CoordGmsImpl


1   // $Id: CoordGmsImpl.java,v 1.7 2004/09/23 16:29:41 belaban Exp $
2   
3   package org.jgroups.protocols;
4   
5   import org.jgroups.Address;
6   import org.jgroups.Event;
7   import org.jgroups.View;
8   import org.jgroups.ViewId;
9   import org.jgroups.blocks.GroupRequest;
10  import org.jgroups.blocks.MethodCall;
11  
12  import java.util.Collections  ;
13  import java.util.HashSet  ;
14  import java.util.Iterator  ;
15  import java.util.Vector  ;
16  
17  
18  public class CoordGmsImpl extends GmsImpl {
19      boolean leaving=false;
20      boolean received_last_view=false;
21      final Object   leave_mutex=new Object  ();
22  
23  
24      public CoordGmsImpl(GMS g) {
25          gms=g;
26      }
27  
28  
29      public void init() {
30          leaving=false;
31          received_last_view=false;
32      }
33  
34  
35      public void join(Address mbr) {
36          wrongMethod("join");
37      }
38  
39  
40      /**
41       * The coordinator itself wants to leave the group
42       */
43      public void leave(Address mbr) {
44          if(mbr.equals(gms.local_addr))
45              leaving=true;
46  
47          handleLeave(mbr, false);    // regular leave
48          synchronized(leave_mutex) {
49              if(leaving && received_last_view)  // handleViewChange() has acquired leave_mutex before us...
50                  return;
51              try {
52                  leave_mutex.wait(gms.leave_timeout); // will be notified by handleViewChange()
53              }
54              catch(Exception   e) {
55              }
56          }
57      }
58  
59  
60      public void suspect(Address mbr) {
61          handleSuspect(mbr);
62      }
63  
64  
65      /**
66       * Invoked upon receiving a MERGE event from the MERGE layer. We have found a partition and
67       * should merge with them, then I will become a Participant.
68       * 
69       * @param other_coords A list of other coordinators found. In the current implementation the list
70       *                     only has a single element
71       */
72      public void merge(Vector   other_coords) {
73          View new_view=null;
74          Address other_coord=other_coords != null? (Address)other_coords.elementAt(0) : null;
75  
76           if(log.isInfoEnabled()) log.info("other_coord = " + other_coord);
77          try {
78              MethodCall call=new MethodCall("handleMerge", new Object  []{gms.view_id, gms.members.getMembers()},
79                      new String  []{ViewId.class.getName(), Vector  .class.getName()});
80              new_view=(View)gms.callRemoteMethod(other_coord, call, GroupRequest.GET_ALL, 0);
81          }
82          catch(Exception   ex) {
83               if(log.isErrorEnabled()) log.error("timed out or was suspected");
84              return;
85          }
86          if(new_view == null) {
87               if(log.isWarnEnabled()) log.warn("received a Merge Denied");
88              gms.passDown(new Event(Event.MERGE_DENIED));
89              return; //Merge denied
90          }
91  
92          //Flushing my old view
93          gms.flush(gms.members.getMembers(), null);
94          MethodCall call=new MethodCall("handleViewChange", new Object  []{new_view.getVid(), new_view.getMembers()},
95                  new String  []{ViewId.class.getName(), Vector  .class.getName()});
96          gms.callRemoteMethods(gms.members.getMembers(), call, GroupRequest.GET_ALL, 0);
97          gms.becomeParticipant();
98           if(log.isInfoEnabled()) log.info("merge done");
99      }
100 
101 
102     public synchronized boolean handleJoin(Address mbr) {
103         Vector   new_mbrs=new Vector  (1);
104 
105         if(log.isInfoEnabled()) log.info("received JOIN request from " + mbr);
106         if(gms.local_addr.equals(mbr)) {
107             if(log.isErrorEnabled()) log.error("cannot join myself !");
108             return false;
109         }
110         if(gms.members.contains(mbr)) {
111             if(log.isWarnEnabled()) log.warn("member " + mbr + " already present !");
112             return true;  // already joined
113         }
114 
115         new_mbrs.addElement(mbr);
116         gms.castViewChange(new_mbrs, null, null);
117         return true;
118     }
119 
120 
121     /**
122      * Exclude <code>mbr</code> from the membership. If <code>suspected</code> is true, then
123      * this member crashed and therefore is forced to leave, otherwise it is leaving voluntarily.
124      */
125     public synchronized void handleLeave(Address mbr, boolean suspected) {
126         Vector   v=new Vector  (1);  // contains either leaving mbrs or suspected mbrs
127         if(!gms.members.contains(mbr)) {
128              if(log.isErrorEnabled()) log.error("mbr " + mbr + " is not a member !");
129             return;
130         }
131         v.addElement(mbr);
132         if(suspected)
133             gms.castViewChange(null, null, v);
134         else
135             gms.castViewChange(null, v, null);
136     }
137 
138 
139     public void handleViewChange(ViewId new_view, Vector   mbrs) {
140         if(leaving) {
141             if(mbrs.contains(gms.local_addr)) {
142                 if(log.isWarnEnabled()) log.warn("received view in which I'm still a member, cannot quit yet");
143                 gms.installView(new_view, mbrs);  // +++ modify
144             }
145             else {
146                 synchronized(leave_mutex) {
147                     received_last_view=true;
148                     leave_mutex.notifyAll();
149                 }
150             }
151             return;
152         }
153         gms.installView(new_view, mbrs);  // +++ modify
154     }
155 
156 
157     /**
158      * Invoked by another coordinator that asks to merge its view with mine.
159      * I 'll be the new coordinator.
160      * We should flush our view, install a new view with all the members and
161      * return the new view that will be installed by the other coordinator before
162      * becoming a participant.
163      */
164     public synchronized View handleMerge(ViewId other_vid, Vector   other_mbrs) {
165 
166             if(log.isInfoEnabled()) log.info("other_vid=" + other_vid + " , other_mbrs=" + other_mbrs);
167 
168         //Check that the views are disjoint otherwire return null (means MERGE_DENIED)
169         for(Iterator   i=other_mbrs.iterator(); i.hasNext();) {
170             if(gms.members.contains((Address)i.next())) {
171                 gms.passDown(new Event(Event.MERGE_DENIED));
172                 return null;
173             }
174         }
175 
176         //Compute new View
177         ViewId vid=new ViewId(gms.local_addr, Math.max(other_vid.getId() + 1, gms.ltime + 1));
178         HashSet   members=new HashSet  (gms.members.getMembers());
179         members.addAll(other_mbrs);
180         Vector   new_mbrs=new Vector  (members);
181         Collections.sort(new_mbrs);
182         View new_view=new View(vid, new_mbrs);
183 
184         //Flush my view
185         gms.flush(gms.members.getMembers(), null);
186 
187         //Install new view
188         MethodCall call=new MethodCall("handleViewChange", new Object  []{vid, new_mbrs},
189                 new String  []{ViewId.class.getName(), Vector  .class.getName()});
190         gms.callRemoteMethods(gms.members.getMembers(), call, GroupRequest.GET_ALL, 0);
191         return new_view;
192     }
193 
194 
195     public void handleSuspect(Address mbr) {
196         if(mbr.equals(gms.local_addr)) {
197             if(log.isErrorEnabled()) log.error("I am the coord and am suspected: am not quitting !");
198             return;
199         }
200         handleLeave(mbr, true); // irregular leave - forced
201     }
202 
203 
204 }
205
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