org.eclipse.gemini.blueprint.extender.internal.dependencies.startup

Class DependencyWaiterApplicationContextExecutor

java.lang.Object

org.eclipse.gemini.blueprint.extender.internal.dependencies.startup.DependencyWaiterApplicationContextExecutor

All Implemented Interfaces:

OsgiBundleApplicationContextExecutor, ContextExecutorAccessor

public class DependencyWaiterApplicationContextExecutor
extends java.lang.Object
implements OsgiBundleApplicationContextExecutor, ContextExecutorAccessor

Dependency waiter executor that breaks the 'traditional' ConfigurableApplicationContext.refresh() in two pieces so that beans are not actually created unless the OSGi service imported are present.

Supports both asynch and synch behaviour.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private class	DependencyWaiterApplicationContextExecutor.CompleteRefreshTask Create the Runnable action which will complete the context creation process.
private class	DependencyWaiterApplicationContextExecutor.WatchDogTask The task for the watch dog.

Field Summary

Fields

Modifier and Type	Field and Description
protected DelegatedExecutionOsgiBundleApplicationContext	delegateContext
private OsgiBundleApplicationContextEventMulticaster	delegatedMulticaster delegated multicaster
protected DependencyServiceManager	dependencyDetector OSGi service dependencyDetector used for detecting dependencies
private java.util.List<OsgiServiceDependencyFactory>	dependencyFactories
private static org.apache.commons.logging.Log	log
private java.lang.Object	monitor this class monitor.
private Counter	monitorCounter A synchronized counter used by the Listener to determine the number of children to wait for when shutting down.
private ContextState	state State of the associated context from the executor POV.
private boolean	synchronousWait Should the waiting be synchrous or not ?
private org.springframework.core.task.TaskExecutor	taskExecutor
private long	timeout waiting timeout
private Counter	waitBarrier Counter used when waiting for dependencies to appear
private java.util.Timer	watchdog the timer used for executing the timeout
private java.util.TimerTask	watchdogTask watchdog task

Constructor Summary

Constructors

Constructor and Description
DependencyWaiterApplicationContextExecutor(DelegatedExecutionOsgiBundleApplicationContext delegateContext, boolean syncWait, java.util.List<OsgiServiceDependencyFactory> dependencyFactories)

Method Summary

Modifier and Type	Method and Description
void	close() The application context is being shutdown.
protected DependencyServiceManager	createDependencyServiceListener(java.lang.Runnable task)
void	fail(java.lang.Throwable t)
private void	fail(java.lang.Throwable t, boolean skipEvent) Fail creating the context.
private org.osgi.framework.Bundle	getBundle()
ContextState	getContextState()
private java.lang.String	getDisplayName()
OsgiBundleApplicationContextEventMulticaster	getEventMulticaster()
protected void	init() Do some sanity checks
private void	logWrongState(ContextState expected) Reduce the code pollution.
void	refresh() Provide a continuation like approach to the application context.
void	setDelegatedMulticaster(OsgiBundleApplicationContextEventMulticaster multicaster) Sets the multicaster for delegating failing events.
void	setMonitoringCounter(Counter contextsStarted) Pass in the context counter.
void	setTaskExecutor(org.springframework.core.task.TaskExecutor taskExec)
void	setTimeout(long timeout) Sets the timeout (in ms) for waiting for service dependencies.
void	setWatchdog(java.util.Timer watchdog)
protected void	stageOne() Start the first stage of the application context refresh.
protected void	stageTwo()
protected void	startWatchDog() Schedule the watchdog task.
protected void	stopWatchDog()
private void	timeout() Cancel waiting due to timeout.

