1/*
2 Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file
3
4 This file is part of libzmq, the ZeroMQ core engine in C++.
5
6 libzmq is free software; you can redistribute it and/or modify it under
7 the terms of the GNU Lesser General Public License (LGPL) as published
8 by the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 As a special exception, the Contributors give you permission to link
12 this library with independent modules to produce an executable,
13 regardless of the license terms of these independent modules, and to
14 copy and distribute the resulting executable under terms of your choice,
15 provided that you also meet, for each linked independent module, the
16 terms and conditions of the license of that module. An independent
17 module is a module which is not derived from or based on this library.
18 If you modify this library, you must extend this exception to your
19 version of the library.
20
21 libzmq is distributed in the hope that it will be useful, but WITHOUT
22 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
23 FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
24 License for more details.
25
26 You should have received a copy of the GNU Lesser General Public License
27 along with this program. If not, see <http://www.gnu.org/licenses/>.
28*/
29
30#ifndef __ZMQ_DECODER_ALLOCATORS_HPP_INCLUDED__
31#define __ZMQ_DECODER_ALLOCATORS_HPP_INCLUDED__
32
33#include <cstddef>
34#include <cstdlib>
35
36#include "atomic_counter.hpp"
37#include "msg.hpp"
38#include "err.hpp"
39
40namespace zmq
41{
42// Static buffer policy.
43class c_single_allocator
44{
45 public:
46 explicit c_single_allocator (std::size_t bufsize_) :
47 _buf_size (bufsize_),
48 _buf (static_cast<unsigned char *> (std::malloc (_buf_size)))
49 {
50 alloc_assert (_buf);
51 }
52
53 ~c_single_allocator () { std::free (_buf); }
54
55 unsigned char *allocate () { return _buf; }
56
57 void deallocate () {}
58
59 std::size_t size () const { return _buf_size; }
60
61 void resize (std::size_t new_size_) { _buf_size = new_size_; }
62
63 private:
64 std::size_t _buf_size;
65 unsigned char *_buf;
66
67 ZMQ_NON_COPYABLE_NOR_MOVABLE (c_single_allocator)
68};
69
70// This allocator allocates a reference counted buffer which is used by v2_decoder_t
71// to use zero-copy msg::init_data to create messages with memory from this buffer as
72// data storage.
73//
74// The buffer is allocated with a reference count of 1 to make sure that is is alive while
75// decoding messages. Otherwise, it is possible that e.g. the first message increases the count
76// from zero to one, gets passed to the user application, processed in the user thread and deleted
77// which would then deallocate the buffer. The drawback is that the buffer may be allocated longer
78// than necessary because it is only deleted when allocate is called the next time.
79class shared_message_memory_allocator
80{
81 public:
82 explicit shared_message_memory_allocator (std::size_t bufsize_);
83
84 // Create an allocator for a maximum number of messages
85 shared_message_memory_allocator (std::size_t bufsize_,
86 std::size_t max_messages_);
87
88 ~shared_message_memory_allocator ();
89
90 // Allocate a new buffer
91 //
92 // This releases the current buffer to be bound to the lifetime of the messages
93 // created on this buffer.
94 unsigned char *allocate ();
95
96 // force deallocation of buffer.
97 void deallocate ();
98
99 // Give up ownership of the buffer. The buffer's lifetime is now coupled to
100 // the messages constructed on top of it.
101 unsigned char *release ();
102
103 void inc_ref ();
104
105 static void call_dec_ref (void *, void *hint_);
106
107 std::size_t size () const;
108
109 // Return pointer to the first message data byte.
110 unsigned char *data ();
111
112 // Return pointer to the first byte of the buffer.
113 unsigned char *buffer () { return _buf; }
114
115 void resize (std::size_t new_size_) { _buf_size = new_size_; }
116
117 zmq::msg_t::content_t *provide_content () { return _msg_content; }
118
119 void advance_content () { _msg_content++; }
120
121 private:
122 void clear ();
123
124 unsigned char *_buf;
125 std::size_t _buf_size;
126 const std::size_t _max_size;
127 zmq::msg_t::content_t *_msg_content;
128 std::size_t _max_counters;
129};
130}
131
132#endif
133