Package org.jgroups.protocols
Class DAISYCHAIN
- java.lang.Object
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- org.jgroups.stack.Protocol
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- org.jgroups.protocols.DAISYCHAIN
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public class DAISYCHAIN extends Protocol
Implementation of daisy chaining. Multicast messages are sent to our neighbor, which sends them to its neighbor etc. A TTL restricts the number of times a message is forwarded. The advantage of daisy chaining is that - for point-to-point transports such as TCP - we can avoid the N-1 issue: when A sends a multicast message to 10 members, it needs to send it 9 times. With daisy chaining, it sends it 1 time, and in the next round, can already send another message. This leads to much better throughput, see the ref in the JIRA. Should be inserted just above MERGE3, in TCP based configurations. JIRA: https://jira.jboss.org/browse/JGRP-1021- Since:
- 2.11
- Author:
- Bela Ban
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Nested Class Summary
Nested Classes Modifier and Type Class Description static class
DAISYCHAIN.DaisyHeader
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Field Summary
Fields Modifier and Type Field Description protected java.util.concurrent.Executor
default_pool
protected Address
local_addr
int
msgs_forwarded
int
msgs_sent
protected Address
next
protected boolean
running
protected int
view_size
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Fields inherited from class org.jgroups.stack.Protocol
after_creation_hook, down_prot, ergonomics, id, log, stack, stats, up_prot
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Constructor Summary
Constructors Constructor Description DAISYCHAIN()
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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.Object
down(Message msg)
A message is sent down the stack.protected void
handleView(View view)
void
init()
Called after instance has been created (null constructor) and before protocol is started.void
resetStats()
void
start()
This method is called on aJChannel.connect(String)
.void
stop()
This method is called on aJChannel.disconnect()
.java.lang.Object
up(Message msg)
A single message was received.void
up(MessageBatch batch)
Sends up a multiple messages in aMessageBatch
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Methods inherited from class org.jgroups.stack.Protocol
accept, afterCreationHook, destroy, enableStats, getConfigurableObjects, getDownProtocol, getDownServices, getId, getIdsAbove, getLevel, getLog, getName, getProtocolStack, getSocketFactory, getThreadFactory, getTransport, getUpProtocol, getUpServices, getValue, isErgonomics, level, parse, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, resetStatistics, setDownProtocol, setErgonomics, setId, setLevel, setProtocolStack, setSocketFactory, setUpProtocol, setValue, statsEnabled, up
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Field Detail
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local_addr
protected volatile Address local_addr
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next
protected volatile Address next
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view_size
protected int view_size
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default_pool
protected java.util.concurrent.Executor default_pool
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running
protected volatile boolean running
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msgs_forwarded
public int msgs_forwarded
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msgs_sent
public int msgs_sent
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Method Detail
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resetStats
public void resetStats()
- Overrides:
resetStats
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 aJChannel.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, soJChannel.connect(String)
will throw an exception
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stop
public void stop()
Description copied from class:Protocol
This method is called on aJChannel.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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down
public java.lang.Object down(Event evt)
Description copied from class:Protocol
An event is to be sent down the stack. A protocol 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 protocol may need to add a header to it (or do nothing at all) before sending it down the stack usingdown_prot.down()
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down
public java.lang.Object down(Message msg)
Description copied from class:Protocol
A message is sent down the stack. Protocols may examine the message and do something (e.g. add a header) with it before passing it down.
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up
public java.lang.Object up(Message msg)
Description copied from class:Protocol
A single message was received. Protocols may examine the message and do something (e.g. add a header) with it before passing it up.
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up
public void up(MessageBatch batch)
Description copied from class:Protocol
Sends up a multiple messages in aMessageBatch
. The sender of the batch is always the same, and so is the destination (null == multicast messages). Messages in a batch can be OOB messages, regular messages, or mixed messages, although the transport itself will create initial MessageBatches that contain only either OOB or regular messages. The default processing below sends messages up the stack individually, based on a matching criteria (callingProtocol.accept(org.jgroups.Message)
), and - if true - callsProtocol.up(org.jgroups.Event)
for that message and removes the message. If the batch is not empty, it is passed up, or else it is dropped. Subclasses should check if there are any messages destined for them (e.g. usingMessageBatch.getMatchingMessages(short,boolean)
), then possibly remove and process them and finally pass the batch up to the next protocol. Protocols can also modify messages in place, e.g. ENCRYPT could decrypt all encrypted messages in the batch, not remove them, and pass the batch up when done.
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handleView
protected void handleView(View view)
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