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source: source/ariba/overlay/modules/chord/Chord.cpp@ 10006

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1// [License]
2// The Ariba-Underlay Copyright
3//
4// Copyright (c) 2008-2009, Institute of Telematics, UniversitÀt Karlsruhe (TH)
5//
6// Institute of Telematics
7// UniversitÀt Karlsruhe (TH)
8// Zirkel 2, 76128 Karlsruhe
9// Germany
10//
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12// modification, are permitted provided that the following conditions are
13// met:
14//
15// 1. Redistributions of source code must retain the above copyright
16// notice, this list of conditions and the following disclaimer.
17// 2. Redistributions in binary form must reproduce the above copyright
18// notice, this list of conditions and the following disclaimer in the
19// documentation and/or other materials provided with the distribution.
20//
21// THIS SOFTWARE IS PROVIDED BY THE INSTITUTE OF TELEMATICS ``AS IS'' AND
22// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
24// PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE ARIBA PROJECT OR
25// CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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30// NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
31// SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
32//
33// The views and conclusions contained in the software and documentation
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#include "ariba/overlay/messages/OverlayMsg.h"
41
42#include "Chord.h"
43#include "detail/chord_routing_table.hpp"
44
45#include "messages/Discovery.h"
46
47namespace ariba {
48namespace overlay {
49
50enum signalMessageTypes {
51 typeDiscovery = OverlayMsg::typeSignalingStart + 0x01,
52 typeLeave = OverlayMsg::typeSignalingStart + 0x02,
53};
54
55typedef chord_routing_table::item route_item;
56
57use_logging_cpp( Chord );
58
59Chord::Chord(BaseOverlay& _baseoverlay, const NodeID& _nodeid,
60 OverlayStructureEvents* _eventsReceiver, const OverlayParameterSet& param) :
61 OverlayInterface(_baseoverlay, _nodeid, _eventsReceiver, param) {
62
63 // create routing table
64 this->table = new chord_routing_table(_nodeid, 4);
65 orphan_removal_counter = 0;
66 discovery_count = 0;
67 stabilize_counter = 0;
68 stabilize_finger = 0;
69}
70
71Chord::~Chord() {
72
73 // delete routing table
74 delete table;
75}
76
77/// helper: sets up a link using the base overlay
78LinkID Chord::setup(const EndpointDescriptor& endpoint, const NodeID& remote ) {
79
80 // check if we already have a connection
81 for (size_t i=0; i<table->size(); i++)
82 if ((*table)[i]->ref_count > 0 && (*table)[i]->id == remote && !((*table)[i]->info.isUnspecified()))
83 return LinkID::UNSPECIFIED;
84
85 // check if we are already trying to establish a link
86 for (size_t i=0; i<pending.size(); i++)
87 if ( pending[i] == remote ) {
88 logging_debug("Already trying to establish a link to node "
89 << remote.toString() );
90 return LinkID::UNSPECIFIED;
91 }
92
93 // adding node to list of pending connections
94 pending.push_back( remote );
95
96 logging_info("Request to setup link to " << endpoint.toString() );
97
98 // establish link via base overlay
99 return baseoverlay.establishLink( endpoint, remote,
100 OverlayInterface::OVERLAY_SERVICE_ID );
101}
102
103/// helper: sends a message using the "base overlay"
104seqnum_t Chord::send( OverlayMsg* msg, const LinkID& link ) {
105 if (link.isUnspecified()) return 0;
106 return baseoverlay.send_link( msg, link );
107}
108
109/// sends a discovery message
110void Chord::send_discovery_to(const NodeID& remote, int ttl) {
111 LinkID link = getNextLinkId(remote);
112 if ( remote == nodeid || link.isUnspecified()) return;
113 if ( table->size() == 0 ) return;
114 ttl = 2;
115
116 OverlayMsg msg( typeDiscovery );
