org.jgroups.protocols
Class Discovery

java.lang.Object
  extended by org.jgroups.stack.Protocol
      extended by org.jgroups.protocols.Discovery
Direct Known Subclasses:
FILE_PING, PING, TCPGOSSIP, TCPPING

public abstract class Discovery
extends Protocol

The Discovery protocol layer retrieves the initial membership (used by the GMS when started by sending event FIND_INITIAL_MBRS down the stack). We do this by specific subclasses, e.g. by mcasting PING requests to an IP MCAST address or, if gossiping is enabled, by contacting the GossipRouter. The responses should allow us to determine the coordinator whom we have to contact, e.g. in case we want to join the group. When we are a server (after having received the BECOME_SERVER event), we'll respond to PING requests with a PING response.

The FIND_INITIAL_MBRS event will eventually be answered with a FIND_INITIAL_MBRS_OK event up the stack. The following properties are available

Author:
Bela Ban

Nested Class Summary
protected static class Discovery.Responses
           
 
Field Summary
protected  java.lang.String group_addr
           
protected  Address local_addr
           
protected  java.util.Vector<Address> members
           
protected  java.util.Set<Discovery.Responses> ping_responses
           
protected  int rank
           
protected  TimeScheduler timer
           
protected  View view
           
 
Fields inherited from class org.jgroups.stack.Protocol
down_prot, ergonomics, id, log, name, stack, stats, up_prot
 
Constructor Summary
Discovery()
           
 
Method Summary
 void discoveryRequestReceived(Address sender, java.lang.String logical_name, java.util.Collection<PhysicalAddress> physical_addrs)
           
 java.lang.Object down(Event evt)
          An event is to be sent down the stack.
 java.util.List<PingData> findAllMembers(Promise<JoinRsp> promise)
           
 java.util.List<View> findAllViews(Promise<JoinRsp> promise)
          Finds the views: sends a GET_MBRS_REQ to all members, waits 'timeout' ms or until 'num_initial_members' have been retrieved
 java.lang.String findAllViewsAsString()
           
 java.util.List<PingData> findInitialMembers(Promise<JoinRsp> promise)
          Finds initial members
protected  java.util.List<PingData> findInitialMembers(Promise<JoinRsp> promise, int num_expected_rsps, boolean break_on_coord, boolean return_views_only)
           
 java.lang.String findInitialMembersAsString()
           
 int getNumberOfDiscoveryRequestsSent()
           
 int getNumInitialMembers()
           
 int getNumPingRequests()
           
 long getTimeout()
           
 java.lang.String getView()
           
 void handleConnect()
           
 void handleDisconnect()
           
 void init()
          Called after instance has been created (null constructor) and before protocol is started.
protected  View makeView(java.util.Vector<Address> mbrs)
           
 java.util.Vector<java.lang.Integer> providedUpServices()
          List of events that are provided to layers above (they will be handled when sent down from above).
 void resetStats()
           
abstract  void sendGetMembersRequest(java.lang.String cluster_name, Promise promise, boolean return_views_only)
           
 void setNumInitialMembers(int num_initial_members)
           
 void setNumPingRequests(int num_ping_requests)
           
 void setTimeout(long timeout)
           
 void start()
          This method is called on a Channel.connect(String).
 void stop()
          This method is called on a Channel.disconnect().
 java.lang.Object up(Event evt)
          An event was received from the layer below.
 
Methods inherited from class org.jgroups.stack.Protocol
destroy, downThreadEnabled, dumpStats, enableStats, getConfigurableObjects, getDownProtocol, getId, getLevel, getName, getProperties, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getValue, isErgonomics, printStats, providedDownServices, requiredDownServices, requiredUpServices, setDownProtocol, setErgonomics, setId, setLevel, setProperties, setPropertiesInternal, setProperty, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, statsEnabled, upThreadEnabled
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

rank

protected int rank

timer

protected TimeScheduler timer

view

protected View view

members

protected final java.util.Vector<Address> members

local_addr

protected Address local_addr

group_addr

protected java.lang.String group_addr

ping_responses

protected final java.util.Set<Discovery.Responses> ping_responses
Constructor Detail

Discovery

public Discovery()
Method Detail

init

public void init()
          throws java.lang.Exception
Description copied from class: Protocol
Called after instance has been created (null constructor) and before protocol is started. Properties are already set. Other protocols are not yet connected and events cannot yet be sent.

