com.atomikos.icatch.imp
Class ReadOnlyParticipant

java.lang.Object
  com.atomikos.icatch.imp.ReadOnlyParticipant

All Implemented Interfaces:

Participant, Serializable

public class ReadOnlyParticipant
extends Object
implements Participant

See Also:

Serialized Form

Field Summary

Fields inherited from interface com.atomikos.icatch.Participant

READ_ONLY

Constructor Summary

ReadOnlyParticipant(CoordinatorImp coordinator)

Method Summary

HeuristicMessage[]	commit(boolean onePhase) Commit the participant's work.
boolean	equals(Object o)
void	forget() Indicate that a heuristic participant can forget about its work.
HeuristicMessage[]	getHeuristicMessages() Get any heuristic messages so far.
String	getURI() Gets a unique URI for this participant.
int	hashCode()
int	prepare() Prepare the participant.
boolean	recover() Recover this instance.
HeuristicMessage[]	rollback() Rollback the participant's work.
void	setCascadeList(Dictionary allParticipants) For cascading 2PC, this method sets the information needed to cascade.
void	setGlobalSiblingCount(int count) Set by the root coordinator: the total no of siblings detected.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ReadOnlyParticipant

public ReadOnlyParticipant(CoordinatorImp coordinator)

Method Detail

recover

public boolean recover()
                throws SysException

Description copied from interface: Participant

Recover this instance. Called by the transaction manager (TM) at recovery time, and this should reconstruct the internal state.

Specified by:

recover in interface Participant

Returns:

boolean False iff the instance could not be recovered. It is up to the TM to determine the severity of this case.

Throws:

SysException - On failure.

getURI

public String getURI()

Description copied from interface: Participant

Gets a unique URI for this participant. Local participants should merely return null.

Specified by:

getURI in interface Participant

Returns:

String The URI for this participant, or null if not applicable.

setCascadeList

public void setCascadeList(Dictionary allParticipants)
                    throws SysException

Description copied from interface: Participant

For cascading 2PC, this method sets the information needed to cascade. This method is relevant only for transaction monitors; leave empty otherwise!

Specified by:

setCascadeList in interface Participant

Parameters:

allParticipants - The information needed by the transaction monitor for

Throws:

SysException - For unexpected failures.

setGlobalSiblingCount

public void setGlobalSiblingCount(int count)

Description copied from interface: Participant

Set by the root coordinator: the total no of siblings detected. This method is relevant only for transaction monitors; leave empty otherwise!

Specified by:

setGlobalSiblingCount in interface Participant

Parameters:

count - The global count.

prepare

public int prepare()
            throws RollbackException,
                   HeurHazardException,
                   HeurMixedException,
                   SysException

Description copied from interface: Participant

Prepare the participant. Any locks for this participant's work should be recoverable (either saved to an external file OR be part of the instance's non-transient state so that they can be flushed into the transaction manager's log).

Specified by:

prepare in interface Participant

Returns:

int If this is READ_ONLY, then no second round is needed. Participants that return this value on prepare will not be called by commit or rollback afterwards.

Throws:

RollbackException - For a NO vote. This indicates that the participant has already rolled back (or marked for rollback) the work on behalf of this participant.

HeurHazardException - On possible conflicts. This happens for remote participants instances, in case of communication failures.

HeurMixedException - If some subordinate participants voted YES, timed out and committed heuristically whereas afterwards some NO votes where received.

SysException - Unexpected errors.

commit

public HeuristicMessage[] commit(boolean onePhase)
                          throws HeurRollbackException,
                                 HeurHazardException,
                                 HeurMixedException,
                                 RollbackException,
                                 SysException

Description copied from interface: Participant

Commit the participant's work. NOTE: custom participant implementations should preferably be made for the server's local VM (e.g., it is better not to do this over RMI). Also, they should rely on the icatch transaction manager for heuristic timeout (and NOT decide to terminate heuristically themselves). In that case, implementations never need to throw any of the heuristic exceptions of this method.

Specified by:

commit in interface Participant

Parameters:

onePhase - If true, one-phase commit is being started. If the participant has received a prepare call earlier, then it should throw a SysException here.

Returns:

HeuristicMessage[] An array of messages, null if none.

Throws:

HeurHazardException - On possible conflicts.

RollbackException - In case of one-phase commit, and the transaction has been rolled back at the time commit is called.

SysException - Unexpected failure.

HeurRollbackException

HeurMixedException

rollback

public HeuristicMessage[] rollback()
                            throws HeurCommitException,
                                   HeurMixedException,
                                   HeurHazardException,
                                   SysException

Description copied from interface: Participant

Rollback the participant's work. NOTE: custom participant implementations should preferably be made for the server's local VM (e.g., it is better not to do this over RMI). Also, they should rely on the icatch transaction manager for heuristic timeout (and NOT decide to terminate heuristically themselves). In that case, implementations never need to throw any of the heuristic exceptions of this method.

Specified by:

rollback in interface Participant

Returns:

HeuristicMessage[] An array of messages, null if none.

Throws:

HeurCommitException - If the participant committed.

HeurMixedException - If part of it was rolled back.

HeurHazardException - If the participant's final state is unsure.

SysException - Unexpected failure.

forget

public void forget()

Description copied from interface: Participant

Indicate that a heuristic participant can forget about its work. If implementations rely on the transaction manager to decide when to do heuristics (rather then deciding in the participant implementation), then leave this method empty.

Specified by:

forget in interface Participant

getHeuristicMessages

public HeuristicMessage[] getHeuristicMessages()

Description copied from interface: Participant

Get any heuristic messages so far. The transaction manager used this method to get information after preparing this participant.

Specified by:

getHeuristicMessages in interface Participant

Returns:

HeuristicMessage[] An array of heuristic messages, or null if none.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object