source: source/ariba/overlay/modules/chord/Chord.cpp@ 3694

Last change on this file since 3694 was 3694, checked in by mies, 15 years ago

fixed discovery issue, when no successor/predecessor is available
File size: 10.7 KB
Line 
1// [License]
2// The Ariba-Underlay Copyright
3//
4// Copyright (c) 2008-2009, Institute of Telematics, UniversitÀt Karlsruhe (TH)
5//
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7// UniversitÀt Karlsruhe (TH)
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9// Germany
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12// modification, are permitted provided that the following conditions are
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23// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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25// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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34// are those of the authors and should not be interpreted as representing
35// official policies, either expressed or implied, of the Institute of
36// Telematics.
37// [License]
38
39#include "ariba/overlay/BaseOverlay.h"
40
41#include "Chord.h"
42#include "messages/ChordMessage.h"
43#include "messages/Discovery.h"
44
45#include "detail/chord_routing_table.hpp"
46
47namespace ariba {
48namespace overlay {
49
50typedef chord_routing_table::item route_item;
51use_logging_cpp( Chord )
52;
53
54Chord::Chord(BaseOverlay& _baseoverlay, const NodeID& _nodeid,
55 OverlayStructureEvents* _eventsReceiver) :
56 OverlayInterface(_baseoverlay, _nodeid, _eventsReceiver) {
57
58 // create routing table
59 this->table = new chord_routing_table(_nodeid, 2);
60 orphan_removal_counter = 0;
61 stabilize_counter = 0;
62 stabilize_finger = 0;
63 bootstrapLink = LinkID::UNSPECIFIED;
64}
65
66Chord::~Chord() {
67
68 // delete routing table
69 delete table;
70}
71
72/// helper: sets up a link using the base overlay
73LinkID Chord::setup(const EndpointDescriptor& endp) {
74
75 logging_debug("request to setup link to " << endp.toString() );
76 // establish link via base overlay
77 return baseoverlay.establishLink(endp, OverlayInterface::OVERLAY_SERVICE_ID);
78}
79
80/// helper: sends a message using the "base overlay"
81seqnum_t Chord::send(Message* msg, const LinkID& link) {
82 if (link.isUnspecified()) return 0;
83 return baseoverlay.sendMessage(msg, link);
84}
85
86/// sends a discovery message
87void Chord::send_discovery_to(const NodeID& destination, int ttl) {
88 logging_debug("Initiating discovery of " << destination.toString() );
89 Message msg;
90 ChordMessage cmsg(ChordMessage::discovery, nodeid, destination);
91 Discovery dmsg;
92 dmsg.setSourceEndpoint(&baseoverlay.getEndpointDescriptor());
93 dmsg.setFollowType(Discovery::normal);
94 dmsg.setTTL((uint8_t) ttl);
95 cmsg.encapsulate(&dmsg);
96 msg.encapsulate(&cmsg);
97 logging_debug("" << (int)cmsg.getType());
98 this->onMessage(&msg, NodeID::UNSPECIFIED, LinkID::UNSPECIFIED);
99}
100
101void Chord::createOverlay() {
102}
103
104void Chord::deleteOverlay() {
105
106}
107
108void Chord::joinOverlay(const EndpointDescriptor& boot) {
109 logging_info( "joining Chord overlay structure through end-point " <<
110 (boot == EndpointDescriptor::UNSPECIFIED ?
