org.jboss.msc.service

Class OptionalDependency

java.lang.Object

org.jboss.msc.service.OptionalDependency

All Implemented Interfaces:

Dependency, Dependent, Value<java.lang.Object>

class OptionalDependency
extends java.lang.Object
implements Dependency, Dependent

An OptionalDependency.
This class establishes a transitive dependency relationship between the dependent and the real dependency. The intermediation performed by this class adds the required optional behavior to the dependency relation, by:

• notifies the dependent that it is in the UP state when the real dependency is unresolved or unavailable
• once the real dependency is available, if there is a demand previously added by the dependent, this dependency does not start forwarding the notifications to the dependent, meaning that the dependent won't even be aware that the dependency is down
• waits for the dependency to be available and the dependent to be inactive, so it can finally start forwarding notifications in both directions (from dependency to dependent and vice-versa)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
private static class	OptionalDependency.DependencyState One of the states of a dependency from the dependent point of view (i.e., based on notifications made by the dependency).

Field Summary

Fields

Modifier and Type	Field and Description
private boolean	demandedByDependent Indicates if this dependency has been demanded by the dependent
private boolean	dependencyFailed Indicates if optionalDependency notified a dependency failure.
private OptionalDependency.DependencyState	dependencyState The optionalDependency state, based on notifications that optionalDependency made to this dependent.
private Dependent	dependent The dependent on this optional dependency
private boolean	dependentStartedNotified Keeps track of whether optionalDependency has been notified of a dependent started.
(package private) boolean	forwardNotifications Indicates if notification should take place
private Dependency	optionalDependency The actual dependency.
private boolean	transitiveDependencyUnavailable Indicates if optional dependency has a transitive dependency unavailable.

Constructor Summary

Constructors

Constructor and Description
OptionalDependency(Dependency optionalDependency)

Method Summary

Modifier and Type	Method and Description
void	addDemand() Notify that a dependent entered active mode.
void	addDependent(Dependent dependent) Add a dependent to this dependency, establishing the dependency relation between this dependency and its dependent.
void	dependencyFailed() Notify this dependent that one of its dependencies (immediate or transitive) failed to start.
void	dependencyFailureCleared() Notify this dependent that all dependency failures previously notified are now cleared.
void	dependentStarted() Notify that a dependent is starting.
void	dependentStopped() Notify that a dependent is stopping.
ServiceControllerImpl<?>	getController() Get the controller of this dependent.
ServiceControllerImpl<?>	getDependencyController() Get the controller for this dependency, or null if there is none currently.
ServiceName	getName() Get the name of this dependency.
java.lang.Object	getValue() Get the installed instance value, if any exists.
void	immediateDependencyAvailable(ServiceName dependencyName) Notify this dependent that one of its immediate dependencies is available, i.e., it is installed and, if not started, should start shortly.
void	immediateDependencyDown() Notify this dependent that one of its immediate dependencies is leaving the UP state.
void	immediateDependencyUnavailable(ServiceName dependencyName) Notify this dependent that one of its immediate dependencies is unavailable. A dependency is unavailable when it is not installed or when it is in NEVER mode.
void	immediateDependencyUp() Notify this dependent that one of its immediate dependencies entered UP state.
void	removeDemand() Notify that a dependent left active mode.
void	removeDependent(Dependent dependent) Remove a dependent from this dependency, breaking the dependency relation between this dependency and its dependent.
void	transitiveDependencyAvailable() Notify this dependent that all unavailable transitive dependencies are now available (i.e., they are installed and will perform an attempt to start shortly).
void	transitiveDependencyUnavailable() Notify this dependent that one of its transitive dependencies is unavailable (either uninstalled, or in NEVER mode).

Methods inherited from class java.lang.Object

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

Field Detail

optionalDependency

private final Dependency optionalDependency

The actual dependency.

dependencyState

private OptionalDependency.DependencyState dependencyState

The optionalDependency state, based on notifications that optionalDependency made to this dependent.

transitiveDependencyUnavailable

private boolean transitiveDependencyUnavailable

Indicates if optional dependency has a transitive dependency unavailable.

dependencyFailed

private boolean dependencyFailed

Indicates if optionalDependency notified a dependency failure.

dependent

private Dependent dependent

The dependent on this optional dependency

demandedByDependent

private boolean demandedByDependent

Indicates if this dependency has been demanded by the dependent

forwardNotifications

boolean forwardNotifications

Indicates if notification should take place

dependentStartedNotified

private boolean dependentStartedNotified

Keeps track of whether optionalDependency has been notified of a dependent started. This field is useful for avoiding dependentStopped notifications that don't have a corresponding previous dependentStarted notification.

Constructor Detail

OptionalDependency

OptionalDependency(Dependency optionalDependency)

Method Detail

addDependent

public void addDependent(Dependent dependent)

Description copied from interface: Dependency

Add a dependent to this dependency, establishing the dependency relation between this dependency and its dependent. This method must not be called under a lock.

