com.cloudera.data.filesystem.ParquetFileSystemDatasetWriter.java Source code

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Here is the source code for com.cloudera.data.filesystem.ParquetFileSystemDatasetWriter.java

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/**
 * Copyright 2013 Cloudera Inc.
 *
 * Licensed 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 com.cloudera.data.filesystem;

import com.cloudera.data.DatasetWriter;
import com.cloudera.data.DatasetWriterException;
import com.google.common.base.Objects;
import com.google.common.base.Preconditions;
import com.google.common.io.Closeables;
import java.io.Closeable;
import java.io.Flushable;
import java.io.IOException;
import org.apache.avro.Schema;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import parquet.avro.AvroParquetWriter;

class ParquetFileSystemDatasetWriter<E> implements DatasetWriter<E>, Flushable, Closeable {

    private static final Logger logger = LoggerFactory.getLogger(ParquetFileSystemDatasetWriter.class);

    private Path path;
    private Schema schema;
    private FileSystem fileSystem;

    private Path pathTmp;
    private AvroParquetWriter<E> avroParquetWriter;
    private ReaderWriterState state;

    public ParquetFileSystemDatasetWriter(FileSystem fileSystem, Path path, Schema schema) {
        this.fileSystem = fileSystem;
        this.path = path;
        this.pathTmp = new Path(path.getParent(), "." + path.getName() + ".tmp");
        this.schema = schema;
        this.state = ReaderWriterState.NEW;
    }

    @Override
    public void open() {
        Preconditions.checkState(state.equals(ReaderWriterState.NEW), "Unable to open a writer from state:%s",
                state);

        logger.debug("Opening data file with pathTmp:{} (final path will be path:{})", pathTmp, path);

        try {
            avroParquetWriter = new AvroParquetWriter<E>(pathTmp.makeQualified(fileSystem), schema);
        } catch (IOException e) {
            throw new DatasetWriterException("Unable to create writer to path:" + pathTmp, e);
        }

        state = ReaderWriterState.OPEN;
    }

    @Override
    public void write(E entity) {
        Preconditions.checkState(state.equals(ReaderWriterState.OPEN), "Attempt to write to a writer in state:%s",
                state);

        try {
            avroParquetWriter.write(entity);
        } catch (IOException e) {
            throw new DatasetWriterException(
                    "Unable to write entity:" + entity + " with writer:" + avroParquetWriter, e);
        }
    }

    @Override
    public void flush() {
        Preconditions.checkState(state.equals(ReaderWriterState.OPEN), "Attempt to write to a writer in state:%s",
                state);

        // Parquet doesn't (currently) expose a flush operation
    }

    @Override
    public void close() {
        if (state.equals(ReaderWriterState.OPEN)) {
            logger.debug("Closing pathTmp:{}", pathTmp);

            try {
                Closeables.close(avroParquetWriter, false);
            } catch (IOException e) {
                throw new DatasetWriterException(
                        "Unable to close writer:" + avroParquetWriter + " to path:" + pathTmp);
            }

            logger.debug("Committing pathTmp:{} to path:{}", pathTmp, path);

            try {
                if (!fileSystem.rename(pathTmp, path)) {
                    throw new DatasetWriterException("Failed to move " + pathTmp + " to " + path);
                }
            } catch (IOException e) {
                throw new DatasetWriterException("Internal error while trying to commit path:" + pathTmp, e);
            }

            state = ReaderWriterState.CLOSED;
        }
    }

    @Override
    public boolean isOpen() {
        return state.equals(ReaderWriterState.OPEN);
    }

    @Override
    public String toString() {
        return Objects.toStringHelper(this).add("path", path).add("schema", schema).add("fileSystem", fileSystem)
                .add("pathTmp", pathTmp).add("avroParquetWriter", avroParquetWriter).add("state", state)
                .omitNullValues().toString();
    }

}