bamboo.softscribe
Class Scribe

java.lang.Object
  ostore.util.StandardStage
      bamboo.softscribe.Scribe

All Implemented Interfaces:

EventHandlerIF, SingleThreadedEventHandlerIF

public class Scribe
extends ostore.util.StandardStage
implements SingleThreadedEventHandlerIF

Scribe on Bamboo.

Version:

$Id: Scribe.java,v 1.2 2003/12/29 22:20:42 davidopp Exp $ Unlike Scribe, there is no CREATE operation. Also unlike Scribe, there are no explicit JOIN and LEAVE network messages; those are purely local operations. allChildGroups is a hashtable mapping a groupguid (the ID for a group, which is the destination GUID for messages for that group, and hence the determinant of the root of the multicast tree for that groupguid) to a hashtable. That second hashtable maps NodeID's of children of this node to Booleans indicating whether we have heard from that child since the last ChildAlarm was received. (We could store a timestamp instead.) myLocalGroups is a vector of groupguids of groups to which this node am subscribed. When a node wants to join a group, and periodically after it has joined, it routes an MCastJoinMsg to the groupguid. Upcalls at non-member nodes simply continue. When the message upcalls at the first member node (or the root), that node records the original sender in allChildGroups, marks the node as being heard from, and kills the message. When the ChildAlarm expires, we delete from allChildGroups all children from which we have not heard since the last ChildAlarm expired (and reset the heard-from flag). When a node multicasts, it routes an MCastUpMsg to the groupguid. Along the path, the message is forwarded. When the message reaches the root, the root generates a MCastDownMsg *network* (not Bamboo) message and sends it to each of its children for that tree. At each node, if the node is in the group, a local MCastDown is dispatched. In all cases the message is re-sent to that node's children, and so on.

Author:

David Oppenheimer

Nested Class Summary

protected static class	Scribe.ChildAlarm
protected static class	Scribe.ParentAlarm

Field Summary

HashMap	allChildGroups
protected static long	app_id
protected boolean	DEBUG_MIN
protected boolean	initialized
protected BigInteger	my_guid
protected ostore.util.SecureHash	my_guid_sh
Vector	myLocalGroups
protected Random	rand
protected LinkedList	wait_q

Fields inherited from class ostore.util.StandardStage

classifier, DEBUG, event_types, inb_msg_types, my_node_id, my_sink, outb_msg_types, tag

Constructor Summary

Scribe()

Method Summary

void	handleEvent(QueueElementIF item)
void	init(ConfigDataIF config)

Methods inherited from class ostore.util.StandardStage

BUG, destroy, dispatch, handleEvents, now_ms, now_us

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEBUG_MIN

protected boolean DEBUG_MIN

rand

protected Random rand

initialized

protected boolean initialized

wait_q

protected LinkedList wait_q

app_id

protected static final long app_id

my_guid

protected BigInteger my_guid

my_guid_sh

protected ostore.util.SecureHash my_guid_sh

allChildGroups

public HashMap allChildGroups

myLocalGroups

public Vector myLocalGroups

Constructor Detail

Scribe

public Scribe()
       throws Exception

Throws:

Exception

Method Detail

init

public void init(ConfigDataIF config)
          throws Exception

Specified by:

init in interface EventHandlerIF

Overrides:

init in class ostore.util.StandardStage

Throws:

Exception

handleEvent

public void handleEvent(QueueElementIF item)

Specified by:

handleEvent in interface EventHandlerIF