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java.lang.Objectorg.jgroups.stack.Protocol
org.jgroups.protocols.FRAG2
public class FRAG2
Fragmentation layer. Fragments messages larger than frag_size into smaller packets. Reassembles fragmented packets into bigger ones. The fragmentation number is prepended to the messages as a header (and removed at the receiving side).
Each fragment is identified by (a) the sender (part of the message to which the header is appended), (b) the fragmentation ID (which is unique per FRAG2 layer (monotonically increasing) and (c) the fragement ID which ranges from 0 to number_of_fragments-1.
Requirement: lossless delivery (e.g. NAK, ACK). No requirement on ordering. Works for both unicast and
multicast messages.
Compared to FRAG, this protocol does not need to serialize the message in order to break it into
smaller fragments: it looks only at the message's buffer, which is a byte[] array anyway. We assume that the
size addition for headers and src and dest address is minimal when the transport finally has to serialize the
message, so we add a constant (200 bytes).
Field Summary |
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Fields inherited from class org.jgroups.stack.Protocol |
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down_prot, log, props, stack, stats, up_prot |
Constructor Summary | |
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FRAG2()
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Method Summary | |
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java.lang.Object |
down(Event evt)
Fragment a packet if larger than frag_size (add a header). |
int |
getFragSize()
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java.lang.String |
getName()
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long |
getNumberOfReceivedFragments()
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long |
getNumberOfReceivedMessages()
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long |
getNumberOfSentFragments()
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long |
getNumberOfSentMessages()
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int |
getOverhead()
Deprecated. overhead was removed in 2.6.10 |
void |
init()
Called after instance has been created (null constructor) and before protocol is started. |
void |
resetStats()
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void |
setFragSize(int s)
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void |
setOverhead(int o)
Deprecated. overhead was removed in 2.6.10 |
boolean |
setProperties(java.util.Properties props)
Setup the Protocol instance acording to the configuration string |
java.lang.Object |
up(Event evt)
If event is a message, if it is fragmented, re-assemble fragments into big message and pass up the stack. |
Methods inherited from class org.jgroups.stack.Protocol |
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destroy, downThreadEnabled, dumpStats, enableStats, getDownProtocol, getProperties, getProtocolStack, getThreadFactory, getTransport, getUpProtocol, printStats, providedDownServices, providedUpServices, requiredDownServices, requiredUpServices, setDownProtocol, setPropertiesInternal, setProtocolStack, setUpProtocol, start, statsEnabled, stop, upThreadEnabled |
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 FRAG2()
Method Detail |
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public final java.lang.String getName()
getName
in class Protocol
public int getFragSize()
public void setFragSize(int s)
public int getOverhead()
public void setOverhead(int o)
public long getNumberOfSentMessages()
public long getNumberOfSentFragments()
public long getNumberOfReceivedMessages()
public long getNumberOfReceivedFragments()
public boolean setProperties(java.util.Properties props)
setProperties
in class Protocol
public void init() throws java.lang.Exception
Protocol
init
in class Protocol
java.lang.Exception
- Thrown if protocol cannot be initialized successfully. This will cause the
ProtocolStack to fail, so the channel constructor will throw an exceptionpublic void resetStats()
resetStats
in class Protocol
public java.lang.Object down(Event evt)
down
in class Protocol
public java.lang.Object up(Event evt)
up
in class Protocol
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