Complete solution thank to @al2o3cr answer
defmodule ETS.Consume do
@moduledoc """
History by key, month, age, value
r ETS.Consume
ETS.Consume.scenario()
table = ETS.Consume.start()
ETS.Consume.populate(table)
ETS.Consume.list(table, "12345678901")
ETS.Consume.list_period(table, "12345678901", 2, 2021, 10, 2021)
"""
@table :cons
@opts [:ordered_set, :protected]
def start do
:ets.new(@table, @opts)
end
def index(age, month) do
age * 100 + month
end
def insert(ref, key, month, age, bytes) do
index = index(age, month)
key = {key, index, age, month}
:ets.insert(ref, {key, bytes})
end
def list(table, key) do
:ets.match(table, {{key, :_, :"$1", :"$2"}, :"$3"})
end
def list_period(table, key, begin_month, begin_age, end_month, end_age) do
begindex = index(begin_age, begin_month)
endex = index(end_age, end_month)
# :ets.fun2ms(
# fn {{key, index, month, age}, bytes} = _entry when
# key == "12345678901" and
# index >= 202301 and index <= 202312 ->
# {month, age, bytes}
# end)
match_spec = [
{{{:"$1", :"$2", :"$3", :"$4"}, :"$5"},
[
{:andalso, {:andalso, {:==, :"$1", key}, {:>=, :"$2", begindex}},
{:"=<", :"$2", endex}}
], [{{:"$3", :"$4", :"$5"}}]}
]
:ets.select(table, match_spec)
end
def populate(table) do
insert(table, "12345678901", 1, 2021, 100)
insert(table, "12345678901", 2, 2021, 200)
insert(table, "12345678901", 3, 2021, 300)
insert(table, "12345678901", 4, 2021, 200)
insert(table, "12345678901", 5, 2021, 300)
insert(table, "12345678901", 6, 2021, 350)
insert(table, "12345678901", 7, 2021, 200)
insert(table, "12345678901", 8, 2021, 100)
insert(table, "12345678901", 9, 2021, 500)
insert(table, "12345678901", 10, 2021, 300)
insert(table, "12345678901", 11, 2021, 200)
insert(table, "12345678901", 12, 2021, 310)
insert(table, "12345678901", 1, 2022, 410)
insert(table, "12345678902", 1, 2021, 310)
end
def scenario do
table = ETS.Consume.start()
ETS.Consume.populate(table)
# ETS.Consume.list(table, "12345678901") |> dbg()
ETS.Consume.list_period(table, "12345678901", 1, 2021, 9, 2021)
end
end
