Package org.dellroad.stuff.vaadin24.data

Class AsyncDataProvider<T>

java.lang.Object

com.vaadin.flow.data.provider.AbstractDataProvider<T,SerializablePredicate<T>>

com.vaadin.flow.data.provider.ListDataProvider<T>

org.dellroad.stuff.vaadin24.data.AsyncDataProvider<T>

All Implemented Interfaces:

ConfigurableFilterDataProvider<T,SerializablePredicate<T>,SerializablePredicate<T>>, DataProvider<T,SerializablePredicate<T>>, InMemoryDataProvider<T>, Serializable

public class AsyncDataProvider<T>
extends ListDataProvider<T>

A ListDataProvider whose contents are gathered in an asynchronous query.

Instances are just a ListDataProvider with support for asynchronous (re)loading of the underlying data in a background thread using an AsyncTaskManager. As a result, the UI never "locks up" while a backend data query executes.

The associated AsyncTaskManager provides status change notifications when a load operation starts, completes, fails, or is canceled. These updates can be used to drive GUI loading spinners, etc.

Load operations are initiated via load(), and may be canceled in progress via cancel(). Initiating a new load operation will cancel and replace any previous load operation still in progress.

All operations are atomic and race free. See AsyncTaskManager for details.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	AsyncDataProvider.Loader<T>	Callback interface for asynchronous loading of data for a AsyncDataProvider.

Constructor Summary

Constructors

Constructor	Description
AsyncDataProvider()	Default constructor.
AsyncDataProvider(AsyncTaskManager<Stream<? extends T>> taskManager)	Constructor.

Method Summary

Modifier and Type	Method	Description
long	cancel()	Cancel any outstanding asynchronous load of this instance.
AsyncTaskManager<Stream<? extends T>>	getAsyncTaskManager()	Get the AsyncTaskManager that manages background load operations.
long	load(AsyncDataProvider.Loader<? extends T> loader)	Trigger a new asynchronous load of this instance.
protected void	updateFromLoad(long id, Stream<? extends T> stream)	Update this data provider's internal list of items using the new data from a successful load operation and fire a refresh notification.

Methods inherited from class com.vaadin.flow.data.provider.ListDataProvider

fetch, getFilter, getItems, getSortComparator, setFilter, setSortComparator, size

Methods inherited from class com.vaadin.flow.data.provider.AbstractDataProvider

addDataProviderListener, addListener, fireEvent, refreshAll, refreshItem, refreshItem

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.vaadin.flow.data.provider.DataProvider

addDataProviderListener, getId, refreshAll, refreshItem, refreshItem, withConfigurableFilter, withConfigurableFilter, withConvertedFilter

Methods inherited from interface com.vaadin.flow.data.provider.InMemoryDataProvider

addFilter, addFilter, addFilterByValue, addSortComparator, addSortOrder, clearFilters, filteringBy, filteringBy, filteringByEquals, filteringByPrefix, filteringByPrefix, filteringBySubstring, filteringBySubstring, isInMemory, setFilter, setFilterByValue, setSortOrder

Constructor Details

AsyncDataProvider

public AsyncDataProvider()

Default constructor.

Caller still must configure an async executor via getAsyncTaskManager().setAsyncExecutor().

Throws:

IllegalStateException - if there is no VaadinSession associated with the current thread

AsyncDataProvider

public AsyncDataProvider(AsyncTaskManager<Stream<? extends T>> taskManager)

Constructor.

Parameters:

taskManager - loading task manager

Throws:

IllegalStateException - if there is no VaadinSession associated with the current thread

Method Details

getAsyncTaskManager

public AsyncTaskManager<Stream<? extends T>> getAsyncTaskManager()

Get the AsyncTaskManager that manages background load operations.

Returns:

this instance's AsyncTaskManager, never null

load

public long load(AsyncDataProvider.Loader<? extends T> loader)

Trigger a new asynchronous load of this instance.

If/when the given load task completes successfully, its results will completely replace the contents of this data provider.

See Loader for important requirements for the behavior of loader.

Parameters:

loader - performs the load operation

Returns:

unique ID for this load attempt

Throws:

IllegalStateException - if the current thread is not associated with the task manager's session

IllegalStateException - if this instance's AsyncTaskManager has no executor configured

IllegalArgumentException - if loader is null

See Also:

• AsyncTaskManager.startTask(org.dellroad.stuff.vaadin24.util.AsyncTask<? extends R>)

cancel

public long cancel()

Cancel any outstanding asynchronous load of this instance.

Returns:

the unique ID of the canceled task, if any, or zero if there is no task outstanding

Throws:

IllegalStateException - if the current thread is not associated with the task manager's session

See Also:

• AsyncTaskManager.cancelTask()

updateFromLoad

protected void updateFromLoad(long id,
 Stream<? extends T> stream)

Update this data provider's internal list of items using the new data from a successful load operation and fire a refresh notification.

This is invoked with the task manager's session locked.

Parameters:

id - task ID

stream - load results

Throws:

IllegalStateException - if the current thread is not associated with the task manager's session

IllegalArgumentException - if stream is null