LeaseRenewalManager.
*
* This code assumes most synchronization is being done at the set level,
* this works because no lease is in more than one set at a given time.
* The only place where additional synchronization is going on is in
* renewals and the logging of renewals.
*
*
*/
class ClientLeaseWrapper implements Lease, Serializable {
private static final long serialVersionUID = 2;
/** Logger for logging messages for this class */
private static final Logger logger = Logger.getLogger("com.sun.jini.norm");
/* Map for comparing lease constraints. */
private static final Method[] leaseToLeaseMethods;
static {
try {
Method cancelMethod =
Lease.class.getMethod("cancel", new Class[] { });
Method renewMethod =
Lease.class.getMethod("renew", new Class[] { long.class });
leaseToLeaseMethods = new Method[] {
cancelMethod, cancelMethod, renewMethod, renewMethod };
} catch (NoSuchMethodException e) {
throw new NoSuchMethodError(e.getMessage());
}
}
/**
* Throwable thrown by the last renew attempt on the client lease.
* null if the renew has not been called yet or
* the last renewal call succeeded.
* @serial
*/
private Throwable lastFailure = null;
/**
* Client lease in marshalled form.
* @serial
*/
private MarshalledInstance marshalledClientLease;
/**
* Most current expiration time of client Lease that we know of
* @serial
*/
private long clientLeaseExpiration;
/**
* Sequence number that uniquely identifies this wrapper
* @serial
*/
private long UID;
/**
* Membership expiration of this lease
* @serial
*/
private long membershipExpiration;
/**
* renewDuration of this lease
* @serial
*/
private long renewDuration;
/**
* The LeaseSet we belong to
*/
private transient LeaseSet set;
/**
* Transient copy of unpacked lease, null if we could not
* unpack or prepare the lease.
*/
private transient Lease clientLease;
/**
* The proxy preparer to use to prepare a newly unmarshalled client lease,
* or null if this instance was created using an already prepared client
* lease, which is how instances are created initially.
*/
private transient ProxyPreparer recoveredLeasePreparer;
/**
* Flag used to check if lease has been persisted since last
* renewal, true means it has not been
*/
private transient boolean renewalPending = false;
/**
* Reference to list of leases that have been renewed, but not
* persisted
*/
private transient List renewedList;
/**
* Simple constructor
* @param clientLease lease from client that is to be renewed
* @param UID ID number for this wrapper unique for all wrappers in a given
* server
* @param renewedList list that wrapper should go on after renewing their
* client lease is renewed
* @param leaseSet the LeaseSet this lease is in
* @param membershipDuration
* initial membership duration for this lease
* @param renewDuration
* initial membership expiration for the lease
* @param now the current time
*/
ClientLeaseWrapper(Lease clientLease, long UID, List renewedList,
LeaseSet leaseSet, long membershipDuration,
long renewDuration, long now)
throws IOException
{
this.renewedList = renewedList;
this.UID = UID;
this.clientLease = clientLease;
set = leaseSet;
clientLeaseExpiration = clientLease.getExpiration();
clientLease.setSerialFormat(Lease.ABSOLUTE);
marshalledClientLease = new MarshalledInstance(clientLease);
this.renewDuration = renewDuration;
calcMembershipExpiration(membershipDuration, now);
}
/**
* Given the current time and a membershipDuration set membershipExpiration
* the correct value.
*/
private void calcMembershipExpiration(long membershipDuration, long now) {
if (membershipDuration == Lease.FOREVER) {
membershipExpiration = Lease.FOREVER;
} else {
membershipExpiration = membershipDuration + now;
// Check for overflow
if (membershipExpiration < 0)
membershipExpiration = Long.MAX_VALUE;
}
}
/**
* Update the membership expiration and renewDuration of this lease
*/
void update(long membershipDuration, long renewDuration, long now) {
this.renewDuration = renewDuration;
calcMembershipExpiration(membershipDuration, now);
}
/**
* Return the membershipExpiration of this lease
*/
long getMembershipExpiration() {
return membershipExpiration;
}
/**
* Return the renewDuration of this lease
*/
long getRenewDuration() {
return renewDuration;
}
/**
* Atomically clear the renewalPending flag.
*/
synchronized void clearRenewed() {
renewalPending = false;
}
/**
* Get a reference to the client lease, unmarshalling and preparing it if
* necessary. If it can't be unpacked or prepared, return null.
