Package org.jgroups.protocols.pbcast
Class STATE_TRANSFER
- java.lang.Object
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- org.jgroups.stack.Protocol
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- org.jgroups.protocols.pbcast.STATE_TRANSFER
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public class STATE_TRANSFER extends Protocol
New STATE_TRANSFER protocol based on PBCAST. Compared to the one in ./protocols, it doesn't need a QUEUE layer above it. A state request is sent to a chosen member (coordinator if null). That member makes a copy D of its current digest and asks the application for a copy of its current state S. Then the member returns both S and D to the requester. The requester first sets its digest to D and then returns the state to the application.- Version:
- $Id: STATE_TRANSFER.java,v 1.76.2.1 2008/02/13 02:13:24 vlada Exp $
- Author:
- Bela Ban
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
STATE_TRANSFER.StateHeader
Wraps data for a state request/response.
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Constructor Summary
Constructors Constructor Description STATE_TRANSFER()
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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.double
getAverageStateSize()
java.lang.String
getName()
All protocol names have to be unique !long
getNumberOfStateBytesSent()
int
getNumberOfStateRequests()
void
init()
Called after instance has been created (null constructor) and before protocol is started.java.util.Vector<java.lang.Integer>
requiredDownServices()
List of events that are required to be answered by some layer below.void
resetStats()
boolean
setProperties(java.util.Properties props)
Configures the protocol initially.void
start()
This method is called on aChannel.connect(String)
.void
stop()
This method is called on aChannel.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, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, printStats, providedDownServices, providedUpServices, requiredUpServices, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, statsEnabled, upThreadEnabled
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Method Detail
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getName
public java.lang.String getName()
All protocol names have to be unique !
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getNumberOfStateRequests
public int getNumberOfStateRequests()
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getNumberOfStateBytesSent
public long getNumberOfStateBytesSent()
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getAverageStateSize
public double getAverageStateSize()
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requiredDownServices
public java.util.Vector<java.lang.Integer> requiredDownServices()
Description copied from class:Protocol
List of events that are required to be answered by some layer below.- Overrides:
requiredDownServices
in classProtocol
- Returns:
- Vector (of Integers)
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resetStats
public void resetStats()
- Overrides:
resetStats
in classProtocol
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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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start
public void start() throws java.lang.Exception
Description copied from class:Protocol
This method is called on aChannel.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 classProtocol
- Throws:
java.lang.Exception
- Thrown if protocol cannot be started successfully. This will cause the ProtocolStack to fail, soChannel.connect(String)
will throw an exception
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stop
public void stop()
Description copied from class:Protocol
This method is called on aChannel.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
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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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