| /* |
| * 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.pig.builtin; |
| |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Iterator; |
| import java.util.List; |
| |
| import org.apache.pig.Accumulator; |
| import org.apache.pig.Algebraic; |
| import org.apache.pig.EvalFunc; |
| import org.apache.pig.FuncSpec; |
| import org.apache.pig.PigException; |
| import org.apache.pig.backend.executionengine.ExecException; |
| import org.apache.pig.data.DataBag; |
| import org.apache.pig.data.DataType; |
| import org.apache.pig.data.Tuple; |
| import org.apache.pig.data.TupleFactory; |
| import org.apache.pig.impl.logicalLayer.FrontendException; |
| import org.apache.pig.impl.logicalLayer.schema.Schema; |
| |
| /** |
| * Generates the count of the number of values in a bag. This count does not |
| * include null values, and thus matches SQL semantics for COUNT(a) (where a is |
| * field) but not for COUNT(*) (where * in SQL indicates all). |
| * <p> |
| * This class |
| * implements {@link org.apache.pig.Algebraic}, so if possible the execution will |
| * performed in a distributed fashion. |
| * <p> |
| * There are no restrictions as to the data types inside the bag to be counted. |
| * <p> |
| * COUNT implements the {@link org.apache.pig.Accumulator} interface as well. |
| * While this will never be |
| * the preferred method of usage it is available in case the combiner can not be |
| * used for a given calculation. |
| */ |
| public class COUNT extends EvalFunc<Long> implements Algebraic, Accumulator<Long>{ |
| private static TupleFactory mTupleFactory = TupleFactory.getInstance(); |
| |
| @Override |
| public Long exec(Tuple input) throws IOException { |
| try { |
| DataBag bag = (DataBag)input.get(0); |
| if(bag==null) |
| return null; |
| |
| Iterator it = bag.iterator(); |
| long cnt = 0; |
| while (it.hasNext()){ |
| Tuple t = (Tuple)it.next(); |
| if (t != null && t.size() > 0 && t.get(0) != null ) |
| cnt++; |
| } |
| return cnt; |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing count in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| |
| public String getInitial() { |
| return Initial.class.getName(); |
| } |
| |
| public String getIntermed() { |
| return Intermediate.class.getName(); |
| } |
| |
| public String getFinal() { |
| return Final.class.getName(); |
| } |
| |
| static public class Initial extends EvalFunc<Tuple> { |
| |
| @Override |
| public Tuple exec(Tuple input) throws IOException { |
| // Since Initial is guaranteed to be called |
| // only in the map, it will be called with an |
| // input of a bag with a single tuple - the |
| // count should always be 1 if bag is non empty |
| DataBag bag = (DataBag)input.get(0); |
| Iterator it = bag.iterator(); |
| if (it.hasNext()){ |
| Tuple t = (Tuple)it.next(); |
| if (t != null && t.size() > 0 && t.get(0) != null) |
| return mTupleFactory.newTuple(Long.valueOf(1)); |
| } |
| return mTupleFactory.newTuple(Long.valueOf(0)); |
| } |
| } |
| |
| static public class Intermediate extends EvalFunc<Tuple> { |
| |
| @Override |
| public Tuple exec(Tuple input) throws IOException { |
| try { |
| return mTupleFactory.newTuple(sum(input)); |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing count in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| } |
| |
| static public class Final extends EvalFunc<Long> { |
| @Override |
| public Long exec(Tuple input) throws IOException { |
| try { |
| return sum(input); |
| } catch (Exception ee) { |
| int errCode = 2106; |
| String msg = "Error while computing count in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, ee); |
| } |
| } |
| } |
| |
| static protected Long sum(Tuple input) throws ExecException, NumberFormatException { |
| DataBag values = (DataBag)input.get(0); |
| long sum = 0; |
| for (Iterator<Tuple> it = values.iterator(); it.hasNext();) { |
| Tuple t = it.next(); |
| // Have faith here. Checking each value before the cast is |
| // just too much. |
| sum += (Long)t.get(0); |
| } |
| return sum; |
| } |
| |
| @Override |
| public Schema outputSchema(Schema input) { |
| return new Schema(new Schema.FieldSchema(null, DataType.LONG)); |
| } |
| |
| /* (non-Javadoc) |
| * @see org.apache.pig.EvalFunc#getArgToFuncMapping() |
| */ |
| @Override |
| public List<FuncSpec> getArgToFuncMapping() throws FrontendException { |
| List<FuncSpec> funcList = new ArrayList<FuncSpec>(); |
| Schema s = new Schema(); |
| s.add(new Schema.FieldSchema(null, DataType.BAG)); |
| funcList.add(new FuncSpec(this.getClass().getName(), s)); |
| return funcList; |
| } |
| |
| /* Accumulator interface implementation */ |
| private long intermediateCount = 0L; |
| |
| @Override |
| public void accumulate(Tuple b) throws IOException { |
| try { |
| DataBag bag = (DataBag)b.get(0); |
| Iterator it = bag.iterator(); |
| while (it.hasNext()){ |
| Tuple t = (Tuple)it.next(); |
| if (t != null && t.size() > 0 && t.get(0) != null) { |
| intermediateCount += 1; |
| } |
| } |
| } catch (ExecException ee) { |
| throw ee; |
| } catch (Exception e) { |
| int errCode = 2106; |
| String msg = "Error while computing min in " + this.getClass().getSimpleName(); |
| throw new ExecException(msg, errCode, PigException.BUG, e); |
| } |
| } |
| |
| @Override |
| public void cleanup() { |
| intermediateCount = 0L; |
| } |
| |
| @Override |
| public Long getValue() { |
| return intermediateCount; |
| } |
| |
| } |