1 /* Copyright (c) 2006-2017. The SimGrid Team. All rights reserved. */
3 /* This program is free software; you can redistribute it and/or modify it
4 * under the terms of the license (GNU LGPL) which comes with this package. */
8 import org.simgrid.msg.Msg;
9 import org.simgrid.msg.Comm;
10 import org.simgrid.msg.Host;
11 import org.simgrid.msg.Task;
12 import org.simgrid.msg.Process;
13 import org.simgrid.msg.MsgException;
14 import org.simgrid.msg.TimeoutException;
15 public class Node extends Process {
17 protected String mailbox;
19 protected String predMailbox;
20 protected int nextFingerToFix;
21 protected Comm commReceive;
22 ///Last time I changed a finger or my predecessor
23 protected double lastChangeDate;
24 private int[] fingers;
26 public Node(Host host, String name, String[] args) {
27 super(host,name,args);
31 public void main(String[] args) throws MsgException {
32 if (args.length != 2 && args.length != 4) {
33 Msg.info("You need to provide 2 or 4 arguments.");
36 double initTime = Msg.getClock();
41 double nextStabilizeDate = initTime + Common.PERIODIC_STABILIZE_DELAY;
42 double nextFixFingersDate = initTime + Common.PERIODIC_FIX_FINGERS_DELAY;
43 double nextCheckPredecessorDate = initTime + Common.PERIODIC_CHECK_PREDECESSOR_DELAY;
44 double nextLookupDate = initTime + Common.PERIODIC_LOOKUP_DELAY;
47 id = Integer.parseInt(args[0]);
49 fingers = new int[Common.NB_BITS];
50 for (i = 0; i < Common.NB_BITS; i++) {
56 if (args.length == 2) {
57 deadline = Integer.parseInt(args[1]);
61 int knownId = Integer.valueOf(args[1]);
62 deadline = Integer.valueOf(args[3]);
63 Msg.debug("Hey! Let's join the system with the id " + id + ".");
65 joinSuccess = join(knownId);
68 double currentClock = Msg.getClock();
69 while (currentClock < (initTime + deadline) && currentClock < Common.MAX_SIMULATION_TIME) {
70 if (commReceive == null) {
71 commReceive = Task.irecv(this.mailbox);
74 if (!commReceive.test()) {
75 if (currentClock >= nextStabilizeDate) {
77 nextStabilizeDate = Msg.getClock() + Common.PERIODIC_STABILIZE_DELAY;
78 } else if (currentClock >= nextFixFingersDate) {
80 nextFixFingersDate = Msg.getClock() + Common.PERIODIC_FIX_FINGERS_DELAY;
81 } else if (currentClock >= nextCheckPredecessorDate) {
82 this.checkPredecessor();
83 nextCheckPredecessorDate = Msg.getClock() + Common.PERIODIC_CHECK_PREDECESSOR_DELAY;
84 } else if (currentClock >= nextLookupDate) {
86 nextLookupDate = Msg.getClock() + Common.PERIODIC_LOOKUP_DELAY;
90 currentClock = Msg.getClock();
92 handleTask(commReceive.getTask());
93 currentClock = Msg.getClock();
98 currentClock = Msg.getClock();
103 if (commReceive != null) {
107 Msg.info("I couldn't join the ring");
111 private void handleTask(Task task) {
112 if (task instanceof FindSuccessorTask) {
113 FindSuccessorTask fTask = (FindSuccessorTask)task;
114 Msg.debug("Receiving a 'Find Successor' request from " + fTask.getIssuerHostName() + " for id " +
115 fTask.getRequestId());
116 // is my successor the successor?
