syn/test/syn_registry_SUITE.erl

%% ==========================================================================================================
%% Syn - A global Process Registry and Process Group manager.
%%
%% The MIT License (MIT)
%%
%% Copyright (c) 2015-2019 Roberto Ostinelli <roberto@ostinelli.net> and Neato Robotics, Inc.
%%
%% 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.
%% ==========================================================================================================
-module(syn_registry_SUITE).

%% callbacks
-export([all/0]).
-export([init_per_suite/1, end_per_suite/1]).
-export([groups/0, init_per_group/2, end_per_group/2]).
-export([init_per_testcase/2, end_per_testcase/2]).

%% tests
-export([
    single_node_register_and_monitor/1,
    single_node_register_and_unregister/1,
    single_node_registration_errors/1,
    single_node_registry_count/1,
    single_node_register_gen_server/1,
    single_node_callback_on_process_exit/1,
    single_node_monitor_after_registry_crash/1
]).
-export([
    two_nodes_register_monitor_and_unregister/1,
    two_nodes_registry_count/1,
    two_nodes_registration_race_condition_conflict_resolution/1
]).
-export([
    three_nodes_partial_netsplit_consistency/1,
    three_nodes_full_netsplit_consistency/1,
    three_nodes_start_syn_before_connecting_cluster_with_conflict/1,
    three_nodes_start_syn_before_connecting_cluster_with_custom_conflict_resolution/1,
    three_nodes_registration_race_condition_custom_conflict_resolution/1
]).

%% support
-export([
    start_syn_delayed_and_register_local_process/3,
    start_syn_delayed_with_custom_handler_register_local_process/4,
    inject_add_to_local_node/3
]).

%% include
-include_lib("common_test/include/ct.hrl").
-include_lib("../src/syn.hrl").

%% ===================================================================
%% Callbacks
%% ===================================================================

%% -------------------------------------------------------------------
%% Function: all() -> GroupsAndTestCases | {skip,Reason}
%% GroupsAndTestCases = [{group,GroupName} | TestCase]
%% GroupName = atom()
%% TestCase = atom()
%% Reason = any()
%% -------------------------------------------------------------------
all() ->
    [
        {group, single_node_process_registration},
        {group, two_nodes_process_registration},
        {group, three_nodes_process_registration}
    ].

%% -------------------------------------------------------------------
%% Function: groups() -> [Group]
%% Group = {GroupName,Properties,GroupsAndTestCases}
%% GroupName = atom()
%% Properties = [parallel | sequence | Shuffle | {RepeatType,N}]
%% GroupsAndTestCases = [Group | {group,GroupName} | TestCase]
%% TestCase = atom()
%% Shuffle = shuffle | {shuffle,{integer(),integer(),integer()}}
%% RepeatType = repeat | repeat_until_all_ok | repeat_until_all_fail |
%%			   repeat_until_any_ok | repeat_until_any_fail
%% N = integer() | forever
%% -------------------------------------------------------------------
groups() ->
    [
        {single_node_process_registration, [shuffle], [
            single_node_register_and_monitor,
            single_node_register_and_unregister,
            single_node_registration_errors,
            single_node_registry_count,
            single_node_register_gen_server,
            single_node_callback_on_process_exit,
            single_node_monitor_after_registry_crash
        ]},
        {two_nodes_process_registration, [shuffle], [
            two_nodes_register_monitor_and_unregister,
            two_nodes_registry_count,
            two_nodes_registration_race_condition_conflict_resolution
        ]},
        {three_nodes_process_registration, [shuffle], [
            three_nodes_partial_netsplit_consistency,
            three_nodes_full_netsplit_consistency,
            three_nodes_start_syn_before_connecting_cluster_with_conflict,
            three_nodes_start_syn_before_connecting_cluster_with_custom_conflict_resolution,
            three_nodes_registration_race_condition_custom_conflict_resolution
        ]}
    ].
%% -------------------------------------------------------------------
%% Function: init_per_suite(Config0) ->
%%				Config1 | {skip,Reason} |
%%              {skip_and_save,Reason,Config1}
%% Config0 = Config1 = [tuple()]
%% Reason = any()
%% -------------------------------------------------------------------
init_per_suite(Config) ->
    Config.

%% -------------------------------------------------------------------
%% Function: end_per_suite(Config0) -> void() | {save_config,Config1}
%% Config0 = Config1 = [tuple()]
%% -------------------------------------------------------------------
end_per_suite(_Config) ->
    ok.

