org.apache.nifi.controller.repository

Interface FlowFileSwapManager

public interface FlowFileSwapManager

Defines a mechanism by which FlowFiles can be move into external storage or memory so that they can be removed from the Java heap and vice-versa

Method Summary

Modifier and Type	Method and Description
Long	getMaxRecordId(String swapLocation) Returns the maximum record id of the FlowFiles stored at the given swap location
QueueSize	getSwapSize(String swapLocation) Determines how many FlowFiles and the size of the FlowFiles that are swapped out at the given location
void	initialize(SwapManagerInitializationContext initializationContext) Initializes the Swap Manager, providing a SwapManagerInitializationContext so that the Swap Manager has access to all of the components necessary to perform its functions
List<FlowFileRecord>	peek(String swapLocation, FlowFileQueue flowFileQueue) Recovers the SwapFiles from the swap file that lives at the given location.
void	purge() Purge all known Swap Files without updating FlowFileRepository or Provenance Repository
List<String>	recoverSwapLocations(FlowFileQueue flowFileQueue) Determines swap files that exist for the given FlowFileQueue
List<FlowFileRecord>	swapIn(String swapLocation, FlowFileQueue flowFileQueue) Recovers the FlowFiles from the swap file that lives at the given location and belongs to the FlowFile Queue with the given identifier.
String	swapOut(List<FlowFileRecord> flowFiles, FlowFileQueue flowFileQueue) Swaps out the given FlowFiles that belong to the queue with the given identifier.

Method Detail

initialize

void initialize(SwapManagerInitializationContext initializationContext)

Initializes the Swap Manager, providing a SwapManagerInitializationContext so that the Swap Manager has access to all of the components necessary to perform its functions

Parameters:

initializationContext - the context the provides the swap manager with access to the resources that it needs to perform its functions

swapOut

String swapOut(List<FlowFileRecord> flowFiles,
               FlowFileQueue flowFileQueue)
        throws IOException

Swaps out the given FlowFiles that belong to the queue with the given identifier.

Parameters:

flowFiles - the FlowFiles to swap out to external storage

flowFileQueue - the queue that the FlowFiles belong to

Returns:

the location of the externally stored swap file

Throws:

IOException - if unable to swap the FlowFiles out

peek

List<FlowFileRecord> peek(String swapLocation,
                          FlowFileQueue flowFileQueue)
                   throws IOException

Recovers the SwapFiles from the swap file that lives at the given location. This action provides a view of the FlowFiles but does not actively swap them in, meaning that the swap file at the given location remains in that location and the FlowFile Repository is not updated.

Parameters:

swapLocation - the location of the swap file

flowFileQueue - the queue that the FlowFiles belong to

Returns:

the FlowFiles that live at the given swap location

Throws:

IOException - if unable to recover the FlowFiles from the given location

swapIn

List<FlowFileRecord> swapIn(String swapLocation,
                            FlowFileQueue flowFileQueue)
                     throws IOException

Recovers the FlowFiles from the swap file that lives at the given location and belongs to the FlowFile Queue with the given identifier. The FlowFile Repository is then updated and the swap file is permanently removed from the external storage

Parameters:

swapLocation - the location of the swap file

flowFileQueue - the queue to which the FlowFiles belong

Returns:

the FlowFiles that are stored in the given location

Throws:

IOException - if unable to recover the FlowFiles from the given location or update the FlowFileRepository

recoverSwapLocations

List<String> recoverSwapLocations(FlowFileQueue flowFileQueue)
                           throws IOException

Determines swap files that exist for the given FlowFileQueue

Parameters:

flowFileQueue - the queue for which the FlowFiles should be recovered

Returns:

all swap locations that have been identified for the given queue, in the order that they should be swapped back in

Throws:

IOException

getSwapSize

QueueSize getSwapSize(String swapLocation)
               throws IOException

Determines how many FlowFiles and the size of the FlowFiles that are swapped out at the given location

Parameters:

swapLocation - the location of the swap file

Returns:

the QueueSize representing the number of FlowFiles and total size of the FlowFiles that are swapped out

Throws:

IOException

getMaxRecordId

Long getMaxRecordId(String swapLocation)
             throws IOException

Returns the maximum record id of the FlowFiles stored at the given swap location

Parameters:

swapLocation - the swap location to read id's from

Returns:

the max record id of any FlowFile in the swap location, or null if no record ID's can be found

Throws:

IOException

purge

void purge()

Purge all known Swap Files without updating FlowFileRepository or Provenance Repository