Class TransactionManager

java.lang.Object

org.jpos.q2.QBeanSupport

org.jpos.transaction.TransactionManager

All Implemented Interfaces:

Runnable, Configurable, QBean, QBeanSupportMBean, QPersist, TransactionConstants, TransactionManagerMBean, Loggeable, MetricsProvider

public class TransactionManager
extends QBeanSupport
implements Runnable, TransactionConstants, TransactionManagerMBean, Loggeable, MetricsProvider

Multi-participant transaction manager.

Reads contexts from a configured input space, walks each transaction through its prepare/commit/abort lifecycle, and persists state to a persistent space so in-flight transactions can be recovered after a restart.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
class	TransactionManager.InputQueueMonitor	Background task that throttles the input queue when active sessions exceed the configured threshold.
class	TransactionManager.RetryTask	Background task that periodically pushes any contexts written to the RETRY_QUEUE back onto the input queue.
static final record	TransactionManager.Trace	Single line of participant trace data accumulated on a LogEvent during a transaction's lifecycle.

Field Summary

Fields

Modifier and Type	Field	Description
static final Integer	COMMITTING	State marker indicating a transaction is in the commit phase.
static final String	CONTEXT	Space-key prefix used to persist a transaction's serialised context.
static final String	DEFAULT_GROUP	Group name used when no explicit group is configured.
static final Integer	DONE	State marker indicating a transaction has reached its terminal state.
protected Map<String, List<TransactionParticipant>>	groups	Configured group-name to participant-list mapping.
static final String	GROUPS	Space-key prefix used to persist a transaction's group execution stack.
static final long	MAX_PARTICIPANTS	Hard ceiling on participants traversed per transaction (loop prevention).
static final long	MAX_WAIT	Default maximum time, in milliseconds, that a session waits for input.
static final Integer	PREPARING	State marker indicating a transaction is in the prepare phase.
static final String	RETRY_QUEUE	Space-key under which retried transactions are queued for re-execution.
static final String	STATE	Space-key prefix used to persist a transaction's lifecycle state.

Fields inherited from class QBeanSupport

cfg, log, scheduledThreadPoolExecutor

Modifier and Type	Field	Description
protected Configuration	cfg	Configuration applied to this bean by the container.
protected Log	log	Logger associated with this bean.
protected ScheduledThreadPoolExecutor	scheduledThreadPoolExecutor	Lazily-allocated scheduler shared with subclasses; see QBeanSupport.getScheduledThreadPoolExecutor().

Fields inherited from interface QBean

DESTROYED, FAILED, STARTED, STARTING, stateString, STOPPED, STOPPING

Modifier and Type	Field	Description
static final int	DESTROYED	QBean has been destroyed.
static final int	FAILED	QBean has failed.
static final int	STARTED	QBean is running.
static final int	STARTING	QBean is in the process of starting.
static final String[]	stateString	Human-readable names for each QBean state, indexed by state constant.
static final int	STOPPED	QBean is stopped.
static final int	STOPPING	QBean is in the process of stopping.

Fields inherited from interface TransactionConstants

ABORTED, FAIL, NO_JOIN, PAUSE, PREPARED, READONLY, RETRY

Modifier and Type	Field	Description
static final int	ABORTED	Transaction has been aborted.
static final int	FAIL	Shortcut for a read-only, non-joining abort (READONLY | NO_JOIN).
static final int	NO_JOIN	This participant does not join the transaction
static final int	PAUSE	Transaction is paused.
static final int	PREPARED	Transaction has been prepared successfully.
static final int	READONLY	Context has not been modified (no need to persist a snapshot)
static final int	RETRY	Transaction should be retried.

Constructor Summary

Constructors

Constructor	Description
TransactionManager()	Creates an unconfigured manager; configuration is supplied by Q2 at deploy time.

