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courses:mapreduce-tutorial:perl-api [2012/01/23 21:18]
straka |
courses:mapreduce-tutorial:perl-api [2012/01/23 21:20]
straka |
| * ''sub setup($self, $context)'' -- executed once before any input (key, value) pairs are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters. | * ''sub setup($self, $context)'' -- executed once before any input (key, value) pairs are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters. |
| * ''sub cleanup($self, $context)'' -- executed once after all input (key, value) pairs are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters. | * ''sub cleanup($self, $context)'' -- executed once after all input (key, value) pairs are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters. |
| | |
| | ===== Hadoop::Reducer ===== |
| | |
| | <code perl> |
| | package Hadoop::Reduce; |
| | use Moose::Role; |
| | |
| | requires 'reduce'; |
| | |
| | sub setup() { 1; } |
| | sub cleanup { 1;} |
| | </code> |
| | * ''sub reduce($self, $key, $values, $context)'' -- executed for every (key, values) input data. |
| | * fsa |
| | The variable '$content' has following methods: |
| | * ''$content%%->%%write($key, $value)'' -- output the (''$key'', ''$value'') pair |
| | * ''$content%%->%%counter($group, $name, $increment)'' -- increases the counter ''$name'' in the group ''$group'' by ''$increment'' |
| | * ''sub setup($self, $context)'' -- executed once before any input (key, values) pairs are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters. |
| | * ''sub cleanup($self, $context)'' -- executed once after all input (key, values) pairs are processed. The ''$context'' can be used to both produce (key, value) pairs and increment counters. |
