1 | // [License]
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2 | // The Ariba-Underlay Copyright
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3 | //
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4 | // Copyright (c) 2008-2009, Institute of Telematics, UniversitÀt Karlsruhe (TH)
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5 | //
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6 | // Institute of Telematics
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7 | // UniversitÀt Karlsruhe (TH)
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8 | // Zirkel 2, 76128 Karlsruhe
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9 | // Germany
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10 | //
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11 | // Redistribution and use in source and binary forms, with or without
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12 | // modification, are permitted provided that the following conditions are
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13 | // met:
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14 | //
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15 | // 1. Redistributions of source code must retain the above copyright
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16 | // notice, this list of conditions and the following disclaimer.
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17 | // 2. Redistributions in binary form must reproduce the above copyright
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18 | // notice, this list of conditions and the following disclaimer in the
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19 | // documentation and/or other materials provided with the distribution.
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20 | //
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21 | // THIS SOFTWARE IS PROVIDED BY THE INSTITUTE OF TELEMATICS ``AS IS'' AND
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22 | // ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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23 | // IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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24 | // PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ARIBA PROJECT OR
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25 | // CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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26 | // EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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27 | // PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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28 | // PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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29 | // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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30 | // NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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31 | // SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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32 | //
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33 | // The views and conclusions contained in the software and documentation
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34 | // are those of the authors and should not be interpreted as representing
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35 | // official policies, either expressed or implied, of the Institute of
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36 | // Telematics.
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37 | // [License]
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38 |
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39 | #include "ariba/overlay/BaseOverlay.h"
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40 |
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41 | #include "Chord.h"
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42 | #include "messages/ChordMessage.h"
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43 | #include "messages/Discovery.h"
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44 |
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45 | #include "detail/chord_routing_table.hpp"
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46 |
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47 | namespace ariba {
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48 | namespace overlay {
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49 |
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50 | typedef chord_routing_table::item route_item;
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51 | use_logging_cpp( Chord )
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52 | ;
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53 |
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54 | Chord::Chord(BaseOverlay& _baseoverlay, const NodeID& _nodeid,
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55 | OverlayStructureEvents* _eventsReceiver) :
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56 | OverlayInterface(_baseoverlay, _nodeid, _eventsReceiver) {
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57 |
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58 | // create routing table
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59 | this->table = new chord_routing_table(_nodeid, 2);
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60 | orphan_removal_counter = 0;
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61 | stabilize_counter = 0;
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62 | stabilize_finger = 0;
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63 | bootstrapLink = LinkID::UNSPECIFIED;
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64 | }
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65 |
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66 | Chord::~Chord() {
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67 |
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68 | // delete routing table
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69 | delete table;
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70 | }
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71 |
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72 | /// helper: sets up a link using the base overlay
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73 | LinkID Chord::setup(const EndpointDescriptor& endp) {
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74 |
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75 | logging_debug("request to setup link to " << endp.toString() );
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76 | // establish link via base overlay
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77 | return baseoverlay.establishLink(endp, OverlayInterface::OVERLAY_SERVICE_ID);
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78 | }
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79 |
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80 | /// helper: sends a message using the "base overlay"
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81 | seqnum_t Chord::send(Message* msg, const LinkID& link) {
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82 | if (link.isUnspecified()) return 0;
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83 | return baseoverlay.sendMessage(msg, link);
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84 | }
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85 |
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86 | /// sends a discovery message
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87 | void Chord::send_discovery_to(const NodeID& destination, int ttl) {
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88 | logging_debug("Initiating discovery of " << destination.toString() );
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89 | Message msg;
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90 | ChordMessage cmsg(ChordMessage::discovery, nodeid, destination);
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91 | Discovery dmsg;
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92 | dmsg.setSourceEndpoint(&baseoverlay.getEndpointDescriptor());
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93 | dmsg.setFollowType(Discovery::normal);
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94 | dmsg.setTTL((uint8_t) ttl);
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95 | cmsg.encapsulate(&dmsg);
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96 | msg.encapsulate(&cmsg);
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97 | logging_debug("" << (int)cmsg.getType());
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98 | this->onMessage(&msg, NodeID::UNSPECIFIED, LinkID::UNSPECIFIED);
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99 | }
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100 |
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101 | void Chord::createOverlay() {
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102 | }
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103 |
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104 | void Chord::deleteOverlay() {
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105 |
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106 | }
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107 |
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108 | void Chord::joinOverlay(const EndpointDescriptor& boot) {
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109 | logging_info( "joining Chord overlay structure through end-point " <<
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110 | (boot == EndpointDescriptor::UNSPECIFIED ?
