org.jgroups.protocols
Class MERGE3
java.lang.Object
org.jgroups.stack.Protocol
org.jgroups.protocols.MERGE3
public class MERGE3
- 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 broadcast its view. If another coordinator receives such a message, and its own
view differs from the received view, it immediately initiates a merge by sending up a MERGE event,
containing the received view and its own view
Provides: sends MERGE event with list of different views up the stack
- Author:
- Bela Ban, Oct 16 2001
Method Summary |
java.lang.Object |
down(Event evt)
An event is to be sent down the stack. |
void |
init()
Called after instance has been created (null constructor) and before protocol is started. |
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, providedUpServices, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setErgonomics, setId, setLevel, setProperties, setPropertiesInternal, setProperty, setProtocolStack, setSocketFactory, setUpProtocol, setValue, setValues, start, statsEnabled, stop, upThreadEnabled |
Methods inherited from class java.lang.Object |
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
MERGE3
public MERGE3()
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
up
public java.lang.Object 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
down_prot.down()
or c) the event (or another event) is sent up
the stack using up_prot.up()
.
- Overrides:
up
in class Protocol
down
public java.lang.Object 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
down_prot.down()
. 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()
.
- Overrides:
down
in class Protocol
Copyright © 1998-2009 Bela Ban / Red Hat. All Rights Reserved.