Method Summary

Modifier and Type	Method	Description
protected void	abort(int session, long id, Serializable context, List<TransactionParticipant> members, boolean recover, LogEvent evt, Profiler prof)	Walks members in order, invoking each participant's abort phase and recording trace and timer information.
protected void	abort(TransactionParticipant p, long id, Serializable context)	Invokes the abort phase on p, swallowing exceptions (logged as warnings) and recording timer metrics.
protected void	addGroup(long id, String groupName)	Pushes a group name onto the persistent execution stack for id.
void	addListener(TransactionStatusListener l)	Registers a listener that observes transaction lifecycle transitions.
protected void	checkRetryTask()	Lazily starts the TransactionManager.RetryTask that drains the retry queue back into the input space.
protected void	checkTail()	Advances the persistent tail pointer past any contiguous already-DONE transactions, purging their state from the space.
protected void	commit(int session, long id, Serializable context, List<TransactionParticipant> members, boolean recover, LogEvent evt, Profiler prof)	Walks members in order, invoking each participant's commit phase and recording trace and timer information.
protected void	commit(TransactionParticipant p, long id, Serializable context)	Invokes the commit phase on p, swallowing exceptions (logged as warnings) and recording timer metrics.
protected void	commitOff(Space sp)	Disables auto-commit on a JDBMSpace; no-op for other space types.
protected void	commitOn(Space sp)	Re-enables auto-commit on a JDBMSpace, flushing any pending writes; no-op for other space types.
TransactionParticipant	createParticipant(org.jdom2.Element e)	Instantiates a participant from a <participant> element, configures it, registers per-participant timers, and tracks any Destroyable for cleanup at shutdown.
protected String	defaultRealm()	Returns the default realm for this bean; subclasses may override.
void	dump(PrintStream ps, String indent)	Dumps a human-readable representation of this object to the print stream.
protected LogEvent	freeze(Serializable context, LogEvent evt, Profiler prof)	This method gives the opportunity to decorate a LogEvent right before it gets logged.
int	getActiveSessions()	Returns the number of session threads currently processing transactions.
static <T extends Serializable> T	getContext()	Returns the current thread's transaction context, narrowed to the caller's expected type.
long	getHead()	Returns the current head index of the transaction queue.
static Long	getId()	Returns the current thread's transaction id, when one is in progress.
Space	getInputSpace()	Returns the externally visible input space used for queueing contexts.
long	getInTransit()	Returns the count of transactions that have been picked up but not yet completed.
protected String	getKey(String prefix, long id)	Builds a persistent-space key by combining the manager name, a prefix, and the transaction id.
int	getMaxSessions()	Returns the configured maximum number of concurrent session threads.
Metrics	getMetrics()	Returns the metrics aggregator owned by this component.
int	getOutstandingTransactions()	Returns the number of in-flight transactions (tail - head).
protected List<TransactionParticipant>	getParticipants(long id)	Returns the participant chain for a specific transaction, combining the default group with any groups pushed onto the persistent execution stack.
protected List<TransactionParticipant>	getParticipants(String groupName)	Returns the configured participants for a named group.
Space	getPersistentSpace()	Returns the persistent space used to recover in-flight transactions across restarts.
String	getQueueName()	Returns the configured input queue name.
static Serializable	getSerializable()	Returns the current thread's transaction context as a raw Serializable.
protected int	getSessionsToStandUp()	This method returns the number of sessions that can be started at this point in time
Space	getSpace()	Returns the volatile space used for in-flight transaction state.
long	getTail()	Returns the current tail index of the transaction queue.
TPS	getTPS()	Returns the TPS counter that tracks transactions per second for this manager.
String	getTPSAsString()	Returns a human-readable summary of TPS statistics.
float	getTPSAvg()	Returns the average transactions-per-second since the last reset.
long	getTPSElapsed()	Returns the elapsed time in milliseconds covered by the current TPS window.
int	getTPSPeak()	Returns the peak transactions-per-second observed since the last reset.
Date	getTPSPeakWhen()	Returns the wall-clock instant at which TransactionManagerMBean.getTPSPeak() was reached.
protected List<TransactionParticipant>	initGroup(org.jdom2.Element e)	Instantiates the participants declared inside a <group> element, skipping any that are explicitly disabled.
protected void	initParticipants(org.jdom2.Element config)	Builds the default participant group plus any named <group> children from the QBean descriptor.
void	initService()	Called during the init lifecycle phase; subclasses may override.
protected void	initStatusListeners(org.jdom2.Element config)	Instantiates and registers any <status-listener> children of the QBean descriptor.
protected boolean	isSessionToStandDown()	Hook used by subclasses to drain a session early.
protected int	prepare(int session, long id, Serializable context, List<TransactionParticipant> members, Iterator<TransactionParticipant> iter, boolean abort, LogEvent evt, Profiler prof, Chronometer chronometer)	Drives the prepare phase across iter, accumulating results into members and aborting on retry signals or participant exceptions.
protected int	prepare(TransactionParticipant p, long id, Serializable context)	Invokes the prepare phase on p, swallowing exceptions (logged as warnings) and recording timer metrics.
protected int	prepareForAbort(TransactionParticipant p, long id, Serializable context)	Invokes AbortParticipant.prepareForAbort(long, Serializable) on p when applicable, swallowing exceptions and recording timer metrics.
protected void	purge(long id, boolean full)	Removes persistent state associated with a transaction.
void	push(Serializable context)	Pushes a context onto the head of the input queue (LIFO ordering).
void	queue(Serializable context)	Enqueues a context at the tail of the input queue (FIFO ordering).
protected void	recover()	Replays every in-flight transaction recorded in the persistent space, advancing the tail pointer as each completes.
protected void	recover(long id)	Replays a single transaction by inspecting its persisted state and driving either the commit or abort path before purging its state.
void	removeListener(TransactionStatusListener l)	Removes a previously registered status listener.
void	resetTPS()	Resets the TPS counters and start time.
void	run()
void	setConfiguration(Configuration cfg)	Configures this object with the supplied Configuration.
protected void	setState(long id, Integer state)	Atomically replaces the persisted lifecycle state for id.
protected void	snapshot(long id, Serializable context)	Snapshots the context for transaction id without changing its state.
protected void	snapshot(long id, Serializable context, Integer status)	Snapshots the context and optionally updates the persisted state for transaction id.
void	startService()	Called during the start lifecycle phase; subclasses may override.
void	stopService()	Called during the stop lifecycle phase; subclasses may override.
protected boolean	tailDone()	Returns whether the transaction at tail is already DONE; when true, removes its persistent state.