*/
// $$$ this might want to be synchronized
Lease getClientLease() {
if (clientLease == null) {
Lease unmarshalledLease = null;
try {
unmarshalledLease = (Lease) marshalledClientLease.get(false);
} catch (IOException e) {
logger.log(Levels.HANDLED,
"Problem unmarshalling lease -- will retry later",
e);
} catch (ClassNotFoundException e) {
logger.log(Levels.HANDLED,
"Problem unmarshalling lease -- will retry later",
e);
}
if (unmarshalledLease != null) {
try {
clientLease = (Lease) recoveredLeasePreparer.prepareProxy(
unmarshalledLease);
} catch (RemoteException e) {
logger.log(Levels.HANDLED,
"Problem preparing lease -- will retry later",
e);
} catch (SecurityException e) {
logger.log(Levels.HANDLED,
"Problem preparing lease -- will retry later",
e);
}
}
}
return clientLease;
}
/**
* Return the client lease in marshalled form. If possible
* marshal using the Lease.DURATION serialization format.
*
* Assumes that no one else will be serializing the lease
* during this call.
*/
MarshalledInstance getMarshalledClientLease() {
final Lease cl = getClientLease();
if (cl == null) {
// We are deformed, best we can do is return the (possibly
// stale) pre-marshalled lease we already have
return marshalledClientLease;
} else {
try {
cl.setSerialFormat(Lease.DURATION);
return new MarshalledInstance(cl);
} catch (IOException e) {
// Can't create a new MarshalledInstance, return the old one
return marshalledClientLease;
} finally {
cl.setSerialFormat(Lease.ABSOLUTE);
}
}
}
// Inherit java doc from super type
public boolean equals(Object that) {
if (that instanceof ClientLeaseWrapper) {
return UID == ((ClientLeaseWrapper) that).UID;
} else {
return false;
}
}
// Inherit java doc from super type
public int hashCode() {
return (int) UID;
}
// Inherit java doc from super type
public String toString() {
return "CLW:" + UID + " exp:" + clientLeaseExpiration + " dexp:" +
membershipExpiration + " dur:" + renewDuration + " failure:" +
lastFailure;
}
// Inherit java doc from super type
public long getExpiration() {
final Lease cl = getClientLease();
if (cl == null) {
// $$$ Why is this synchronized?
synchronized (this) {
return clientLeaseExpiration;
}
} else {
return cl.getExpiration();
}
}
/**
* Always throws UnsupportedOperationException since
* a lease renewal service should never cancel a client lease.
*/
public void cancel() {
throw new UnsupportedOperationException("ClientLeaseWrapper.cancel:" +
"LRS should not being canceling client leases ");
}
/**
* Return the exception (if any) that occured at the last renewal attempt
*/
Throwable getLastFailure() {
return lastFailure;
}
/**
* Atomically test and set the renewalPending flag.
* @return the state of the renewalPending flag before it was set
*/
private synchronized boolean testAndSetRenewalPending() {
final boolean result = renewalPending;
renewalPending = true;
return result;
}
/**
* Called when a renewal thread changes the persistent state of the
* this wrapper. If necessary places this object on the queue of
* wrappers to be persisted.
*/
private void changed() {
if (!testAndSetRenewalPending()) {
synchronized (renewedList) {
renewedList.add(this);
renewedList.notifyAll();
}
}
}
/**
* Called by ClientLeaseMapWrapper to see if the set associated with
* this wrapper is still valid. Returns true if it still is
*/
boolean ensureCurrent(long now) {
return set.ensureCurrent(now);
}
/**
* Sets lastFailure and adds the this to the renewed list so it
* so the change can be logged. Note this is only called from
* from renew methods that are renewing the client lease associated
* with this wrapper so additional synchronization should not be
* necessary.
*/
void failedRenewal(Throwable t) {
lastFailure = t;
changed();
}
/**
* Log a successful lease renewalNote this is only called from
* from renew methods that are renewing the client lease associated
* with this wrapper so additional synchronization should not be
* necessary.
