org.apache.beam.runners.dataflow.worker.SinkRegistry.java Source code

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Here is the source code for org.apache.beam.runners.dataflow.worker.SinkRegistry.java

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/*
 * 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.beam.runners.dataflow.worker;

import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Lists;
import com.google.common.collect.Sets;
import java.util.HashMap;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.Set;
import javax.annotation.Nullable;
import org.apache.beam.runners.dataflow.util.CloudObject;
import org.apache.beam.runners.dataflow.worker.util.common.worker.Sink;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.util.common.ReflectHelpers;

/**
 * An immutable registry from {@link String} identifiers (provided to the worker by the Dataflow
 * service) to appropriate {@link SinkFactory} instances.
 */
public final class SinkRegistry implements SinkFactory {

    /**
     * A {@link SinkRegistry} with each {@link SinkFactory} known to the Dataflow worker already
     * registered.
     *
     * <p>Uses {@link ServiceLoader} to dynamically bind well known types to sink factories via {@link
     * SinkFactory.Registrar}.
     */
    public static SinkRegistry defaultRegistry() {
        Set<SinkFactory.Registrar> readerFactoryRegistrars = Sets
                .newTreeSet(ReflectHelpers.ObjectsClassComparator.INSTANCE);
        readerFactoryRegistrars.addAll(Lists
                .newArrayList(ServiceLoader.load(SinkFactory.Registrar.class, ReflectHelpers.findClassLoader())));

        ImmutableMap.Builder<String, SinkFactory> factories = ImmutableMap.builder();
        for (SinkFactory.Registrar registrar : readerFactoryRegistrars) {
            factories.putAll(registrar.factories());
        }
        return new SinkRegistry(factories.build());
    }

    /** Builds a new {@link SinkRegistry} with the provided mappings. */
    private SinkRegistry(Map<String, SinkFactory> factories) {
        this.factories = factories;
    }

    /** A map from the short names of predefined sinks to the associated {@link SinkFactory}. */
    private final Map<String, SinkFactory> factories;

    /**
     * Returns a new {@link SinkRegistry} with the provided identifier associated with the provided
     * {@link SinkFactory}, overriding any existing binding for that identifier.
     */
    public SinkRegistry register(String readerSpecType, SinkFactory factory) {
        Map<String, SinkFactory> newFactories = new HashMap<>();
        newFactories.putAll(factories);
        newFactories.put(readerSpecType, factory);
        return new SinkRegistry(newFactories);
    }

    /**
     * Creates a {@link Sink} from a Dataflow API Sink definition. It wraps the sink from the factory
     * in a {@link SizeReportingSinkWrapper}.
     *
     * @throws Exception if the sink could not be decoded and constructed
     */
    @Override
    public SizeReportingSinkWrapper<?> create(CloudObject sinkSpec, Coder<?> coder,
            @Nullable PipelineOptions options, @Nullable DataflowExecutionContext executionContext,
            DataflowOperationContext operationContext) throws Exception {

        String objClassName = sinkSpec.getClassName();

        SinkFactory factory = factories.get(objClassName);
        if (factory == null) {
            throw new IllegalArgumentException(
                    String.format("Unable to create a Sink: Unknown Sink type in specification: %s", objClassName));
        }

        Sink<?> sink = factory.create(sinkSpec, coder, options, executionContext, operationContext);
        @SuppressWarnings("unchecked")
        Sink<Object> typedSink = (Sink<Object>) sink;
        return new SizeReportingSinkWrapper<>(typedSink, executionContext);
    }
}