| 1 | //-----------------------------------------------------------------------------
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| 2 | // Part of reboost (http://reboost.org). Released under the
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| 3 | // BSD 2-clause license (http://www.opensource.org/licenses/bsd-license.php).
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| 4 | // Copyright 2012, Sebastian Mies <mies@reboost.org> --- All rights reserved.
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| 5 | //-----------------------------------------------------------------------------
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| 6 |
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| 7 | #ifndef REBOOST_MESSAGE_HPP_
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| 8 | #define REBOOST_MESSAGE_HPP_
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| 9 |
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| 10 | #include<boost/thread.hpp>
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| 11 | #include<boost/shared_ptr.hpp>
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| 12 | #include<cstring>
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| 13 |
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| 14 | #include "shared_buffer.hpp"
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| 15 |
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| 16 | namespace reboost {
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| 17 |
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| 18 | /// message size type
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| 19 | //typedef signed char mlength_t; // <--- don't do this!!
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| 20 | //typedef size_t mlength_t;
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| 21 | typedef int mlength_t; // signed int seems necessary
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| 22 |
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| 23 | /// maximum number of buffers per message (default is 8)
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| 24 | const mlength_t message_max_buffers = (1L << 3);
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| 25 | //const mlength_t message_max_buffers = (1L << 4);
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| 26 |
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| 27 | //! A Copy-on-Write Message with Shared Buffers.
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| 28 | /**
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| 29 | * A Copy-on-Write Message with Shared Buffers.
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| 30 | *
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| 31 | * A message holds a limited (defined by <code>message_max_buffers</code>)
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| 32 | * number of shared buffers. One can add new buffers and messages in front and
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| 33 | * at the end of a message. If the no. of buffers exceed
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| 34 | * <code>message_max_buffers</code>, then the two smallest successive buffers
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| 35 | * are compacted to one buffer.
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| 36 | *
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| 37 | * @author Sebastian Mies <mies@reboost.org>
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| 38 | */
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| 39 | class message_t {
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| 40 | private:
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| 41 | // read sub-message
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| 42 | struct sub_message {
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| 43 | message_t* msg;
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| 44 | inline void operator()(shared_buffer_t buf) {
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| 45 | msg->push_back(buf);
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| 46 | }
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| 47 | };
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| 48 |
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| 49 | // read from buffer
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| 50 | struct read_buffer {
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| 51 | boctet_t* buffer;
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| 52 | inline void operator()(buffer_t buf) {
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| 53 | memcpy((void*) buffer, (void*) buf.data(), buf.size());
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| 54 | buffer += buf.size();
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| 55 | }
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| 56 | };
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| 57 |
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| 58 | // write to buffer
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| 59 | struct write_buffer {
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| 60 | const boctet_t* buffer;
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| 61 | inline void operator()(buffer_t buf) {
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| 62 | memcpy((void*) buf.data(), (void*) buffer, buf.size());
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| 63 | buffer += buf.size();
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| 64 | }
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| 65 | };
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| 66 |
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| 67 | public:
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| 68 | /// Create a new message
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| 69 | inline message_t() :
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| 70 | imsg() {
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| 71 | }
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| 72 |
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| 73 | /// Copy message
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| 74 | inline message_t(const message_t& msg) :
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| 75 | imsg(msg.imsg)
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| 76 | {
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| 77 | if ( imsg )
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| 78 | imsg->owner = NULL;
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| 79 | }
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| 80 |
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| 81 | /// Linearize message
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| 82 | inline operator shared_buffer_t() const {
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| 83 | return linearize();
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| 84 | }
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| 85 |
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| 86 | /// Assign another message
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| 87 | inline message_t& operator=(const message_t& msg) {
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| 88 | msg.imsg->owner = NULL;
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| 89 | imsg = msg.imsg;
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| 90 | return *this;
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| 91 | }
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| 92 |
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| 93 | /// Adds a shared buffer of given site at the end
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| 94 | inline shared_buffer_t& push_back( bsize_t size ) {
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| 95 | shared_buffer_t b(size); push_back(b);
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| 96 | return imsg->at(-1);
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| 97 | }
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| 98 |
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| 99 | /// Adds a buffer at the end of the message
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| 100 | inline void push_back(const shared_buffer_t& buf) {