Methods inherited from class QBeanSupport

addAttr, close, createElement, destroy, destroyService, getAttrs, getAttrs, getConfiguration, getDump, getFactory, getLoader, getLoaderURLS, getLog, getLogger, getName, getPersist, getProperties, getProperty, getRealm, getScheduledThreadPoolExecutor, getServer, getState, getStateAsString, init, isModified, running, setAttr, setLogger, setModified, setName, setPersist, setProperty, setRealm, setServer, setState, start, stop

Modifier and Type	Method	Description
protected void	addAttr(org.jdom2.Element e, String name, Object obj, String type)	Appends an <attr> child element with name/type/value to e.
protected void	close(Closeable... closeables)	Closes a sequence of Closeable resources, logging any failures as a warning.
protected org.jdom2.Element	createElement(String name, Class mbeanClass)	Builds a JDOM Element reflecting the bean's persistent attributes, driven by the JavaBean introspection of mbeanClass.
void	destroy()	destroy the service
protected void	destroyService()	Called during the destroy lifecycle phase; subclasses may override.
protected Iterator	getAttrs()	Iterates over top-level <attr> children of the persisted element.
protected Iterator	getAttrs(String parent)	Iterates over <attr> children nested under the given parent element name.
Configuration	getConfiguration()	Returns the configuration applied to this bean.
String	getDump()	Returns a textual dump of this bean's state.
QFactory	getFactory()	Returns the QFactory associated with the hosting Q2 server.
QClassLoader	getLoader()	Returns the QClassLoader for this bean.
URL[]	getLoaderURLS()	Returns the URLs registered with the class loader.
Log	getLog()	Returns the Log used by this bean.
String	getLogger()	Returns the logger name.
String	getName()	Returns the bean name.
org.jdom2.Element	getPersist()	Returns the persistent configuration element for this QBean.
protected Iterator	getProperties(String parent)	Iterates over <property> children nested under the given parent element name.
protected String	getProperty(Iterator props, String name)	Returns the value of the named property from an iterator of <property> elements.
String	getRealm()	Returns the logging realm.
protected ScheduledThreadPoolExecutor	getScheduledThreadPoolExecutor()	Lazily creates and returns a ScheduledThreadPoolExecutor for use by subclasses.
Q2	getServer()	Returns the Q2 server instance.
int	getState()	Returns the current state of this QBean.
String	getStateAsString()	Returns the current state as a human-readable string.
void	init()	init the service
boolean	isModified()	Returns true if this QBean's configuration has been modified since last save.
boolean	running()	Indicates whether this bean is currently starting or running.
protected void	setAttr(Iterator attrs, String name, Object obj)	Updates the value of the named attribute within an iterator of <attr> elements.
void	setLogger(String loggerName)	Sets the logger by name.
void	setModified(boolean modified)	Marks this bean's persistent state as modified or in sync.
void	setName(String name)	Sets the bean name.
void	setPersist(org.jdom2.Element persist)	Sets the persistent configuration element.
protected void	setProperty(Iterator props, String name, String value)	Updates the value attribute of the named property within an iterator of <property> elements.
void	setRealm(String realm)	Sets the logging realm.
void	setServer(Q2 server)	Sets the Q2 server instance for this QBean.
void	setState(int state)	Sets the lifecycle state of this bean.
void	start()	start the service
void	stop()	stop the service