117 msg.setRegisterRelay(true);
118 Discovery dmsg( Discovery::normal, (uint8_t)ttl, baseoverlay.getEndpointDescriptor() );
119 msg.encapsulate(&dmsg);
120
121 // send to node
122 baseoverlay.send_node( &msg, remote );
123}
124
125void Chord::discover_neighbors( const LinkID& link ) {
126 uint8_t ttl = 1;
127 {
128 // send predecessor discovery
129 OverlayMsg msg( typeDiscovery );
130 msg.setRegisterRelay(true);
131 Discovery dmsg( Discovery::predecessor, ttl,
132 baseoverlay.getEndpointDescriptor() );
133 msg.encapsulate(&dmsg);
134 send(&msg, link);
135 }
136 {
137 // send successor discovery
138 OverlayMsg msg( typeDiscovery );
139 msg.setSourceEndpoint( baseoverlay.getEndpointDescriptor() );
140 msg.setRegisterRelay(true);
141 Discovery dmsg( Discovery::successor, ttl,
142 baseoverlay.getEndpointDescriptor() );
143 msg.encapsulate(&dmsg);
144 send(&msg, link);
145 }
146}
147
148
149void Chord::createOverlay() {
150}
151
152void Chord::deleteOverlay() {
153
154}
155
156void Chord::joinOverlay(const EndpointDescriptor& boot) {
157 logging_info( "joining Chord overlay structure through end-point " <<
158 (boot.isUnspecified() ? "local" : boot.toString()) );
159
160 // initiator? no->setup first link
161 if (!boot.isUnspecified())
162 bootstrapLinks.push_back( setup(boot) );
163
164 // timer for stabilization management
165 Timer::setInterval(1000);
166 Timer::start();
167}
168
169void Chord::leaveOverlay() {
170 Timer::stop();
171 for (size_t i = 0; i < table->size(); i++) {
172 route_item* it = (*table)[i];
173 OverlayMsg msg( typeLeave );
174 send( &msg, it->info );
175 }
176}
177
178/// @see OverlayInterface.h
179const EndpointDescriptor& Chord::resolveNode(const NodeID& node) {
180 const route_item* item = table->get(node);
181 if (item == NULL || item->info.isUnspecified()) return EndpointDescriptor::UNSPECIFIED();
182 return baseoverlay.getEndpointDescriptor(item->info);
183}
184
185/// @see OverlayInterface.h
186bool Chord::isClosestNodeTo( const NodeID& node ) {
187 return table->is_closest_to(node);
188}
189
190/// @see OverlayInterface.h
191const LinkID& Chord::getNextLinkId( const NodeID& id ) const {
192 // get next hop
193 const route_item* item = table->get_next_hop(id);
194
195 // returns a unspecified id when this is itself
196 if (item == NULL || item->id == nodeid)
197 return LinkID::UNSPECIFIED;
198
199 /// return routing info
200 return item->info;
201}
202
203OverlayInterface::NodeList Chord::getKnownNodes(bool deep) const {
204 OverlayInterface::NodeList nodelist;
205
206 if( deep ){
207 // all nodes that I know, fingers, succ/pred
208 for (size_t i = 0; i < table->size(); i++){
209 if ((*table)[i]->ref_count != 0
210 && !(*table)[i]->info.isUnspecified())
211 nodelist.push_back((*table)[i]->id);
212 }
213 } else {
214 // only succ and pred
215 if( table->get_predesessor() != NULL ){
216 nodelist.push_back( *(table->get_predesessor()) );
217 }
218 if( table->get_successor() != NULL ){
219 OverlayInterface::NodeList::iterator i =
220 std::find( nodelist.begin(), nodelist.end(), *(table->get_successor()) );
221 if( i == nodelist.end() )
222 nodelist.push_back( *(table->get_successor()) );
223 }
224 }
225
226 return nodelist;
227}
228
229/// @see CommunicationListener.h
230/// @see OverlayInterface.h
231void Chord::onLinkUp(const LinkID& lnk, const NodeID& remote) {
232 logging_info("link_up: link=" << lnk.toString() << " remote=" <<
233 remote.toString() );
234 for (vector<NodeID>::iterator i=pending.begin(); i!=pending.end(); i++)
235 if (*i == remote) {
236 pending.erase(i);
237 break;
238 }
239
240 if (remote==nodeid) {
241 logging_warn("dropping link that has been established to myself (nodes have same nodeid?)");
242 baseoverlay.dropLink(lnk);
243 return;
244 }
245
246 route_item* item = table->insert(remote);
247
248 // item added to routing table?
