bboss.org.jgroups.util.Digest Maven / Gradle / Ivy
package bboss.org.jgroups.util;
import static java.lang.Math.max;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import bboss.org.jgroups.Address;
import bboss.org.jgroups.Global;
import bboss.org.jgroups.annotations.Immutable;
import bboss.org.jgroups.logging.Log;
import bboss.org.jgroups.logging.LogFactory;
/**
* 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.
* @author Bela Ban
* @version $Id: Digest.java,v 1.14 2009/09/21 09:57:23 belaban Exp $
*/
public class Digest implements Externalizable, Streamable {
public static final Digest EMPTY_DIGEST = new Digest();
/** Map<Address, Entry> */
protected final Map senders;
protected static final Log log=LogFactory.getLog(Digest.class);
private static final long serialVersionUID=6611464897656359215L;
/** Used for externalization */
public Digest() {
senders=createSenders(7);
}
public Digest(int size) {
senders=createSenders(size);
}
/** Creates a new digest from an existing map by copying the keys and values from map */
public Digest(Map map) {
senders=createSenders(map);
}
public Digest(Digest d) {
this(d.senders);
}
public Digest(Address sender, long low, long highest_delivered, long highest_received) {
senders=createSenders(1);
senders.put(sender, new Entry(low, highest_delivered, highest_received));
}
public Digest(Address sender, long low, long highest_delivered) {
senders=createSenders(1);
senders.put(sender, new Entry(low, highest_delivered));
}
/** Returns an unmodifiable map, so modifications will result in exceptions */
public Map getSenders() {
return Collections.unmodifiableMap(senders);
}
public boolean equals(Object obj) {
if(!(obj instanceof Digest))
return false;
Digest other=(Digest)obj;
return senders.equals(other.senders);
}
public boolean contains(Address sender) {
return senders.containsKey(sender);
}
/** Returns the Entry for the given sender. Note that Entry is immutable */
public Entry get(Address sender) {
return senders.get(sender);
}
/**
* Compares two digests and returns true if the senders are the same, otherwise false.
* @param other
* @return True if senders are the same, otherwise false.
*/
public boolean sameSenders(Digest other) {
if(other == null) return false;
if(this.senders.size() != other.senders.size()) return false;
Set my_senders=senders.keySet(), other_senders=other.senders.keySet();
return my_senders.equals(other_senders);
}
public Digest difference(Digest other) {
if(other == null) return copy();
Digest result=EMPTY_DIGEST;
if(this.equals(other)) {
return result;
}
else {
//find intersection and compare their entries
Map resultMap=new ConcurrentHashMap(7);
Set intersection=new TreeSet(this.senders.keySet());
intersection.retainAll(other.senders.keySet());
for(Address address : intersection) {
Entry e1=this.get(address);
Entry e2=other.get(address);
if(e1.getHighestDeliveredSeqno() != e2.getHighestDeliveredSeqno()) {
long low=Math.min(e1.highest_delivered_seqno, e2.highest_delivered_seqno);
long high=max(e1.highest_delivered_seqno, e2.highest_delivered_seqno);
Entry r=new Entry(low, high);
resultMap.put(address, r);
}
}
//any entries left in (this - intersection)?
//if yes, add them to result
if(intersection.size() != this.senders.keySet().size()) {
Set thisMinusInteresection=new TreeSet(this.senders.keySet());
thisMinusInteresection.removeAll(intersection);
for(Address address : thisMinusInteresection) {
resultMap.put(address, new Entry(this.get(address)));
}
}
//any entries left in (other - intersection)?
//if yes, add them to result
if(intersection.size() != other.senders.keySet().size()) {
Set otherMinusInteresection=new TreeSet(other.senders.keySet());
otherMinusInteresection.removeAll(intersection);
for(Address address : otherMinusInteresection) {
resultMap.put(address, new Entry(other.get(address)));
}
}
result=new Digest(resultMap);
}
return result;
}
public Digest highestSequence(Digest other) {
if(other == null) return copy();
Digest result=EMPTY_DIGEST;
if(this.equals(other)) {
return this;
}
else {
//find intersection and compare their entries
Map resultMap=new ConcurrentHashMap(7);
Set intersection=new TreeSet(this.senders.keySet());
intersection.retainAll(other.senders.keySet());
for(Address address : intersection) {
Entry e1=this.get(address);
Entry e2=other.get(address);
long high=max(e1.highest_delivered_seqno, e2.highest_delivered_seqno);
Entry r=new Entry(0, high);
resultMap.put(address, r);
}
//any entries left in (this - intersection)?
