Package org.jgroups.protocols.pbcast
Class STABLE
- java.lang.Object
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- org.jgroups.stack.Protocol
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- org.jgroups.protocols.pbcast.STABLE
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public class STABLE extends Protocol
Computes the broadcast messages that are stable; i.e., have been received by all members. Sends STABLE events up the stack when this is the case. This allows NAKACK to garbage collect messages that have been seen by all members.Works as follows: periodically we mcast our highest seqnos (seen for each member) to the group. A stability vector, which maintains the highest seqno for each member and initially contains no data, is updated when such a message is received. The entry for a member P is computed set to min(entry[P], digest[P]). When messages from all members have been received, a stability message is mcast, which causes all members to send a STABLE event up the stack (triggering garbage collection in the NAKACK layer).
New: when
max_bytes
is exceeded (unless disabled by setting it to 0), a STABLE task will be started (unless it is already running). Design in docs/design/STABLE.txt- Version:
- $Id: STABLE.java,v 1.85.2.3 2009/02/05 09:21:50 belaban Exp $
- Author:
- Bela Ban
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
STABLE.StableHeader
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Constructor Summary
Constructors Constructor Description STABLE()
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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.long
getBytes()
long
getDesiredAverageGossip()
long
getMaxBytes()
java.lang.String
getName()
int
getStabilityReceived()
int
getStabilitySent()
int
getStableReceived()
int
getStableSent()
java.util.Vector<java.lang.Integer>
requiredDownServices()
List of events that are required to be answered by some layer below.void
resetStats()
void
runMessageGarbageCollection()
void
setDesiredAverageGossip(long gossip_interval)
void
setMaxBytes(long max_bytes)
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, init, printStats, providedDownServices, providedUpServices, requiredUpServices, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, statsEnabled, upThreadEnabled
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Method Detail
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getDesiredAverageGossip
public long getDesiredAverageGossip()
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setDesiredAverageGossip
public void setDesiredAverageGossip(long gossip_interval)
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getMaxBytes
public long getMaxBytes()
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setMaxBytes
public void setMaxBytes(long max_bytes)
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getBytes
public long getBytes()
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getStableSent
public int getStableSent()
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getStableReceived
public int getStableReceived()
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getStabilitySent
public int getStabilitySent()
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getStabilityReceived
public int getStabilityReceived()
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resetStats
public void resetStats()
- Overrides:
resetStats
in classProtocol
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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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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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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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runMessageGarbageCollection
public void runMessageGarbageCollection()
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