Methods inherited from class Object

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

Methods inherited from interface Loggeable

dump

Modifier and Type	Method	Description
default void	dump(PrintStream p, String indent, LogRenderer.Type type)	Dumps a representation of this object using the specified renderer type.

Field Details

CONTEXT

public static final String CONTEXT

Space-key prefix used to persist a transaction's serialised context.

See Also:

• Constant Field Values

STATE

public static final String STATE

Space-key prefix used to persist a transaction's lifecycle state.

See Also:

• Constant Field Values

GROUPS

public static final String GROUPS

Space-key prefix used to persist a transaction's group execution stack.

See Also:

• Constant Field Values

RETRY_QUEUE

public static final String RETRY_QUEUE

Space-key under which retried transactions are queued for re-execution.

See Also:

• Constant Field Values

PREPARING

public static final Integer PREPARING

State marker indicating a transaction is in the prepare phase.

COMMITTING

public static final Integer COMMITTING

State marker indicating a transaction is in the commit phase.

DONE

public static final Integer DONE

State marker indicating a transaction has reached its terminal state.

DEFAULT_GROUP

public static final String DEFAULT_GROUP

Group name used when no explicit group is configured.

See Also:

• Constant Field Values

MAX_PARTICIPANTS

public static final long MAX_PARTICIPANTS

Hard ceiling on participants traversed per transaction (loop prevention).

See Also:

• Constant Field Values

MAX_WAIT

public static final long MAX_WAIT

Default maximum time, in milliseconds, that a session waits for input.

See Also:

• Constant Field Values

groups

protected Map<String, List<TransactionParticipant>> groups

Configured group-name to participant-list mapping.

Constructor Details

TransactionManager

public TransactionManager()

Creates an unconfigured manager; configuration is supplied by Q2 at deploy time.

Method Details

defaultRealm

protected String defaultRealm()

Description copied from class: QBeanSupport

Returns the default realm for this bean; subclasses may override.

Overrides:

defaultRealm in class QBeanSupport

Returns:

default realm string, or null

initService

public void initService()
                 throws ConfigurationException

Description copied from class: QBeanSupport

Called during the init lifecycle phase; subclasses may override.

Overrides:

initService in class QBeanSupport

Throws:

ConfigurationException

startService

public void startService()
                  throws Exception

Description copied from class: QBeanSupport

Called during the start lifecycle phase; subclasses may override.

Overrides:

startService in class QBeanSupport

Throws:

Exception - on error

stopService

public void stopService()

Description copied from class: QBeanSupport

Called during the stop lifecycle phase; subclasses may override.

Overrides:

stopService in class QBeanSupport

queue

public void queue(Serializable context)

Enqueues a context at the tail of the input queue (FIFO ordering).

Parameters:

context - serialisable transaction context

push

public void push(Serializable context)

Pushes a context onto the head of the input queue (LIFO ordering).

Parameters:

context - serialisable transaction context

getQueueName

public String getQueueName()

Returns the configured input queue name.

Returns:

the name of the input queue this manager consumes from

getSpace

public Space getSpace()

Returns the volatile space used for in-flight transaction state.

Returns:

the working Space

getInputSpace

public Space getInputSpace()

Returns the externally visible input space used for queueing contexts.

Returns:

the input Space

getPersistentSpace

public Space getPersistentSpace()

Returns the persistent space used to recover in-flight transactions across restarts.

