com.amazon.ask.mvc.view.resolver.cache.SingleThreadedViewCache Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of ask-sdk-mvc Show documentation

The Alexa Skills Kit MVC Framework extends the existing ASK SDK, adding features for mapping requests to methods and rendering responses via view scripts and templates such as Nashorn Javascript and Freemarker. It also integrates with the ASK SDK Interaction Model Mapper framework to create a single environment where both the interaction model and business logic of skills can be managed as code packages.

The newest version!

/*
    Copyright 2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.

    Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file
    except in compliance with the License. A copy of the License is located at

        http://aws.amazon.com/apache2.0/

    or in the "license" file accompanying this file. This file 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 com.amazon.ask.mvc.view.resolver.cache;

import com.amazon.ask.mvc.view.View;

import java.util.LinkedHashMap;
import java.util.Map;
import java.util.concurrent.Callable;

import static com.amazon.ask.util.ValidationUtils.assertIsPositive;

/**
 * A non-thread-safe cache for skills running in a single-threaded environment such as AWS Lambda
 */
public class SingleThreadedViewCache implements ViewCache {
    private final Map cache;

    public SingleThreadedViewCache(Builder builder) {
        this(builder.capacity);
    }

    public SingleThreadedViewCache(int capacity) {
        assertIsPositive(capacity, "capacity");
        this.cache = new LinkedHashMap(capacity, 0.75f, true) {
            @Override
            protected boolean removeEldestEntry(Map.Entry eldest) {
                return size() > capacity;
            }
        };
    }

    @Override
    public View getOrCreate(String key, Callable callable) throws Exception {
        View view = cache.get(key);
        if (view == null) {
            view = callable.call();
            cache.put(key, view);
        }
        return view;
    }

    /**
     * @return a single threaded view cache with default capacity
     */
    public static SingleThreadedViewCache defaultCache() {
        return SingleThreadedViewCache.builder().build();
    }

    public static Builder builder() {
        return new Builder();
    }

    public static class Builder {
        private int capacity = DEFAULT_CACHE_CAPACITY;

        public Builder withCapacity(int capacity) {
            this.capacity = capacity;
            return this;
        }

        public SingleThreadedViewCache build() {
            return new SingleThreadedViewCache(this);
        }
    }
}