73    }
74
75    @Override
76    public void flush() throws IOException {
77        super.flush();
78        delegate.flush();
79    }
80
81    @Override
82    public void close() throws IOException {
83        super.close();
84        delegate.close();
85    }
86
87}
88