Returns:

the persistent Space

run

public void run()

Specified by:

run in interface Runnable

getTail

public long getTail()

Description copied from interface: TransactionManagerMBean

Returns the current tail index of the transaction queue.

Specified by:

getTail in interface TransactionManagerMBean

Returns:

queue tail index

getHead

public long getHead()

Description copied from interface: TransactionManagerMBean

Returns the current head index of the transaction queue.

Specified by:

getHead in interface TransactionManagerMBean

Returns:

queue head index

getInTransit

public long getInTransit()

Returns the count of transactions that have been picked up but not yet completed.

Returns:

number of in-flight transactions

setConfiguration

public void setConfiguration(Configuration cfg)
                      throws ConfigurationException

Description copied from interface: Configurable

Configures this object with the supplied Configuration.

Specified by:

setConfiguration in interface Configurable

Overrides:

setConfiguration in class QBeanSupport

Parameters:

cfg - Configuration object

Throws:

ConfigurationException - if the configuration is invalid

addListener

public void addListener(TransactionStatusListener l)

Registers a listener that observes transaction lifecycle transitions.

Parameters:

l - listener to add

removeListener

public void removeListener(TransactionStatusListener l)

Removes a previously registered status listener.

Parameters:

l - listener to remove

getTPS

public TPS getTPS()

Returns the TPS counter that tracks transactions per second for this manager.

Returns:

the TPS counter

getTPSAsString

public String getTPSAsString()

Description copied from interface: TransactionManagerMBean

Returns a human-readable summary of TPS statistics.

Specified by:

getTPSAsString in interface TransactionManagerMBean

Returns:

TPS snapshot suitable for diagnostics

getTPSAvg

public float getTPSAvg()

Description copied from interface: TransactionManagerMBean

Returns the average transactions-per-second since the last reset.

Specified by:

getTPSAvg in interface TransactionManagerMBean

Returns:

mean TPS

getTPSPeak

public int getTPSPeak()

Description copied from interface: TransactionManagerMBean

Returns the peak transactions-per-second observed since the last reset.

Specified by:

getTPSPeak in interface TransactionManagerMBean

Returns:

peak TPS

getTPSPeakWhen

public Date getTPSPeakWhen()

Description copied from interface: TransactionManagerMBean

Returns the wall-clock instant at which TransactionManagerMBean.getTPSPeak() was reached.

Specified by:

getTPSPeakWhen in interface TransactionManagerMBean

Returns:

timestamp of the TPS peak, or null if not yet observed

getTPSElapsed

public long getTPSElapsed()

Description copied from interface: TransactionManagerMBean

Returns the elapsed time in milliseconds covered by the current TPS window.

Specified by:

getTPSElapsed in interface TransactionManagerMBean

Returns:

elapsed window in milliseconds

resetTPS

public void resetTPS()

Description copied from interface: TransactionManagerMBean

Resets the TPS counters and start time.

Specified by:

resetTPS in interface TransactionManagerMBean

getMetrics

public Metrics getMetrics()

Description copied from interface: MetricsProvider

Returns the metrics aggregator owned by this component.

Specified by:

getMetrics in interface MetricsProvider

Returns:

the live Metrics instance

dump

public void dump(PrintStream ps,
 String indent)

Description copied from interface: Loggeable

Dumps a human-readable representation of this object to the print stream.

Specified by:

dump in interface Loggeable

Parameters:

ps - the output stream

indent - indentation prefix

commit

protected void commit(int session,
 long id,
 Serializable context,
 List<TransactionParticipant> members,
 boolean recover,
 LogEvent evt,
 Profiler prof)

Walks members in order, invoking each participant's commit phase and recording trace and timer information.

Parameters:

session - session index that owns this transaction

id - transaction identifier

context - serialised transaction context

members - participants whose commit hooks will run

recover - when true, the manager is replaying a transaction after restart and should call ContextRecovery

evt - optional log event to receive trace messages, or null

prof - optional profiler to receive checkpoints, or null

abort

protected void abort(int session,
 long id,
 Serializable context,
 List<TransactionParticipant> members,
 boolean recover,
 LogEvent evt,
 Profiler prof)

Walks members in order, invoking each participant's abort phase and recording trace and timer information.

