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java.lang.Objectorg.jgroups.stack.Protocol
org.jgroups.protocols.PRIO
public class PRIO
This protocol will provide message sending and receiving prioritization. The protocol assumes that any prioritized
message will contain a PrioHeader header entry that will contain the byte value priority. Priority values are from
0 to 255 where 0 is the highest priority.
When a message is received (up/down), it is added to the up/downMessageQueue. The up/downMessageThread will block
on the queue until new message is added. Messages with the highest priority (0=highest) will bubble to the top
of the queue and those be processed before other messages received at the same time.
Example of setting a message priority:
// Create a message to send to everyone
Message message = new Message( null, null, messagePayload );
// Add the priority protocol header
PrioHeader header = new PrioHeader( 1 );
short protocolId = ClassConfigurator.getProtocolId(PRIO.class);
message.putHeader( protocolId, header);
Field Summary |
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Fields inherited from class org.jgroups.stack.Protocol |
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down_prot, ergonomics, id, log, name, stack, stats, up_prot |
Constructor Summary | |
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PRIO()
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Method Summary | |
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java.lang.Object |
down(Event evt)
An event is to be sent down the stack. |
void |
start()
This method is called on a Channel.connect(String) . |
void |
stop()
This method is called on a Channel.disconnect() . |
java.lang.Object |
up(Event evt)
An event was received from the layer below. |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public PRIO()
Method Detail |
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public void start() throws java.lang.Exception
Channel.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.
start
in class Protocol
java.lang.Exception
- Thrown if protocol cannot be started successfully. This will cause the ProtocolStack
to fail, so Channel.connect(String)
will throw an exceptionpublic void stop()
Channel.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
stop
in class Protocol
public java.lang.Object up(Event evt)
down_prot.down()
or c) the event (or another event) is sent up
the stack using up_prot.up()
.
up
in class Protocol
public java.lang.Object down(Event evt)
down_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 using up_prot.up()
.
down
in class Protocol
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