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java.lang.Objectorg.jgroups.protocols.pbcast.Digest
public class Digest
A message digest, which is used by the PBCAST layer for gossiping (also used by NAKACK for keeping track of current seqnos for all members). It contains pairs of senders and a range of seqnos (low and high), where each sender is associated with its highest and lowest seqnos seen so far. That is, the lowest seqno which was not yet garbage-collected and the highest that was seen so far and is deliverable (or was already delivered) to the application. A range of [0 - 0] means no messages have been received yet.
April 3 2001 (bela): Added high_seqnos_seen member. It is used to disseminate information about the last (highest) message M received from a sender P. Since we might be using a negative acknowledgment message numbering scheme, we would never know if the last message was lost. Therefore we periodically gossip and include the last message seqno. Members who haven't seen it (e.g. because msg was dropped) will request a retransmission. See DESIGN for details.
Nested Class Summary | |
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static class |
Digest.Entry
Class keeping track of the lowest and highest sequence numbers delivered, and the highest sequence numbers received, per member |
Field Summary | |
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protected static org.apache.commons.logging.Log |
log
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Constructor Summary | |
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Digest()
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Digest(int size)
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Method Summary | |
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void |
add(Address sender,
long low_seqno,
long high_seqno)
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void |
add(Address sender,
long low_seqno,
long high_seqno,
long high_seqno_seen)
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void |
add(Digest d)
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void |
clear()
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boolean |
contains(Address sender)
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Digest |
copy()
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boolean |
equals(java.lang.Object obj)
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Digest.Entry |
get(Address sender)
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long |
highSeqnoAt(Address sender)
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long |
highSeqnoSeenAt(Address sender)
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void |
incrementHighSeqno(Address sender)
Increments the sender's high_seqno by 1. |
long |
lowSeqnoAt(Address sender)
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void |
merge(Address sender,
long low_seqno,
long high_seqno,
long high_seqno_seen)
Similar to add(), but if the sender already exists, its seqnos will be modified (no new entry) as follows: this.low_seqno=min(this.low_seqno, low_seqno) this.high_seqno=max(this.high_seqno, high_seqno) this.high_seqno_seen=max(this.high_seqno_seen, high_seqno_seen) If the sender doesn not exist, a new entry will be added (provided there is enough space) |
void |
merge(Digest d)
Adds a digest to this digest. |
java.lang.String |
printHighSeqnos()
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java.lang.String |
printHighSeqnosSeen()
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void |
readExternal(java.io.ObjectInput in)
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void |
readFrom(java.io.DataInputStream in)
Read the state of the current object (including superclasses) from instream Note that the input stream must not be closed |
void |
replace(Digest d)
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void |
resetAt(Address sender)
Resets the seqnos for the sender at 'index' to 0. |
boolean |
sameSenders(Digest other)
Compares two digests and returns true if the senders are the same, otherwise false. |
long |
serializedSize()
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boolean |
set(Address sender,
long low_seqno,
long high_seqno,
long high_seqno_seen)
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void |
setHighestDeliveredAndSeenSeqnos(Address sender,
long high_seqno,
long high_seqno_seen)
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void |
setHighSeqnoAt(Address sender,
long high_seqno)
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void |
setHighSeqnoSeenAt(Address sender,
long high_seqno_seen)
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int |
size()
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java.lang.String |
toString()
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void |
writeExternal(java.io.ObjectOutput out)
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void |
writeTo(java.io.DataOutputStream out)
Write the entire state of the current object (including superclasses) to outstream. |
Methods inherited from class java.lang.Object |
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clone, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait |
Field Detail |
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protected static final org.apache.commons.logging.Log log
Constructor Detail |
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public Digest()
public Digest(int size)
Method Detail |
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public boolean equals(java.lang.Object obj)
equals
in class java.lang.Object
public void add(Address sender, long low_seqno, long high_seqno)
public void add(Address sender, long low_seqno, long high_seqno, long high_seqno_seen)
public void add(Digest d)
public void replace(Digest d)
public Digest.Entry get(Address sender)
public boolean set(Address sender, long low_seqno, long high_seqno, long high_seqno_seen)
public void merge(Digest d)
public void merge(Address sender, long low_seqno, long high_seqno, long high_seqno_seen)
public boolean contains(Address sender)
public boolean sameSenders(Digest other)
other
-
public void incrementHighSeqno(Address sender)
public int size()
public void resetAt(Address sender)
public void clear()
public long lowSeqnoAt(Address sender)
public long highSeqnoAt(Address sender)
public long highSeqnoSeenAt(Address sender)
public void setHighSeqnoAt(Address sender, long high_seqno)
public void setHighSeqnoSeenAt(Address sender, long high_seqno_seen)
public void setHighestDeliveredAndSeenSeqnos(Address sender, long high_seqno, long high_seqno_seen)
public Digest copy()
public java.lang.String toString()
toString
in class java.lang.Object
public java.lang.String printHighSeqnos()
public java.lang.String printHighSeqnosSeen()
public void writeExternal(java.io.ObjectOutput out) throws java.io.IOException
writeExternal
in interface java.io.Externalizable
java.io.IOException
public void readExternal(java.io.ObjectInput in) throws java.io.IOException, java.lang.ClassNotFoundException
readExternal
in interface java.io.Externalizable
java.io.IOException
java.lang.ClassNotFoundException
public void writeTo(java.io.DataOutputStream out) throws java.io.IOException
Streamable
writeTo
in interface Streamable
java.io.IOException
public void readFrom(java.io.DataInputStream in) throws java.io.IOException, java.lang.IllegalAccessException, java.lang.InstantiationException
Streamable
readFrom
in interface Streamable
java.io.IOException
java.lang.IllegalAccessException
java.lang.InstantiationException
public long serializedSize()
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