Parameters:

session - session index that owns this transaction

id - transaction identifier

context - serialised transaction context

members - participants whose abort hooks will run

recover - when true, the manager is replaying a transaction after restart and should call ContextRecovery

evt - optional log event to receive trace messages, or null

prof - optional profiler to receive checkpoints, or null

prepareForAbort

protected int prepareForAbort(TransactionParticipant p,
 long id,
 Serializable context)

Invokes AbortParticipant.prepareForAbort(long, Serializable) on p when applicable, swallowing exceptions and recording timer metrics.

Parameters:

p - participant

id - transaction identifier

context - serialised transaction context

Returns:

result code from the participant, or ABORTED | NO_JOIN when p is not an AbortParticipant or threw

prepare

protected int prepare(TransactionParticipant p,
 long id,
 Serializable context)

Invokes the prepare phase on p, swallowing exceptions (logged as warnings) and recording timer metrics.

Parameters:

p - participant

id - transaction identifier

context - serialised transaction context

Returns:

result code from the participant, or ABORTED when p threw

commit

protected void commit(TransactionParticipant p,
 long id,
 Serializable context)

Invokes the commit phase on p, swallowing exceptions (logged as warnings) and recording timer metrics.

Parameters:

p - participant

id - transaction identifier

context - serialised transaction context

abort

protected void abort(TransactionParticipant p,
 long id,
 Serializable context)

Invokes the abort phase on p, swallowing exceptions (logged as warnings) and recording timer metrics.

Parameters:

p - participant

id - transaction identifier

context - serialised transaction context

prepare

protected int prepare(int session,
 long id,
 Serializable context,
 List<TransactionParticipant> members,
 Iterator<TransactionParticipant> iter,
 boolean abort,
 LogEvent evt,
 Profiler prof,
 Chronometer chronometer)

Drives the prepare phase across iter, accumulating results into members and aborting on retry signals or participant exceptions.

Parameters:

session - session index that owns this transaction

id - transaction identifier

context - serialised transaction context

members - accumulator of participants whose prepare ran

iter - participant iterator (may include selectors / groups)

abort - when true, drive the prepare-for-abort path

evt - optional log event to receive trace messages, or null

prof - optional profiler to receive checkpoints, or null

chronometer - chronometer used to enforce max-time

Returns:

the bitwise OR of every participant result, suitable for the lifecycle dispatcher

getParticipants

protected List<TransactionParticipant> getParticipants(String groupName)

Returns the configured participants for a named group.

Parameters:

groupName - group name (use DEFAULT_GROUP for the default chain)

Returns:

participants in declaration order; an empty list when groupName is unknown

getParticipants

protected List<TransactionParticipant> getParticipants(long id)

Returns the participant chain for a specific transaction, combining the default group with any groups pushed onto the persistent execution stack.

Parameters:

id - transaction identifier

Returns:

participants to invoke in order

initStatusListeners

protected void initStatusListeners(org.jdom2.Element config)
                            throws ConfigurationException

Instantiates and registers any <status-listener> children of the QBean descriptor.

Parameters:

config - descriptor element

Throws:

ConfigurationException - if a listener cannot be instantiated or configured

initParticipants

protected void initParticipants(org.jdom2.Element config)
                         throws ConfigurationException

Builds the default participant group plus any named <group> children from the QBean descriptor.

Parameters:

config - descriptor element

Throws:

ConfigurationException - if a group is missing a name, duplicates an existing group, or a participant fails to instantiate

initGroup

protected List<TransactionParticipant> initGroup(org.jdom2.Element e)
                                          throws ConfigurationException

Instantiates the participants declared inside a <group> element, skipping any that are explicitly disabled.

Parameters:

e - group element

Returns:

participants in declaration order

Throws:

ConfigurationException - if a participant fails to instantiate

createParticipant

public TransactionParticipant createParticipant(org.jdom2.Element e)
                                         throws ConfigurationException

Instantiates a participant from a <participant> element, configures it, registers per-participant timers, and tracks any Destroyable for cleanup at shutdown.

Parameters:

e - participant element

Returns:

the configured participant

Throws:

ConfigurationException - if instantiation, configuration, or timer registration fails

getOutstandingTransactions

public int getOutstandingTransactions()

Description copied from interface: TransactionManagerMBean

Returns the number of in-flight transactions (tail - head).

