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package org.glassfish.jersey.examples.feedcombiner.manager;
import java.io.Serializable;
import java.util.Collection;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import org.glassfish.jersey.examples.feedcombiner.model.CombinedFeed;
import org.glassfish.jersey.examples.feedcombiner.store.DataStoreObserver;
import org.glassfish.jersey.examples.feedcombiner.store.InMemoryDataStore;
/**
* This class is used for purposes of processing and listening a new saved or
* removed entities in {@link InMemoryDataStore} and according to
* its {@link CombinedFeed#getRefreshPeriod()} property is able to give an entity
* into the queue for another processing which is dedicated to consumers.
*
* @author Petr Bouda (petr.bouda at oracle.com)
*/
public class FeedDataStoreManager implements DataStoreObserver {
private static final long START_DELAY = 0L;
private static final TimeUnit DEFAULT_TIME_UNIT = TimeUnit.SECONDS;
private final ScheduledExecutorService scheduler;
private final FeedTaskFactory taskFactory;
// Concurrent Map used for purposes of cancellation tasks in the given executor
private final Map<String, ScheduledFuture<?>> scheduledTasks = new ConcurrentHashMap<>();
public FeedDataStoreManager(FeedTaskFactory taskFactory) {
this(taskFactory, Executors.newScheduledThreadPool(1));
}
public FeedDataStoreManager(FeedTaskFactory taskFactory, ScheduledExecutorService scheduler) {
this.taskFactory = taskFactory;
this.scheduler = scheduler;
}
@Override
public void save(Serializable entity) {
createTask(entity);
}
@Override
public void saveAll(Collection<Serializable> entities) {
entities.forEach(this::createTask);
}
private void createTask(Serializable serializableEntity) {
if (serializableEntity instanceof CombinedFeed) {
CombinedFeed feed = (CombinedFeed) serializableEntity;
ScheduledFuture<?> scheduledTask = scheduler.scheduleAtFixedRate(
taskFactory.get(feed), START_DELAY, feed.getRefreshPeriod(), DEFAULT_TIME_UNIT);
scheduledTasks.put(feed.getId(), scheduledTask);
}
}
@Override
public void remove(String key) {
removeTask(key);
}
@Override
public void removeAll(Collection<String> keys) {
keys.forEach(this::removeTask);
}
private void removeTask(String key) {
ScheduledFuture<?> scheduledTask = scheduledTasks.get(key);
if (scheduledTask != null) {
scheduledTask.cancel(true);
scheduledTasks.remove(key);
}
}
}