111 "local" : boot.toString()) );
112
113 // initiator? no->setup first link
114 if (!(boot == EndpointDescriptor::UNSPECIFIED)) bootstrapLink = setup(boot);
115
116 // timer for stabilization management
117 Timer::setInterval(2500);
118 Timer::start();
119}
120
121void Chord::leaveOverlay() {
122 Timer::stop();
123 for (size_t i = 0; i < table->size(); i++) {
124 route_item* it = (*table)[i];
125 ChordMessage msg(ChordMessage::leave, nodeid, it->id);
126 send(&msg,it->info);
127 }
128}
129
130const EndpointDescriptor& Chord::resolveNode(const NodeID& node) {
131 const route_item* item = table->get(node);
132 if (item == NULL || item->info.isUnspecified()) return EndpointDescriptor::UNSPECIFIED;
133 return baseoverlay.getEndpointDescriptor(item->info);
134}
135
136void Chord::routeMessage(const NodeID& destnode, Message* msg) {
137 // get next hop
138 const route_item* item = table->get_next_hop(destnode);
139
140 // message for this node? yes-> delegate to base overlay
141 if (item->id == nodeid) baseoverlay.incomingRouteMessage(msg);
142 else { // no-> send to next hop
143 ChordMessage cmsg(ChordMessage::route, nodeid, destnode);
144 cmsg.encapsulate(msg);
145 send(&cmsg, item->info);
146 }
147}
148
149OverlayInterface::NodeList Chord::getKnownNodes() const {
150 OverlayInterface::NodeList nodelist;
151 for (size_t i = 0; i < table->size(); i++)
152 if ((*table)[i]->ref_count != 0) nodelist.push_back((*table)[i]->id);
153 return nodelist;
154}
155
156/// @see CommunicationListener.h
157/// @see OverlayInterface.h
158void Chord::onLinkUp(const LinkID& lnk, const NodeID& remote) {
159 logging_debug("link_up: link=" << lnk.toString() << " remote=" <<
160 remote.toString() );
161 route_item* item = table->insert(remote);
162
163 if (!bootstrapLink.isUnspecified() && lnk == bootstrapLink) {
164 send_discovery_to(nodeid);
165 bootstrapLink = LinkID::UNSPECIFIED;
166 }
167
168 // item added to routing table?
169 if (item != NULL) { // yes-> add to routing table
170 logging_debug("new routing neighbor: " << remote.toString() );
171 item->info = lnk;
172 } else { // no-> add orphan entry to routing table
173 logging_debug("new orphan: " << remote.toString() );
174 table->insert_orphan(remote)->info = lnk;
175 }
176}
177
178/// @see CommunicationListener.h or @see OverlayInterface.h
179void Chord::onLinkDown(const LinkID& lnk, const NodeID& remote) {
180 logging_debug("link_down: link=" << lnk.toString() << " remote=" <<
181 remote.toString() );
182
183 // remove link from routing table
184 table->remove(remote);
185}
186
187/// @see CommunicationListener.h
188/// @see OverlayInterface.h
189void Chord::onMessage(const DataMessage& msg, const NodeID& remote,
190 const LinkID& link) {
191
192 // decode message
193 typedef ChordMessage M;
194 M* m = msg.getMessage()->convert<ChordMessage> ();
195 if (m == NULL) return;
196
197 // handle messages
198 switch (m->getType()) {
199
200 // invalid message
201 case M::invalid:
202 break;
203
204 // route message with payload
205 case M::route: {
206 // find next hop
207 const route_item* item = table->get_next_hop(m->getDestination());
208
209 // next hop == myself?
