org.dellroad.stuff.vaadin23.data.VaadinSessionDataProvider Maven / Gradle / Ivy
Show all versions of dellroad-stuff-vaadin23 Show documentation
/*
* Copyright (C) 2022 Archie L. Cobbs. All rights reserved.
*/
package org.dellroad.stuff.vaadin23.data;
import com.google.common.base.Preconditions;
import com.vaadin.flow.server.VaadinService;
import com.vaadin.flow.server.VaadinServlet;
import com.vaadin.flow.server.VaadinServletService;
import com.vaadin.flow.server.VaadinSession;
import java.util.ArrayList;
import java.util.Comparator;
import java.util.List;
import java.util.concurrent.Future;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.Function;
import org.dellroad.stuff.vaadin23.servlet.SimpleSpringServlet;
import org.dellroad.stuff.vaadin23.util.VaadinUtil;
/**
* A {@link DataProvider} that provides an object corresponding to each live {@link VaadinSession}.
*
*
* The sessions are retrieved from the {@link SimpleSpringServlet}, which must be configured with session tracking enabled.
*
*
* Sessions are represented by {@link SessionInfo}, which may be subclassed to add application-specific information
* (e.g., currently logged-in user).
*
*
* Sessions are orderded by reverse creation time (newest first).
*
* @see SimpleSpringServlet
*/
@SuppressWarnings("serial")
public class VaadinSessionDataProvider extends AsyncDataProvider {
protected final SimpleSpringServlet servlet;
protected final Function infoCreator;
/**
* Constructor.
*
*
* The {@link infoCreator} gathers whatever information is needed by this instance from the given session,
* and may assume that the given session is locked.
*
*
* If {@link infoCreator} returns null, that session is omitted.
*
*
* Caller still must configure an async executor; see {@link AsyncDataProvider#AsyncDataProvider()}.
*
* @param infoCreator extracts data provider information from each session
* @throws IllegalStateException if there is no current {@link VaadinSession} associated with the current thread
* @throws IllegalArgumentException if the associated {@link VaadinService} is not a {@link VaadinServletService}
* @throws IllegalArgumentException if the associated {@link VaadinServlet} is not a {@link SimpleSpringServlet}
* @throws IllegalArgumentException if {@code infoCreator} is null
*/
public VaadinSessionDataProvider(Function infoCreator) {
this(null, infoCreator);
}
/**
* Constructor.
*
*
* The {@link infoCreator} gathers whatever information is needed by this instance from the given session,
* and may assume that the given session is locked.
*
*
* If {@link infoCreator} returns null, that session is omitted.
*
* @param executor the executor used to execute async load tasks
* @param infoCreator extracts data provider information from each session
* @throws IllegalStateException if there is no current {@link VaadinSession} associated with the current thread
* @throws IllegalArgumentException if the associated {@link VaadinService} is not a {@link VaadinServletService}
* @throws IllegalArgumentException if the associated {@link VaadinServlet} is not a {@link SimpleSpringServlet}
* @throws IllegalArgumentException if {@code infoCreator} is null
*/
public VaadinSessionDataProvider(Function> executor,
Function infoCreator) {
Preconditions.checkArgument(infoCreator != null, "null infoCreator");
this.servlet = SimpleSpringServlet.forSession(this.getAsyncTaskManager().getVaadinSession());
this.infoCreator = infoCreator;
if (executor != null)
this.getAsyncTaskManager().setAsyncExecutor(executor);
}
/**
* Load or reload this data provider.
*
*
* If there is already an async load in progress, this method will {@link #cancel cancel()} it first.
* You can check this ahead of time via {@link #isBusy}.
*
* @return unique ID for this load attempt
* @throws IllegalStateException if this instance is already in the process of reloading
* @throws IllegalStateException if this instance's {@link VaadinSession} is not locked
*/
public void reload() {
this.load(id -> this.buildSessionList().stream());
}
// ListDataProvider
/**
* Get the {@link SessionInfo}'s currently in this container.
*/
@Override
public List getItems() {
return (List)super.getItems();
}
/**
* {@inheritDoc}
*
*
* The implementation in {@code VaadinSessionDataProvider} returns {@code item.getId()}
* if {@code item} is not null, otherwise null.
*
* @param item data item
*/
@Override
public String getId(T item) {
return item != null ? item.getId() : null;
}
/**
* Build the list of sessions.
*
*
* @throws IllegalStateException if any session lock is held
*/
protected List buildSessionList() throws InterruptedException {
// Sanity check
VaadinUtil.assertNoSession();
// Grab list of live sessions from servlet
final List sessionList = this.servlet.getSessions();
// Sort by reverse creation time
sessionList.sort(Comparator.
comparingLong(otherSession -> otherSession.getSession().getCreationTime()).reversed()
.thenComparing(otherSession -> otherSession.getSession().getId()));
// Extract session info, locking each session while we do it
final ArrayList sessionInfoList = new ArrayList<>(sessionList.size());
final AtomicReference sessionInfoRef = new AtomicReference<>();
for (VaadinSession otherSession : sessionList) {
if (Thread.interrupted()) // we got canceled
throw new InterruptedException();
otherSession.accessSynchronously(() -> sessionInfoRef.set(infoCreator.apply(otherSession)));
final T sessionInfo = sessionInfoRef.get();
if (sessionInfo != null)
sessionInfoList.add(sessionInfo);
}
// Done
return sessionInfoList;
}
}