%% -------------------------------------------------------------------
%% Function: init_per_group(GroupName, Config0) ->
%%				Config1 | {skip,Reason} |
%%              {skip_and_save,Reason,Config1}
%% GroupName = atom()
%% Config0 = Config1 = [tuple()]
%% Reason = any()
%% -------------------------------------------------------------------
init_per_group(two_nodes_process_registration, Config) ->
    %% start slave
    {ok, SlaveNode} = syn_test_suite_helper:start_slave(syn_slave),
    %% config
    [{slave_node, SlaveNode} | Config];
init_per_group(three_nodes_process_registration, Config) ->
    %% start slave
    {ok, SlaveNode1} = syn_test_suite_helper:start_slave(syn_slave_1),
    {ok, SlaveNode2} = syn_test_suite_helper:start_slave(syn_slave_2),
    %% config
    [{slave_node_1, SlaveNode1}, {slave_node_2, SlaveNode2} | Config];
init_per_group(_GroupName, Config) ->
    Config.

%% -------------------------------------------------------------------
%% Function: end_per_group(GroupName, Config0) ->
%%				void() | {save_config,Config1}
%% GroupName = atom()
%% Config0 = Config1 = [tuple()]
%% -------------------------------------------------------------------
end_per_group(two_nodes_process_registration, Config) ->
    SlaveNode = proplists:get_value(slave_node, Config),
    syn_test_suite_helper:connect_node(SlaveNode),
    syn_test_suite_helper:clean_after_test(),
    syn_test_suite_helper:stop_slave(syn_slave),
    timer:sleep(1000);
end_per_group(three_nodes_process_registration, Config) ->
    SlaveNode1 = proplists:get_value(slave_node_1, Config),
    syn_test_suite_helper:connect_node(SlaveNode1),
    SlaveNode2 = proplists:get_value(slave_node_2, Config),
    syn_test_suite_helper:connect_node(SlaveNode2),
    syn_test_suite_helper:clean_after_test(),
    syn_test_suite_helper:stop_slave(syn_slave_1),
    syn_test_suite_helper:stop_slave(syn_slave_2),
    timer:sleep(1000);
end_per_group(_GroupName, _Config) ->
    syn_test_suite_helper:clean_after_test().

%% -------------------------------------------------------------------
%% Function: init_per_testcase(TestCase, Config0) ->
%%				Config1 | {skip,Reason} | {skip_and_save,Reason,Config1}
%% TestCase = atom()
%% Config0 = Config1 = [tuple()]
%% Reason = any()
%% -------------------------------------------------------------------
init_per_testcase(_TestCase, Config) ->
    Config.

%% -------------------------------------------------------------------
%% Function: end_per_testcase(TestCase, Config0) ->
%%				void() | {save_config,Config1} | {fail,Reason}
%% TestCase = atom()
%% Config0 = Config1 = [tuple()]
%% Reason = any()
%% -------------------------------------------------------------------
end_per_testcase(_, _Config) ->
    syn_test_suite_helper:clean_after_test().

%% ===================================================================
%% Tests
%% ===================================================================
single_node_register_and_monitor(_Config) ->
    %% start
    ok = syn:start(),
    %% start processes
    Pid = syn_test_suite_helper:start_process(),
    PidWithMeta = syn_test_suite_helper:start_process(),
    %% retrieve
    undefined = syn:whereis(<<"my proc">>),
    %% register
    ok = syn:register(<<"my proc">>, Pid),
    ok = syn:register(<<"my proc 2">>, Pid),
    ok = syn:register(<<"my proc with meta">>, PidWithMeta, {meta, <<"meta">>}),
    %% retrieve
    Pid = syn:whereis(<<"my proc">>),
    Pid = syn:whereis(<<"my proc 2">>),
    {PidWithMeta, {meta, <<"meta">>}} = syn:whereis(<<"my proc with meta">>, with_meta),
    %% re-register
    ok = syn:register(<<"my proc with meta">>, PidWithMeta, {meta2, <<"meta2">>}),
    {PidWithMeta, {meta2, <<"meta2">>}} = syn:whereis(<<"my proc with meta">>, with_meta),
    %% kill process
    syn_test_suite_helper:kill_process(Pid),
    syn_test_suite_helper:kill_process(PidWithMeta),
    timer:sleep(100),
    %% retrieve
    undefined = syn:whereis(<<"my proc">>),
    undefined = syn:whereis(<<"my proc 2">>),
    undefined = syn:whereis(<<"my proc with meta">>).