117 if (isInInterval(fTask.getRequestId(), this.id + 1, fingers[0])) {
118 Msg.debug("Send the request to " + fTask.getAnswerTo() + " with answer " + fingers[0]);
119 FindSuccessorAnswerTask answer = new FindSuccessorAnswerTask(getHost().getName(), mailbox, fingers[0]);
120 answer.dsend(fTask.getAnswerTo());
122 // otherwise, forward the request to the closest preceding finger in my table
123 int closest = closestPrecedingNode(fTask.getRequestId());
124 Msg.debug("Forward the request to " + closest);
125 fTask.dsend(Integer.toString(closest));
127 } else if (task instanceof GetPredecessorTask) {
128 GetPredecessorTask gTask = (GetPredecessorTask)(task);
129 Msg.debug("Receiving a 'Get Predecessor' request from " + gTask.getIssuerHostName());
130 GetPredecessorAnswerTask answer = new GetPredecessorAnswerTask(getHost().getName(), mailbox, predId);
131 answer.dsend(gTask.getAnswerTo());
132 } else if (task instanceof NotifyTask) {
133 NotifyTask nTask = (NotifyTask)task;
134 notify(nTask.getRequestId());
136 Msg.debug("Ignoring unexpected task of type:" + task);
140 private void leave() {
141 Msg.debug("Well Guys! I Think it's time for me to quit ;)");
142 quitNotify(1); //Notify my successor
143 quitNotify(-1); //Notify my predecessor.
147 * @brief Notifies the successor or the predecessor of the current node of the departure
148 * @param to 1 to notify the successor, -1 to notify the predecessor
150 static private void quitNotify( int to) {
154 /** @brief Initializes the current node as the first one of the system */
155 private void create() {
156 Msg.debug("Create a new Chord ring...");
160 // Makes the current node join the ring, knowing the id of a node already in the ring
161 private boolean join(int knownId) {
162 Msg.info("Joining the ring with id " + this.id + " knowing node " + knownId);
164 int successorId = remoteFindSuccessor(knownId, this.id);
165 if (successorId == -1) {
166 Msg.info("Cannot join the ring.");
168 setFinger(0, successorId);
170 return successorId != -1;
173 private void setPredecessor(int predecessorId) {
174 if (predecessorId != predId) {
175 predId = predecessorId;
176 if (predecessorId != -1) {
177 predMailbox = Integer.toString(predId);
179 lastChangeDate = Msg.getClock();
184 * @brief Asks another node its predecessor.
185 * @param askTo the node to ask to
186 * @return the id of its predecessor node, or -1 if the request failed(or if the node does not know its predecessor)
188 private int remoteGetPredecessor(int askTo) {
189 int predecessorId = -1;
190 boolean stop = false;
191 Msg.debug("Sending a 'Get Predecessor' request to " + askTo);
192 String mailboxTo = Integer.toString(askTo);
193 GetPredecessorTask sendTask = new GetPredecessorTask(getHost().getName(), this.mailbox);
195 sendTask.send(mailboxTo, Common.TIMEOUT);
198 if (commReceive == null) {
199 commReceive = Task.irecv(this.mailbox);
201 commReceive.waitCompletion(Common.TIMEOUT);
202 Task taskReceived = commReceive.getTask();
203 if (taskReceived instanceof GetPredecessorAnswerTask) {
204 predecessorId = ((GetPredecessorAnswerTask) taskReceived).getAnswerId();
207 handleTask(taskReceived);
212 catch (MsgException e) {
217 catch (MsgException e) {
218 Msg.debug("Failed to send the Get Predecessor request");
220 return predecessorId;
224 * @brief Makes the current node find the successor node of an id.
225 * @param node the current node
226 * @param id the id to find
227 * @return the id of the successor node, or -1 if the request failed
229 private int findSuccessor(int id) {
230 if (isInInterval(id, this.id + 1, fingers[0])) {
234 int closest = this.closestPrecedingNode(id);
235 return remoteFindSuccessor(closest, id);
238 // Asks another node the successor node of an id.
239 private int remoteFindSuccessor(int askTo, int id) {
241 boolean stop = false;
242 String askToMailbox = Integer.toString(askTo);
243 Task sendTask = new FindSuccessorTask(getHost().getName(), this.mailbox, id);
244 Msg.debug("Sending a 'Find Successor' request to " + askToMailbox + " for id " + id);
246 sendTask.send(askToMailbox, Common.TIMEOUT);
248 if (commReceive == null) {
249 commReceive = Task.irecv(this.mailbox);
252 commReceive.waitCompletion(Common.TIMEOUT);
253 Task task = commReceive.getTask();
254 if (task instanceof FindSuccessorAnswerTask) {
255 //TODO: Check if this this our answer.
