PING


1   // $Id: PING.java,v 1.25 2005/04/26 15:22:12 belaban Exp $
2   
3   package org.jgroups.protocols;
4   
5   import org.jgroups.*;
6   import org.jgroups.stack.GossipClient;
7   import org.jgroups.stack.IpAddress;
8   import org.jgroups.util.List;
9   import org.jgroups.util.Util;
10  
11  import java.net.InetAddress  ;
12  import java.util.Enumeration  ;
13  import java.util.Properties  ;
14  import java.util.StringTokenizer  ;
15  import java.util.Vector  ;
16  
17  
18  /**
19   * The PING protocol layer retrieves the initial membership (used by the GMS when started
20   * by sending event FIND_INITIAL_MBRS down the stack). We do this by mcasting PING
21   * requests to an IP MCAST address (or, if gossiping is enabled, by contacting the GossipServer).
22   * The responses should allow us to determine the coordinator whom we have to
23   * contact, e.g. in case we want to join the group.  When we are a server (after having
24   * received the BECOME_SERVER event), we'll respond to PING requests with a PING
25   * response.<p> The FIND_INITIAL_MBRS event will eventually be answered with a
26   * FIND_INITIAL_MBRS_OK event up the stack.
27   * The following properties are available
28   * property: gossip_host - if you are using GOSSIP then this defines the host of the GossipServer, default is null
29   * property: gossip_port - if you are using GOSSIP then this defines the port of the GossipServer, default is null
30   */
31  public class PING extends Discovery {
32      String         gossip_host=null;
33      int          gossip_port=0;
34      long         gossip_refresh=20000; // time in msecs after which the entry in GossipServer will be refreshed
35      GossipClient client;
36      int          port_range=1;        // number of ports to be probed for initial membership
37      List         initial_hosts=null;  // hosts to be contacted for the initial membership
38      public static final String   name="PING";
39  
40  
41      public String   getName() {
42          return name;
43      }
44  
45  
46  
47      /**
48       * sets the properties of the PING protocol.
49       * The following properties are available
50       * property: timeout - the timeout (ms) to wait for the initial members, default is 3000=3 secs
51       * property: num_initial_members - the minimum number of initial members for a FIND_INITAL_MBRS, default is 2
52       * property: gossip_host - if you are using GOSSIP then this defines the host of the GossipServer, default is null
53       * property: gossip_port - if you are using GOSSIP then this defines the port of the GossipServer, default is null
54       *
55       * @param props - a property set containing only PING properties
56       * @return returns true if all properties were parsed properly
57       *         returns false if there are unrecnogized properties in the property set
58       */
59      public boolean setProperties(Properties   props) {
60          String   str;
61  
62          str=props.getProperty("gossip_host");
63          if(str != null) {
64              gossip_host=str;
65              props.remove("gossip_host");
66          }
67  
68          str=props.getProperty("gossip_port");
69          if(str != null) {
70              gossip_port=Integer.parseInt(str);
71              props.remove("gossip_port");
72          }
73  
74          str=props.getProperty("gossip_refresh");
75          if(str != null) {
76              gossip_refresh=Long.parseLong(str);
77              props.remove("gossip_refresh");
78          }
79  
80          if(gossip_host != null && gossip_port != 0) {
81              try {
82                  client=new GossipClient(new IpAddress(InetAddress.getByName(gossip_host), gossip_port), gossip_refresh);
83              }
84              catch(Exception   e) {
85                  if(log.isErrorEnabled()) log.error("creation of GossipClient failed, exception=" + e);
86                  return false; // will cause stack creation to abort
87              }
88          }
89  
90          str=props.getProperty("port_range");           // if member cannot be contacted on base port,
91          if(str != null) {                              // how many times can we increment the port
92              port_range=Integer.parseInt(str);
93              if(port_range < 1) {
94                  port_range=1;
95              }
96              props.remove("port_range");
97          }
98  
99          str=props.getProperty("initial_hosts");
100         if(str != null) {
101             props.remove("initial_hosts");
102             initial_hosts=createInitialHosts(str);
103         }
104 
105         return super.setProperties(props);
106     }
107 
108 
109     public void stop() {
110         super.stop();
111         if(client != null) {
112             client.stop();
113         }
114     }
115 
116 
117     public void localAddressSet(Address addr) {
118         // Add own address to initial_hosts if not present: we must always be able to ping ourself !