Specified by:

addDependent in interface Dependency

Parameters:

dependent - the dependent to add

removeDependent

public void removeDependent(Dependent dependent)

Description copied from interface: Dependency

Remove a dependent from this dependency, breaking the dependency relation between this dependency and its dependent. This method must not be called under a lock.

Specified by:

removeDependent in interface Dependency

Parameters:

dependent - the dependent to remove

addDemand

public void addDemand()

Description copied from interface: Dependency

Notify that a dependent entered active mode. This method must not be called under a lock.

Specified by:

addDemand in interface Dependency

removeDemand

public void removeDemand()

Description copied from interface: Dependency

Notify that a dependent left active mode. This method must not be called under a lock.

Specified by:

removeDemand in interface Dependency

dependentStarted

public void dependentStarted()

Description copied from interface: Dependency

Notify that a dependent is starting. This method must not be called under a lock.

Specified by:

dependentStarted in interface Dependency

dependentStopped

public void dependentStopped()

Description copied from interface: Dependency

Notify that a dependent is stopping. This method must not be called under a lock.

Specified by:

dependentStopped in interface Dependency

getValue

public java.lang.Object getValue()
                          throws java.lang.IllegalStateException

Description copied from interface: Dependency

Get the installed instance value, if any exists.

Specified by:

getValue in interface Dependency

Specified by:

getValue in interface Value<java.lang.Object>

Returns:

the installed service value

Throws:

java.lang.IllegalStateException - if an error occurs

getName

public ServiceName getName()

Description copied from interface: Dependency

Get the name of this dependency.

Specified by:

getName in interface Dependency

Returns:

the name

getDependencyController

public ServiceControllerImpl<?> getDependencyController()

Description copied from interface: Dependency

Get the controller for this dependency, or null if there is none currently.

Specified by:

getDependencyController in interface Dependency

Returns:

the controller, or null for none

immediateDependencyAvailable

public void immediateDependencyAvailable(ServiceName dependencyName)

Description copied from interface: Dependent

Notify this dependent that one of its immediate dependencies is available, i.e., it is installed and, if not started, should start shortly.

This method must not be called under a lock.

Specified by:

immediateDependencyAvailable in interface Dependent

Parameters:

dependencyName - the name of the immediate dependency that is now available

immediateDependencyUnavailable

public void immediateDependencyUnavailable(ServiceName dependencyName)

Description copied from interface: Dependent

Notify this dependent that one of its immediate dependencies is unavailable.
A dependency is unavailable when it is not installed or when it is in NEVER mode.

This method must not be called under a lock.

Specified by:

immediateDependencyUnavailable in interface Dependent

Parameters:

dependencyName - the name of the immediate dependency that is now unavailable

immediateDependencyUp

public void immediateDependencyUp()

Description copied from interface: Dependent

Notify this dependent that one of its immediate dependencies entered UP state.

This method must not be called under a lock.

Specified by:

immediateDependencyUp in interface Dependent

immediateDependencyDown

public void immediateDependencyDown()

Description copied from interface: Dependent

Notify this dependent that one of its immediate dependencies is leaving the UP state.

This method must not be called under a lock.

Specified by:

immediateDependencyDown in interface Dependent

dependencyFailed

public void dependencyFailed()

Description copied from interface: Dependent

Notify this dependent that one of its dependencies (immediate or transitive) failed to start. This method is called after the dependency state transitions from STARTING to START_FAILED.

Dependency failures that occur after the notified failure do not result in new dependencyFailed notifications, as the dependent will never receive two or more dependencyFailed calls in a row. A dependencyFailed notification is only invoked again to notify of new failures if the previous failures have been cleared.

This method must not be called under a lock.

Specified by:

dependencyFailed in interface Dependent

dependencyFailureCleared

public void dependencyFailureCleared()

Description copied from interface: Dependent

Notify this dependent that all dependency failures previously notified are now cleared. This method is called only after all affected dependencies left START_FAILED state.

This method must not be called under a lock.

Specified by:

dependencyFailureCleared in interface Dependent

transitiveDependencyAvailable

public void transitiveDependencyAvailable()

Description copied from interface: Dependent

Notify this dependent that all unavailable transitive dependencies are now available (i.e., they are installed and will perform an attempt to start shortly).

This method must not be called under a lock.

Specified by:

transitiveDependencyAvailable in interface Dependent

getController

public ServiceControllerImpl<?> getController()

Description copied from interface: Dependent

Get the controller of this dependent.

Specified by:

getController in interface Dependent

Returns:

the controller

transitiveDependencyUnavailable

public void transitiveDependencyUnavailable()

Description copied from interface: Dependent

Notify this dependent that one of its transitive dependencies is unavailable (either uninstalled, or in NEVER mode).

New transitive dependencies that become unavailable after the notified one do not result in new dependencyUnavailable notifications, as the dependent will never receive two or more dependencyUnavailable calls in a row. A dependencyUnavailable notification is only invoked again to notify of newly found unavailable dependencies if all the previously unavailable dependencies have become available.

This method must not be called under a lock.

Specified by:

transitiveDependencyUnavailable in interface Dependent