/**
* Handles paxos prepare messages
*
* @param msg the incomming message
* @return a response message
*/
public FleaseMessage handlePREPARE(FleaseMessage msg) {
final FleaseAcceptorCell cc = getCell(msg);
cc.touch();
if ((cc.getPrepared() != null) && (cc.getPrepared().after(msg))) {
if (Logging.isDebug() && config.isDebugPrintMessages()) {
final String preped =
(cc.getPrepared() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getPrepared().getProposalNo().toString();
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A prepare NACK p:" + preped + " is after " + msg.getProposalNo() + "");
}
FleaseMessage reject = new FleaseMessage(FleaseMessage.MsgType.MSG_PREPARE_NACK, msg);
reject.setPrevProposalNo(cc.getPrepared().getProposalNo());
reject.setLeaseHolder(null);
reject.setLeaseTimeout(0);
reject.setSendTimestamp(TimeSync.getGlobalTime());
return reject;
} else {
if (Logging.isDebug() && config.isDebugPrintMessages()) {
final String preped =
(cc.getPrepared() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getPrepared().getProposalNo().toString();
final String acced =
(cc.getAccepted() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getAccepted().getProposalNo()
+ "="
+ cc.getAccepted().getLeaseHolder()
+ "/"
+ cc.getAccepted().getLeaseTimeout();
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A prepare ACK p:" + preped + " -> " + msg.getProposalNo() + " a:" + acced);
}
// lastPrepared = msg;
cc.setPrepared(msg);
// FIXME:Persistently write to disk
FleaseMessage response = new FleaseMessage(FleaseMessage.MsgType.MSG_PREPARE_ACK, msg);
if (cc.getAccepted() != null) {
response.setPrevProposalNo(cc.getAccepted().getProposalNo());
response.setLeaseHolder(cc.getAccepted().getLeaseHolder());
assert (response.getLeaseHolder() != null);
response.setLeaseTimeout(cc.getAccepted().getLeaseTimeout());
}
response.setSendTimestamp(TimeSync.getGlobalTime());
return response;
}
}
/**
* Handles paxos learn messages. Removes oudated instances and updates maxLearnedInstId
* accordingly
*
* @param msg incomming message
*/
public void handleLEARN(FleaseMessage msg) {
final FleaseAcceptorCell cc = getCell(msg);
cc.touch();
if ((cc.getPrepared() != null) && (cc.getPrepared().after(msg))
|| (cc.getAccepted() != null) && (cc.getAccepted().after(msg))) {
if (Logging.isDebug() && config.isDebugPrintMessages())
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A ignore outdated LEARN message " + msg.getProposalNo());
} else {
if (Logging.isDebug() && config.isDebugPrintMessages()) {
final String preped =
(cc.getPrepared() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getPrepared().getProposalNo().toString();
final String acced =
(cc.getAccepted() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getAccepted().getProposalNo()
+ "="
+ cc.getAccepted().getLeaseHolder()
+ "/"
+ cc.getAccepted().getLeaseTimeout();
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A learn p:"
+ preped
+ " a: "
+ acced
+ " -> "
+ msg.getProposalNo()
+ "="
+ msg.getLeaseHolder()
+ "/"
+ msg.getLeaseTimeout());
}
cc.setAccepted(msg);
cc.setPrepared(msg);
cc.setLatestLearn(msg);
evtListener.learnedEvent(
msg.getCellId(), msg.getLeaseHolder(), msg.getLeaseTimeout(), msg.getMasterEpochNumber());
}
}
private FleaseAcceptorCell getCell(ASCIIString cellId) {
FleaseAcceptorCell cc = cells.get(cellId);
if (cc == null) {
cc = new FleaseAcceptorCell();
cells.put(cellId, cc);
} else {
if ((cc.lastAccess + config.getCellTimeout()) < System.currentTimeMillis()) {
if (Logging.isDebug())
Logging.logMessage(
Logging.LEVEL_DEBUG, Category.replication, this, "A GCed cell " + cellId);
// Cell is outdated and GCed.
// Create a new cell and transfer the previous view.