210 if (m->getDestination() == nodeid) { // yes-> route to base overlay
211 logging_debug("send message to baseoverlay");
212 baseoverlay.incomingRouteMessage(m);
213 }
214 // no-> route to next hop
215 else {
216 logging_debug("route chord message to " << item->id.toString() );
217 send(m, item->info);
218 }
219 break;
220 }
221
222 // discovery request
223 case M::discovery: {
224 // decapsulate message
225 Discovery* dmsg = m->decapsulate<Discovery> ();
226 logging_debug("received discovery message with"
227 << " dest=" << m->getDestination().toString()
228 << " ttl=" << (int)dmsg->getTTL()
229 << " type=" << (int)dmsg->getFollowType()
230 );
231
232 // check if source node can be added to routing table and setup link
233 if (m->getSource() != nodeid && table->is_insertable(m->getSource())) setup(
234 *dmsg->getSourceEndpoint());
235
236 // delegate discovery message
237 switch (dmsg->getFollowType()) {
238
239 // normal: route discovery message like every other message
240 case Discovery::normal:
241 // closest node? yes-> split to follow successor and predecessor
242 if (table->is_closest_to(m->getDestination())) {
243
244 if (table->get_successor() != NULL) {
245 // send successor message
246 ChordMessage cmsg_s(*m);
247 Discovery dmsg_s(*dmsg);
248 dmsg_s.setFollowType(Discovery::successor);
249 cmsg_s.encapsulate(&dmsg_s);
250 route_item* succ_item = table->get(*table->get_successor());
251 logging_debug("split: routing discovery message to successor "
252 << succ_item->id.toString() );
253 send(&cmsg_s, succ_item->info);
254 }
255
256 // send predecessor message
257 if (table->get_predesessor() != NULL) {
258 ChordMessage cmsg_p(*m);
259 Discovery dmsg_p(*dmsg);
260 dmsg_p.setFollowType(Discovery::predecessor);
261 cmsg_p.encapsulate(&dmsg_p);
262 route_item* pred_item = table->get(
263 *table->get_predesessor());
264 logging_debug("split: routing discovery message to predecessor "
265 << pred_item->id.toString() );
266 send(&cmsg_p, pred_item->info);
267 }
268 }
269 // no-> route message
270 else {
271 // find next hop
272 const route_item* item = table->get_next_hop(
273 m->getDestination());
274 if (item->id == nodeid) break;
275 logging_debug("routing discovery message to " <<
276 item->id.toString() );
277 send(m, item->info);
278 }
279 break;
280
281 // successor mode: follow the successor until TTL is zero
282 case Discovery::successor:
283 case Discovery::predecessor: {
284 // time to live ended? yes-> stop routing
285 if (dmsg->getTTL() == 0) break;
286
287 // decrease time-to-live
288 dmsg->setTTL(dmsg->getTTL() - 1);
289
290 const route_item* item = NULL;
291 if (dmsg->getFollowType() == Discovery::successor &&
292 table->get_successor() != NULL) {
293 item = table->get(*table->get_successor());
294 } else {
295 if (table->get_predesessor()!=NULL)
296 item = table->get(*table->get_predesessor());
297 }
298 if (item == NULL) break;
299 logging_debug("routing discovery message to succ/pred "
300 << item->id.toString() );
301 ChordMessage cmsg(*m);
302 cmsg.encapsulate(dmsg);
303 send(&cmsg, item->info);
304 break;
305 }
306 }
307 break;
308 }
309
310 // leave
311 case M::leave: {
312 baseoverlay.dropLink(link);
313 break;
314 }
315 }
316}
317
318void Chord::eventFunction() {
319 stabilize_counter++;
320 if (stabilize_counter == 3) {
321 stabilize_counter = 0;
322 stabilize_finger = ((stabilize_finger+1) % table->get_finger_table_size() );
323 logging_debug("sending discovery message to my neighbors");
324 send_discovery_to(nodeid);
325 send_discovery_to(
326 table->get_finger_table(stabilize_finger).get_compare().get_center()
327 );
328 orphan_removal_counter++;
329 if (orphan_removal_counter == 2) {
330 orphan_removal_counter = 0;
331 for (size_t i = 0; i < table->size(); i++) {
332 route_item* it = (*table)[i];
333 if (it->ref_count == 0) {
334 baseoverlay.dropLink(it->info);
335 logging_debug("dropping orphaned link " << it->info.toString() << " to " << it->id.toString());
336 }
337 }
338 }
339 }
340 logging_debug("--- chord routing information ----------------------------------");
341 logging_debug("predecessor: " << (table->get_predesessor()==NULL? "<none>" : table->get_predesessor()->toString()) );
342 logging_debug("node_id : " << nodeid.toString() );
343 logging_debug("successor : " << (table->get_successor()==NULL? "<none>" : table->get_successor()->toString()));
344 logging_debug("----------------------------------------------------------------");
345}
346
347}
348} // namespace ariba, overlay
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