com.mitchellbosecke.pebble.cache.DefaultTemplateLoadingCache Maven / Gradle / Ivy

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package com.mitchellbosecke.pebble.cache;

import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;
import java.util.concurrent.FutureTask;

import com.mitchellbosecke.pebble.error.PebbleException;
import com.mitchellbosecke.pebble.template.PebbleTemplate;

public class DefaultTemplateLoadingCache implements TemplateLoadingCache {

	private final ConcurrentMap> cache = new ConcurrentHashMap<>();

	@Override
	public PebbleTemplate get(String key, Callable loadingFunction) throws PebbleException {

		Future future = cache.get(key);

		if (future == null) {
			FutureTask futureTask = new FutureTask(loadingFunction);
			future = cache.putIfAbsent(key, futureTask);

			if (future == null) {
				future = futureTask;
				futureTask.run();
			}
		}
		try {
			return future.get();
		} catch (ExecutionException | InterruptedException e) {
			if(e.getCause() instanceof PebbleException){
				throw (PebbleException)e.getCause();
			}
			throw new RuntimeException("An error occurred while retrieving from cache");
		}
	}

}