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courses:mapreduce-tutorial:perl-api [2012/01/23 21:29]
straka
courses:mapreduce-tutorial:perl-api [2012/01/23 21:34]
straka
Line 39: Line 39:
 requires 'map'; requires 'map';
  
-sub setup() { 1; +sub setup() {} 
-sub cleanup { 1;}+sub cleanup {}
 </code> </code>
   * ''sub map($self, $key, $value, $context)'' -- executed for every (key, value) input pair. The variable '$content' has following methods:   * ''sub map($self, $key, $value, $context)'' -- executed for every (key, value) input pair. The variable '$content' has following methods:
Line 56: Line 56:
 requires 'reduce'; requires 'reduce';
  
-sub setup() { 1; +sub setup() {} 
-sub cleanup { 1;}+sub cleanup {}
 </code> </code>
   * ''sub reduce($self, $key, $values, $context)'' -- executed for every ''$key''. The ''$values'' is an iterator with the following methods:   * ''sub reduce($self, $key, $values, $context)'' -- executed for every ''$key''. The ''$values'' is an iterator with the following methods:
Line 68: Line 68:
   * ''sub setup($self, $context)'' -- executed once before any input keys are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters.   * ''sub setup($self, $context)'' -- executed once before any input keys are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters.
   * ''sub cleanup($self, $context)'' -- executed once after all input keys are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters.   * ''sub cleanup($self, $context)'' -- executed once after all input keys are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters.
 +
 +===== Hadoop::Partitioner =====
 +
 +<code perl>
 +package Hadoop::Partitioner;
 +use Moose::Role;
 +
 +requires 'getPartition';
 +
 +sub setup {}
 +sub cleanup {}
 +
 +</code>
 +  * ''sub getPartition($self, $key, $value, $partitions)'' -- executed for every output (key, value) pair. It must return a number of partition in range 0..$partitions-1, where the output (key, value) pair should be placed.
 +  * ''sub setup($self)'' -- executed once before any input (key, value) pairs are processed.
 +  * ''sub cleanup($self)'' -- executed once after all input (key, value) pairs are processed. 
 +

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