Java tutorial
/* * 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.phoenix.hive.mapreduce; import static org.apache.phoenix.monitoring.MetricType.SCAN_BYTES; import java.io.IOException; import java.sql.SQLException; import java.util.List; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.client.Scan; import org.apache.hadoop.hbase.util.Bytes; import org.apache.hadoop.io.NullWritable; import org.apache.hadoop.io.WritableComparable; import org.apache.hadoop.mapred.InputSplit; import org.apache.hadoop.mapred.RecordReader; import org.apache.hadoop.mapreduce.lib.db.DBWritable; import org.apache.hadoop.util.ReflectionUtils; import org.apache.phoenix.compile.QueryPlan; import org.apache.phoenix.compile.StatementContext; import org.apache.phoenix.coprocessor.BaseScannerRegionObserver; import org.apache.phoenix.hive.PhoenixRowKey; import org.apache.phoenix.hive.util.PhoenixStorageHandlerUtil; import org.apache.phoenix.iterate.ConcatResultIterator; import org.apache.phoenix.iterate.LookAheadResultIterator; import org.apache.phoenix.iterate.MapReduceParallelScanGrouper; import org.apache.phoenix.iterate.PeekingResultIterator; import org.apache.phoenix.iterate.ResultIterator; import org.apache.phoenix.iterate.RoundRobinResultIterator; import org.apache.phoenix.iterate.SequenceResultIterator; import org.apache.phoenix.iterate.TableResultIterator; import org.apache.phoenix.jdbc.PhoenixResultSet; import org.apache.phoenix.monitoring.ReadMetricQueue; import com.google.common.base.Throwables; import com.google.common.collect.Lists; /** * @RecordReader implementation that iterates over the the records. */ @SuppressWarnings("rawtypes") public class PhoenixRecordReader<T extends DBWritable> implements RecordReader<WritableComparable, T> { private static final Log LOG = LogFactory.getLog(PhoenixRecordReader.class); private final Configuration configuration; private final QueryPlan queryPlan; private WritableComparable key; private T value = null; private Class<T> inputClass; private ResultIterator resultIterator = null; private PhoenixResultSet resultSet; private long readCount; private boolean isTransactional; public PhoenixRecordReader(Class<T> inputClass, final Configuration configuration, final QueryPlan queryPlan) throws IOException { this.inputClass = inputClass; this.configuration = configuration; this.queryPlan = queryPlan; isTransactional = PhoenixStorageHandlerUtil.isTransactionalTable(configuration); } public void initialize(InputSplit split) throws IOException { final PhoenixInputSplit pSplit = (PhoenixInputSplit) split; final List<Scan> scans = pSplit.getScans(); if (LOG.isInfoEnabled()) { LOG.info("Target table : " + queryPlan.getTableRef().getTable().getPhysicalName()); } if (LOG.isDebugEnabled()) { LOG.debug("Scan count[" + scans.size() + "] : " + Bytes.toStringBinary(scans.get(0).getStartRow()) + " ~ " + Bytes.toStringBinary(scans.get(scans.size() - 1).getStopRow())); LOG.debug("First scan : " + scans.get(0) + " scanAttribute : " + scans.get(0).getAttributesMap()); for (int i = 0, limit = scans.size(); i < limit; i++) { LOG.debug("EXPECTED_UPPER_REGION_KEY[" + i + "] : " + Bytes.toStringBinary( scans.get(i).getAttribute(BaseScannerRegionObserver.EXPECTED_UPPER_REGION_KEY))); } } try { List<PeekingResultIterator> iterators = Lists.newArrayListWithExpectedSize(scans.size()); StatementContext ctx = queryPlan.getContext(); ReadMetricQueue readMetrics = ctx.getReadMetricsQueue(); String tableName = queryPlan.getTableRef().getTable().getPhysicalName().getString(); long renewScannerLeaseThreshold = queryPlan.getContext().getConnection().getQueryServices() .getRenewLeaseThresholdMilliSeconds(); for (Scan scan : scans) { scan.setAttribute(BaseScannerRegionObserver.SKIP_REGION_BOUNDARY_CHECK, Bytes.toBytes(true)); final TableResultIterator tableResultIterator = new TableResultIterator( queryPlan.getContext().getConnection().getMutationState(), scan, readMetrics.allotMetric(SCAN_BYTES, tableName), renewScannerLeaseThreshold, queryPlan, MapReduceParallelScanGrouper.getInstance()); PeekingResultIterator peekingResultIterator = LookAheadResultIterator.wrap(tableResultIterator); iterators.add(peekingResultIterator); } ResultIterator iterator = queryPlan.useRoundRobinIterator() ? RoundRobinResultIterator.newIterator(iterators, queryPlan) : ConcatResultIterator.newIterator(iterators); if (queryPlan.getContext().getSequenceManager().getSequenceCount() > 0) { iterator = new SequenceResultIterator(iterator, queryPlan.getContext().getSequenceManager()); } this.resultIterator = iterator; // Clone the row projector as it's not thread safe and would be used // simultaneously by multiple threads otherwise. this.resultSet = new PhoenixResultSet(this.resultIterator, queryPlan.getProjector().cloneIfNecessary(), queryPlan.getContext()); } catch (SQLException e) { LOG.error(String.format(" Error [%s] initializing PhoenixRecordReader. ", e.getMessage())); Throwables.propagate(e); } } @Override public boolean next(WritableComparable key, T value) throws IOException { try { if (!resultSet.next()) { return false; } value.readFields(resultSet); if (isTransactional) { ((PhoenixResultWritable) value).readPrimaryKey((PhoenixRowKey) key); } ++readCount; if (LOG.isTraceEnabled()) { LOG.trace("Result[" + readCount + "] : " + ((PhoenixResultWritable) value).getResultMap()); } return true; } catch (SQLException e) { LOG.error(String.format(" Error [%s] occurred while iterating over the resultset. ", e.getMessage())); throw new RuntimeException(e); } } @Override public WritableComparable createKey() { if (isTransactional) { key = new PhoenixRowKey(); } else { key = NullWritable.get(); } return key; } @Override public T createValue() { value = ReflectionUtils.newInstance(inputClass, this.configuration); return value; } @Override public long getPos() throws IOException { return 0; } @Override public void close() throws IOException { if (LOG.isInfoEnabled()) { LOG.info("Read Count : " + readCount); } if (resultIterator != null) { try { resultIterator.close(); } catch (SQLException e) { LOG.error(" Error closing resultset."); throw new RuntimeException(e); } } } @Override public float getProgress() throws IOException { return 0; } }