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package protocols.implementations;
import java.util.ArrayList;
import java.util.Vector;
import core.VSMessage;
import protocols.VSAbstractProtocol;
/**
* The class VSTwoPhaseCommitProtocol, an implementation of the two phase
* commit protocol.
*
* @author Paul C. Buetow
*/
public class VSTwoPhaseCommitProtocol extends VSAbstractProtocol {
/**
* Instantiates a two phase commit protocol object.
*/
public VSTwoPhaseCommitProtocol() {
super(VSAbstractProtocol.HAS_ON_SERVER_START);
setClassname(getClass().toString());
}
/** PIDs of all processes which still have to vote */
private ArrayList<Integer> votePids;
/** PIDs of all processes which have to acknowledge that they recv the
* global vote result
*/
private ArrayList<Integer> ackPids;
/** The gloal vote result */
private boolean voteResult;
/* (non-Javadoc)
* @see events.VSAbstractProtocol#onServerInit()
*/
public void onServerInit() {
Vector<Integer> vec = new Vector<Integer>();
vec.add(2);
vec.add(3);
initVector("pids", vec, "PIDs beteiligter Prozesse");
initLong("timeout", 2500, "Zeit bis erneute Anfrage", "ms");
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onServerReset()
*/
public void onServerReset() {
if (votePids != null) {
voteResult = true;
votePids.clear();
votePids.addAll(getVector("pids"));
ackPids.clear();
ackPids.addAll(getVector("pids"));
}
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onServerStart()
*/
public void onServerStart() {
if (votePids == null) {
voteResult = true;
votePids = new ArrayList<Integer>();
votePids.addAll(getVector("pids"));
ackPids = new ArrayList<Integer>();
ackPids.addAll(getVector("pids"));
}
if (votePids.size() != 0) {
long timeout = getLong("timeout") + process.getTime();
/* Will run onServerSchedule() at the specified local time */
scheduleAt(timeout);
VSMessage message = new VSMessage();
message.setBoolean("wantVote", true);
sendMessage(message);
} else if (ackPids.size() != 0) {
long timeout = getLong("timeout") + process.getTime();
/* Will run onServerSchedule() at the specified local time */
scheduleAt(timeout);
VSMessage message = new VSMessage();
message.setBoolean("isVoteResult", true);
message.setBoolean("voteResult", voteResult);
sendMessage(message);
}
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onServerRecv(core.VSMessage)
*/
public void onServerRecv(VSMessage recvMessage) {
if (votePids.size() != 0 && recvMessage.getBoolean("isVote")) {
Integer pid = recvMessage.getIntegerObj("pid");
if (votePids.contains(pid))
votePids.remove(pid);
else
return;
boolean vote = recvMessage.getBoolean("vote");
log("Vote from process " + pid + " received! Result: " + vote);
if (!vote)
voteResult = false;
if (votePids.size() == 0) {
log("Votes from all involved processes received! Global result: " + voteResult);
/* Remove the active schedule which has been created in the
onServerStart method */
removeSchedules();
/* Create a new schedule and send the vote result */
onServerStart();
}
} else if (ackPids.size() != 0 && recvMessage.getBoolean("isAck")) {
Integer pid = recvMessage.getIntegerObj("pid");
if (ackPids.contains(pid))
ackPids.remove(pid);
else
return;
if (ackPids.size() == 0) {
/* Remove the active schedule which has been created in the
onServerStart method */
removeSchedules();
log("All participants have received the vote");
}
}
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onServerSchedule()
*/
public void onServerSchedule() {
onServerStart();
}
/* Server variables */
private boolean voteSent;
private boolean myVote;
/* (non-Javadoc)
* @see events.VSAbstractProtocol#onClientInit()
*/
public void onClientInit() {
initInteger("ackProb", 50, "Festschreibw'keit", 0, 100, "%");
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onClientReset()
*/
public void onClientReset() {
voteSent = false;
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onClientRecv(core.VSMessage)
*/
public void onClientRecv(VSMessage recvMessage) {
if (recvMessage.getBoolean("wantVote")) {
if (!voteSent) {
voteSent = true;
myVote = process.getRandomPercentage() <= getInteger("ackProb");
}
VSMessage message = new VSMessage();
message.setBoolean("isVote", true);
message.setBoolean("vote", myVote);
message.setInteger("pid", process.getProcessID());
sendMessage(message);
log("Vote " + myVote + " sent");
} else if (recvMessage.getBoolean("isVoteResult")) {
boolean voteResult = recvMessage.getBoolean("voteResult");
log("Global voting result received. Result: " + voteResult);
VSMessage message = new VSMessage();
message.setBoolean("isAck", true);
message.setInteger("pid", process.getProcessID());
sendMessage(message);
}
}
/* (non-Javadoc)
* @see protocols.VSAbstractProtocol#onClientSchedule()
*/
public void onClientSchedule() {
}
}
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