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source: source/ariba/overlay/modules/chord/Chord.cpp@ 5308

Last change on this file since 5308 was 5151, checked in by Christoph Mayer, 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,
27// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
28// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
29// LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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
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;
51
52use_logging_cpp( Chord );
53
54Chord::Chord(BaseOverlay& _baseoverlay, const NodeID& _nodeid,
55 OverlayStructureEvents* _eventsReceiver, const OverlayParameterSet& param) :
56 OverlayInterface(_baseoverlay, _nodeid, _eventsReceiver, param) {
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, const NodeID& node) {
74
75 logging_debug("request to setup link to " << endp.toString() );
76
77 for (size_t i=0; i<pending.size(); i++)
78 if (pending[i]==node) return LinkID::UNSPECIFIED;
79 pending.push_back(node);
80
81 // establish link via base overlay
82 return baseoverlay.establishLink(endp, node, OverlayInterface::OVERLAY_SERVICE_ID);
83}
84
85/// helper: sends a message using the "base overlay"
86seqnum_t Chord::send(Message* msg, const LinkID& link) {
87 if (link.isUnspecified()) return 0;
88 return baseoverlay.sendMessage(msg, link);
89}
90
91/// sends a discovery message
92void Chord::send_discovery_to(const NodeID& destination, int ttl) {
93// logging_debug("Initiating discovery of " << destination.toString() );
94 Message msg;
95 ChordMessage cmsg(ChordMessage::discovery, nodeid, destination);
96 Discovery dmsg;
97 dmsg.setSourceEndpoint(&baseoverlay.getEndpointDescriptor());
98 dmsg.setFollowType(Discovery::normal);
99 dmsg.setTTL((uint8_t) ttl);
100 cmsg.encapsulate(&dmsg);
101 msg.encapsulate(&cmsg);
102 this->onMessage(&msg, NodeID::UNSPECIFIED, LinkID::UNSPECIFIED);
103}
104
105void Chord::createOverlay() {
106}
107
108void Chord::deleteOverlay() {
109
110}
111
112void Chord::joinOverlay(const EndpointDescriptor& boot) {
113 logging_info( "joining Chord overlay structure through end-point " <<
114 (boot == EndpointDescriptor::UNSPECIFIED ?
115 "local" : boot.toString()) );
116
117 // initiator? no->setup first link
118 if (!(boot == EndpointDescriptor::UNSPECIFIED))
119 bootstrapLink = setup(boot);
120
121 // timer for stabilization management
122 Timer::setInterval(2500);
123 Timer::start();
124}
125
126void Chord::leaveOverlay() {
127 Timer::stop();
128 for (size_t i = 0; i < table->size(); i++) {
129 route_item* it = (*table)[i];
130 ChordMessage msg(ChordMessage::leave, nodeid, it->id);
131 send(&msg,it->info);
132 }
133}
134
135const EndpointDescriptor& Chord::resolveNode(const NodeID& node) {
136 const route_item* item = table->get(node);
137 if (item == NULL || item->info.isUnspecified()) return EndpointDescriptor::UNSPECIFIED;
138 return baseoverlay.getEndpointDescriptor(item->info);
139}
140
141void Chord::routeMessage(const NodeID& destnode, Message* msg) {
142 // get next hop
143 const route_item* item = table->get_next_hop(destnode);
144
145 // message for this node? yes-> delegate to base overlay
146 if (item->id == nodeid || destnode == nodeid)
147 baseoverlay.incomingRouteMessage( msg, LinkID::UNSPECIFIED, nodeid );
148
149 else { // no-> send to next hop
150 ChordMessage cmsg(ChordMessage::route, nodeid, destnode);
151 cmsg.encapsulate(msg);
152 send(&cmsg, item->info);
153 }
154}
155
156/// @see OverlayInterface.h
157void Chord::routeMessage(const NodeID& node, const LinkID& link, Message* msg) {
158 logging_debug("Redirect over Chord to node id=" << node.toString()
159 << " link id=" << link.toString() );
160 ChordMessage cmsg(ChordMessage::route, nodeid, node);
161 cmsg.encapsulate(msg);
162 send(&cmsg, link);
163}
164
165/// @see OverlayInterface.h
166const LinkID& Chord::getNextLinkId( const NodeID& id ) const {
167 // get next hop
168 const route_item* item = table->get_next_hop(id);
169
170 // returns a unspecified id when this is itself
171 if (item == NULL || item->id == nodeid)
172 return LinkID::UNSPECIFIED;
173
174 /// return routing info
175 return item->info;
176}
177
178OverlayInterface::NodeList Chord::getKnownNodes() const {
179 OverlayInterface::NodeList nodelist;
180 for (size_t i = 0; i < table->size(); i++)
181 if ((*table)[i]->ref_count != 0
182 && !(*table)[i]->info.isUnspecified())
183 nodelist.push_back((*table)[i]->id);
184 return nodelist;
185}
186
187/// @see CommunicationListener.h
188/// @see OverlayInterface.h
189void Chord::onLinkUp(const LinkID& lnk, const NodeID& remote) {
190 logging_debug("link_up: link=" << lnk.toString() << " remote=" <<
191 remote.toString() );
192 for (vector<NodeID>::iterator i=pending.begin(); i!=pending.end(); i++)
193 if (*i == remote) {
194 pending.erase(i);
195 break;
196 }
197 route_item* item = table->insert(remote);
198
199 // item added to routing table?