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| 101 | own().push_back(buf);
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| 102 | }
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| 103 |
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| 104 | /// Adds a message at the end of the message
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| 105 | inline void push_back(const message_t& msg) {
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| 106 | own();
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| 107 | for (mlength_t i = 0; i < msg.length(); i++)
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| 108 | push_back(msg[i]);
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| 109 | }
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| 110 |
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| 111 | /// Adds a shared buffer of given size at the front
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| 112 | inline shared_buffer_t& push_front( bsize_t size ) {
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| 113 | shared_buffer_t b(size); push_front(b);
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| 114 | return imsg->at(0);
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| 115 | }
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| 116 |
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| 117 | /// Adds a buffer at the front of the messsage
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| 118 | inline void push_front(const shared_buffer_t& buf) {
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| 119 | own().push_front(buf);
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| 120 | }
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| 121 |
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| 122 | /// Adds a message at the end of the message
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| 123 | inline void push_front(const message_t& msg) {
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| 124 | own();
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| 125 | for (mlength_t i = msg.length() - 1; i != 0; i--)
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| 126 | push_front(msg[i]);
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| 127 | }
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| 128 |
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| 129 | /// Removes a buffer from the end of the message
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| 130 | inline shared_buffer_t pop_back() {
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| 131 | return own().pop_back();
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| 132 | }
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| 133 |
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| 134 | /// Removes a buffer from the beginning of this message.
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| 135 | inline shared_buffer_t pop_front() {
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| 136 | return own().pop_front();
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| 137 | }
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| 138 |
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| 139 | /// Returns the size of the message in bytes (or octets).
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| 140 | inline size_t size() const {
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| 141 | size_t s = 0;
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| 142 | for (mlength_t i = 0; i < length(); i++)
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| 143 | s += operator[](i).size();
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| 144 | return (s);
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| 145 | }
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| 146 |
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| 147 | /// Returns the number of buffers inside this message.
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| 148 | inline mlength_t length() const {
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| 149 | if ( ! imsg )
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| 150 | return 0;
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| 151 |
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| 152 | return (imsg->length);
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| 153 | }
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| 154 |
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| 155 | /// Returns the buffer at the given index.
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| 156 | inline shared_buffer_t& operator[](mlength_t idx) {
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| 157 | return at(idx);
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| 158 | }
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| 159 |
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| 160 | /// Returns the buffer at the given index.
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| 161 | inline shared_buffer_t& at(mlength_t idx) {
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| 162 | return imsg->at(idx);
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| 163 | }
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| 164 |
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| 165 | /// Returns the constant buffer at the given index.
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| 166 | inline const shared_buffer_t& operator[](mlength_t idx) const {
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| 167 | return at(idx);
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| 168 | }
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| 169 |
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| 170 | /// Returns the buffer at the given index
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| 171 | inline const shared_buffer_t& at(mlength_t idx) const {
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| 172 | return imsg->at(idx);
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| 173 | }
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| 174 |
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| 175 | /// Iterates over a partial set of buffers.
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| 176 | template<typename T>
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| 177 | inline void msg_foreach(const T& work, size_t index_ = 0, size_t size_ = 0) const {
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| 178 | T op = work;
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| 179 | if (size_ == 0) size_ = size() - index_;
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| 180 |
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| 181 | // get first buffer
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| 182 | mlength_t f = 0, pf = 0;
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| 183 | for (; (pf + at(f).size()) <= index_ && f < imsg->length;
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| 184 | pf += at(f).size(), f++);
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| 185 | // get last buffer
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| 186 | mlength_t l = f, pl = pf;
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| 187 | for (; (pl + at(l).size()) < (index_ + size_) && l < imsg->length;
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| 188 | pl += at(l).size(), l++);
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| 189 |
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| 190 | // same buffer? yes-> get sub-buffer
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| 191 | if (l == f) op(at(l)(index_ - pf, size_));
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| 192 | else { // no-> get sub-buffers :)
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| 193 | op(at(f)(index_ - pf));
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| 194 | for (mlength_t i = f + 1; i < l; i++) op(at(i));
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| 195 | op(at(l)(0, index_ + size_ - pl));
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| 196 | }
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| 197 | }
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| 198 |
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| 199 | /// Read bytes (gather).