*/
void successfulRenewal() {
lastFailure = null;
// Update the marshalled version of the lease
// $$$ We could only do this in writeObject but then we would have
// to make sure it had changed since the last serialization, the
// renewalPending flag almost does this but not quite (maybe it should
// and we don't have it quite right...maybe writeObject should
// clear the flag instead of explicit clearing it after writing
// the clw out?). Not clear doing it here is significantly less
// efficient.
try {
marshalledClientLease = new MarshalledInstance(clientLease);
} catch (IOException e) {
// $$$ Besides printing a message drop this on the floor,
// exception in some pathological cases we are extremely
// unlikely to get this exception, further more this is really
// just a logging error, which our current policy is to drop.
// In the abstract it would be better to do this in writeObject
// since this really is an error while trying to persist the
// state of this object, however, that solution would require
// more synchronization. Lastly this method may go away if
// we decide to stop using the LRM.
logger.log(Level.WARNING,
"IOException while marshalling client lease " +
"after renewal",
e);
}
// synchronize in case long assignment is not atomic
synchronized (this) {
clientLeaseExpiration = clientLease.getExpiration();
}
// If necessary notify rest of system that this lease has to
// be persisted
changed();
}
// Inherit java doc from super type
// This method assumes that only this thread is renewing this lease
public void renew(long duration)
throws LeaseDeniedException, UnknownLeaseException, RemoteException
{
// Check to make sure the set has not expired
if (!set.ensureCurrent(System.currentTimeMillis())) {
// The set has expired, throw an exception that will
// tell the failure logging thread to ignore this failure
throw LRMEventListener.EXPIRED_SET_EXCEPTION;
// Note, we don't call failedRenewal() because the set is
// dead so logging changes is pointless (besides, there
// is no change to log.)
}
// Do we have the real lease in unmarshalled form?
if (clientLease == null) {
// try to unmarshal client lease
Lease unmarshalledLease;
try {
unmarshalledLease = (Lease) marshalledClientLease.get(false);
} catch (IOException e) {
UnmarshalException t = new UnmarshalException(
"ClientLeaseWrapper.renew:Could not unmarshal client " +
"lease for renewal", e);
failedRenewal(t);
throw t;
} catch (ClassNotFoundException e) {
UnmarshalException t = new UnmarshalException(
"ClientLeaseWrapper.renew:Could not unmarshal client " +
"lease for renewal", e);
failedRenewal(t);
throw t;
}
// Try to prepare the client lease
try {
clientLease = (Lease) recoveredLeasePreparer.prepareProxy(
unmarshalledLease);
} catch (RemoteException e) {
failedRenewal(e);
throw e;
} catch (SecurityException e) {
failedRenewal(e);
throw e;
}
}
// If we get here clientLease must be non-null
// $$$ do we want to ensure that the lease on the set is
// current here or just rely on the expiration thread.
try {
clientLease.renew(duration);
} catch (LeaseDeniedException e) {
failedRenewal(e);
throw e;
} catch (UnknownLeaseException e) {
failedRenewal(e);
throw e;
} catch (RemoteException e) {
failedRenewal(e);
throw e;
} catch (RuntimeException e) {
failedRenewal(e);
throw e;
} catch (Error e) {
failedRenewal(e);
throw e;
}
// If we get here we must have successfully renewed the lease
successfulRenewal();
}
/**
* Always throws UnsupportedOperationException. The
* LeaseRenewalManager should never call this method and
* norm always serializes the wrapper with absolute times.
*/
public void setSerialFormat(int format) {
throw new UnsupportedOperationException(
"ClientLeaseWrapper.setSerialFormat:" +
"LRS should not be setting serial format through the wrapper");
}
/**
* Always throws UnsupportedOperationException. The
* LeaseRenewalManager should never call this method and
* norm always serializes the wrapper with absolute times.
*/
public int getSerialFormat() {
throw new UnsupportedOperationException(
"ClientLeaseWrapper.setSerialFormat:" +
"LRS should not be setting serial format through the wrapper");
}
// Inherit java doc from super type
public LeaseMap createLeaseMap(long duration) {
if (isDeformed()) {
return new DeformedClientLeaseMapWrapper(this, duration);
} else {
return new ClientLeaseMapWrapper(this, duration);
}
}
/**
* Another lease can be batched with this one if it is a
* ClientLeaseMapWrapper, if it is either a member of the same lease
* renewal set or sets are not isolated, if neither lease is deformed, if
* the leases either both have the same client constraints or do not
* implement RemoteMethodControl, and if the underlying client leases can
* be batched.
