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source: source/ariba/overlay/modules/chord/Chord.cpp@ 6185

Last change on this file since 6185 was 5914, checked in by mies, 15 years ago
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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//
11// Redistribution and use in source and binary forms, with or without
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,
26// EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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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 (int 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
186const LinkID& Chord::getNextLinkId( const NodeID& id ) const {
187 // get next hop
188 const route_item* item = table->get_next_hop(id);
189
190 // returns a unspecified id when this is itself
191 if (item == NULL || item->id == nodeid)
192 return LinkID::UNSPECIFIED;
193
194 /// return routing info
195 return item->info;
196}
197
198OverlayInterface::NodeList Chord::getKnownNodes(bool deep) const {
199 OverlayInterface::NodeList nodelist;
200
201 if( deep ){
202 // all nodes that I know, fingers, succ/pred
203 for (size_t i = 0; i < table->size(); i++){
204 if ((*table)[i]->ref_count != 0
205 && !(*table)[i]->info.isUnspecified())
206 nodelist.push_back((*table)[i]->id);
207 }
208 } else {
209 // only succ and pred
210 if( table->get_predesessor() != NULL ){
211 nodelist.push_back( *(table->get_predesessor()) );
212 }
213 if( table->get_successor() != NULL ){
214 OverlayInterface::NodeList::iterator i =
215 std::find( nodelist.begin(), nodelist.end(), *(table->get_successor()) );
216 if( i == nodelist.end() )
217 nodelist.push_back( *(table->get_successor()) );
218 }
219 }
220
221 return nodelist;
222}
223
224/// @see CommunicationListener.h
225/// @see OverlayInterface.h
226void Chord::onLinkUp(const LinkID& lnk, const NodeID& remote) {
227 logging_info("link_up: link=" << lnk.toString() << " remote=" <<
228 remote.toString() );
229 for (vector<NodeID>::iterator i=pending.begin(); i!=pending.end(); i++)
230 if (*i == remote) {
231 pending.erase(i);
232 break;
233 }
234
235 if (remote==nodeid) {
236 baseoverlay.dropLink(lnk);
237 return;
238 }
239
240 route_item* item = table->insert(remote);
241
242 // item added to routing table?
243 if (item != NULL) { // yes-> add to routing table
244 logging_info("new routing neighbor: " << remote.toString()
245 << " with link " << lnk.toString());
246 // replace with new link
247 if (!item->info.isUnspecified() || item->info!=lnk)
248 baseoverlay.dropLink(item->info);
249 item->info = lnk;
250
251 // discover neighbors of new overlay neighbor
252 showLinks();
253 } else { // no-> add orphan entry to routing table
254 logging_info("new orphan: " << remote.toString()
255 << " with link " << lnk.toString());
256 table->insert_orphan(remote)->info = lnk;
257 }
258
259 // erase bootstrap link
260 vector<LinkID>::iterator it = std::find(bootstrapLinks.begin(), bootstrapLinks.end(), lnk);
261 if( it != bootstrapLinks.end() ) bootstrapLinks.erase( it );
262}
263
264/// @see CommunicationListener.h or @see OverlayInterface.h
265void Chord::onLinkDown(const LinkID& lnk, const NodeID& remote) {
266 logging_debug("link_down: link=" << lnk.toString() << " remote=" <<
267 remote.toString() );
268
269 // remove link from routing table
270 route_item* item = table->get(remote);
271 if (item!=NULL && item->info==lnk) {
272 item->info = LinkID::UNSPECIFIED;
273 table->remove(remote);
274 }
275}
276
277/// @see CommunicationListener.h
278/// @see OverlayInterface.h
279void Chord::onMessage(const DataMessage& msg, const NodeID& remote,
280 const LinkID& link) {
281
282 // decode message
283 OverlayMsg* m = dynamic_cast<OverlayMsg*>(msg.getMessage());
284 if (m == NULL) return;
285
286 // handle messages
287 switch (m->getType()) {
288
289 // discovery request
290 case typeDiscovery: {
291 // decapsulate message
292 Discovery* dmsg = m->decapsulate<Discovery> ();
293 logging_debug("Received discovery message with"
294 << " src=" << m->getSourceNode().toString()
295 << " dst=" << m->getDestinationNode().toString()
296 << " ttl=" << (int)dmsg->getTTL()
297 << " type=" << (int)dmsg->getType()
298 );
299
300 // add discovery node id
301 bool found = false;
302 BOOST_FOREACH( NodeID& value, discovery )
303 if (value == m->getSourceNode()) {
304 found = true;
305 break;
306 }
307 if (!found) discovery.push_back(m->getSourceNode());
308
309 // check if source node can be added to routing table and setup link
310 if (m->getSourceNode() != nodeid)
311 setup( dmsg->getEndpoint(), m->getSourceNode() );
312
313 // delegate discovery message
314 switch (dmsg->getType()) {
315
316 // normal: route discovery message like every other message
317 case Discovery::normal: {
318 // closest node? yes-> split to follow successor and predecessor
319 if ( table->is_closest_to(m->getDestinationNode()) ) {
320 logging_debug("Discovery split:");
321 if (!table->get_successor()->isUnspecified()) {
322 OverlayMsg omsg(*m);
323 dmsg->setType(Discovery::successor);
324 omsg.encapsulate(dmsg);
325 logging_debug("* Routing to successor "
326 << table->get_successor()->toString() );
327 baseoverlay.send( &omsg, *table->get_successor() );
328 }
329
330 // send predecessor message
331 if (!table->get_predesessor()->isUnspecified()) {
332 OverlayMsg omsg(*m);
333 dmsg->setType(Discovery::predecessor);
334 omsg.encapsulate(dmsg);
335 logging_debug("* Routing to predecessor "
336 << table->get_predesessor()->toString() );
337 baseoverlay.send( &omsg, *table->get_predesessor() );
338 }
339 }
340 // no-> route message
341 else {
342 baseoverlay.route( m );
343 }
344 break;
345 }
346
347 // successor mode: follow the successor until TTL is zero
348 case Discovery::successor:
349 case Discovery::predecessor: {
350 // reached destination? no->forward!