//if yes, add them to result
if(intersection.size() != this.senders.keySet().size()) {
Set thisMinusInteresection=new TreeSet(this.senders.keySet());
thisMinusInteresection.removeAll(intersection);
for(Address address : thisMinusInteresection) {
resultMap.put(address, new Entry(this.get(address)));
}
}
//any entries left in (other - intersection)?
//if yes, add them to result
if(intersection.size() != other.senders.keySet().size()) {
Set otherMinusInteresection=new TreeSet(other.senders.keySet());
otherMinusInteresection.removeAll(intersection);
for(Address address : otherMinusInteresection) {
resultMap.put(address, new Entry(other.get(address)));
}
}
result=new Digest(resultMap);
}
return result;
}
public int size() {
return senders.size();
}
public long lowSeqnoAt(Address sender) {
Entry entry=senders.get(sender);
if(entry == null)
return -1;
else
return entry.low_seqno;
}
public long highestDeliveredSeqnoAt(Address sender) {
Entry entry=senders.get(sender);
if(entry == null)
return -1;
else
return entry.highest_delivered_seqno;
}
public long highestReceivedSeqnoAt(Address sender) {
Entry entry=senders.get(sender);
if(entry == null)
return -1;
else
return entry.highest_received_seqno;
}
/**
* Returns true if all senders of the current digest have their seqnos >= the ones from other
* @param other
* @return
*/
public boolean isGreaterThanOrEqual(Digest other) {
if(other == null)
return true;
Map our_map=getSenders();
Address sender;
Entry my_entry, their_entry;
long my_highest, their_highest;
for(Map.Entry entry: our_map.entrySet()) {
sender=entry.getKey();
my_entry=entry.getValue();
their_entry=other.get(sender);
if(their_entry == null)
continue;
my_highest=my_entry.getHighest();
their_highest=their_entry.getHighest();
if(my_highest < their_highest)
return false;
}
return true;
}
public Digest copy() {
return new Digest(senders);
}
public String toString() {
StringBuilder sb=new StringBuilder();
boolean first=true;
if(senders.isEmpty()) return "[]";
for(Map.Entry entry: senders.entrySet()) {
Address key=entry.getKey();
Entry val=entry.getValue();
if(!first)
sb.append(", ");
else
first=false;
sb.append(key).append(": ").append('[').append(val.low_seqno).append(" : ");
sb.append(val.highest_delivered_seqno);
if(val.highest_received_seqno >= 0)
sb.append(" (").append(val.highest_received_seqno).append(")");
sb.append("]");
}
return sb.toString();
}
public String printHighestDeliveredSeqnos() {
StringBuilder sb=new StringBuilder("[");
boolean first=true;
TreeMap copy=new TreeMap(senders);
for(Map.Entry entry: copy.entrySet()) {
Address key=entry.getKey();
Entry val=entry.getValue();
if(!first)
sb.append(", ");
else
first=false;
sb.append(key).append("#").append(val.highest_delivered_seqno);
}
sb.append(']');
return sb.toString();
}
public String printHighestReceivedSeqnos() {
StringBuilder sb=new StringBuilder();
boolean first=true;
for(Map.Entry entry: senders.entrySet()) {
Address key=entry.getKey();
Entry val=entry.getValue();
if(!first)
sb.append(", ");
else {
sb.append('[');
first=false;
}
sb.append(key).append("#").append(val.highest_received_seqno);
}
sb.append(']');
return sb.toString();
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject(senders);
}
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
Map tmp=(Map)in.readObject();
senders.clear();
senders.putAll(tmp);
}
public void writeTo(DataOutputStream out) throws IOException {
out.writeShort(senders.size());
for(Map.Entry entry: senders.entrySet()) {
Entry val=entry.getValue();
Util.writeAddress(entry.getKey(), out);
out.writeLong(val.low_seqno);
out.writeLong(val.highest_delivered_seqno);
out.writeLong(val.highest_received_seqno);
}
}
public void readFrom(DataInputStream in) throws IOException, IllegalAccessException, InstantiationException {