249 if (item != NULL) { // yes-> add to routing table
250 logging_info("new routing neighbor: " << remote.toString()
251 << " with link " << lnk.toString());
252
253 // replace with new link if link is "better"
254 if (item->info!=lnk && item->info.isUnspecified()==false) {
255 if (baseoverlay.compare( item->info, lnk ) == 1) {
256 logging_info("Replacing link due to concurrent link establishment.");
257 baseoverlay.dropLink(item->info);
258 item->info = lnk;
259 }
260 } else {
261 item->info = lnk;
262 }
263
264 // discover neighbors of new overlay neighbor
265 showLinks();
266 } else { // no-> add orphan entry to routing table
267 logging_info("new orphan: " << remote.toString()
268 << " with link " << lnk.toString());
269 table->insert_orphan(remote)->info = lnk;
270 }
271
272 // erase bootstrap link
273 vector<LinkID>::iterator it = std::find(bootstrapLinks.begin(), bootstrapLinks.end(), lnk);
274 if( it != bootstrapLinks.end() ) bootstrapLinks.erase( it );
275}
276
277/// @see CommunicationListener.h or @see OverlayInterface.h
278void Chord::onLinkDown(const LinkID& lnk, const NodeID& remote) {
279 logging_debug("link_down: link=" << lnk.toString() << " remote=" <<
280 remote.toString() );
281
282 // remove link from routing table
283 route_item* item = table->get(remote);
284 if (item!=NULL && item->info==lnk) {
285 item->info = LinkID::UNSPECIFIED;
286 table->remove(remote);
287 }
288}
289
290/// @see CommunicationListener.h
291/// @see OverlayInterface.h
292void Chord::onMessage(const DataMessage& msg, const NodeID& remote,
293 const LinkID& link) {
294
295 // decode message
296 OverlayMsg* m = dynamic_cast<OverlayMsg*>(msg.getMessage());
297 if (m == NULL) return;
298
299 // handle messages
300 switch ((signalMessageTypes)m->getType()) {
301
302 // discovery request
303 case typeDiscovery: {
304 // decapsulate message
305 Discovery* dmsg = m->decapsulate<Discovery> ();
306 logging_debug("Received discovery message with"
307 << " src=" << m->getSourceNode().toString()
308 << " dst=" << m->getDestinationNode().toString()
309 << " ttl=" << (int)dmsg->getTTL()
310 << " type=" << (int)dmsg->getType()
311 );
312
313 // add discovery node id
314 bool found = false;
315 BOOST_FOREACH( NodeID& value, discovery )
316 if (value == m->getSourceNode()) {
317 found = true;
318 break;
319 }
320 if (!found) discovery.push_back(m->getSourceNode());
321
322 // check if source node can be added to routing table and setup link
323 if (m->getSourceNode() != nodeid)
324 setup( dmsg->getEndpoint(), m->getSourceNode() );
325
326 // process discovery message -------------------------- switch start --
327 switch (dmsg->getType()) {
328
329 // normal: route discovery message like every other message
330 case Discovery::normal: {
331 // closest node? yes-> split to follow successor and predecessor
332 if ( table->is_closest_to(m->getDestinationNode()) ) {
333 logging_debug("Discovery split:");
334 if (!table->get_successor()->isUnspecified()) {
335 OverlayMsg omsg(*m);
336 dmsg->setType(Discovery::successor);
337 omsg.encapsulate(dmsg);
338 logging_debug("* Routing to successor "
339 << table->get_successor()->toString() );
340 baseoverlay.send( &omsg, *table->get_successor() );
341 }
342
343 // send predecessor message
344 if (!table->get_predesessor()->isUnspecified()) {
345 OverlayMsg omsg(*m);
346 dmsg->setType(Discovery::predecessor);
347 omsg.encapsulate(dmsg);
348 logging_debug("* Routing to predecessor "
349 << table->get_predesessor()->toString() );
350 baseoverlay.send( &omsg, *table->get_predesessor() );
351 }
352 }
353 // no-> route message
354 else {
355 baseoverlay.route( m );
356 }
357 break;
358 }
359
360 // successor mode: follow the successor until TTL is zero
361 case Discovery::successor:
362 case Discovery::predecessor: {
363 // reached destination? no->forward!