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| 200 | inline void read(boctet_t* mem, size_t idx = 0, size_t size_ = 0) const {
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| 201 | struct read_buffer rb = { mem };
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| 202 | msg_foreach(rb, idx, size_);
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| 203 | }
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| 204 |
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| 205 | /// write bytes
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| 206 | inline void write(const boctet_t* mem, size_t idx = 0, size_t size_ = 0) {
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| 207 | struct write_buffer wb = { mem };
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| 208 | msg_foreach(wb, idx, size_);
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| 209 | }
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| 210 |
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| 211 | /// Read an arbitrary, binary object.
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| 212 | template<class T>
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| 213 | inline T read(size_t index) {
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| 214 | T obj;
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| 215 | read((boctet_t*) &obj, index, sizeof(T));
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| 216 | return obj;
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| 217 | }
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| 218 |
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| 219 | /// Write an arbitrary, binary object.
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| 220 | template<class T>
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| 221 | inline void write(const T& value, size_t index) {
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| 222 | write((boctet_t*) &value, index, sizeof(T));
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| 223 | }
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| 224 |
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| 225 | /// Calculate a (ELF-like) hash.
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| 226 | inline size_t hash() const {
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| 227 | size_t h = 0;
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| 228 | for (mlength_t i = 0; i < length(); i++)
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| 229 | h += at(i).hash() * (i + 1);
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| 230 | return h;
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| 231 | }
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| 232 |
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| 233 | /// Returns a sub-message.
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| 234 | message_t operator()(size_t index, size_t size = 0) const {
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| 235 | message_t m;
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| 236 | struct sub_message sm = { &m };
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| 237 | msg_foreach(sm, index, size);
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| 238 | return m;
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| 239 | }
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| 240 |
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| 241 | /// Linearizes the complete/partial message into one shared buffer.
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| 242 | inline shared_buffer_t linearize(size_t index = 0, size_t size_ = 0) const {
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| 243 | shared_buffer_t b(size_ == 0 ? size() : size_);
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| 244 | read(b.mutable_data(), index, size_);
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| 245 | return b;
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| 246 | }
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| 247 |
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| 248 | private:
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| 249 | class imsg_t {
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| 250 | public:
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| 251 | volatile message_t* owner;
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| 252 | shared_buffer_t buffers[message_max_buffers];
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| 253 | mlength_t index, length;
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| 254 | public:
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| 255 | inline imsg_t() :
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| 256 | index(0), length(0) {
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| 257 | }
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| 258 | inline imsg_t(const imsg_t& imsg) :
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| 259 | index(imsg.index), length(imsg.length) {
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| 260 | for (mlength_t i = 0; i < length; i++)
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| 261 | at(index + i) = imsg.at(index + i);
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| 262 | }
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| 263 | inline shared_buffer_t& at(mlength_t idx) {
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| 264 | if (idx < 0) idx += length;
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| 265 | return buffers[(idx + index) & (message_max_buffers - 1)];
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| 266 | }
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| 267 | inline const shared_buffer_t& at(mlength_t idx) const {
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| 268 | if (idx < 0) idx += length;
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| 269 | return buffers[(idx + index) & (message_max_buffers - 1)];
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| 270 | }
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| 271 |
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| 272 | inline void push_back(const shared_buffer_t& buf) {
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| 273 | if (buf.size() == 0) return;
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| 274 | if (length == message_max_buffers) compact();
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| 275 | at(length) = buf;
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| 276 | length++;
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| 277 | }
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| 278 |
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| 279 | inline void push_front(const shared_buffer_t& buf) {
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| 280 | if (buf.size() == 0) return;
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| 281 | if (length == message_max_buffers) compact();
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| 282 | index--;
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| 283 | length++;