single_node_register_and_unregister(_Config) ->
    %% start
    ok = syn:start(),
    %% start process
    Pid = syn_test_suite_helper:start_process(),
    %% retrieve
    undefined = syn:whereis(<<"my proc">>),
    %% register
    ok = syn:register(<<"my proc">>, Pid),
    ok = syn:register(<<"my proc 2">>, Pid),
    %% retrieve
    Pid = syn:whereis(<<"my proc">>),
    Pid = syn:whereis(<<"my proc 2">>),
    %% unregister 1
    ok = syn:unregister(<<"my proc">>),
    %% retrieve
    undefined = syn:whereis(<<"my proc">>),
    Pid = syn:whereis(<<"my proc 2">>),
    %% unregister 2
    ok = syn:unregister(<<"my proc 2">>),
    {error, undefined} = syn:unregister(<<"my proc 2">>),
    %% retrieve
    undefined = syn:whereis(<<"my proc">>),
    undefined = syn:whereis(<<"my proc 2">>).

single_node_registration_errors(_Config) ->
    %% start
    ok = syn:start(),
    %% start process
    Pid = syn_test_suite_helper:start_process(),
    Pid2 = syn_test_suite_helper:start_process(),
    %% register
    ok = syn:register(<<"my proc">>, Pid),
    {error, taken} = syn:register(<<"my proc">>, Pid2),
    %% kill processes
    syn_test_suite_helper:kill_process(Pid),
    syn_test_suite_helper:kill_process(Pid2),
    timer:sleep(100),
    %% retrieve
    undefined = syn:whereis(<<"my proc">>),
    %% try registering a dead pid
    {error, not_alive} = syn:register(<<"my proc">>, Pid).

single_node_registry_count(_Config) ->
    %% start
    ok = syn:start(),
    %% start process
    Pid = syn_test_suite_helper:start_process(),
    Pid2 = syn_test_suite_helper:start_process(),
    PidUnregistered = syn_test_suite_helper:start_process(),
    %% register
    ok = syn:register(<<"my proc">>, Pid),
    ok = syn:register(<<"my proc 2">>, Pid2),
    %% count
    2 = syn:registry_count(),
    2 = syn:registry_count(node()),
    %% kill & unregister
    syn_test_suite_helper:kill_process(Pid),
    ok = syn:unregister(<<"my proc 2">>),
    syn_test_suite_helper:kill_process(PidUnregistered),
    timer:sleep(100),
    %% count
    0 = syn:registry_count(),
    0 = syn:registry_count(node()).

single_node_register_gen_server(_Config) ->
    %% start
    ok = syn:start(),
    %% start gen server via syn
    {ok, Pid} = syn_test_gen_server:start_link(),
    %% retrieve
    Pid = syn:whereis(syn_test_gen_server),
    %% call
    pong = syn_test_gen_server:ping(),
    %% send via syn
    syn:send(syn_test_gen_server, {self(), send_ping}),
    receive
        send_pong -> ok
    after 1000 ->
        ok = did_not_receive_gen_server_pong
    end,
    %% stop server
    syn_test_gen_server:stop(),
    timer:sleep(200),
    %% retrieve
    undefined = syn:whereis(syn_test_gen_server),
    %% send via syn
    {badarg, {syn_test_gen_server, anything}} = (catch syn:send(syn_test_gen_server, anything)).

single_node_callback_on_process_exit(_Config) ->
    %% use custom handler
    syn_test_suite_helper:use_custom_handler(),
    %% start
    ok = syn:start(),
    %% start process
    Pid = syn_test_suite_helper:start_process(),
    Pid2 = syn_test_suite_helper:start_process(),
    %% register
    TestPid = self(),
    ok = syn:register(<<"my proc">>, Pid, {pid, TestPid}),
    ok = syn:register(<<"my proc - alternate">>, Pid, {pid_alternate, TestPid}),
    ok = syn:register(<<"my proc 2">>, Pid2, {pid2, TestPid}),
    %% kill 1
    syn_test_suite_helper:kill_process(Pid),
    receive
        {received_event_on, pid} ->
            ok;
        {received_event_on, pid2} ->
            ok = callback_on_process_exit_was_received_by_pid2
    after 1000 ->
        ok = callback_on_process_exit_was_not_received_by_pid
    end,
    receive
        {received_event_on, pid_alternate} ->
            ok;
        {received_event_on, pid2} ->
            ok = callback_on_process_exit_was_received_by_pid2
    after 1000 ->
        ok = callback_on_process_exit_was_not_received_by_pid
    end,
    %% unregister & kill 2
    ok = syn:unregister(<<"my proc 2">>),
    syn_test_suite_helper:kill_process(Pid2),
    receive
        {received_event_on, pid2} ->
            ok = callback_on_process_exit_was_received_by_pid2
    after 1000 ->
        ok
    end.

