protoio.hh revision 9397 
1/*
2 * Copyright (c) 2012 ARM Limited
3 * All rights reserved
4 *
5 * The license below extends only to copyright in the software and shall
6 * not be construed as granting a license to any other intellectual
7 * property including but not limited to intellectual property relating
8 * to a hardware implementation of the functionality of the software
9 * licensed hereunder.  You may use the software subject to the license
10 * terms below provided that you ensure that this notice is replicated
11 * unmodified and in its entirety in all distributions of the software,
12 * modified or unmodified, in source code or in binary form.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions are
16 * met: redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer;
18 * redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution;
21 * neither the name of the copyright holders nor the names of its
22 * contributors may be used to endorse or promote products derived from
23 * this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
26 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
27 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
28 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
29 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
30 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
31 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
32 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
35 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
36 *
37 * Authors: Andreas Hansson
38 */
39
40
41/**
42 * @file
43 * Declaration of a wrapper for protobuf output streams.
44 */
45
46#ifndef __PROTO_PROTOIO_HH__
47#define __PROTO_PROTOIO_HH__
48
49#include <google/protobuf/io/coded_stream.h>
50#include <google/protobuf/io/gzip_stream.h>
51#include <google/protobuf/io/zero_copy_stream_impl.h>
52#include <google/protobuf/message.h>
53
54#include <fstream>
55
56/**
57 * A ProtoOutputStream wraps a coded stream, potentially with
58 * compression, based on looking at the file name. Writing to the
59 * stream is done to enable interaction with the file on a per-message
60 * basis to avoid having to deal with huge data structures. The latter
61 * is made possible by encoding the length of each message in the
62 * stream.
63 */
64class ProtoOutputStream
65{
66
67  public:
68
69    /**
70     * Create an output stream for a given file name. If the filename
71     * ends with .gz then the file will be compressed accordinly.
72     *
73     * @param filename Path to the file to create or truncate
74     */
75    ProtoOutputStream(const std::string& filename);
76
77    /**
78     * Destruct the output stream, and also flush and close the
79     * underlying file streams and coded streams.
80     */
81    ~ProtoOutputStream();
82
83    /**
84     * Write a message to the stream, preprending it with the message
85     * size.
86     *
87     * @param msg Message to write to the stream
88     */
89    void write(const google::protobuf::Message& msg);
90
91  private:
92
93    /// Underlying file output stream
94    std::ofstream fileStream;
95
96    /// Zero Copy stream wrapping the STL output stream
97    google::protobuf::io::OstreamOutputStream* zeroCopyStream;
98
99    /// Optional Gzip stream to wrap the Zero Copy stream
100    google::protobuf::io::GzipOutputStream* gzipStream;
101
102    /// Top-level coded stream that messages are written to
103    google::protobuf::io::CodedOutputStream* codedStream;
104
105};
106
107#endif //__PROTO_PROTOIO_HH
108