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| 284 | at(0) = buf;
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| 285 | }
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| 286 |
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| 287 | inline shared_buffer_t pop_back() {
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| 288 | shared_buffer_t& buf = at(-1);
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| 289 | shared_buffer_t ret = buf;
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| 290 | buf.reset();
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| 291 | length--;
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| 292 | return ret;
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| 293 | }
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| 294 |
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| 295 | inline shared_buffer_t pop_front() {
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| 296 | shared_buffer_t& buf = at(0);
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| 297 | shared_buffer_t ret = buf;
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| 298 | buf.reset();
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| 299 | length--;
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| 300 | index++;
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| 301 | return ret;
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| 302 | }
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| 303 |
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| 304 | /// compacts the buffers, so one more buffer is available
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| 305 | inline void compact() {
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| 306 |
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| 307 | // find compacting candidate
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| 308 | bsize_t min_size=~0, min_pos=0;
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| 309 | for (mlength_t i=0; i<length; i++) {
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| 310 | bsize_t c = at(i).size() + at(i+1).size();
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| 311 | if (c < min_size || min_size == ~(bsize_t)0 ) {
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| 312 | min_size = c;
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| 313 | min_pos = i;
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| 314 | }
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| 315 | }
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| 316 |
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| 317 | // compact buffers
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| 318 | shared_buffer_t nb(min_size);
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| 319 | at(min_pos).copy_to( nb, 0 );
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| 320 | at(min_pos+1).copy_to( nb, at(min_pos).size() );
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| 321 |
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| 322 | // move buffers and assign new buffer
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| 323 | for (mlength_t i=min_pos+1; i<length; i++) at(i) = at(i+1);
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| 324 | at(min_pos) = nb;
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| 325 |
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| 326 | length--;
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| 327 | }
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| 328 | };
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| 329 | /// own a new message
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| 330 | inline imsg_t& own() {
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| 331 | if (imsg.get() != NULL && imsg->owner == this) return *imsg;
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| 332 | if (imsg.get() == NULL) imsg = boost::shared_ptr<imsg_t>(new imsg_t());
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| 333 | else imsg = boost::shared_ptr<imsg_t>(new imsg_t(*imsg));
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| 334 | imsg->owner = this;
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| 335 | return *imsg;
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| 336 | }
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| 337 | boost::shared_ptr<imsg_t> imsg;
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| 338 | };
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| 339 |
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| 340 | inline message_t operator+(const message_t& lhs, const message_t& rhs) {
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| 341 | message_t m = lhs;
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| 342 | m.push_back(rhs);
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| 343 | return m;
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| 344 | }
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| 345 |
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| 346 | inline message_t operator+(const message_t& lhs, const buffer_t& rhs) {
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| 347 | message_t m = lhs;
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| 348 | m.push_back(rhs);
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| 349 | return m;
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| 350 | }
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| 351 |
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| 352 | inline message_t operator+(const shared_buffer_t& lhs, const message_t& rhs) {
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| 353 | message_t m = rhs;
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| 354 | m.push_front(lhs);
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| 355 | return m;
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| 356 | }
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| 357 |
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| 358 | inline message_t operator+(const shared_buffer_t& lhs,
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| 359 | const shared_buffer_t& rhs) {
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| 360 | message_t m;
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| 361 | m.push_back(lhs);
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| 362 | m.push_back(rhs);
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| 363 | return m;
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| 364 | }
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| 365 |
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| 366 | std::ostream& operator<<(std::ostream&, const message_t);
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| 367 |
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| 368 | } /* namespace reboost */
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| 369 |
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| 370 | #endif /* REBOOST_MESSAGE_HPP_ */
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