/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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 org.apache.wayang.spark.execution;

import org.apache.spark.api.java.JavaSparkContext;
import org.apache.wayang.core.platform.CrossPlatformExecutor;
import org.apache.wayang.core.platform.ExecutionResourceTemplate;

/**
 * Wraps and manages a {@link JavaSparkContext} to avoid steady re-creation.
 */
public class SparkContextReference extends ExecutionResourceTemplate {

    /**
     * The wrapped {@link JavaSparkContext}.
     */
    private final JavaSparkContext sparkContext;

    /**
     * Creates a new instance.
     *
     * @param sparkContext the {@link JavaSparkContext} to be wrapped
     */
    public SparkContextReference(CrossPlatformExecutor crossPlatformExecutor, JavaSparkContext sparkContext) {
        super(null);
        if (crossPlatformExecutor != null) {
            crossPlatformExecutor.registerGlobal(this);
        }
        this.sparkContext = sparkContext;
    }

    @Override
    protected void doDispose() throws Throwable {
        assert !this.isDisposed();

        this.sparkContext.close();
    }

    /**
     * Provides the {@link JavaSparkContext}. This instance must not be disposed, yet.
     *
     * @return the wrapped {@link JavaSparkContext}
     */
    public JavaSparkContext get() {
        assert !this.isDisposed();
        return this.sparkContext;
    }
}