single_node_monitor_after_registry_crash(_Config) ->
    %% start
    ok = syn:start(),
    %% start processes
    Pid = syn_test_suite_helper:start_process(),
    %% register
    ok = syn:register(<<"my proc">>, Pid),
    %% kill registry
    exit(whereis(syn_registry), kill),
    timer:sleep(200),
    %% retrieve
    Pid = syn:whereis(<<"my proc">>),
    %% kill process
    syn_test_suite_helper:kill_process(Pid),
    timer:sleep(200),
    %% retrieve
    undefined = syn:whereis(<<"my proc 2">>).

two_nodes_register_monitor_and_unregister(Config) ->
    %% get slave
    SlaveNode = proplists:get_value(slave_node, Config),
    %% start
    ok = syn:start(),
    ok = rpc:call(SlaveNode, syn, start, []),
    timer:sleep(100),
    %% start processes
    LocalPid = syn_test_suite_helper:start_process(),
    RemotePid = syn_test_suite_helper:start_process(SlaveNode),
    RemotePidRegRemote = syn_test_suite_helper:start_process(SlaveNode),
    %% retrieve
    undefined = syn:whereis(<<"local proc">>),
    undefined = syn:whereis(<<"remote proc">>),
    undefined = syn:whereis(<<"remote proc reg_remote">>),
    undefined = rpc:call(SlaveNode, syn, whereis, [<<"local proc">>]),
    undefined = rpc:call(SlaveNode, syn, whereis, [<<"remote proc">>]),
    undefined = rpc:call(SlaveNode, syn, whereis, [<<"remote proc reg_remote">>]),
    %% register
    ok = syn:register(<<"local proc">>, LocalPid),
    ok = syn:register(<<"remote proc">>, RemotePid),
    ok = rpc:call(SlaveNode, syn, register, [<<"remote proc reg_remote">>, RemotePidRegRemote]),
    timer:sleep(500),
    %% retrieve
    LocalPid = syn:whereis(<<"local proc">>),
    RemotePid = syn:whereis(<<"remote proc">>),
    RemotePidRegRemote = syn:whereis(<<"remote proc reg_remote">>),
    LocalPid = rpc:call(SlaveNode, syn, whereis, [<<"local proc">>]),
    RemotePid = rpc:call(SlaveNode, syn, whereis, [<<"remote proc">>]),
    RemotePidRegRemote = rpc:call(SlaveNode, syn, whereis, [<<"remote proc reg_remote">>]),
    %% kill & unregister processes
    syn_test_suite_helper:kill_process(LocalPid),
    ok = syn:unregister(<<"remote proc">>),
    syn_test_suite_helper:kill_process(RemotePidRegRemote),
    timer:sleep(100),
    %% retrieve
    undefined = syn:whereis(<<"local proc">>),
    undefined = syn:whereis(<<"remote proc">>),
    undefined = syn:whereis(<<"remote proc reg_remote">>),
    undefined = rpc:call(SlaveNode, syn, whereis, [<<"local proc">>]),
    undefined = rpc:call(SlaveNode, syn, whereis, [<<"remote proc">>]),
    undefined = rpc:call(SlaveNode, syn, whereis, [<<"remote proc reg_remote">>]).

two_nodes_registry_count(Config) ->
    %% get slave
    SlaveNode = proplists:get_value(slave_node, Config),
    %% start
    ok = syn:start(),
    ok = rpc:call(SlaveNode, syn, start, []),
    timer:sleep(100),
    %% start processes
    LocalPid = syn_test_suite_helper:start_process(),
    RemotePid = syn_test_suite_helper:start_process(SlaveNode),
    RemotePidRegRemote = syn_test_suite_helper:start_process(SlaveNode),
    PidUnregistered = syn_test_suite_helper:start_process(),
    %% register
    ok = syn:register(<<"local proc">>, LocalPid),
    ok = syn:register(<<"remote proc">>, RemotePid),
    ok = rpc:call(SlaveNode, syn, register, [<<"remote proc reg_remote">>, RemotePidRegRemote]),
    timer:sleep(500),
    %% count
    3 = syn:registry_count(),
    1 = syn:registry_count(node()),
    2 = syn:registry_count(SlaveNode),
    %% kill & unregister processes
    syn_test_suite_helper:kill_process(LocalPid),
    ok = syn:unregister(<<"remote proc">>),
    syn_test_suite_helper:kill_process(RemotePidRegRemote),
    timer:sleep(100),
    %% count
    0 = syn:registry_count(),
    0 = syn:registry_count(node()),
    0 = syn:registry_count(SlaveNode).

