java/pig-galago/src/com/yahoo/pig/EvalFunc.java

   1 /*
   2  * Copyright (c) 2007 Yahoo! Inc.  All rights reserved.
   3  * See accompanying LICENSE file.
   4  */
   5 package com.yahoo.pig;
   6
   7 import java.io.IOException;
   8
   9 import com.yahoo.pig.impl.logicalLayer.schema.SchemaItem;
  10 import com.yahoo.pig.impl.mapreduceExec.PigMapReduce;
  11
  12 /**
  13  * The class is used to implement functions to be applied to
  14  * a dataset. The function is applied to each Tuple in the set.
  15  * The programmer should not make assumptions about state maintained
  16  * between invocations of the invoke() method since the Pig runtime
  17  * will schedule and localize invocations based on information provided
  18  * at runtime.
  19  *
  20  * @author database-systems@yahoo.research
  21  *
  22  */
  23 public abstract class EvalFunc extends InstantiatedFunc {
  24
  25     // report that progress is being made (otherwise hadoop times out after 600 seconds working on one outer tuple)
  26     protected void progress() {
  27         if (PigMapReduce.reporter != null) {
  28             PigMapReduce.reporter.progress();
  29         }
  30     }
  31
  32     /**
  33          * Returns the String representation of the function.
  34          */
  35         public String toString() {
  36                 return getName();
  37         }
  38
  39     public SchemaItem outputSchema() {
  40         return null;
  41     }
  42 }