SessionHolder.java

/*
 * Copyright 2023 Haulmont.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.jmix.flowui.sys;

import com.google.common.base.Strings;
import com.vaadin.flow.server.ServiceInitEvent;
import com.vaadin.flow.server.SessionInitEvent;
import com.vaadin.flow.server.VaadinServiceInitListener;
import com.vaadin.flow.server.VaadinSession;
import com.vaadin.flow.server.WrappedSession;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.lang.Nullable;
import org.springframework.security.core.Authentication;
import org.springframework.security.core.context.SecurityContext;
import org.springframework.security.core.userdetails.UserDetails;
import org.springframework.security.web.context.HttpSessionSecurityContextRepository;
import org.springframework.stereotype.Component;

import java.lang.ref.WeakReference;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;

/**
 * Holds vaadin sessions for all users
 */
@Component("flowui_SessionHolder")
public class SessionHolder implements VaadinServiceInitListener {

    private static final Logger log = LoggerFactory.getLogger(SessionHolder.class);

    protected final ReadWriteLock lock = new ReentrantReadWriteLock();
    protected final List<WeakReference<VaadinSession>> sessions = new ArrayList<>();

    /**
     * Provides active (not collected by gc) vaadin sessions mapped on specified usernames
     *
     * @param usernames usernames of users which sessions should be provided.
     *                  Null means that sessions for all users will be returned.
     * @return active user vaadin sessions
     */
    public Map<String, List<VaadinSession>> getActiveSessionsForUsernames(@Nullable Collection<String> usernames) {
        Map<String, List<VaadinSession>> userActiveSessions = new HashMap<>();
        Set<String> usernamesSet = usernames != null ? new HashSet<>(usernames) : null;
        int removed = 0;
        lock.readLock().lock();
        try {
            for (Iterator<WeakReference<VaadinSession>> iterator = sessions.iterator(); iterator.hasNext(); ) {
                WeakReference<VaadinSession> reference = iterator.next();
                VaadinSession session = reference.get();
                if (session != null) {
                    String sessionUsername = getUsernameFromVaadinSession(session);
                    if (Strings.isNullOrEmpty(sessionUsername)) {
                        log.debug("Skip Vaadin session {} as it does not contain security context or" +
                                " authentication with username", session);
                    } else if (usernamesSet == null || usernamesSet.contains(sessionUsername)) {
                        List<VaadinSession> vaadinSessions =
                                userActiveSessions.computeIfAbsent(sessionUsername, k -> new ArrayList<>());
                        vaadinSessions.add(session);
                    }
                } else {
                    lock.readLock().unlock();
                    lock.writeLock().lock();
                    try {
                        iterator.remove();
                        lock.readLock().lock();
                    } finally {
                        lock.writeLock().unlock();
                    }
                    removed++;
                }
            }
        } finally {
            lock.readLock().unlock();
        }

        if (removed > 0) {
            log.debug("Removed {} Vaadin sessions", removed);
        }
        return userActiveSessions;
    }

    @Nullable
    protected String getUsernameFromVaadinSession(VaadinSession session) {
        WrappedSession wrappedSession = session.getSession();
        if (wrappedSession == null) {
            return null;
        }
        SecurityContext securityContext = (SecurityContext) wrappedSession.getAttribute(
                HttpSessionSecurityContextRepository.SPRING_SECURITY_CONTEXT_KEY);
        if (securityContext == null || securityContext.getAuthentication() == null) {
            return null;
        }
        Authentication authentication = securityContext.getAuthentication();
        if (!(authentication.getPrincipal() instanceof UserDetails)) {
            return null;
        }
        return ((UserDetails) authentication.getPrincipal()).getUsername();
    }

    @Override
    public void serviceInit(ServiceInitEvent event) {
        event.getSource().addSessionInitListener(this::onSessionInit);
    }

    protected void onSessionInit(SessionInitEvent event) {
        lock.writeLock().lock();
        try {
            sessions.add(new WeakReference<>(event.getSession()));
            log.trace("Added session: " + event.getSession());
        } finally {
            lock.writeLock().unlock();
        }
    }
}