two_nodes_registration_race_condition_conflict_resolution(Config) ->
    ConflictingName = "COMMON",
    %% get slaves
    SlaveNode = proplists:get_value(slave_node, Config),
    %% start syn on nodes
    ok = syn:start(),
    ok = rpc:call(SlaveNode, syn, start, []),
    timer:sleep(100),
    %% start processes
    Pid0 = syn_test_suite_helper:start_process(),
    Pid1 = syn_test_suite_helper:start_process(SlaveNode),
    %% inject into syn to simulate concurrent registration
    ok = rpc:call(SlaveNode, ?MODULE, inject_add_to_local_node, [ConflictingName, Pid1, SlaveNode]),
    %% register on master node to trigger conflict resolution
    ok = syn:register(ConflictingName, Pid0, node()),
    timer:sleep(1000),
    %% check metadata
    case syn:whereis(ConflictingName, with_meta) of
        {Pid0, Meta} ->
            Meta = node(),
            %% check that other nodes' data corresponds
            {Pid0, Meta} = rpc:call(SlaveNode, syn, whereis, [ConflictingName, with_meta]),
            %% check that other processes are not alive because syn killed them
            true = is_process_alive(Pid0),
            false = rpc:call(SlaveNode, erlang, is_process_alive, [Pid1]);
        {Pid1, Meta} ->
            SlaveNode = Meta,
            %% check that other nodes' data corresponds
            {Pid1, Meta} = rpc:call(SlaveNode, syn, whereis, [ConflictingName, with_meta]),
            %% check that other processes are not alive because syn killed them
            false = is_process_alive(Pid0),
            true = rpc:call(SlaveNode, erlang, is_process_alive, [Pid1]);
        _ ->
            ok = no_process_is_registered_with_conflicting_name
    end.

three_nodes_partial_netsplit_consistency(Config) ->
    %% get slaves
    SlaveNode1 = proplists:get_value(slave_node_1, Config),
    SlaveNode2 = proplists:get_value(slave_node_2, Config),
    %% start syn on nodes
    ok = syn:start(),
    ok = rpc:call(SlaveNode1, syn, start, []),
    ok = rpc:call(SlaveNode2, syn, start, []),
    timer:sleep(100),
    %% start processes
    Pid0 = syn_test_suite_helper:start_process(),
    Pid0Changed = syn_test_suite_helper:start_process(),
    Pid1 = syn_test_suite_helper:start_process(SlaveNode1),
    Pid2 = syn_test_suite_helper:start_process(SlaveNode2),
    timer:sleep(100),
    %% retrieve
    undefined = syn:whereis(<<"proc0">>),
    undefined = syn:whereis(<<"proc0-changed">>),
    undefined = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc0-changed">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc1">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc2">>]),
    %% register (mix nodes)
    ok = rpc:call(SlaveNode2, syn, register, [<<"proc0">>, Pid0]),
    ok = syn:register(<<"proc1">>, Pid1),
    ok = rpc:call(SlaveNode1, syn, register, [<<"proc2">>, Pid2]),
    ok = rpc:call(SlaveNode1, syn, register, [<<"proc0-changed">>, Pid0Changed]),
    timer:sleep(200),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    Pid0Changed = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    Pid2 = syn:whereis(<<"proc2">>),
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    Pid0 = rpc:call(SlaveNode2, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode2, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode2, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode2, syn, whereis, [<<"proc2">>]),
    %% disconnect slave 2 from main (slave 1 can still see slave 2)
    syn_test_suite_helper:disconnect_node(SlaveNode2),
    timer:sleep(500),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    Pid0Changed = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>), %% main has lost slave 2 so 'proc2' is removed
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]), %% slave 1 still has slave 2 so 'proc2' is still there
    %% disconnect slave 1
    syn_test_suite_helper:disconnect_node(SlaveNode1),
    timer:sleep(500),
    %% unregister proc0-changed
    ok = syn:unregister(<<"proc0-changed">>),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    undefined = syn:whereis(<<"proc0-changed">>),
    undefined = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>),
    %% reconnect all
    syn_test_suite_helper:connect_node(SlaveNode1),
    syn_test_suite_helper:connect_node(SlaveNode2),
    timer:sleep(5000),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    undefined = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    Pid2 = syn:whereis(<<"proc2">>),
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    Pid0 = rpc:call(SlaveNode2, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode2, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode2, syn, whereis, [<<"proc2">>]).

