All Packages  Class Hierarchy  This Package  Previous  Next  Index

Class semper.txlayer.transaction.Transaction

java.lang.Object
   |
   +----semper.txlayer.transaction.Transaction

public abstract class Transaction

extends Object

implements Runnable, Serializable

_observers

A list of observers that might get notified of certain state changes.

_signal

status and signal of the transaction.

_thr

This is the thread the transaction runs in.

_tid

The transaction id.

_timeout

This may hold the timeout value that was passed to us with beginAndBlock(m).

ABORTED

COMMITTED

NO_SIGNAL

PREPARED

RUNNING

TO_BE_ABORTED

Constants for defining signals to be given to the transaction.

TO_BE_COMMITTED

UNPREPARED

Constants for defining the state the transaction is in.

Transaction()

Empty constructor.

Transaction(TransactionID)

Constructor with transaction id as parameter.

abort()

With this method the outer world can set a signal to abort the transaction.

addObserver(TransactionObserver)

Adds an observer object to the transaction.

begin()

Starts the transaction and returns to main thread of execution.

beginAndBlock()

Starts the transaction and blocks as long as it lasts.

beginAndBlock(long)

Starts the transaction and blocks as long as it lasts, but almost m milliseconds.

checkForSignal()

Checks if a signal has been set, and consequently changes the control flow of the program, that means triggers methods on a signal.

commit()

Makes the transaction real: The last step in successfully finishing a transaction.

deleteObserver(TransactionObserver)

Deletes an observer object from the transaction.

doAbort()

Does whatever is necessary to abort the transaction.

doCommit()

Does whatever is necessary to commit the transaction.

end()

Executed at the end of join() Notifies all registered observers.

getException()

This method can be called to examine the reason of a Transaction.ABORTED status.

getStatus()

getTID()

join()

Borrowed from thread.

join(long)

Same as join(), but with a timeout in milliseconds.

newSubTID(int)

Generates a new subtransaction id that fits to the current tid and the parameter i.

notifyObserver()

Notify all registered observers.

rollback()

performs the recovery to the last saved savepoint.

run()

The Thread's run method, for satisfaction of the Runnable interface.

setException(TXLayerException)

Sets the internal _exception variable, which will be thrown when somebody calls join() or beginAndBlock().

setSignal(int)

Used to set a signal to the transaction.

setStatus(int)

Used to set the status of the transaction.

setTID(TransactionID)

 public static final int UNPREPARED

Constants for defining the state the transaction is in.

 public static final int PREPARED

 public static final int RUNNING

 public static final int ABORTED

 public static final int COMMITTED

 protected static final int TO_BE_ABORTED

Constants for defining signals to be given to the transaction.

 protected static final int TO_BE_COMMITTED

 protected static final int NO_SIGNAL

 protected long _timeout

This may hold the timeout value that was passed to us with beginAndBlock(m). If no value is set, this variable is zero.

 protected TransactionID _tid

The transaction id.

 protected int _signal

status and signal of the transaction.

 protected transient Thread _thr

This is the thread the transaction runs in.

 protected Vector _observers

A list of observers that might get notified of certain state changes.

 public Transaction()

Empty constructor. Can be used, a new transaction id is generated automatically.

 public Transaction(TransactionID tid)

Constructor with transaction id as parameter. The given id will be used.

 protected boolean checkForSignal()

Checks if a signal has been set, and consequently changes the control flow of the program, that means triggers methods on a signal. The running transaction thread uses this to poll a desired action.

 protected boolean setStatus(int s)

Used to set the status of the transaction. Derived transactions (e.g., StatementTransaction) might want to use this.

Parameters:

s - The status that is to be set. You MUST use the constants defined above (UNPREPARED...COMMITTED).

Returns:

true in any case. (?) Note that no one should use integer, but only the symbolic Names. Because these Constants will be real constants (objects) in future.

 protected boolean setSignal(int s)

Used to set a signal to the transaction. Derived transactions (e.g., StatementTransaction) might want to use this.