Overrides:
init in class Protocol
Throws:
java.lang.Exception - Thrown if protocol cannot be initialized successfully. This will cause the ProtocolStack to fail, so the channel constructor will throw an exception

sendGetMembersRequest

public abstract void sendGetMembersRequest(java.lang.String cluster_name,
                                           Promise promise,
                                           boolean return_views_only)
                                    throws java.lang.Exception
Throws:
java.lang.Exception

handleDisconnect

public void handleDisconnect()

handleConnect

public void handleConnect()

discoveryRequestReceived

public void discoveryRequestReceived(Address sender,
                                     java.lang.String logical_name,
                                     java.util.Collection<PhysicalAddress> physical_addrs)

getTimeout

public long getTimeout()

setTimeout

public void setTimeout(long timeout)

getNumInitialMembers

public int getNumInitialMembers()

setNumInitialMembers

public void setNumInitialMembers(int num_initial_members)

getNumPingRequests

public int getNumPingRequests()

setNumPingRequests

public void setNumPingRequests(int num_ping_requests)

getNumberOfDiscoveryRequestsSent

public int getNumberOfDiscoveryRequestsSent()

getView

public java.lang.String getView()

providedUpServices

public java.util.Vector<java.lang.Integer> providedUpServices()
Description copied from class: Protocol
List of events that are provided to layers above (they will be handled when sent down from above).

Overrides:
providedUpServices in class Protocol
Returns:
Vector (of Integers)

resetStats

public void resetStats()
Overrides:
resetStats in class Protocol

start

public void start()
           throws java.lang.Exception
Description copied from class: Protocol
This method is called on a Channel.connect(String). Starts work. Protocols are connected and queues are ready to receive events. Will be called from bottom to top. This call will replace the START and START_OK events.

Overrides:
start in class Protocol
Throws:
java.lang.Exception - Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, so Channel.connect(String) will throw an exception

stop

public void stop()
Description copied from class: Protocol
This method is called on a Channel.disconnect(). Stops work (e.g. by closing multicast socket). Will be called from top to bottom. This means that at the time of the method invocation the neighbor protocol below is still working. This method will replace the STOP, STOP_OK, CLEANUP and CLEANUP_OK events. The ProtocolStack guarantees that when this method is called all messages in the down queue will have been flushed

Overrides:
stop in class Protocol

findAllViews

public java.util.List<View> findAllViews(Promise<JoinRsp> promise)
Finds the views: sends a GET_MBRS_REQ to all members, waits 'timeout' ms or until 'num_initial_members' have been retrieved

Returns:
List

findInitialMembers

public java.util.List<PingData> findInitialMembers(Promise<JoinRsp> promise)
Finds initial members

Parameters:
promise -
Returns:

findAllMembers

public java.util.List<PingData> findAllMembers(Promise<JoinRsp> promise)

findInitialMembers

protected java.util.List<PingData> findInitialMembers(Promise<JoinRsp> promise,
                                                      int num_expected_rsps,
                                                      boolean break_on_coord,
                                                      boolean return_views_only)

findInitialMembersAsString

public java.lang.String findInitialMembersAsString()

findAllViewsAsString

public java.lang.String findAllViewsAsString()

up

public java.lang.Object up(Event evt)
An event was received from the layer below. Usually the current layer will want to examine the event type and - depending on its type - perform some computation (e.g. removing headers from a MSG event type, or updating the internal membership list when receiving a VIEW_CHANGE event). Finally the event is either a) discarded, or b) an event is sent down the stack using PassDown or c) the event (or another event) is sent up the stack using PassUp.

For the PING protocol, the Up operation does the following things. 1. If the event is a Event.MSG then PING will inspect the message header. If the header is null, PING simply passes up the event If the header is PingHeader.GET_MBRS_REQ then the PING protocol will PassDown a PingRequest message If the header is PingHeader.GET_MBRS_RSP we will add the message to the initial members vector and wake up any waiting threads. 2. If the event is Event.SET_LOCAL_ADDR we will simple set the local address of this protocol 3. For all other messages we simple pass it up to the protocol above

Overrides:
up in class Protocol
Parameters:
evt - - the event that has been sent from the layer below

down

public java.lang.Object down(Event evt)
An event is to be sent down the stack. The layer may want to examine its type and perform some action on it, depending on the event's type. If the event is a message MSG, then the layer may need to add a header to it (or do nothing at all) before sending it down the stack using PassDown. In case of a GET_ADDRESS event (which tries to retrieve the stack's address from one of the bottom layers), the layer may need to send a new response event back up the stack using up_prot.up(). The PING protocol is interested in several different down events, Event.FIND_INITIAL_MBRS - sent by the GMS layer and expecting a GET_MBRS_OK Event.TMP_VIEW and Event.VIEW_CHANGE - a view change event Event.BECOME_SERVER - called after client has joined and is fully working group member Event.CONNECT, Event.DISCONNECT.

Overrides:
down in class Protocol

makeView

protected final View makeView(java.util.Vector<Address> mbrs)


Copyright © 1998-2009 Bela Ban / Red Hat. All Rights Reserved.