Class UNICAST
- All Implemented Interfaces:
AckSenderWindow.RetransmitCommand
,AgeOutCache.Handler<Address>
This
layer is used to reliably transmit point-to-point messages, that is, either messages sent to a
single receiver (vs. messages multicast to a group) or for example replies to a multicast message. The
sender uses an AckSenderWindow
which retransmits messages for which it hasn't received
an ACK, the receiver uses AckReceiverWindow
which keeps track of the lowest seqno
received so far, and keeps messages in order.
Messages in both AckSenderWindows and AckReceiverWindows will be removed. A message will be removed from
AckSenderWindow when an ACK has been received for it and messages will be removed from AckReceiverWindow
whenever a message is received: the new message is added and then we try to remove as many messages as
possible (until we stop at a gap, or there are no more messages).
UNICAST was enhanced in April 2009, the new design is described in doc/design/UNICAST.new.txt
- Version:
- $Id: UNICAST.java,v 1.91.2.14.2.7 2009/04/29 14:34:00 belaban Exp $
- Author:
- Bela Ban
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Nested Class Summary
Nested Classes -
Field Summary
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionAn event is to be sent down the stack.void
Called by AgeOutCache, to removed expired connectionsint
long
getName()
All protocol names have to be unique !long
long
int
long
int
The number of messages in all Entry.sent_msgs tables (haven't received an ACK yet)long
long
long
long
void
This method is public only so it can be invoked by unit testing, but should not otherwise be used !boolean
removeConnection
(Address mbr) Removes and resets from connection table (which is already locked).void
void
retransmit
(long seqno, Message msg) Called by AckSenderWindow to resend messages for which no ACK has been received yetvoid
setMaxRetransmitTime
(long max_retransmit_time) boolean
setProperties
(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()
.An event was received from the layer below.Methods inherited from class org.jgroups.stack.Protocol
destroy, downThreadEnabled, enableStats, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, init, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, statsEnabled, upThreadEnabled
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Constructor Details
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UNICAST
public UNICAST()
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Method Details
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getName
All protocol names have to be unique ! -
getLocalAddress
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getMembers
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printConnections
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getNumMessagesSent
public long getNumMessagesSent() -
getNumMessagesReceived
public long getNumMessagesReceived() -
getNumBytesSent
public long getNumBytesSent() -
getNumBytesReceived
public long getNumBytesReceived() -
getNumAcksSent
public long getNumAcksSent() -
getNumAcksReceived
public long getNumAcksReceived() -
getNumberOfRetransmitRequestsReceived
public long getNumberOfRetransmitRequestsReceived() -
getMaxRetransmitTime
public long getMaxRetransmitTime() -
setMaxRetransmitTime
public void setMaxRetransmitTime(long max_retransmit_time) -
getAgeOutCacheSize
public int getAgeOutCacheSize() -
printAgeOutCache
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getAgeOutCache
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getNumberOfUnackedMessages
public int getNumberOfUnackedMessages()The number of messages in all Entry.sent_msgs tables (haven't received an ACK yet) -
getUnackedMessages
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getNumberOfMessagesInReceiveWindows
public int getNumberOfMessagesInReceiveWindows() -
resetStats
public void resetStats()- Overrides:
resetStats
in classProtocol
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dumpStats
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setProperties
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
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:
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 -
up
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
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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removeConnection
Removes and resets from connection table (which is already locked). Returns true if member was found, otherwise false. This method is public only so it can be invoked by unit testing, but should not otherwise be used ! -
removeAllConnections
public void removeAllConnections()This method is public only so it can be invoked by unit testing, but should not otherwise be used ! -
retransmit
Called by AckSenderWindow to resend messages for which no ACK has been received yet- Specified by:
retransmit
in interfaceAckSenderWindow.RetransmitCommand
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expired
Called by AgeOutCache, to removed expired connections- Specified by:
expired
in interfaceAgeOutCache.Handler<Address>
- Parameters:
key
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