Specified by:

getOutstandingTransactions in interface TransactionManagerMBean

Returns:

outstanding transaction count

getKey

protected String getKey(String prefix,
 long id)

Builds a persistent-space key by combining the manager name, a prefix, and the transaction id.

Parameters:

prefix - key namespace (e.g. CONTEXT, STATE)

id - transaction identifier

Returns:

the assembled space key

commitOff

protected void commitOff(Space sp)

Disables auto-commit on a JDBMSpace; no-op for other space types.

Parameters:

sp - the space whose auto-commit should be turned off

commitOn

protected void commitOn(Space sp)

Re-enables auto-commit on a JDBMSpace, flushing any pending writes; no-op for other space types.

Parameters:

sp - the space whose auto-commit should be turned back on

checkTail

protected void checkTail()

Advances the persistent tail pointer past any contiguous already-DONE transactions, purging their state from the space.

tailDone

protected boolean tailDone()

Returns whether the transaction at tail is already DONE; when true, removes its persistent state.

Returns:

true when the tail transaction has reached terminal state

snapshot

protected void snapshot(long id,
 Serializable context)

Snapshots the context for transaction id without changing its state.

Parameters:

id - transaction identifier

context - serialised transaction context, or null to clear it

snapshot

protected void snapshot(long id,
 Serializable context,
 Integer status)

Snapshots the context and optionally updates the persisted state for transaction id. Skipped when recovery is disabled and the status is not DONE.

Parameters:

id - transaction identifier

context - serialised transaction context, or null to clear it

status - new persisted state, or null to leave it unchanged

setState

protected void setState(long id,
 Integer state)

Atomically replaces the persisted lifecycle state for id.

Parameters:

id - transaction identifier

state - new state, or null to clear it

addGroup

protected void addGroup(long id,
 String groupName)

Pushes a group name onto the persistent execution stack for id.

Parameters:

id - transaction identifier

groupName - group to schedule, or null for a no-op

purge

protected void purge(long id,
 boolean full)

Removes persistent state associated with a transaction.

Parameters:

id - transaction identifier

full - when true, also removes the lifecycle state entry (otherwise only context and group entries are cleared)

recover

protected void recover()

Replays every in-flight transaction recorded in the persistent space, advancing the tail pointer as each completes. No-op when recovery is disabled.

recover

protected void recover(long id)

Replays a single transaction by inspecting its persisted state and driving either the commit or abort path before purging its state.

Parameters:

id - transaction identifier

checkRetryTask

protected void checkRetryTask()

Lazily starts the TransactionManager.RetryTask that drains the retry queue back into the input space.

freeze

protected LogEvent freeze(Serializable context,
 LogEvent evt,
 Profiler prof)

This method gives the opportunity to decorate a LogEvent right before it gets logged. When overriding it, unless you know what you're doing, you should return a FrozenLogEvent in order to prevent concurrency issues.

Parameters:

context - current Context

evt - current LogEvent

prof - profiler (may be null)

Returns:

FrozenLogEvent

getSessionsToStandUp

protected int getSessionsToStandUp()

This method returns the number of sessions that can be started at this point in time

Returns:

number of sessions

isSessionToStandDown

protected boolean isSessionToStandDown()

Hook used by subclasses to drain a session early. The default implementation never asks a session to stand down.

Returns:

true if the current session should stop accepting new transactions

getActiveSessions

public int getActiveSessions()

Description copied from interface: TransactionManagerMBean

Returns the number of session threads currently processing transactions.

Specified by:

getActiveSessions in interface TransactionManagerMBean

Returns:

live session count

getMaxSessions

public int getMaxSessions()

Description copied from interface: TransactionManagerMBean

Returns the configured maximum number of concurrent session threads.

Specified by:

getMaxSessions in interface TransactionManagerMBean

Returns:

the maximum number of sessions this manager may scale up to

getSerializable

public static Serializable getSerializable()

Returns the current thread's transaction context as a raw Serializable.

Returns:

the thread-local context, or null when no transaction is in progress

getContext

public static <T extends Serializable> T getContext()

Returns the current thread's transaction context, narrowed to the caller's expected type.

Type Parameters:

T - caller-supplied context type

Returns:

the thread-local context, or null when no transaction is in progress

getId

public static Long getId()

Returns the current thread's transaction id, when one is in progress.

Returns:

the thread-local transaction id, or null