Package org.dataloader.registries

Class ScheduledDataLoaderRegistry

java.lang.Object

org.dataloader.DataLoaderRegistry

org.dataloader.registries.ScheduledDataLoaderRegistry

All Implemented Interfaces:

AutoCloseable

@ExperimentalApi
@NullMarked
public class ScheduledDataLoaderRegistry
extends DataLoaderRegistry
implements AutoCloseable

This DataLoaderRegistry will use DispatchPredicates when dispatchAll() is called to test (for each DataLoader in the registry) if a dispatch should proceed. If the predicate returns false, then a task is scheduled to perform that predicate dispatch again via the ScheduledExecutorService.

It;s possible to have a DispatchPredicate per dataloader as well as a default DispatchPredicate for the whole ScheduledDataLoaderRegistry.

This will continue to loop (test false and reschedule) until such time as the predicate returns true, in which case no rescheduling will occur, and you will need to call dispatch again to restart the process.

In the default mode, when tickerMode is false, the registry will continue to loop (test false and reschedule) until such time as the predicate returns true, in which case no rescheduling will occur, and you will need to call dispatch again to restart the process.

However, when tickerMode is true, the registry will always reschedule continuously after the first ever call to dispatchAll().

This will allow you to chain together DataLoader load calls like this :

   CompletableFuture<String> future = dataLoaderA.load("A")
                                          .thenCompose(value -> dataLoaderB.load(value));
 

However, it may mean your batching will not be as efficient as it might be. In environments like graphql this might mean you are too eager in fetching. The DispatchPredicate still runs to decide if dispatch should happen however in ticker mode it will be continuously rescheduled.

When tickerMode is true, you really SHOULD close the registry say at the end of a request otherwise you will leave a job on the ScheduledExecutorService that is continuously dispatching.

If you wanted to create a ScheduledDataLoaderRegistry that started a rescheduling immediately, just create one and call rescheduleNow().

By default, it uses a Executors.newSingleThreadScheduledExecutor()} to schedule the tasks. However, if you are creating a ScheduledDataLoaderRegistry per request you will want to look at sharing this ScheduledExecutorService to avoid creating a new thread per registry created.

This code is currently marked as ExperimentalApi

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ScheduledDataLoaderRegistry.Builder

Field Summary

Fields inherited from class org.dataloader.DataLoaderRegistry

dataLoaders, instrumentation

Method Summary

Modifier and Type	Method	Description
void	close()	Once closed this registry will never again reschedule checks
ScheduledDataLoaderRegistry	combine(DataLoaderRegistry registry)	This will combine all the current data loaders in this registry and all the data loaders from the specified registry and return a new combined registry
void	dispatchAll()	This will be called DataLoader.dispatch() on each of the registered DataLoaders
void	dispatchAllImmediately()	This will immediately dispatch the DataLoaders in the registry without testing the predicates
int	dispatchAllWithCount()	Similar to DataLoaderRegistry.dispatchAll(), this calls DataLoader.dispatch() on each of the registered DataLoaders, but returns the number of dispatches.
int	dispatchAllWithCountImmediately()	This will immediately dispatch the DataLoaders in the registry without testing the predicates
Map<DataLoader<?,?>,DispatchPredicate>	getDataLoaderPredicates()
DispatchPredicate	getDispatchPredicate()	There is a default predicate that applies to the whole ScheduledDataLoaderRegistry
ScheduledExecutorService	getScheduledExecutorService()
Duration	getScheduleDuration()
boolean	isTickerMode()
static ScheduledDataLoaderRegistry.Builder	newScheduledRegistry()	By default, this will create use a Executors.newSingleThreadScheduledExecutor() and a schedule duration of 10 milliseconds.
ScheduledDataLoaderRegistry	register(String key, DataLoader<?,?> dataLoader, DispatchPredicate dispatchPredicate)	This will register a new dataloader and dispatch predicate associated with that data loader
void	rescheduleNow()	This will schedule a task to check the predicate and dispatch if true right now.
ScheduledDataLoaderRegistry	unregister(String key)	This will unregister a new dataloader

Methods inherited from class org.dataloader.DataLoaderRegistry

computeIfAbsent, dispatchDepth, getDataLoader, getDataLoaders, getDataLoadersMap, getInstrumentation, getKeys, getStatistics, newRegistry, register, register, registerAndGet

Methods inherited from class java.lang.Object

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

Method Details

close

public void close()

Once closed this registry will never again reschedule checks

Specified by:

close in interface AutoCloseable

getScheduledExecutorService

public ScheduledExecutorService getScheduledExecutorService()

Returns:

executor being used by this registry

getScheduleDuration

public Duration getScheduleDuration()

Returns:

how long the ScheduledExecutorService task will wait before checking the predicate again

isTickerMode

public boolean isTickerMode()

Returns:

true of the registry is in ticker mode or false otherwise

combine

public ScheduledDataLoaderRegistry combine(DataLoaderRegistry registry)

This will combine all the current data loaders in this registry and all the data loaders from the specified registry and return a new combined registry

Overrides:

combine in class DataLoaderRegistry

Parameters:

registry - the registry to combine into this registry

Returns:

a new combined registry

unregister

public ScheduledDataLoaderRegistry unregister(String key)

This will unregister a new dataloader

Overrides:

unregister in class DataLoaderRegistry

Parameters:

key - the key of the data loader to unregister

Returns:

this registry

getDataLoaderPredicates

public Map<DataLoader<?,?>,DispatchPredicate> getDataLoaderPredicates()

Returns:

a map of data loaders to specific dispatch predicates

getDispatchPredicate

public DispatchPredicate getDispatchPredicate()

There is a default predicate that applies to the whole ScheduledDataLoaderRegistry

Returns:

the default dispatch predicate

register

public ScheduledDataLoaderRegistry register(String key,
 DataLoader<?,?> dataLoader,
 DispatchPredicate dispatchPredicate)

This will register a new dataloader and dispatch predicate associated with that data loader

Parameters:

key - the key to put the data loader under

dataLoader - the data loader to register

dispatchPredicate - the dispatch predicate to associate with this data loader

Returns:

this registry

dispatchAll

public void dispatchAll()

Description copied from class: DataLoaderRegistry

This will be called DataLoader.dispatch() on each of the registered DataLoaders

Overrides:

dispatchAll in class DataLoaderRegistry

dispatchAllWithCount

public int dispatchAllWithCount()

Description copied from class: DataLoaderRegistry

Similar to DataLoaderRegistry.dispatchAll(), this calls DataLoader.dispatch() on each of the registered DataLoaders, but returns the number of dispatches.

Overrides:

dispatchAllWithCount in class DataLoaderRegistry

Returns:

total number of entries that were dispatched from registered DataLoaders.

dispatchAllImmediately

public void dispatchAllImmediately()

This will immediately dispatch the DataLoaders in the registry without testing the predicates

dispatchAllWithCountImmediately

public int dispatchAllWithCountImmediately()

This will immediately dispatch the DataLoaders in the registry without testing the predicates

Returns:

total number of entries that were dispatched from registered DataLoaders.

rescheduleNow

public void rescheduleNow()

This will schedule a task to check the predicate and dispatch if true right now. It will not do a pre-check of the predicate like dispatchAll() would

newScheduledRegistry

public static ScheduledDataLoaderRegistry.Builder newScheduledRegistry()

By default, this will create use a Executors.newSingleThreadScheduledExecutor() and a schedule duration of 10 milliseconds.

Returns:

A builder of ScheduledDataLoaderRegistrys