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111 | "local" : boot.toString()) );
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112 |
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113 | // initiator? no->setup first link
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114 | if (!(boot == EndpointDescriptor::UNSPECIFIED)) bootstrapLink = setup(boot);
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115 |
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116 | // timer for stabilization management
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117 | Timer::setInterval(2500);
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118 | Timer::start();
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119 | }
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120 |
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121 | void Chord::leaveOverlay() {
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122 | Timer::stop();
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123 | for (size_t i = 0; i < table->size(); i++) {
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124 | route_item* it = (*table)[i];
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125 | ChordMessage msg(ChordMessage::leave, nodeid, it->id);
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126 | send(&msg,it->info);
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127 | }
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128 | }
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129 |
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130 | const EndpointDescriptor& Chord::resolveNode(const NodeID& node) {
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131 | const route_item* item = table->get(node);
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132 | if (item == NULL || item->info.isUnspecified()) return EndpointDescriptor::UNSPECIFIED;
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133 | return baseoverlay.getEndpointDescriptor(item->info);
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134 | }
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135 |
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136 | void Chord::routeMessage(const NodeID& destnode, Message* msg) {
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137 | // get next hop
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138 | const route_item* item = table->get_next_hop(destnode);
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139 |
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140 | // message for this node? yes-> delegate to base overlay
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141 | if (item->id == nodeid) baseoverlay.incomingRouteMessage(msg);
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142 | else { // no-> send to next hop
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143 | ChordMessage cmsg(ChordMessage::route, nodeid, destnode);
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144 | cmsg.encapsulate(msg);
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145 | send(&cmsg, item->info);
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146 | }
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147 | }
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148 |
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149 | OverlayInterface::NodeList Chord::getKnownNodes() const {
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150 | OverlayInterface::NodeList nodelist;
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151 | for (size_t i = 0; i < table->size(); i++)
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152 | if ((*table)[i]->ref_count != 0) nodelist.push_back((*table)[i]->id);
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153 | return nodelist;
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154 | }
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155 |
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156 | /// @see CommunicationListener.h
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157 | /// @see OverlayInterface.h
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158 | void Chord::onLinkUp(const LinkID& lnk, const NodeID& remote) {
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159 | logging_debug("link_up: link=" << lnk.toString() << " remote=" <<
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160 | remote.toString() );
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161 | route_item* item = table->insert(remote);
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162 |
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163 | if (!bootstrapLink.isUnspecified() && lnk == bootstrapLink) {
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164 | send_discovery_to(nodeid);
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165 | bootstrapLink = LinkID::UNSPECIFIED;
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166 | }
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167 |
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168 | // item added to routing table?
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169 | if (item != NULL) { // yes-> add to routing table
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170 | logging_debug("new routing neighbor: " << remote.toString() );
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171 | item->info = lnk;
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172 | } else { // no-> add orphan entry to routing table
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173 | logging_debug("new orphan: " << remote.toString() );
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174 | table->insert_orphan(remote)->info = lnk;
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175 | }
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176 | }
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177 |
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178 | /// @see CommunicationListener.h or @see OverlayInterface.h
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179 | void Chord::onLinkDown(const LinkID& lnk, const NodeID& remote) {
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180 | logging_debug("link_down: link=" << lnk.toString() << " remote=" <<
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181 | remote.toString() );
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182 |
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183 | // remove link from routing table
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184 | route_item* item = table->get(remote);
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185 | if (item!=NULL) item->info = LinkID::UNSPECIFIED;
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186 | table->remove(remote);
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187 | }
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188 |
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189 | /// @see CommunicationListener.h
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190 | /// @see OverlayInterface.h
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191 | void Chord::onMessage(const DataMessage& msg, const NodeID& remote,
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192 | const LinkID& link) {
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193 |
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194 | // decode message
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195 | typedef ChordMessage M;
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196 | M* m = msg.getMessage()->convert<ChordMessage> ();
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197 | if (m == NULL) return;
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198 |
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199 | // handle messages
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200 | switch (m->getType()) {
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201 |
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202 | // invalid message
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203 | case M::invalid:
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204 | break;
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205 |
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206 | // route message with payload
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207 | case M::route: {
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208 | // find next hop
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209 | const route_item* item = table->get_next_hop(m->getDestination());
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210 |
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211 | // next hop == myself?
