org.apache.nifi.controller.state.providers.local

Class WriteAheadLocalStateProvider

java.lang.Object

org.apache.nifi.components.AbstractConfigurableComponent

org.apache.nifi.controller.state.providers.AbstractStateProvider

org.apache.nifi.controller.state.providers.local.WriteAheadLocalStateProvider

All Implemented Interfaces:

ConfigurableComponent, StateProvider

public class WriteAheadLocalStateProvider
extends AbstractStateProvider

Provides state management for local (standalone) state, backed by a write-ahead log

Constructor Summary

Constructors

Constructor and Description
WriteAheadLocalStateProvider()

Method Summary

Modifier and Type	Method and Description
void	clear(java.lang.String componentId) Removes all values from the component's state that is stored using the given scope
StateMap	getState(java.lang.String componentId) Returns the currently configured state for the component.
java.util.List<PropertyDescriptor>	getSupportedPropertyDescriptors() Allows subclasses to register which property descriptor objects are supported.
Scope[]	getSupportedScopes() Provides a listing of Scopes supported by the StateProvider
void	init(StateProviderInitializationContext context)
void	onComponentRemoved(java.lang.String componentId) This method is called whenever a component is removed from the NiFi instance.
boolean	replace(StateMap oldValue, java.util.Map<java.lang.String,java.lang.String> newValue, java.lang.String componentId) Updates the value of the component's state to the new value if and only if the value currently is the same as the given oldValue.
void	setState(java.util.Map<java.lang.String,java.lang.String> state, java.lang.String componentId) Updates the value of the component's state, setting the new value to the given state
void	shutdown() Shuts down the StateProvider and cleans up any resources held by it.

Methods inherited from class org.apache.nifi.controller.state.providers.AbstractStateProvider

disable, enable, getIdentifier, initialize, isEnabled

Methods inherited from class org.apache.nifi.components.AbstractConfigurableComponent

customValidate, equals, getPropertyDescriptor, getPropertyDescriptors, getSupportedDynamicPropertyDescriptor, hashCode, onPropertyModified, toString, validate

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.nifi.components.ConfigurableComponent

getPropertyDescriptor, getPropertyDescriptors, onPropertyModified, validate

Constructor Detail

WriteAheadLocalStateProvider

public WriteAheadLocalStateProvider()

Method Detail

init

public void init(StateProviderInitializationContext context)
          throws java.io.IOException

Specified by:

init in class AbstractStateProvider

Throws:

java.io.IOException

getSupportedPropertyDescriptors

public java.util.List<PropertyDescriptor> getSupportedPropertyDescriptors()

Description copied from class: AbstractConfigurableComponent

Allows subclasses to register which property descriptor objects are supported. Default return is an empty set.

Overrides:

getSupportedPropertyDescriptors in class AbstractConfigurableComponent

Returns:

PropertyDescriptor objects this processor currently supports

shutdown

public void shutdown()

Description copied from interface: StateProvider

Shuts down the StateProvider and cleans up any resources held by it. Once this method has returned, the StateProvider may be initialized once again via the StateProvider.initialize(StateProviderInitializationContext) method.

getState

public StateMap getState(java.lang.String componentId)
                  throws java.io.IOException

Description copied from interface: StateProvider

Returns the currently configured state for the component. The returned StateMap will never be null. The version of the StateMap will be -1 and the state will contain no key/value pairs if the state has never been set.

Parameters:

componentId - the id of the component for which state is to be retrieved

Returns:

the currently configured value for the component's state

Throws:

java.io.IOException - if unable to communicate with the underlying storage mechanism

setState

public void setState(java.util.Map<java.lang.String,java.lang.String> state,
                     java.lang.String componentId)
              throws java.io.IOException

Description copied from interface: StateProvider

Updates the value of the component's state, setting the new value to the given state

Parameters:

state - the value to change the state to

componentId - the id of the component for which state is being set

Throws:

java.io.IOException - if unable to communicate with the underlying storage mechanism

replace

public boolean replace(StateMap oldValue,
                       java.util.Map<java.lang.String,java.lang.String> newValue,
                       java.lang.String componentId)
                throws java.io.IOException

Description copied from interface: StateProvider

Updates the value of the component's state to the new value if and only if the value currently is the same as the given oldValue.

Parameters:

oldValue - the old value to compare against

newValue - the new value to use if and only if the state's value is the same as the given oldValue

componentId - the id of the component for which state is being retrieved

Returns:

true if the state was updated to the new value, false if the state's value was not equal to oldValue

Throws:

java.io.IOException - if unable to communicate with the underlying storage mechanism

clear

public void clear(java.lang.String componentId)
           throws java.io.IOException

Description copied from interface: StateProvider

Removes all values from the component's state that is stored using the given scope

Parameters:

componentId - the id of the component for which state is being cleared

Throws:

java.io.IOException - if unable to communicate with the underlying storage mechanism

onComponentRemoved

public void onComponentRemoved(java.lang.String componentId)
                        throws java.io.IOException

Description copied from interface: StateProvider

This method is called whenever a component is removed from the NiFi instance. This allows the State Provider to perform tasks when a component is removed in order to clean up resources that may be associated with that component

Parameters:

componentId - the ID of the component that was added to the NiFi instance

Throws:

java.io.IOException - if unable to perform the necessary cleanup

getSupportedScopes

public Scope[] getSupportedScopes()

Description copied from interface: StateProvider

Provides a listing of Scopes supported by the StateProvider

Returns:

the Scopes supported by the configuration