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package protocols.implementations;
import protocols.VSProtocol;
import prefs.VSPrefs;
import core.VSMessage;
import java.util.HashMap;
public class BerkelyTimeProtocol extends VSProtocol {
/* Berkely Server variables */
/* Integer: Process ID, Long: Local time of the process */
private HashMap<Integer,Long> processTimes = new HashMap<Integer,Long>();
/* Integer: Process ID, Long: Time of receiving the response from the process */
private HashMap<Integer,Long> recvTimes = new HashMap<Integer,Long>();
/* Integer: Process ID, Long: Calculated process times (using the RTT) */
private HashMap<Integer,Long> realTimesRTT = new HashMap<Integer,Long>();
/* Time the request/response has started */
private long requestTime;
public BerkelyTimeProtocol() {
setClassname(getClass().toString());
/* Those prefs are editable through the VSProtocol VSEditor GUI. t_min and t_max in milliseconds */
setInteger("numProcesses", 0);
}
protected void onInit() {
}
protected void onClientReset() {
processTimes.clear();
recvTimes.clear();
realTimesRTT.clear();
}
protected void onClientStart() {
requestTime = process.getTime();
VSMessage message = new VSMessage(getClassname());
message.setBoolean("isRequest", true);
sendMessage(message);
}
protected void onClientRecv(VSMessage recvMessage) {
/* Ignore all protocol messages which are not a response message, e.g. itself */
if (!recvMessage.getBoolean("isResponse"))
return;
Integer processID = new Integer(recvMessage.getInteger("processID"));
Long time = new Long(recvMessage.getLong("time"));
processTimes.put(processID, time);
recvTimes.put(processID, new Long(process.getTime()));
/* All processes have comitted the response */
if (processTimes.size() == getInteger("numProcesses")) {
long avgTime = calculateAverageTime();
/* Set the local's process time to the new avg reference time */
process.setTime(avgTime);
/* Tell all other processes what to do in order to justify their times */
sendJustifyRequests(avgTime);
/* Start "clean" next time */
onClientReset();
}
}
/**
* Calculate the new average time
*/
private long calculateAverageTime() {
long sum = 0;
for (Integer processID : processTimes.keySet()) {
Long localTime = processTimes.get(processID);
Long recvTime = recvTimes.get(processID);
long rtt = recvTime.longValue() - requestTime;
long realProcessTime = localTime + (long) (rtt / 2);
realTimesRTT.put(processID, new Long(realProcessTime));
sum += realProcessTime;
}
/* Include the time of the local process */
sum += process.getTime();
return (long) sum / (1 + getInteger("numProcesses"));
}
/**
* Sends to all clients a value to justify their local clocks
*/
private void sendJustifyRequests(long avgTime) {
for (Integer processID : processTimes.keySet()) {
long realProcessTime = realTimesRTT.get(processID).longValue();
long diff = avgTime - realProcessTime;
VSMessage message = new VSMessage(getClassname());
message.setBoolean("isJustify", true);
message.setLong("timeDiff", diff);
message.setInteger("receiverProcessID", processID);
sendMessage(message);
}
}
protected void onServerReset() {
}
protected void onServerRecv(VSMessage recvMessage) {
if (recvMessage.getBoolean("isRequest")) {
VSMessage message = new VSMessage(getClassname());
message.setInteger("processID", process.getProcessID());
message.setLong("time", process.getTime());
message.setBoolean("isResponse", true);
sendMessage(message);
} else if (recvMessage.getBoolean("isJustify")) {
/* Check if it's "my" justify message */
if (recvMessage.getInteger("receiverProcessID") != process.getProcessID())
return;
long timeDiff = recvMessage.getLong("timeDiff");
long recvTime = process.getTime();
long newTime = process.getTime() + timeDiff;
logg("Neue Zeit: " + newTime);
process.setTime(newTime);
}
}
public String toString() {
return super.toString();
}
}
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