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212 | if (m->getDestination() == nodeid) { // yes-> route to base overlay
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213 | logging_debug("send message to baseoverlay");
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214 | baseoverlay.incomingRouteMessage(m);
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215 | }
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216 | // no-> route to next hop
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217 | else {
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218 | logging_debug("route chord message to " << item->id.toString() );
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219 | send(m, item->info);
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220 | }
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221 | break;
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222 | }
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223 |
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224 | // discovery request
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225 | case M::discovery: {
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226 | // decapsulate message
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227 | Discovery* dmsg = m->decapsulate<Discovery> ();
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228 | logging_debug("received discovery message with"
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229 | << " dest=" << m->getDestination().toString()
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230 | << " ttl=" << (int)dmsg->getTTL()
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231 | << " type=" << (int)dmsg->getFollowType()
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232 | );
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233 |
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234 | // check if source node can be added to routing table and setup link
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235 | if (m->getSource() != nodeid && table->is_insertable(m->getSource())) setup(
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236 | *dmsg->getSourceEndpoint());
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237 |
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238 | // delegate discovery message
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239 | switch (dmsg->getFollowType()) {
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240 |
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241 | // normal: route discovery message like every other message
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242 | case Discovery::normal:
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243 | // closest node? yes-> split to follow successor and predecessor
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244 | if (table->is_closest_to(m->getDestination())) {
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245 |
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246 | if (table->get_successor() != NULL) {
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247 | // send successor message
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248 | ChordMessage cmsg_s(*m);
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249 | Discovery dmsg_s(*dmsg);
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250 | dmsg_s.setFollowType(Discovery::successor);
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251 | cmsg_s.encapsulate(&dmsg_s);
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252 | route_item* succ_item = table->get(*table->get_successor());
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253 | logging_debug("split: routing discovery message to successor "
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254 | << succ_item->id.toString() );
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255 | send(&cmsg_s, succ_item->info);
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256 | }
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257 |
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258 | // send predecessor message
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259 | if (table->get_predesessor() != NULL) {
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260 | ChordMessage cmsg_p(*m);
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261 | Discovery dmsg_p(*dmsg);
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262 | dmsg_p.setFollowType(Discovery::predecessor);
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263 | cmsg_p.encapsulate(&dmsg_p);
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264 | route_item* pred_item = table->get(
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265 | *table->get_predesessor());
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266 | logging_debug("split: routing discovery message to predecessor "
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267 | << pred_item->id.toString() );
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268 | send(&cmsg_p, pred_item->info);
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269 | }
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270 | }
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271 | // no-> route message
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272 | else {
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273 | // find next hop
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274 | const route_item* item = table->get_next_hop(
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275 | m->getDestination());
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276 | if (item->id == nodeid) break;
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277 | logging_debug("routing discovery message to " <<
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278 | item->id.toString() );
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279 | send(m, item->info);
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280 | }
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281 | break;
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282 |
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283 | // successor mode: follow the successor until TTL is zero
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284 | case Discovery::successor:
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285 | case Discovery::predecessor: {
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286 | // time to live ended? yes-> stop routing
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287 | if (dmsg->getTTL() == 0) break;
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288 |
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289 | // decrease time-to-live
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290 | dmsg->setTTL(dmsg->getTTL() - 1);
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291 |
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292 | const route_item* item = NULL;
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293 | if (dmsg->getFollowType() == Discovery::successor &&
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294 | table->get_successor() != NULL) {
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295 | item = table->get(*table->get_successor());
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296 | } else {
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297 | if (table->get_predesessor()!=NULL)
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298 | item = table->get(*table->get_predesessor());
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299 | }
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300 | if (item == NULL) break;
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301 | logging_debug("routing discovery message to succ/pred "
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302 | << item->id.toString() );
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303 | ChordMessage cmsg(*m);
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304 | cmsg.encapsulate(dmsg);
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305 | send(&cmsg, item->info);
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306 | break;
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307 | }
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308 | }
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309 | break;
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310 | }
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311 |
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312 | // leave
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313 | case M::leave: {
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314 | baseoverlay.dropLink(link);
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315 | break;
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316 | }
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317 | }
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318 | }
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319 |
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320 | void Chord::eventFunction() {
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321 | stabilize_counter++;
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322 | if (stabilize_counter == 3) {
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323 | stabilize_counter = 0;
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324 | stabilize_finger = ((stabilize_finger+1) % table->get_finger_table_size() );
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325 | logging_debug("sending discovery message to my neighbors");
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326 | send_discovery_to(nodeid);
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327 | send_discovery_to(
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328 | table->get_finger_table(stabilize_finger).get_compare().get_center()
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329 | );
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330 | orphan_removal_counter++;
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331 | if (orphan_removal_counter == 2) {
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332 | orphan_removal_counter = 0;
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333 | for (size_t i = 0; i < table->size(); i++) {
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334 | route_item* it = (*table)[i];
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335 | if (it->ref_count == 0) {
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336 | baseoverlay.dropLink(it->info);
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337 | logging_debug("dropping orphaned link " << it->info.toString() << " to " << it->id.toString());
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338 | }
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339 | }
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340 | }
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341 | }
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342 | logging_debug("--- chord routing information ----------------------------------");
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343 | logging_debug("predecessor: " << (table->get_predesessor()==NULL? "<none>" : table->get_predesessor()->toString()) );
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344 | logging_debug("node_id : " << nodeid.toString() );
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345 | logging_debug("successor : " << (table->get_successor()==NULL? "<none>" : table->get_successor()->toString()));
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346 | logging_debug("----------------------------------------------------------------");
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347 | }
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348 |
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349 | }
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350 | } // namespace ariba, overlay
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