256 FindSuccessorAnswerTask fTask = (FindSuccessorAnswerTask) task;
258 successor = fTask.getAnswerId();
264 catch (TimeoutException e) {
270 catch (TimeoutException e) {
271 Msg.debug("Failed to send the 'Find Successor' request");
273 catch (MsgException e) {
274 Msg.debug("Failed to receive Find Successor");
280 // This function is called periodically. It checks the immediate successor of the current node.
281 private void stabilize() {
282 Msg.debug("Stabilizing node");
284 int successorId = fingers[0];
285 if (successorId != this.id){
286 candidateId = remoteGetPredecessor(successorId);
288 candidateId = predId;
290 //This node is a candidate to become my new successor
291 if (candidateId != -1 && isInInterval(candidateId, this.id + 1, successorId - 1)) {
292 setFinger(0, candidateId);
294 if (successorId != this.id) {
295 remoteNotify(successorId, this.id);
300 * @brief Notifies the current node that its predecessor may have changed.
301 * @param candidate_id the possible new predecessor
303 private void notify(int predecessorCandidateId) {
304 if (predId == -1 || isInInterval(predecessorCandidateId, predId + 1, this.id - 1 )) {
305 setPredecessor(predecessorCandidateId);
310 * @brief Notifies a remote node that its predecessor may have changed.
311 * @param notify_id id of the node to notify
312 * @param candidate_id the possible new predecessor
314 private void remoteNotify(int notifyId, int predecessorCandidateId) {
315 Msg.debug("Sending a 'Notify' request to " + notifyId);
316 Task sentTask = new NotifyTask(getHost().getName(), this.mailbox, predecessorCandidateId);
317 sentTask.dsend(Integer.toString(notifyId));
320 // This function is called periodically.
321 // It refreshes the finger table of the current node.
322 private void fixFingers() {
323 Msg.debug("Fixing fingers");
324 int i = this.nextFingerToFix;
325 int successorId = this.findSuccessor(this.id + (int)Math.pow(2,i)); //FIXME: SLOW
326 if (successorId != -1) {
327 if (successorId != fingers[i]) {
328 setFinger(i, successorId);
330 nextFingerToFix = (i + 1) % Common.NB_BITS;
334 // This function is called periodically.
335 // It checks whether the predecessor has failed
336 private void checkPredecessor() {
340 // Performs a find successor request to a random id.
341 private void randomLookup() {
343 //Msg.info("Making a lookup request for id " + id);
348 * @brief Returns the closest preceding finger of an id with respect to the finger table of the current node.
349 * @param id the id to find
350 * @return the closest preceding finger of that id
352 private int closestPrecedingNode(int id) {
353 for (int i = Common.NB_BITS - 1; i >= 0; i--) {
354 if (isInInterval(fingers[i], this.id + 1, id - 1)) {
362 * @brief Returns whether an id belongs to the interval [start, end].
364 * The parameters are noramlized to make sure they are between 0 and nb_keys - 1).
365 * 1 belongs to [62, 3]
366 * 1 does not belong to [3, 62]
367 * 63 belongs to [62, 3]
368 * 63 does not belong to [3, 62]
369 * 24 belongs to [21, 29]
370 * 24 does not belong to [29, 21]
372 * @param id id to check
373 * @param start lower bound
374 * @param end upper bound
375 * @return a non-zero value if id in in [start, end]
377 static private boolean isInInterval(int id, int start, int end) {
378 int normId = normalize(id);
379 int normStart = normalize(start);
380 int normEnd = normalize(end);
382 // make sure end >= start and id >= start
383 if (normEnd < normStart) {
384 normEnd += Common.NB_KEYS;
386 if (normId < normStart) {
387 normId += Common.NB_KEYS;
389 return (normId <= normEnd);
393 * @brief Turns an id into an equivalent id in [0, nb_keys).
395 * @return the corresponding normalized id
397 static private int normalize(int id) {
398 return id & (Common.NB_KEYS - 1);
402 * @brief Sets a finger of the current node.
403 * @param finger_index index of the finger to set (0 to nb_bits - 1)
404 * @param id the id to set for this finger
406 private void setFinger(int fingerIndex, int id) {
407 if (id != fingers[fingerIndex]) {
408 fingers[fingerIndex] = id;
409 lastChangeDate = Msg.getClock();