*/
public boolean canBatch(Lease lease) {
if (!(lease instanceof ClientLeaseWrapper))
return false;
final ClientLeaseWrapper clw = (ClientLeaseWrapper) lease;
if (set.isolateSets() && !set.equals(clw.set))
return false;
if (isDeformed() || clw.isDeformed())
return false;
Lease clientLease = getClientLease();
Lease otherClientLease = clw.getClientLease();
return sameConstraints(clientLease, otherClientLease) &&
clientLease.canBatch(otherClientLease);
}
/**
* Returns true if the two leases both implement RemoteMethodControl and
* have the same constraints for Lease methods, or both don't implement
* RemoteMethodControl, else returns false.
*/
private static boolean sameConstraints(Lease l1, Lease l2) {
if (!(l1 instanceof RemoteMethodControl)) {
return !(l2 instanceof RemoteMethodControl);
} else if (!(l2 instanceof RemoteMethodControl)) {
return false;
} else {
return ConstrainableProxyUtil.equivalentConstraints(
((RemoteMethodControl) l1).getConstraints(),
((RemoteMethodControl) l2).getConstraints(),
leaseToLeaseMethods);
}
}
/**
* After recovering a lease wrapper call this method before using
* any other of the wrappers methods and before allocating any new
* wrappers can not recover itself.
* @param renewedList List that wrapper should go on after renewing their
* client lease is renewed
* @param generator ID generator being used to generate IDs client lease
* wrappers
* @param leaseSet the set this wrapper is associated with
* @param recoveredLeasePreparer the proxy preparer to use to prepare
* client leases recovered from persistent storage
*/
void recoverTransient(List renewedList, UIDGenerator generator,
LeaseSet leaseSet,
ProxyPreparer recoveredLeasePreparer)
{
this.renewedList = renewedList;
set = leaseSet;
generator.inUse(UID);
this.recoveredLeasePreparer = recoveredLeasePreparer;
// Try to get the client lease unpacked
getClientLease();
// Add to set's lease table now that the transient state is
// restored and we have tried unpacking once
set.addToLeaseTable(this);
}
/**
* Return true if the underlying client lease has not yet been deserialized
*/
boolean isDeformed() {
return getClientLease() == null;
}
/**
* The LeaseSet this lease is in
*/
LeaseSet getLeaseSet() {
return set;
}
/**
* Return an EventFactory that will create an
* appropriate RenewalFailureEvent for the client
* lease associated with this wrapper. This method assumes
* that no one else will be setting the serialization format
* of the lease during the course of the call.
* @param source Source object for the event
* @throws IOException if the client lease could not be pre
* marshalled.
*/
EventFactory newFailureFactory(LeaseRenewalSet source) throws IOException {
final MarshalledInstance ml = getMarshalledClientLease();
MarshalledInstance mt = null;
if (lastFailure != null)
mt = new MarshalledInstance(lastFailure);
return new FailureFactory(source, ml, mt);
}
/**
* Nested top-level implementation of EventFactory that
* generates RenewalFailureEvent events
*/
// $$$ We could have this object share state with wrapper, but weird
// things could happen if the wrapper then changes -- right now
// the wrapper won't change after this method is called but in the
// future who is to say.
private class FailureFactory implements EventFactory {
/** Source for event */
private LeaseRenewalSet source;
/** Client lease that could not be renewed in marshalled form */
final private MarshalledInstance marshalledLease;
/**
* Throwable (if any) that was thrown when we tried to renew the lease
* in marshalled form
*/
final private MarshalledInstance marshalledThrowable;
/**
* Simple constructor
* @param source event source
* @param marshalledLease client lease that could not be renewed
* in marshalled form
* @param marshalledThrowable exception (if any) that was thrown when
* the lease could not be renewed
*/
private FailureFactory(LeaseRenewalSet source,
MarshalledInstance marshalledLease,
MarshalledInstance marshalledThrowable)
{
this.source = source;
this.marshalledLease = marshalledLease;
this.marshalledThrowable = marshalledThrowable;
}
// Inherit java doc from super type
public RemoteEvent createEvent(long eventID,
long seqNum,
MarshalledObject handback)
{
return new BasicRenewalFailureEvent(source, seqNum,
handback, marshalledLease, marshalledThrowable);
}
}
}