Parameters:

s - The signal that is to be set. You MUST use the constants defined above (TO_BE_ABORTED...NO_SIGNAL).

Returns:

true in any case. (?) Note that no one should use integer, but only the symbolic Names. Because these Constants will be real constants (objects) in future.

 protected void setException(TXLayerException e)

Sets the internal _exception variable, which will be thrown when somebody calls join() or beginAndBlock().

Parameters:

e - The internal _exception is set to e.

 protected boolean doAbort()

Does whatever is necessary to abort the transaction.

Returns:

true When abort was successfull, false otherwise.

 protected boolean doCommit()

Does whatever is necessary to commit the transaction.

Returns:

true When abort was successfull, false otherwise.

 protected boolean notifyObserver()

Notify all registered observers. Doesn't do anything up to now!

Returns:

false When notification failed.

 public TransactionID newSubTID(int i)

Generates a new subtransaction id that fits to the current tid and the parameter i. Tom: What's the difference to newSubtransactionID(i)?

Parameters:

i - Parameter which is combined with current tid to new subtid.

 public abstract void run()

The Thread's run method, for satisfaction of the Runnable interface. DON'T CALL this method from outside.

 public void begin()

Starts the transaction and returns to main thread of execution. The transaction runs in the background.

 public void beginAndBlock() throws TXLayerException

Starts the transaction and blocks as long as it lasts.

Throws: TXLayerException

On problems in executing the transaction.

 public void beginAndBlock(long m) throws TXLayerException

Starts the transaction and blocks as long as it lasts, but almost m milliseconds.

Parameters:

m - Time in milliseconds that we should wait for the completion of the transaction.

Throws: TXLayerException

On problems in executing the transaction.

 public boolean abort()

With this method the outer world can set a signal to abort the transaction. All observers are notified of onAbort.

Returns:

true if the signal could be set, false otherwise.

 public boolean rollback()

performs the recovery to the last saved savepoint. All observers are notified with onRollback.

Returns:

false.

 public boolean commit()

Makes the transaction real: The last step in successfully finishing a transaction. All observers are notified with onCommit

Returns:

true if the signal could be set, false otherwise.

 public boolean end()

Executed at the end of join() Notifies all registered observers.

Returns:

false.

 public void join() throws TXLayerException

Borrowed from thread. Blocks the caller until the transaction has finished. Calls end() and thus notifies all observers.

Throws: TXLayerException

On problems in executing the transaction.

 public void join(long millis) throws TXLayerException

Same as join(), but with a timeout in milliseconds. Calls end() and thus notifies all observers.

Parameters:

m - Time in milliseconds that we should wait for the completion of the transaction.

Throws: TXLayerException

On problems in executing the transaction.

 public int getStatus()

Returns:

The status of a transaction. This is a constants, element of Transaction.UNPREPARED, Transaction.PREPARED, Transaction.RUNNING, Transaction.ABORTED, Transaction.COMITTED.

 public TXLayerException getException()

This method can be called to examine the reason of a Transaction.ABORTED status.

Returns:

An Exception that was thrown inside the Transaction and led to the ABORTED status. Beware, this may be null!

 public TransactionID getTID()

Returns:

the TransactionID.

 public boolean setTID(TransactionID tid)

 public boolean addObserver(TransactionObserver o)

Adds an observer object to the transaction. The observer will be notified about important events. Notification does not happen in a well defined manner up to now! Ask [email protected] or [email protected] if you plan to use this!

Parameters:

o - The observer to be added.

Returns:

true in any case.

 public boolean deleteObserver(TransactionObserver o)

Deletes an observer object from the transaction. Notification does not happen in a well defined manner up to now! Ask [email protected] or [email protected] if you plan to use this!

Parameters:

o - The observer to be deleted.

Returns:

True if o could be deleted, false otherwise.

All Packages  Class Hierarchy  This Package  Previous  Next  Index