FleaseAcceptorCell tmp = new FleaseAcceptorCell();
tmp.setViewId(cc.getViewId());
if (cc.isViewInvalidated()) {
tmp.invalidateView();
}
cells.put(cellId, tmp);
cc = tmp;
}
}
/*if (Logging.isDebug())
Logging.logMessage(Logging.LEVEL_DEBUG,this,"using cell "+cellId);*/
cc.touch();
return cc;
}
/**
* Creates a new instance of PxAcceptor
*
* @param port port to listen on
* @param debug
*/
public FleaseAcceptor(
LearnEventListener evtListener,
FleaseConfig localConfig,
String lockfileDir,
boolean ignoreLockFileForTesting)
throws IOException {
this.config = localConfig;
cells = new HashMap<ASCIIString, FleaseAcceptorCell>();
quit = false;
lockfile = lockfileDir + "/" + LOCKFILE_NAME + config.getIdentity().hashCode();
this.evtListener = evtListener;
File lock = new File(lockfile);
if (lock.exists() && !ignoreLockFileForTesting) {
/*waitUntilTimestamp_ms = TimeSync.getLocalSystemTime()+TimeSync.getLocalRenewInterval()+
config.getRestartWait();*/
waitUntilTimestamp_ms = System.currentTimeMillis() + config.getRestartWait();
Logging.logMessage(
Logging.LEVEL_INFO,
Category.replication,
this,
"restarted after crash (lock file %s exists). acceptor will ignore all messages for %d ms (recovery period until %s)",
lockfile,
config.getRestartWait(),
(new Date(waitUntilTimestamp_ms)).toString());
} else {
waitUntilTimestamp_ms = 0;
if (ignoreLockFileForTesting) lock.delete();
if (!lock.createNewFile()) throw new IOException("Lock file exists!");
}
}
/**
* string representation
*
* @return a string
*/
public String toString() {
return "Acceptor @ " + config.getIdentity();
}
/** main loop */
public FleaseMessage processMessage(FleaseMessage msg) {
assert (!quit);
/*if (Logging.isDebug())
Logging.logMessage(Logging.LEVEL_DEBUG,this,"received %s",msg.toString());*/
final long now = TimeSync.getLocalSystemTime();
if (msg.getSendTimestamp() + config.getMessageTimeout() < TimeSync.getGlobalTime()) {
// old message, ignore
if (Logging.isDebug() && config.isDebugPrintMessages())
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A outdated message discarded: %s",
msg.toString());
return null;
}
if (this.waitUntilTimestamp_ms >= now) {
if (Logging.isDebug() && config.isDebugPrintMessages())
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A message discarded, acceptor is still in recovery period");
return null;
}
assert (msg.getCellId() != null);
final FleaseAcceptorCell cc = getCell(msg.getCellId());
if (cc.getViewId() < msg.getViewId()) {
// If the local view is lower than the delivered one, the view listener has to be informed to
// update
// the local view. But the request can still be answered.
viewListener.viewIdChangeEvent(msg.getCellId(), msg.getViewId());
} else if (cc.getViewId() > msg.getViewId()
|| (cc.getViewId() == msg.getViewId() && cc.isViewInvalidated())) {
// If the request is from an older view, or the a view that has been invalidated on this
// AcceptorCell, the request has to be aborted.
FleaseMessage response = new FleaseMessage(FleaseMessage.MsgType.MSG_WRONG_VIEW, msg);
response.setViewId(cc.getViewId());
return response;
}
FleaseMessage response = null;
if (msg.getMsgType() == FleaseMessage.MsgType.MSG_PREPARE) response = handlePREPARE(msg);
else if (msg.getMsgType() == FleaseMessage.MsgType.MSG_ACCEPT) response = handleACCEPT(msg);
else if (msg.getMsgType() == FleaseMessage.MsgType.MSG_LEARN) handleLEARN(msg);
/*else if (msg.getMsgType() == FleaseMessage.MsgType.MSG_GET_LEASE)
response = handleGETLEASE(msg);
else if (msg.getMsgType() == FleaseMessage.MsgType.MSG_RENEW_LEASE)
response = handleRENEWINSTANCE(msg);*/
else
Logging.logMessage(
Logging.LEVEL_ERROR,
Category.replication,
this,
"A invalid message type received: %s",
msg.toString());
/*if (Logging.isDebug())
Logging.logMessage(Logging.LEVEL_DEBUG,this,"response %s",(response != null) ? response.toString() : "<empty>");*/
return response;
}
/**
* Handles paxos accept (vote) messages.
*
* @param msg incomming message
* @return a response message or null
*/
public FleaseMessage handleACCEPT(FleaseMessage msg) {
final FleaseAcceptorCell cc = getCell(msg);
cc.touch();
if ((cc.getPrepared() != null) && (cc.getPrepared().after(msg))) {
// reject the request
if (Logging.isDebug() && config.isDebugPrintMessages()) {
final String preped =
(cc.getPrepared() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getPrepared().getProposalNo().toString();
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A accept NACK p:" + preped + " is after " + msg.getProposalNo() + "");
}
FleaseMessage tmp = new FleaseMessage(FleaseMessage.MsgType.MSG_ACCEPT_NACK, msg);
tmp.setSendTimestamp(TimeSync.getGlobalTime());
tmp.setLeaseHolder(null);
tmp.setLeaseTimeout(0);
tmp.setPrevProposalNo(cc.getPrepared().getProposalNo());
return tmp;
} else {
// okay accept it
if (Logging.isDebug() && config.isDebugPrintMessages()) {
final String preped =
(cc.getPrepared() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getPrepared().getProposalNo().toString();
final String acced =
(cc.getAccepted() == null)
? ProposalNumber.EMPTY_PROPOSAL_NUMBER.toString()
: cc.getAccepted().getProposalNo()
+ "="
+ cc.getAccepted().getLeaseHolder()
+ "/"
+ cc.getAccepted().getLeaseTimeout();
Logging.logMessage(
Logging.LEVEL_DEBUG,
Category.replication,
this,
"A accept ACK p:"
+ preped
+ " a: "
+ acced
+ " -> "
+ msg.getProposalNo()
+ "="
+ msg.getLeaseHolder()
+ "/"
+ msg.getLeaseTimeout());
}
assert (msg.getLeaseHolder() != null);
cc.setAccepted(msg);
cc.setPrepared(msg);
FleaseMessage tmp = new FleaseMessage(FleaseMessage.MsgType.MSG_ACCEPT_ACK, msg);
tmp.setSendTimestamp(TimeSync.getGlobalTime());
return tmp;
}
}