Package org.jgroups.protocols
Class MERGE3
- java.lang.Object
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- org.jgroups.stack.Protocol
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- org.jgroups.protocols.MERGE3
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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 a "I'm the coordinator" message. If a coordinator receives such
a message, it immediately initiates a merge by sending up a MERGE event
Provides: sends MERGE event with list of coordinators up the stack
- Author:
- Bela Ban, Oct 16 2001
- If coordinator: periodically broadcast a "I'm the coordinator" message. If a coordinator receives such
a message, it immediately initiates a merge by sending up a MERGE event
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
MERGE3.CoordAnnouncement
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Constructor Summary
Constructors Constructor Description MERGE3()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description java.lang.Object
down(Event evt)
An event is to be sent down the stack.java.lang.String
getName()
void
init()
Called after instance has been created (null constructor) and before protocol is started.boolean
setProperties(java.util.Properties props)
Configures the protocol initially.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, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStats, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, start, statsEnabled, stop, upThreadEnabled
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Method Detail
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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 classProtocol
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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.
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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 usingdown_prot.down()
or c) the event (or another event) is sent up the stack usingup_prot.up()
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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 usingdown_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 usingup_prot.up()
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