cbtRead.java

import com.bouncex.ingestion.ProductFeedOptions;
import com.google.cloud.bigtable.beam.CloudBigtableIO;
import com.google.cloud.bigtable.beam.CloudBigtableScanConfiguration;
import com.google.cloud.bigtable.beam.CloudBigtableTableConfiguration;
import com.google.cloud.bigtable.data.v2.models.Row;
import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.io.BoundedSource;
import org.apache.beam.sdk.io.FileSystems;
import org.apache.beam.sdk.io.gcp.bigtable.BigtableIO;
import org.apache.beam.sdk.options.PipelineOptions;
import org.apache.beam.sdk.options.PipelineOptionsFactory;
import org.apache.beam.sdk.transforms.Create;
import org.apache.beam.sdk.transforms.DoFn;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.transforms.ParDo;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.TypeDescriptor;
import org.apache.hadoop.hbase.client.Result;
import org.apache.hadoop.hbase.client.Scan;
import org.apache.hadoop.yarn.webapp.hamlet.Hamlet;

class Scratch {
    private class Foo {
        private String data;
        public String getKey() {
            return data + "#" + data;
        }
    }

    private static class ToKey extends DoFn<Foo, String> {
        @ProcessElement
        public void processElement(ProcessContext ctx) {
            ctx.output(ctx.element().getKey());
        }
    }

    private static class ToScan extends DoFn<String, Scan> {
         @ProcessElement
        public void processElement(ProcessContext ctx) {
             ctx.output(new Scan(ctx.element().getBytes(), ctx.element().getBytes()));
         }
    }

    private static class Read extends PTransform<PCollection<Scan>, PCollection<Row>> {
        private CloudBigtableTableConfiguration config;
        private PipelineOptions options;

        public Read(CloudBigtableTableConfiguration config, PipelineOptions options) {
            this.config = config;
            this.options = options;
        }

        private static class ReadSource extends DoFn<BoundedSource<Result>, PCollection<Result>> {
            @ProcessElement
            public void processElement(ProcessContext ctx) {
                BoundedSource.BoundedReader<Result> reader = ctx.element().createReader(options);
                try {
                    for (boolean available = reader.start(); available; available = reader.advance()) {
                        Result item = reader.getCurrent();
                    }
                } finally {
                    reader.close();
                }
            }
        }

        @Override
        public PCollection<Row> expand(PCollection<Scan> input) {
            input.apply("GetSource", ParDo.of(new DoFn<Scan, BoundedSource<Result>>() {
                @ProcessElement
                public void processElement(ProcessContext ctx) {
                    ctx.output(CloudBigtableIO.read(CloudBigtableScanConfiguration.fromConfig(config, ctx.element())));
                }
            }));
        }
    }

    public static void main(String[] args) {
        PipelineOptionsFactory.register(ProductFeedOptions.class);
        final PipelineOptions options = PipelineOptionsFactory
                .fromArgs(args)
                .withValidation()
                .as(PipelineOptions.class);

        FileSystems.setDefaultPipelineOptions(options);

        final Pipeline pipeline = Pipeline.create(options);

        CloudBigtableTableConfiguration config = new CloudBigtableTableConfiguration.Builder()
            .withProjectId("")
            .withInstanceId("")
            .withTableId("")
            .build();

        pipeline
                .apply("emptyfoo", Create.empty(new TypeDescriptor<Foo>() {}))
                .apply("toKeys", ParDo.of(new ToKey()))
                .apply("toScan", ParDo.of(new ToScan()))
                .apply("Read", new Read(config, options));
    }
}