MapReduce编程模型

MapReduce编程模型

map(String key, String value):
	//key: document name
	//value: document contents
	for each word w in value
		EmitIntermediate(w,"1");

reduce(String key, Iterator values):
	//key: a word
	//values: a list of counts
	int result = 0;
	for each v in values:
		result += ParseInt(v);
	Emit(AsString(result));

Counter* uppercase;
uppercase = getCounter("uppercase");

map(String name, String contents):
	for each word w in contents:
		if (IsCapitalized(w))
			uppercase->Increment();
		EmitIntermediate(w,"1");