sohailgerman / swirl

High Performance Erlang Stream Processor

swirl

Authors: Louis-Philippe Gauthier.

Lightweight Distributed Stream Processor

Requirements

• Erlang 16.0 +

Environment variables

Name	Type	Default	Description
mappers_max	pos_integer()	100	maximum number of mappers
reducers_max	pos_integer()	100	maximum number of reducers

Examples

Starting a flow

ok = application:start(swirl),

FlowMod = swirl_flow_example,
FlowOpts = [
    {stream_names, [delivery]},
    {stream_filter, "exchange_id = 3 AND bidder_id IS NOT NULL"}
],
MapperNodes = [node()],
ReducerNode = node(),
{ok, Flow} = swirl_flow:start(FlowMod, FlowOpts, MapperNodes, ReducerNode),

StreamName = delivery,
Event = #{exchange_id => 1, bidder_id => 10},

swirl_stream:emit(StreamName, Event),

ok = swirl_flow:stop(Flow)

Implementing a flow

-module(swirl_flow_example).
-include_lib("swirl/include/swirl.hrl").

-behavior(swirl_flow).
-export([
    map/3,
    reduce/3,
    output/4
]).

%% swirl_flow callbacks
map(StreamName, Event, _MapperOpts) ->
    Type = ?L(type, Event),
    ExchangeId = ?L(exchange_id, Event),
    BidderId = ?L(bidder_id, Event),

    Key = {Type, StreamName, ExchangeId, BidderId},
    CounterIncrements = {1, 10},

    {Key, CounterIncrements}.

reduce(_Flow, Row, _ReducerOpts) ->
    Row.

output(_Flow, _Period, Rows, OutputOpts) ->
    %% do something with the output
    io:format("rows: ~p~n", [Rows]),

Stream Filter

exchange_id = 3 AND bidder_id IS NOT NULL
flight_id in (10, 12, 23) OR tag_id = 20
buyer_id notnull AND seller_id > 103

Swirl QL

variables:

atom()

values:

integer() | float() | binary()

boolean operators:

'and' | 'or'

comparison operators:

'<' | '<=' | '=' | '>=' | '>' | '<>'

inclusion operators:

in | notin

null operators:

null | notnull

TODO

• node discovery
• boolean expression indexing

Tests

make eunit
make build-plt && make dialyze

License

The MIT License (MIT)

Copyright (c) 2015 Louis-Philippe Gauthier

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.