Sha256: 1dbeb069a886e1f4cb23b4e7556d0d66edc5bd241db25d9af60278a755dc0ba5
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Contents
module Wukong
module Streamer
#
# Roll up all records from a given key into a single list.
#
class ListReducer < Wukong::Streamer::AccumulatingReducer
attr_accessor :values
# start with an empty list
def start! *args
self.values = []
end
# aggregate all records.
# note that this accumulates the full *record* -- key, value, everything.
def accumulate *record
self.values << record
end
# emit the key and all records, tab-separated
#
# you will almost certainly want to override this method to do something
# interesting with the values (or override accumulate to gather scalar
# values)
#
def finalize
yield [key, values.to_flat.join(";")].flatten
end
end
end
end
Version data entries
16 entries across 16 versions & 1 rubygems