three_nodes_full_netsplit_consistency(Config) ->
    %% get slaves
    SlaveNode1 = proplists:get_value(slave_node_1, Config),
    SlaveNode2 = proplists:get_value(slave_node_2, Config),
    %% start syn on nodes
    ok = syn:start(),
    ok = rpc:call(SlaveNode1, syn, start, []),
    ok = rpc:call(SlaveNode2, syn, start, []),
    timer:sleep(100),
    %% start processes
    Pid0 = syn_test_suite_helper:start_process(),
    Pid0Changed = syn_test_suite_helper:start_process(),
    Pid1 = syn_test_suite_helper:start_process(SlaveNode1),
    Pid2 = syn_test_suite_helper:start_process(SlaveNode2),
    timer:sleep(100),
    %% retrieve
    undefined = syn:whereis(<<"proc0">>),
    undefined = syn:whereis(<<"proc0-changed">>),
    undefined = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc0-changed">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc1">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc2">>]),
    %% register (mix nodes)
    ok = rpc:call(SlaveNode2, syn, register, [<<"proc0">>, Pid0]),
    ok = rpc:call(SlaveNode2, syn, register, [<<"proc0-changed">>, Pid0Changed]),
    ok = syn:register(<<"proc1">>, Pid1),
    ok = rpc:call(SlaveNode1, syn, register, [<<"proc2">>, Pid2]),
    timer:sleep(200),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    Pid0Changed = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    Pid2 = syn:whereis(<<"proc2">>),
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    Pid0 = rpc:call(SlaveNode2, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode2, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode2, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode2, syn, whereis, [<<"proc2">>]),
    %% disconnect slave 2 from main (slave 1 can still see slave 2)
    syn_test_suite_helper:disconnect_node(SlaveNode2),
    timer:sleep(500),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    Pid0Changed = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>), %% main has lost slave 2 so 'proc2' is removed
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]), %% slave 1 still has slave 2 so 'proc2' is still there
    %% disconnect slave 2 from slave 1
    rpc:call(SlaveNode1, syn_test_suite_helper, disconnect_node, [SlaveNode2]),
    timer:sleep(500),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    Pid0Changed = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>), %% main has lost slave 2 so 'proc2' is removed
    undefined = syn:whereis(<<"proc2">>, with_meta),
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    Pid0Changed = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    %% disconnect slave 1
    syn_test_suite_helper:disconnect_node(SlaveNode1),
    timer:sleep(500),
    %% unregister
    ok = syn:unregister(<<"proc0-changed">>),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    undefined = syn:whereis(<<"proc0-changed">>),
    undefined = syn:whereis(<<"proc1">>),
    undefined = syn:whereis(<<"proc2">>),
    %% reconnect all
    syn_test_suite_helper:connect_node(SlaveNode1),
    syn_test_suite_helper:connect_node(SlaveNode2),
    rpc:call(SlaveNode1, syn_test_suite_helper, connect_node, [SlaveNode2]),
    timer:sleep(1500),
    %% retrieve
    Pid0 = syn:whereis(<<"proc0">>),
    undefined = syn:whereis(<<"proc0-changed">>),
    Pid1 = syn:whereis(<<"proc1">>),
    Pid2 = syn:whereis(<<"proc2">>),
    Pid0 = rpc:call(SlaveNode1, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode1, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode1, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode1, syn, whereis, [<<"proc2">>]),
    Pid0 = rpc:call(SlaveNode2, syn, whereis, [<<"proc0">>]),
    undefined = rpc:call(SlaveNode2, syn, whereis, [<<"proc0-changed">>]),
    Pid1 = rpc:call(SlaveNode2, syn, whereis, [<<"proc1">>]),
    Pid2 = rpc:call(SlaveNode2, syn, whereis, [<<"proc2">>]).