119         if(initial_hosts != null && local_addr != null) {
120             List hlist;
121             boolean inInitialHosts=false;
122             for(Enumeration   en=initial_hosts.elements(); en.hasMoreElements() && !inInitialHosts;) {
123                 hlist=(List)en.nextElement();
124                 if(hlist.contains(local_addr)) {
125                     inInitialHosts=true;
126                 }
127             }
128             if(!inInitialHosts) {
129                 hlist=new List();
130                 hlist.add(local_addr);
131                 initial_hosts.add(hlist);
132                 if(log.isDebugEnabled())
133                     log.debug("adding my address (" + local_addr + ") to initial_hosts; initial_hosts=" + initial_hosts);
134             }
135         }
136     }
137 
138 
139     public void handleConnect() {
140         if(client != null)
141             client.register(group_addr, local_addr);
142     }
143 
144     public void handleDisconnect() {
145         if(client != null)
146             client.stop();
147     }
148 
149 
150 
151     public void sendGetMembersRequest() {
152         Message msg;
153         PingHeader hdr;
154         Vector   gossip_rsps=null;
155 
156         if(client != null) {
157             gossip_rsps=client.getMembers(group_addr);
158             if(gossip_rsps != null && gossip_rsps.size() > 0) {
159                 // Set a temporary membership in the UDP layer, so that the following multicast
160                 // will be sent to all of them
161                 Event view_event=new Event(Event.TMP_VIEW, makeView(gossip_rsps));
162                 passDown(view_event); // needed e.g. by failure detector or UDP
163             }
164             else {
165                 passUp(new Event(Event.FIND_INITIAL_MBRS_OK, null));
166                 return;
167             }
168 
169             if(gossip_rsps != null && gossip_rsps.size() > 0) {
170                 for(int i=0; i < gossip_rsps.size(); i++) {
171                     Address dest=(Address)gossip_rsps.elementAt(i);
172                     msg=new Message(dest, null, null);  // mcast msg
173                     msg.putHeader(getName(), new PingHeader(PingHeader.GET_MBRS_REQ, null));
174                     passDown(new Event(Event.MSG, msg));
175                 }
176             }
177 
178             Util.sleep(500);
179         }
180         else {
181             if(initial_hosts != null && initial_hosts.size() > 0) {
182                 IpAddress h;
183                 List hlist;
184                 int numMemberInitialHosts;
185                 int numMembers;
186                 Address coord;
187                 msg=new Message(null, null, null);
188                 msg.putHeader(getName(), new PingHeader(PingHeader.GET_MBRS_REQ, null));
189 
190                 synchronized(members) {
191                     numMembers=members.size();
192                     numMemberInitialHosts=0;
193                     coord=numMembers > 0 ? (Address)members.firstElement() : local_addr;
194                 }
195                 for(Enumeration   en=initial_hosts.elements(); en.hasMoreElements();) {
196                     hlist=(List)en.nextElement();
197                     boolean isMember=false;
198 
199 //                    for(Enumeration hen=hlist.elements(); hen.hasMoreElements() && !isMember && numMemberInitialHosts < numMembers;) {
200 //                        h=(IpAddress)hen.nextElement();
201 //                        if(members_set.contains(h)) {
202 //                            //update the initial_members list for this already connected member
203 //                            initial_members.add(new PingRsp(h, coord));
204 //                            isMember=true;
205 //                            numMemberInitialHosts++;
206 //                            if(log.isDebugEnabled())
207 //                                log.debug("[FIND_INITIAL_MBRS] " + h + " is already a member");
208 //                        }
209 //                    }
210                     for(Enumeration   hen=hlist.elements(); hen.hasMoreElements() && !isMember;) {
211                         h=(IpAddress)hen.nextElement();
212                         msg.setDest(h);
213                         if(log.isTraceEnabled())
214                             log.trace("[FIND_INITIAL_MBRS] sending PING request to " + msg.getDest());
215                         passDown(new Event(Event.MSG, msg.copy()));
216                     }
217                 }
218             }
219             else {
220                 // 1. Mcast GET_MBRS_REQ message
221                 hdr=new PingHeader(PingHeader.GET_MBRS_REQ, null);
222                 msg=new Message(null, null, null);  // mcast msg
223                 msg.putHeader(getName(), hdr); // needs to be getName(), so we might get "MPING" !
224                 sendMcastDiscoveryRequest(msg);
225             }
226         }
227     }
228 
229     void sendMcastDiscoveryRequest(Message discovery_request) {
230         passDown(new Event(Event.MSG, discovery_request));
231     }
232 
233     /* -------------------------- Private methods ---------------------------- */
234 
235 
236 
237     /**
238      * Input is "daddy[8880],sindhu[8880],camille[5555]. Return List of IpAddresses
239      */
240     private List createInitialHosts(String   l) {
241         List tmp=new List();
242         StringTokenizer   tok=new StringTokenizer  (l, ",");
243         String   t;
244 
245         while(tok.hasMoreTokens()) {
246             try {
247                 t=tok.nextToken();
248                 String   host=t.substring(0, t.indexOf('['));
249                 int port=Integer.parseInt(t.substring(t.indexOf('[') + 1, t.indexOf(']')));
250                 List hosts=new List();
251                 for(int i=port; i < port + port_range; i++) {
252                     hosts.add(new IpAddress(host, i));
253                 }
254                 tmp.add(hosts);
255             }
256             catch(NumberFormatException   e) {
257                 if(log.isErrorEnabled()) log.error("exeption is " + e);
258             }
259         }
260         return tmp;
261     }
262 
263 
264 }
265
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