200 if (item != NULL) { // yes-> add to routing table
201 logging_info("new routing neighbor: " << remote.toString()
202 << " with link " << lnk.toString());
203 item->info = lnk;
204 } else { // no-> add orphan entry to routing table
205 logging_info("new orphan: " << remote.toString()
206 << " with link " << lnk.toString());
207 table->insert_orphan(remote)->info = lnk;
208 }
209
210 if (!bootstrapLink.isUnspecified() && lnk == bootstrapLink) {
211 send_discovery_to(nodeid);
212 bootstrapLink = LinkID::UNSPECIFIED;
213 }
214}
215
216/// @see CommunicationListener.h or @see OverlayInterface.h
217void Chord::onLinkDown(const LinkID& lnk, const NodeID& remote) {
218 logging_debug("link_down: link=" << lnk.toString() << " remote=" <<
219 remote.toString() );
220
221 // remove link from routing table
222 route_item* item = table->get(remote);
223 if (item!=NULL) item->info = LinkID::UNSPECIFIED;
224 table->remove(remote);
225}
226
227/// @see CommunicationListener.h
228/// @see OverlayInterface.h
229void Chord::onMessage(const DataMessage& msg, const NodeID& remote,
230 const LinkID& link) {
231
232 // decode message
233 typedef ChordMessage M;
234 M* m = msg.getMessage()->convert<ChordMessage> ();
235 if (m == NULL) return;
236
237 // handle messages
238 switch (m->getType()) {
239
240 // invalid message
241 case M::invalid:
242 break;
243
244 // route message with payload
245 case M::route: {
246 // find next hop
247 const route_item* item = table->get_next_hop(m->getDestination());
248
249 // next hop == myself?
250 if (m->getDestination() == nodeid) { // yes-> route to base overlay
251 logging_debug("Send message to baseoverlay");
252 baseoverlay.incomingRouteMessage( m, item->info, remote );
253 }
254 // no-> route to next hop
255 else {
256 logging_debug("Route chord message to "
257 << item->id.toString() << " (destination=" << m->getDestination() << ")");
258 send(m, item->info);
259 }
260 break;
261 }
262
263 // discovery request
264 case M::discovery: {
265 // decapsulate message
266 Discovery* dmsg = m->decapsulate<Discovery> ();
267 logging_debug("received discovery message with"
268 << " dest=" << m->getDestination().toString()
269 << " ttl=" << (int)dmsg->getTTL()
270 << " type=" << (int)dmsg->getFollowType()
271 );
272
273 // check if source node can be added to routing table and setup link
274 if (m->getSource() != nodeid && table->is_insertable(m->getSource()))
275 setup(*dmsg->getSourceEndpoint(), m->getSource() );
276
277 // delegate discovery message
278 switch (dmsg->getFollowType()) {
279
280 // normal: route discovery message like every other message
281 case Discovery::normal:
282 // closest node? yes-> split to follow successor and predecessor
283 if (table->is_closest_to(m->getDestination())) {
284
285 if (table->get_successor() != NULL) {
286 // send successor message
287 ChordMessage cmsg_s(*m);
288 Discovery dmsg_s(*dmsg);
289 dmsg_s.setFollowType(Discovery::successor);
290 cmsg_s.encapsulate(&dmsg_s);
291 route_item* succ_item = table->get(*table->get_successor());
292 logging_debug("split: routing discovery message to successor "
293 << succ_item->id.toString() );
294 send(&cmsg_s, succ_item->info);
295 }
296
297 // send predecessor message
298 if (table->get_predesessor() != NULL) {
299 ChordMessage cmsg_p(*m);
300 Discovery dmsg_p(*dmsg);
301 dmsg_p.setFollowType(Discovery::predecessor);
302 cmsg_p.encapsulate(&dmsg_p);
303 route_item* pred_item = table->get(
