com.arjuna.ats.arjuna.coordinator

Class TransactionReaper

java.lang.Object

com.arjuna.ats.arjuna.coordinator.TransactionReaper

public class TransactionReaper
extends Object

Class to record transactions with non-zero timeout values, and class to implement a transaction reaper thread which terminates these transactions once their timeout elapses.

Since:

JTS 1.0.

Version:

$Id: TransactionReaper.java 2342 2006-03-30 13:06:17Z $

Author:

Mark Little (mark@arjuna.com)

Field Summary

Fields

Modifier and Type	Field and Description
static long	defaultCancelFailWaitPeriod
static long	defaultCancelWaitPeriod
static long	defaultCheckPeriod
static int	defaultZombieMax
static String	DYNAMIC
static String	NORMAL
static String	PERIODIC

Method Summary

Methods

Modifier and Type	Method and Description
void	addListener(ReaperMonitor listener)
void	check() process all entries in the timeout queue which have expired.
long	checkingPeriod()
void	doCancellations()
long	getRemainingTimeoutMills(Object control) Given the transaction instance, this will return the time left before the transaction is automatically rolled back if it has not been terminated.
int	getTimeout(Object control) Given a Control, return the associated timeout, or 0 if we do not know about it.
void	insert(Reapable control, int timeout) timeout is given in seconds, but we work in milliseconds.
static void	instantiate() Currently we let the reaper thread run at same priority as other threads.
static boolean	isDynamic()
long	numberOfTimeouts() Return the number of timeouts registered.
long	numberOfTransactions()
void	remove(Object control)
boolean	removeListener(ReaperMonitor listener)
static void	terminate(boolean waitForTransactions) Terminate the transaction reaper.
static long	transactionLifetime()
static TransactionReaper	transactionReaper() Starting with 4.8, this method will always return an instance, will never return null.
void	waitForCancellations()

Methods inherited from class java.lang.Object

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

Field Detail

NORMAL

public static final String NORMAL

See Also:

Constant Field Values

DYNAMIC

public static final String DYNAMIC

See Also:

Constant Field Values

PERIODIC

public static final String PERIODIC

See Also:

Constant Field Values

defaultCheckPeriod

public static final long defaultCheckPeriod

See Also:

Constant Field Values

defaultCancelWaitPeriod

public static final long defaultCancelWaitPeriod

See Also:

Constant Field Values

defaultCancelFailWaitPeriod

public static final long defaultCancelFailWaitPeriod

See Also:

Constant Field Values

defaultZombieMax

public static final int defaultZombieMax

See Also:

Constant Field Values

Method Detail

checkingPeriod

public final long checkingPeriod()

check

public final void check()

process all entries in the timeout queue which have expired. entries for newly expired transactions are passed to a worker thread for cancellation and requeued for subsequent progress checks. the worker is given a kick if such checks find it is wedged.

Timeout is given in milliseconds.

waitForCancellations

public final void waitForCancellations()

doCancellations

public final void doCancellations()

numberOfTransactions

public final long numberOfTransactions()

Returns:

the number of items in the reaper's list.

Since:

JTS 2.2. Note: this is a) expensive and b) an approximation. Should be called only by test code.

numberOfTimeouts

public final long numberOfTimeouts()

Return the number of timeouts registered. Note: this is a) expensive and b) an approximation. Should be called only by test code.

Returns:

The number of timeouts registered.

addListener

public final void addListener(ReaperMonitor listener)

removeListener

public final boolean removeListener(ReaperMonitor listener)

insert

public final void insert(Reapable control,
          int timeout)

timeout is given in seconds, but we work in milliseconds. Attempting to insert an element that is already present is an error (IllegalStateException)

remove

public final void remove(Object control)

getRemainingTimeoutMills

public final long getRemainingTimeoutMills(Object control)

Given the transaction instance, this will return the time left before the transaction is automatically rolled back if it has not been terminated.

Parameters:

control -

Returns:

the remaining time in milliseconds.

getTimeout

public final int getTimeout(Object control)

Given a Control, return the associated timeout, or 0 if we do not know about it.

Return in seconds! Takes an Object because TransactionFactoryImple.getTransactionInfo and ArjunaTransactionImple.propagationContext use it and don't have a Reapable.

instantiate

public static void instantiate()

Currently we let the reaper thread run at same priority as other threads. Could get priority from environment.

transactionReaper

public static TransactionReaper transactionReaper()

Starting with 4.8, this method will always return an instance, will never return null. This causes the reaper to be instantiated unnecessarily in some cases, but that's cheaper than the alternatives.

Returns:

a TransactionReaper singleton.

terminate

public static void terminate(boolean waitForTransactions)

Terminate the transaction reaper. This is a synchronous operation and will only return once the reaper has been shutdown cleanly.

Note, this method assumes that the transaction system has been shutdown already so no new transactions can be created, or we could be here for a long time!

Parameters:

waitForTransactions - if true then the reaper will wait until all transactions have terminated (or been terminated by it). If false then the reaper will call setRollbackOnly on all the transactions.

isDynamic

public static boolean isDynamic()

transactionLifetime

public static long transactionLifetime()