three_nodes_start_syn_before_connecting_cluster_with_conflict(Config) ->
    ConflictingName = "COMMON",
    %% get slaves
    SlaveNode1 = proplists:get_value(slave_node_1, Config),
    SlaveNode2 = proplists:get_value(slave_node_2, Config),
    %% start processes
    Pid0 = syn_test_suite_helper:start_process(),
    Pid1 = syn_test_suite_helper:start_process(SlaveNode1),
    Pid2 = syn_test_suite_helper:start_process(SlaveNode2),
    %% start delayed
    start_syn_delayed_and_register_local_process(ConflictingName, Pid0, 1500),
    rpc:cast(SlaveNode1, ?MODULE, start_syn_delayed_and_register_local_process, [ConflictingName, Pid1, 1500]),
    rpc:cast(SlaveNode2, ?MODULE, start_syn_delayed_and_register_local_process, [ConflictingName, Pid2, 1500]),
    timer:sleep(500),
    %% disconnect all
    rpc:call(SlaveNode1, syn_test_suite_helper, disconnect_node, [SlaveNode2]),
    syn_test_suite_helper:disconnect_node(SlaveNode1),
    syn_test_suite_helper:disconnect_node(SlaveNode2),
    timer:sleep(1500),
    [] = nodes(),
    %% reconnect all
    syn_test_suite_helper:connect_node(SlaveNode1),
    syn_test_suite_helper:connect_node(SlaveNode2),
    rpc:call(SlaveNode1, syn_test_suite_helper, connect_node, [SlaveNode2]),
    timer:sleep(1500),
    %% count
    1 = syn:registry_count(),
    1 = rpc:call(SlaveNode1, syn, registry_count, []),
    1 = rpc:call(SlaveNode2, syn, registry_count, []),
    %% retrieve
    true = lists:member(syn:whereis(ConflictingName), [Pid0, Pid1, Pid2]),
    true = lists:member(rpc:call(SlaveNode1, syn, whereis, [ConflictingName]), [Pid0, Pid1, Pid2]),
    true = lists:member(rpc:call(SlaveNode2, syn, whereis, [ConflictingName]), [Pid0, Pid1, Pid2]),
    %% check metadata
    case syn:whereis(ConflictingName, with_meta) of
        {Pid0, Meta} ->
            CurrentNode = node(),
            %% check that other nodes' data corresponds
            {Pid0, CurrentNode} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
            {Pid0, CurrentNode} = rpc:call(SlaveNode2, syn, whereis, [ConflictingName, with_meta]),
            %% check that other processes are not alive because syn killed them
            true = is_process_alive(Pid0),
            false = rpc:call(SlaveNode1, erlang, is_process_alive, [Pid1]),
            false = rpc:call(SlaveNode2, erlang, is_process_alive, [Pid2]);
        {Pid1, Meta} ->
            SlaveNode1 = Meta,
            %% check that other nodes' data corresponds
            {Pid1, Meta} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
            {Pid1, Meta} = rpc:call(SlaveNode2, syn, whereis, [ConflictingName, with_meta]),
            %% check that other processes are not alive because syn killed them
            false = is_process_alive(Pid0),
            true = rpc:call(SlaveNode1, erlang, is_process_alive, [Pid1]),
            false = rpc:call(SlaveNode2, erlang, is_process_alive, [Pid2]);
        {Pid2, Meta} ->
            SlaveNode2 = Meta,
            %% check that other nodes' data corresponds
            {Pid2, Meta} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
            {Pid2, Meta} = rpc:call(SlaveNode2, syn, whereis, [ConflictingName, with_meta]),
            %% check that other processes are not alive because syn killed them
            false = is_process_alive(Pid0),
            false = rpc:call(SlaveNode1, erlang, is_process_alive, [Pid1]),
            true = rpc:call(SlaveNode2, erlang, is_process_alive, [Pid2]);
        _ ->
            ok = no_process_is_registered_with_conflicting_name
    end.

three_nodes_start_syn_before_connecting_cluster_with_custom_conflict_resolution(Config) ->
    ConflictingName = "COMMON",
    %% get slaves
    SlaveNode1 = proplists:get_value(slave_node_1, Config),
    SlaveNode2 = proplists:get_value(slave_node_2, Config),
    %% start processes
    Pid0 = syn_test_suite_helper:start_process(),
    Pid1 = syn_test_suite_helper:start_process(SlaveNode1),
    Pid2 = syn_test_suite_helper:start_process(SlaveNode2),
    %% start delayed
    start_syn_delayed_with_custom_handler_register_local_process(ConflictingName, Pid0, {node, node()}, 1500),
    rpc:cast(
        SlaveNode1,
        ?MODULE,
        start_syn_delayed_with_custom_handler_register_local_process,
        [ConflictingName, Pid1, keep_this_one, 1500])
    ,
    rpc:cast(
        SlaveNode2,
        ?MODULE,
        start_syn_delayed_with_custom_handler_register_local_process,
        [ConflictingName, Pid2, {node, SlaveNode2}, 1500]
    ),
    timer:sleep(500),
    %% disconnect all
    rpc:call(SlaveNode1, syn_test_suite_helper, disconnect_node, [SlaveNode2]),
    syn_test_suite_helper:disconnect_node(SlaveNode1),
    syn_test_suite_helper:disconnect_node(SlaveNode2),
    timer:sleep(1500),
    [] = nodes(),
    %% reconnect all
    syn_test_suite_helper:connect_node(SlaveNode1),
    syn_test_suite_helper:connect_node(SlaveNode2),
    rpc:call(SlaveNode1, syn_test_suite_helper, connect_node, [SlaveNode2]),
    timer:sleep(5000),
    %% count
    1 = syn:registry_count(),
    1 = rpc:call(SlaveNode1, syn, registry_count, []),
    1 = rpc:call(SlaveNode2, syn, registry_count, []),
    %% retrieve
    true = lists:member(syn:whereis(ConflictingName), [Pid0, Pid1, Pid2]),
    true = lists:member(rpc:call(SlaveNode1, syn, whereis, [ConflictingName]), [Pid0, Pid1, Pid2]),
    true = lists:member(rpc:call(SlaveNode2, syn, whereis, [ConflictingName]), [Pid0, Pid1, Pid2]),
    %% check metadata that we kept the correct process on all nodes
    {Pid1, keep_this_one} = syn:whereis(ConflictingName, with_meta),
    {Pid1, keep_this_one} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
    {Pid1, keep_this_one} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
    %% check that other processes are still alive because we didn't kill them
    true = is_process_alive(Pid0),
    true = rpc:call(SlaveNode1, erlang, is_process_alive, [Pid1]),
    true = rpc:call(SlaveNode2, erlang, is_process_alive, [Pid2]).