304 *table->get_predesessor());
305 logging_debug("split: routing discovery message to predecessor "
306 << pred_item->id.toString() );
307 send(&cmsg_p, pred_item->info);
308 }
309 }
310 // no-> route message
311 else {
312 // find next hop
313 const route_item* item = table->get_next_hop(
314 m->getDestination());
315 if (item->id == nodeid) break;
316 logging_debug("routing discovery message to " <<
317 item->id.toString() );
318 send(m, item->info);
319 }
320 break;
321
322 // successor mode: follow the successor until TTL is zero
323 case Discovery::successor:
324 case Discovery::predecessor: {
325 // time to live ended? yes-> stop routing
326 if (dmsg->getTTL() == 0) break;
327
328 // decrease time-to-live
329 dmsg->setTTL(dmsg->getTTL() - 1);
330
331 const route_item* item = NULL;
332 if (dmsg->getFollowType() == Discovery::successor &&
333 table->get_successor() != NULL) {
334 item = table->get(*table->get_successor());
335 } else {
336 if (table->get_predesessor()!=NULL)
337 item = table->get(*table->get_predesessor());
338 }
339 if (item == NULL) break;
340 logging_debug("routing discovery message to succ/pred "
341 << item->id.toString() );
342 ChordMessage cmsg(*m);
343 cmsg.encapsulate(dmsg);
344 send(&cmsg, item->info);
345 break;
346 }
347 }
348 break;
349 }
350
351 // leave
352 case M::leave: {
353 if (link!=LinkID::UNSPECIFIED) {
354 route_item* item = table->get(remote);
355 if (item!=NULL) item->info = LinkID::UNSPECIFIED;
356 table->remove(remote);
357 baseoverlay.dropLink(link);
358 }
359 break;
360 }
361 }
362}
363
364void Chord::eventFunction() {
365 stabilize_counter++;
366 if (stabilize_counter == 3) {
367 pending.clear();
368 size_t numNeighbors = 0;
369 for (size_t i = 0; i < table->size(); i++) {
370 route_item* it = (*table)[i];
371 if (it->ref_count != 0 && !it->info.isUnspecified()) numNeighbors++;
372 }
373 logging_info("Running stabilization: #links="
374 << table->size() << " #neighbors=" << numNeighbors );
375 stabilize_counter = 0;
376 stabilize_finger = ((stabilize_finger+1) % table->get_finger_table_size() );
377 logging_debug("Sending discovery message to my neighbors and fingers");
378 const NodeID& disc1 = nodeid;
379 const NodeID& disc2 = table->get_finger_table(stabilize_finger).get_compare().get_center();
380 send_discovery_to(disc1);
381 if (disc1 != disc2) send_discovery_to(disc2);
382 orphan_removal_counter++;
383 if (orphan_removal_counter == 2) {
384 logging_info("Running orphan removal");
385 orphan_removal_counter = 0;
386 for (size_t i = 0; i < table->size(); i++) {
387 route_item* it = (*table)[i];
388 if (it->ref_count == 0 && !it->info.isUnspecified()) {
389 logging_info("Dropping orphaned link " << it->info.toString() << " to " << it->id.toString());
390 baseoverlay.dropLink(it->info);
391 it->info = LinkID::UNSPECIFIED;
392 }
393 }
394 }
395 }
396 logging_debug("--- chord routing information ----------------------------------");
397 logging_debug("predecessor: " << (table->get_predesessor()==NULL? "<none>" :
398 table->get_predesessor()->toString()) );
399 logging_debug("node_id : " << nodeid.toString() );
400 logging_debug("successor : " << (table->get_successor()==NULL? "<none>" :
401 table->get_successor()->toString()));
402 logging_debug("----------------------------------------------------------------");
403}
404
405}} // namespace ariba, overlay
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