364 if (m->getDestinationNode() != nodeid) {
365 OverlayMsg omsg(*m);
366 omsg.encapsulate(dmsg);
367 omsg.setService(OverlayInterface::OVERLAY_SERVICE_ID);
368 baseoverlay.route( &omsg );
369 break;
370 }
371
372 // time to live ended? yes-> stop routing
373 if (dmsg->getTTL() == 0 || dmsg->getTTL() > 10) break;
374
375 // decrease time-to-live
376 dmsg->setTTL(dmsg->getTTL() - 1);
377
378 const route_item* item = NULL;
379 if (dmsg->getType() == Discovery::successor &&
380 table->get_successor() != NULL) {
381 item = table->get(*table->get_successor());
382 } else {
383 if (table->get_predesessor()!=NULL)
384 item = table->get(*table->get_predesessor());
385 }
386 if (item == NULL)
387 break;
388
389 logging_debug("Routing discovery message to succ/pred "
390 << item->id.toString() );
391 OverlayMsg omsg(*m);
392 omsg.encapsulate(dmsg);
393 omsg.setDestinationNode(item->id);
394 omsg.setService(OverlayInterface::OVERLAY_SERVICE_ID);
395 baseoverlay.send(&omsg, omsg.getDestinationNode());
396 break;
397 }
398 case Discovery::invalid:
399 break;
400
401 default:
402 break;
403 }
404 // process discovery message ---------------------------- switch end --
405
406 delete dmsg;
407 break;
408 }
409
410 // leave
411 case typeLeave: {
412 if (link!=LinkID::UNSPECIFIED) {
413 route_item* item = table->get(remote);
414 if (item!=NULL) item->info = LinkID::UNSPECIFIED;
415 table->remove(remote);
416 baseoverlay.dropLink(link);
417 }
418 break;
419 }}
420}
421
422void Chord::eventFunction() {
423 stabilize_counter++;
424 if (stabilize_counter < 0 || stabilize_counter == 2) {
425
426 // reset counter
427 stabilize_counter = 0;
428
429 // clear pending connections
430 pending.clear();
431
432 // get number of real neighbors
433 size_t numNeighbors = 0;
434 for (size_t i = 0; i < table->size(); i++) {
435 route_item* it = (*table)[i];
436 if (it->ref_count != 0 && !it->info.isUnspecified()) numNeighbors++;
437 }
438 logging_info("Running stabilization: #links="
439 << table->size() << " #neighbors=" << numNeighbors );
440
441 // updating neighbors
442 logging_debug("Discover new ring neighbors");
443 for (size_t i=0; i<table->size(); i++) {
444 LinkID id = (*table)[i]->info;
445 if (!id.isUnspecified()) discover_neighbors(id);
446 }
447
448 // sending discovery
449 logging_debug("Sending discovery message to my neighbors and fingers");
450 stabilize_finger = ((stabilize_finger+1) % table->get_finger_table_size() );
451 const NodeID disc = table->get_finger_table(stabilize_finger).get_compare().get_center();
452 if (disc != nodeid)
453 send_discovery_to(disc);
454
455 // remove orphan links
456 orphan_removal_counter++;
457 if (orphan_removal_counter <0 || orphan_removal_counter >= 2) {
458 logging_info("Discovered nodes: ");
459 BOOST_FOREACH( NodeID& id, discovery )
460 logging_info("* " << id.toString());
461 discovery.clear();
462 logging_info("Running orphan removal");
463 orphan_removal_counter = 0;
464 for (size_t i = 0; i < table->size(); i++) {
465 route_item* it = (*table)[i];
466 if (it->ref_count == 0 && !it->info.isUnspecified()) {
467 logging_info("Dropping orphaned link " << it->info.toString() << " to " << it->id.toString());
468 table->insert(it->id);
469 if (it->ref_count==0) {
470 LinkID id = it->info;
471 it->info = LinkID::UNSPECIFIED;
472 baseoverlay.dropLink(id);
473 }
474 }
475 }
476 }
477 }
478}
479
480void Chord::showLinks() {
481 logging_info("--- chord routing information ----------------------------------");
482 logging_info("predecessor: " << (table->get_predesessor()==NULL? "<none>" :
483 table->get_predesessor()->toString()) );
484 logging_info("node_id : " << nodeid.toString() );
485 logging_info("successor : " << (table->get_successor()==NULL? "<none>" :
486 table->get_successor()->toString()));
487 logging_info("----------------------------------------------------------------");
488}
489
490/// @see OverlayInterface.h
491std::string Chord::debugInformation() const {
492 std::ostringstream s;
493 s << "protocol : Chord" << endl;
494 s << "node_id : " << nodeid.toString() << endl;
495 s << "predecessor: " << (table->get_predesessor()==NULL? "<none>" :
496 table->get_predesessor()->toString()) << endl;
497 s << "successor : " << (table->get_successor()==NULL? "<none>" :
498 table->get_successor()->toString()) << endl;
499 s << "nodes: " << endl;
500 for (size_t i = 0; i < table->size(); i++) {
501 route_item* it = (*table)[i];
502 if (it->ref_count != 0 && !it->info.isUnspecified()) {
503 s << it->id.toString().substr(0,6)
504 << " using " << it->info.toString().substr(0,6) << endl;
505 }
506 }
507 return s.str();
508}
509
510
511
512}} // namespace ariba, overlay
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