Dotted Version Vector Sets example on conflict detection

dvvset_test.erl

-module(dvvset_test).
-export([main/0]).

%% NOTE: we always generate a new client ID to enforce consistency.

main() ->
	%% client 1 write
	Dot0 = dvvset:update(dvvset:new("value-0"), generate_id()),

	%% server
	Dot0_Server = dvvset:sync([Dot0]),
	1 = length(dvvset:values(Dot0_Server)),
	%% => Dot0_Server saved on server

	%% client 1 update
	Context1 = dvvset:join(Dot0_Server),
	Dot1 = dvvset:update(dvvset:new(Context1, "value-1"), Dot0_Server, generate_id()),

	%% server
	Dot1_Server = dvvset:sync([Dot0_Server, Dot1]),
	1 = length(dvvset:values(Dot1_Server)),
	%% => Dot1_Server saved on server

	%% client 1b update
	Context1b = dvvset:join(Dot0_Server),
	Dot1b = dvvset:update(dvvset:new(Context1b, "value-1b"), Dot0_Server, generate_id()),

	%% server CONFLICT!
	Dot1b_Server = dvvset:sync([Dot1_Server, Dot1b]),
	2 = length(dvvset:values(Dot1b_Server)),
	%% => Dot1_Server KEPT on server

	[Value] = dvvset:values(Dot1_Server),
	Value.

generate_id() ->
	binary:encode_hex(crypto:hash(sha256, erlang:term_to_binary({node(), erlang:system_time()}))).