three_nodes_registration_race_condition_custom_conflict_resolution(Config) ->
    ConflictingName = "COMMON",
    %% get slaves
    SlaveNode1 = proplists:get_value(slave_node_1, Config),
    SlaveNode2 = proplists:get_value(slave_node_2, Config),
    %% use customer handler
    syn_test_suite_helper:use_custom_handler(),
    rpc:call(SlaveNode1, syn_test_suite_helper, use_custom_handler, []),
    rpc:call(SlaveNode2, syn_test_suite_helper, use_custom_handler, []),
    %% start syn on nodes
    ok = syn:start(),
    ok = rpc:call(SlaveNode1, syn, start, []),
    ok = rpc:call(SlaveNode2, syn, start, []),
    timer:sleep(500),
    %% start processes
    Pid0 = syn_test_suite_helper:start_process(),
    Pid1 = syn_test_suite_helper:start_process(SlaveNode1),
    Pid2 = syn_test_suite_helper:start_process(SlaveNode2),
    %% inject into syn to simulate concurrent registration
    ok = rpc:call(SlaveNode1, ?MODULE, inject_add_to_local_node, [ConflictingName, Pid1, keep_this_one]),
    ok = rpc:call(SlaveNode2, ?MODULE, inject_add_to_local_node, [ConflictingName, Pid2, SlaveNode2]),
    %% register on master node to trigger conflict resolution
    ok = syn:register(ConflictingName, Pid0, node()),
    timer:sleep(1000),
    %% retrieve
    true = lists:member(syn:whereis(ConflictingName), [Pid0, Pid1, Pid2]),
    true = lists:member(rpc:call(SlaveNode1, syn, whereis, [ConflictingName]), [Pid0, Pid1, Pid2]),
    true = lists:member(rpc:call(SlaveNode2, syn, whereis, [ConflictingName]), [Pid0, Pid1, Pid2]),
    %% check metadata that we kept the correct process on all nodes
    {Pid1, keep_this_one} = syn:whereis(ConflictingName, with_meta),
    {Pid1, keep_this_one} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
    {Pid1, keep_this_one} = rpc:call(SlaveNode1, syn, whereis, [ConflictingName, with_meta]),
    %% check that other processes are still alive because we didn't kill them
    true = is_process_alive(Pid0),
    true = rpc:call(SlaveNode1, erlang, is_process_alive, [Pid1]),
    true = rpc:call(SlaveNode2, erlang, is_process_alive, [Pid2]).

%% ===================================================================
%% Internal
%% ===================================================================
start_syn_delayed_and_register_local_process(Name, Pid, Ms) ->
    spawn(fun() ->
        lists:foreach(fun(Node) ->
            syn_test_suite_helper:disconnect_node(Node)
        end, nodes()),
        timer:sleep(Ms),
        [] = nodes(),
        %%
        syn:start(),
        ok = syn:register(Name, Pid, node())
    end).

start_syn_delayed_with_custom_handler_register_local_process(Name, Pid, Meta, Ms) ->
    spawn(fun() ->
        lists:foreach(fun(Node) ->
            syn_test_suite_helper:disconnect_node(Node)
        end, nodes()),
        timer:sleep(Ms),
        [] = nodes(),
        %% use customer handler
        syn_test_suite_helper:use_custom_handler(),
        %%
        syn:start(),
        ok = syn:register(Name, Pid, Meta)
    end).

inject_add_to_local_node(Name, Pid, Meta) ->
    mnesia:dirty_write(#syn_registry_table{
        name = Name,
        pid = Pid,
        node = node(Pid),
        meta = Meta,
        monitor_ref = undefined
    }).