org.javagroups.protocols
Class MERGE2
java.lang.Object
|
+--org.javagroups.stack.Protocol
|
+--org.javagroups.protocols.MERGE2
- public class MERGE2
- extends Protocol
Protocol to discover subgroups, e.g. existing due to a network partition (that healed). Example: group
{p,q,r,s,t,u,v,w} is split into 3 subgroups {p,q}, {r,s,t,u} and {v,w}. This protocol will eventually send
a MERGE event with the coordinators of each subgroup up the stack: {p,r,v}. Note that - depending on the time
of subgroup discovery - there could also be 2 MERGE events, which first join 2 of the subgroups, and then the
resulting group to the last subgroup. The real work of merging the subgroups into one larger group is done
somewhere above this protocol (typically in the GMS protocol).
This protocol works as follows:
- If coordinator: periodically retrieve the initial membership (using the FIND_INITIAL_MBRS event provided e.g.
by PING or TCPPING protocols. This list contains {coord,addr} pairs.
- If there is more than 1 coordinator:
- Get all coordinators
- Create a MERGE event with the list of coordinators as argument
- Send the event up the stack
Requires: FIND_INITIAL_MBRS event from below
Provides: sends MERGE event with list of coordinators up the stack
- Author:
- Bela Ban, Oct 16 2001
Fields inherited from class org.javagroups.stack.Protocol |
down_handler, down_prot, down_queue, down_thread, observer, props, stack, up_handler, up_prot, up_queue, up_thread |
Method Summary |
void |
down(Event evt)
An event is to be sent down the stack. |
java.lang.String |
getName()
|
java.util.Vector |
requiredDownServices()
List of events that are required to be answered by some layer below. |
boolean |
setProperties(java.util.Properties props)
Configures the protocol initially. |
void |
startDownHandler()
DON'T REMOVE ! This prevents the down-handler thread to be created, which is not needed in the protocol. |
void |
startUpHandler()
DON'T REMOVE ! This prevents the up-handler thread to be created, which is not needed in the protocol. |
void |
up(Event evt)
An event was received from the layer below. |
Methods inherited from class org.javagroups.stack.Protocol |
getDownProtocol, getDownQueue, getProperties, getUpProtocol, getUpQueue, init, passDown, passUp, providedDownServices, providedUpServices, receiveDownEvent, receiveUpEvent, requiredUpServices, setDownProtocol, setObserver, setPropertiesInternal, setProtocolStack, setUpProtocol, stopInternal |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
MERGE2
public MERGE2()
getName
public java.lang.String getName()
- Overrides:
getName
in class Protocol
setProperties
public boolean setProperties(java.util.Properties props)
- Description copied from class:
Protocol
- Configures the protocol initially. A configuration string consists of name=value
items, separated by a ';' (semicolon), e.g.:
"loopback=false;unicast_inport=4444"
- Overrides:
setProperties
in class Protocol
requiredDownServices
public java.util.Vector requiredDownServices()
- Description copied from class:
Protocol
- List of events that are required to be answered by some layer below.
- Overrides:
requiredDownServices
in class Protocol
- Following copied from class:
org.javagroups.stack.Protocol
- Returns:
- Vector (of Integers)
startUpHandler
public void startUpHandler()
- DON'T REMOVE ! This prevents the up-handler thread to be created, which is not needed in the protocol.
- Overrides:
startUpHandler
in class Protocol
startDownHandler
public void startDownHandler()
- DON'T REMOVE ! This prevents the down-handler thread to be created, which is not needed in the protocol.
- Overrides:
startDownHandler
in class Protocol
up
public void up(Event evt)
- Description copied from class:
Protocol
- 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()
.
- Overrides:
up
in class Protocol
down
public void down(Event evt)
- Description copied from class:
Protocol
- 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 passUp()
.
- Overrides:
down
in class Protocol
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