Methods inherited from class java.lang.Object

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

Field Detail

log

private static final org.apache.commons.logging.Log log

monitor

private final java.lang.Object monitor

this class monitor. Since multiple threads will access this object, we have to use synchronization to guarantee thread visibility

timeout

private long timeout

waiting timeout

watchdog

private java.util.Timer watchdog

the timer used for executing the timeout

watchdogTask

private java.util.TimerTask watchdogTask

watchdog task

dependencyDetector

protected DependencyServiceManager dependencyDetector

OSGi service dependencyDetector used for detecting dependencies

delegateContext

protected final DelegatedExecutionOsgiBundleApplicationContext delegateContext

state

private ContextState state

State of the associated context from the executor POV.

taskExecutor

private org.springframework.core.task.TaskExecutor taskExecutor

monitorCounter

private Counter monitorCounter

A synchronized counter used by the Listener to determine the number of children to wait for when shutting down.

synchronousWait

private final boolean synchronousWait

Should the waiting be synchrous or not ?

waitBarrier

private final Counter waitBarrier

Counter used when waiting for dependencies to appear

delegatedMulticaster

private OsgiBundleApplicationContextEventMulticaster delegatedMulticaster

delegated multicaster

dependencyFactories

private java.util.List<OsgiServiceDependencyFactory> dependencyFactories

Constructor Detail

DependencyWaiterApplicationContextExecutor

public DependencyWaiterApplicationContextExecutor(DelegatedExecutionOsgiBundleApplicationContext delegateContext,
                                                  boolean syncWait,
                                                  java.util.List<OsgiServiceDependencyFactory> dependencyFactories)

Method Detail

refresh

public void refresh()
             throws org.springframework.beans.BeansException,
                    java.lang.IllegalStateException

Provide a continuation like approach to the application context. Will execute just some parts of refresh and then leave the rest of to be executed after a number of conditions have been met.

Specified by:

refresh in interface OsgiBundleApplicationContextExecutor

Throws:

org.springframework.beans.BeansException

java.lang.IllegalStateException

init

protected void init()

Do some sanity checks

stageOne

protected void stageOne()

Start the first stage of the application context refresh. Determines the service dependencies and if there are any, registers a OSGi service dependencyDetector which will continue the refresh process asynchronously.

Based on the synchronousWait, the current thread can simply end if there are any dependencies (the default) or wait to either timeout or have all its dependencies met.

stageTwo

protected void stageTwo()

close

public void close()

The application context is being shutdown. Deregister the listener and prevent classes from being loaded since it's Doom's day.

Specified by:

close in interface OsgiBundleApplicationContextExecutor

fail

public void fail(java.lang.Throwable t)

Specified by:

fail in interface ContextExecutorAccessor

fail

private void fail(java.lang.Throwable t,
                  boolean skipEvent)

Fail creating the context. Figure out unsatisfied dependencies and provide a very nice log message before closing the appContext.

Normally this method is called when an exception is caught.

Parameters:

t - - the offending Throwable which caused our demise

timeout

private void timeout()

Cancel waiting due to timeout.

createDependencyServiceListener

protected DependencyServiceManager createDependencyServiceListener(java.lang.Runnable task)

startWatchDog

protected void startWatchDog()

Schedule the watchdog task.

stopWatchDog

protected void stopWatchDog()

setTimeout

public void setTimeout(long timeout)

Sets the timeout (in ms) for waiting for service dependencies.

Parameters:

timeout -

setTaskExecutor

public void setTaskExecutor(org.springframework.core.task.TaskExecutor taskExec)

getBundle

private org.osgi.framework.Bundle getBundle()

getDisplayName

private java.lang.String getDisplayName()

setWatchdog

public void setWatchdog(java.util.Timer watchdog)

logWrongState

private void logWrongState(ContextState expected)

Reduce the code pollution.

Parameters:

expected - the expected value for the context state.

setMonitoringCounter

public void setMonitoringCounter(Counter contextsStarted)

Pass in the context counter. Used by the listener to track the number of contexts started.

Parameters:

asynchCounter -

setDelegatedMulticaster

public void setDelegatedMulticaster(OsgiBundleApplicationContextEventMulticaster multicaster)

Sets the multicaster for delegating failing events.

Parameters:

multicaster -

getContextState

public ContextState getContextState()

Specified by:

getContextState in interface ContextExecutorAccessor

getEventMulticaster

public OsgiBundleApplicationContextEventMulticaster getEventMulticaster()

Specified by:

getEventMulticaster in interface ContextExecutorAccessor