351 if (m->getDestinationNode() != nodeid) {
352 OverlayMsg omsg(*m);
353 omsg.encapsulate(dmsg);
354 omsg.setService(OverlayInterface::OVERLAY_SERVICE_ID);
355 baseoverlay.route( &omsg );
356 break;
357 }
358
359 // time to live ended? yes-> stop routing
360 if (dmsg->getTTL() == 0 || dmsg->getTTL() > 10) break;
361
362 // decrease time-to-live
363 dmsg->setTTL(dmsg->getTTL() - 1);
364
365 const route_item* item = NULL;
366 if (dmsg->getType() == Discovery::successor &&
367 table->get_successor() != NULL) {
368 item = table->get(*table->get_successor());
369 } else {
370 if (table->get_predesessor()!=NULL)
371 item = table->get(*table->get_predesessor());
372 }
373 if (item == NULL)
374 break;
375
376 logging_debug("Routing discovery message to succ/pred "
377 << item->id.toString() );
378 OverlayMsg omsg(*m);
379 omsg.encapsulate(dmsg);
380 omsg.setDestinationNode(item->id);
381 omsg.setService(OverlayInterface::OVERLAY_SERVICE_ID);
382 baseoverlay.send(&omsg, omsg.getDestinationNode());
383 break;
384 }}
385 delete dmsg;
386 break;
387 }
388
389 // leave
390 case typeLeave: {
391 if (link!=LinkID::UNSPECIFIED) {
392 route_item* item = table->get(remote);
393 if (item!=NULL) item->info = LinkID::UNSPECIFIED;
394 table->remove(remote);
395 baseoverlay.dropLink(link);
396 }
397 break;
398 }}
399}
400
401void Chord::eventFunction() {
402 stabilize_counter++;
403 if (stabilize_counter < 0 || stabilize_counter == 2) {
404
405 // reset counter
406 stabilize_counter = 0;
407
408 // clear pending connections
409 pending.clear();
410
411 // get number of real neighbors
412 size_t numNeighbors = 0;
413 for (size_t i = 0; i < table->size(); i++) {
414 route_item* it = (*table)[i];
415 if (it->ref_count != 0 && !it->info.isUnspecified()) numNeighbors++;
416 }
417 logging_info("Running stabilization: #links="
418 << table->size() << " #neighbors=" << numNeighbors );
419
420 // updating neighbors
421 logging_debug("Discover new ring neighbors");
422 for (int i=0; i<table->size(); i++) {
423 LinkID id = (*table)[i]->info;
424 if (!id.isUnspecified()) discover_neighbors(id);
425 }
426
427 // sending discovery
428 logging_debug("Sending discovery message to my neighbors and fingers");
429 stabilize_finger = ((stabilize_finger+1) % table->get_finger_table_size() );
430 const NodeID disc = table->get_finger_table(stabilize_finger).get_compare().get_center();
431 if (disc != nodeid)
432 send_discovery_to(disc);
433
434 // remove orphan links
435 orphan_removal_counter++;
436 if (orphan_removal_counter <0 || orphan_removal_counter >= 2) {
437 logging_info("Discovered nodes: ");
438 BOOST_FOREACH( NodeID& id, discovery )
439 logging_info("* " << id.toString());
440 discovery.clear();
441 logging_info("Running orphan removal");
442 orphan_removal_counter = 0;
443 for (size_t i = 0; i < table->size(); i++) {
444 route_item* it = (*table)[i];
445 if (it->ref_count == 0 && !it->info.isUnspecified()) {
446 logging_info("Dropping orphaned link " << it->info.toString() << " to " << it->id.toString());
447 table->insert(it->id);
448 if (it->ref_count==0) {
449 LinkID id = it->info;
450 it->info = LinkID::UNSPECIFIED;
451 baseoverlay.dropLink(id);
452 }
453 }
454 }
455 }
456 }
457}
458
459void Chord::showLinks() {
460 logging_info("--- chord routing information ----------------------------------");
461 logging_info("predecessor: " << (table->get_predesessor()==NULL? "<none>" :
462 table->get_predesessor()->toString()) );
463 logging_info("node_id : " << nodeid.toString() );
464 logging_info("successor : " << (table->get_successor()==NULL? "<none>" :
465 table->get_successor()->toString()));
466 logging_info("----------------------------------------------------------------");
467}
468
469}} // namespace ariba, overlay
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