| """ |
| * 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 |
| * |
| * https://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. |
| """ |
| |
| __all__=["WordCountTask"] |
| |
| from avro.tether import TetherTask |
| |
| import logging |
| |
| #TODO::Make the logging level a parameter we can set |
| #logging.basicConfig(level=logging.INFO) |
| class WordCountTask(TetherTask): |
| """ |
| Implements the mappper and reducer for the word count example |
| """ |
| |
| def __init__(self): |
| """ |
| """ |
| |
| inschema="""{"type":"string"}""" |
| midschema="""{"type":"record", "name":"Pair","namespace":"org.apache.avro.mapred","fields":[ |
| {"name":"key","type":"string"}, |
| {"name":"value","type":"long","order":"ignore"}] |
| }""" |
| outschema=midschema |
| TetherTask.__init__(self,inschema,midschema,outschema) |
| |
| |
| #keep track of the partial sums of the counts |
| self.psum=0 |
| |
| |
| def map(self,record,collector): |
| """Implement the mapper for the word count example |
| |
| Parameters |
| ---------------------------------------------------------------------------- |
| record - The input record |
| collector - The collector to collect the output |
| """ |
| |
| words=record.split() |
| |
| for w in words: |
| logging.info("WordCountTask.Map: word={0}".format(w)) |
| collector.collect({"key":w,"value":1}) |
| |
| def reduce(self,record, collector): |
| """Called with input values to generate reducer output. Inputs are sorted by the mapper |
| key. |
| |
| The reduce function is invoked once for each value belonging to a given key outputted |
| by the mapper. |
| |
| Parameters |
| ---------------------------------------------------------------------------- |
| record - The mapper output |
| collector - The collector to collect the output |
| """ |
| |
| self.psum+=record["value"] |
| |
| def reduceFlush(self,record, collector): |
| """ |
| Called with the last intermediate value in each equivalence run. |
| In other words, reduceFlush is invoked once for each key produced in the reduce |
| phase. It is called after reduce has been invoked on each value for the given key. |
| |
| Parameters |
| ------------------------------------------------------------------ |
| record - the last record on which reduce was invoked. |
| """ |
| |
| #collect the current record |
| logging.info("WordCountTask.reduceFlush key={0} value={1}".format(record["key"],self.psum)) |
| |
| collector.collect({"key":record["key"],"value":self.psum}) |
| |
| #reset the sum |
| self.psum=0 |