short size=in.readShort();
Map tmp=new HashMap(size);
Address key;
for(int i=0; i < size; i++) {
key=Util.readAddress(in);
tmp.put(key, new Entry(in.readLong(), in.readLong(), in.readLong()));
}
senders.clear();
senders.putAll(tmp);
}
public long serializedSize() {
long retval=Global.SHORT_SIZE; // number of elements in 'senders'
if(!senders.isEmpty()) {
Address addr=senders.keySet().iterator().next();
int len=Util.size(addr);
len+=Entry.SIZE; // 3 longs in one Entry
retval+=len * senders.size();
}
return retval;
}
private static Map createSenders(int size) {
return new ConcurrentHashMap(size);
}
private static Map createSenders(Map map) {
return new ConcurrentHashMap(map);
}
/**
* Class keeping track of the lowest and highest sequence numbers delivered, and the highest
* sequence numbers received, per member. This class is immutable
*/
@Immutable
public static class Entry implements Externalizable, Streamable {
private long low_seqno=0;
private long highest_delivered_seqno=0; // the highest delivered seqno, e.g. in 1,2,4,5,7 --> 2
private long highest_received_seqno=0; //the highest received seqno, e.g. in 1,2,4,5,7 --> 7
final static int SIZE=Global.LONG_SIZE * 3;
private static final long serialVersionUID=-4468945932249281704L;
public Entry() {
}
public Entry(long low_seqno, long highest_delivered_seqno, long highest_received_seqno) {
this.low_seqno=low_seqno;
this.highest_delivered_seqno=highest_delivered_seqno;
this.highest_received_seqno=highest_received_seqno;
check();
}
public Entry(long low_seqno, long highest_delivered_seqno) {
this.low_seqno=low_seqno;
this.highest_delivered_seqno=highest_delivered_seqno;
check();
}
public Entry(Entry other) {
if(other != null) {
low_seqno=other.low_seqno;
highest_delivered_seqno=other.highest_delivered_seqno;
highest_received_seqno=other.highest_received_seqno;
check();
}
}
public final long getLow() {return low_seqno;}
public final long getHighestDeliveredSeqno() {return highest_delivered_seqno;}
public final long getHighestReceivedSeqno() {return highest_received_seqno;}
/** Return the max of the highest delivered or highest received seqno */
public final long getHighest() {return max(highest_delivered_seqno, highest_received_seqno);}
public boolean equals(Object obj) {
if(!(obj instanceof Entry))
return false;
Entry other=(Entry)obj;
return low_seqno == other.low_seqno && highest_delivered_seqno == other.highest_delivered_seqno && highest_received_seqno == other.highest_received_seqno;
}
public int hashCode() {
return (int)(low_seqno + highest_delivered_seqno + highest_received_seqno);
}
public String toString() {
return new StringBuilder("low=").append(low_seqno).append(", highest delivered=").append(highest_delivered_seqno).
append(", highest received=").append(highest_received_seqno).toString();
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeLong(low_seqno);
out.writeLong(highest_delivered_seqno);
out.writeLong(highest_received_seqno);
}
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
low_seqno=in.readLong();
highest_delivered_seqno=in.readLong();
highest_received_seqno=in.readLong();
}
public static int size() {
return SIZE;
}
public void writeTo(DataOutputStream out) throws IOException {
out.writeLong(low_seqno);
out.writeLong(highest_delivered_seqno);
out.writeLong(highest_received_seqno);
}
public void readFrom(DataInputStream in) throws IOException, IllegalAccessException, InstantiationException {
low_seqno=in.readLong();
highest_delivered_seqno=in.readLong();
highest_received_seqno=in.readLong();
}
private void check() {
if(low_seqno > highest_delivered_seqno)
throw new IllegalArgumentException("low_seqno (" + low_seqno + ") is greater than highest_delivered_seqno (" + highest_delivered_seqno + ")");
}
}
}