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View Code? Open in Web Editor NEWDHT implementation in Erlang
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martin31hao loucash camshaft amaliujia knewter charlie-chang digideskio keichan34 teotikalki m-2k quviq hengestone renesugar davidalphafox x603dht's Issues
Wrong data is being sent on the socket
For some reason, the socket is sending the wrong data. The following is the counterexample which should be studied. Chances are this is a model error.
(x1).........xxxxxx(144 times)
0
{{state,[#{hi => 128,lo => 0,nodes => [],split => true}],false,0,[],[]},
{state,0,false,#Fun<dht_routing_table_eqc.0.26523270>,#{}},
{state,false,0}}
[{init,
{[{dht_state_eqc,{state,false,0}},
{dht_net_eqc,{state,false,1729,[],[]}},
{dht_store_eqc,{state,[],false}},
{dht_routing_meta_eqc,
{state,[#{hi => 128,lo => 0,nodes => [],split => true}],false,0,[],[]}},
{dht_routing_table_eqc,
{state,0,false,#Fun<dht_routing_table_eqc.0.26523270>,#{}}},
{dht_time_eqc,{state,0,[],0}}],
[{blocked_calls,[]},
{fresh_id,1},
{workers,[]},
{command_timeout,{var,command_timeout}},
{async_timeout,{var,async_timeout}},
{meta_cmd_stack,[]}]}},
{set,
{var,1},
{call,dht_state_eqc,start_link,
[0,[]],
[{id,1},
{self,{var,{pid,root}}},
{res,true},
{callouts,
{seq,
{res,
{internal,dht_routing_table_eqc,new,
[0,0,128],
[{id,1},{self,{var,{pid,root}}}],
empty},
'ROUTING_TABLE'},
{seq,
[{internal,dht_routing_meta_eqc,new,
['ROUTING_TABLE'],
[{id,1},{self,{var,{pid,root}}}],
{seq,
[empty,
{seq,
{res,
{internal,dht_time_eqc,monotonic_time,[],
[{id,1},{self,{var,{pid,root}}}],
{seq,[{callout,dht_time,monotonic_time,[],0},{return,0}]}},
0},
{seq,
[{internal,dht_routing_table_eqc,node_list,
['ROUTING_TABLE'],
[{id,1},{self,{var,{pid,root}}}],
empty},
{seq,
[{internal,dht_routing_table_eqc,node_id,
['ROUTING_TABLE'],
[{id,1},{self,{var,{pid,root}}}],
empty},
{seq,
[{seq,
[{internal,dht_routing_table_eqc,ranges,
['_'],
[{id,1},{self,{var,{pid,root}}}],
empty},
{seq,
{res,
{internal,dht_time_eqc,monotonic_time,[],
[{id,1},{self,{var,{pid,root}}}],
{seq,
[{callout,dht_time,monotonic_time,[],0},{return,0}]}},
0},
{seq,
[{seq,
[{callout,dht_time,convert_time_unit,
[0,native,milli_seconds],
0},
{return,0}]},
{seq,
{res,
{internal,dht_time_eqc,send_after,
[900000,<0.20836.0>,{inactive_range,{0,128}}],
[{id,1},{self,{var,{pid,root}}}],
{seq,
[{callout,dht_time,send_after,
[900000,'_',{inactive_range,{0,128}}],
{tref,0}},
{return,{tref,0}}]}},
{tref,0}},
{internal,dht_routing_meta_eqc,add_timer_for_range,
[{0,128},{tref,0}],
[{id,1},{self,{var,{pid,root}}}],
empty}}]}}]},
{seq,
[{internal,dht_routing_meta_eqc,init_nodes,
[[],0],
[{id,1},{self,{var,{pid,root}}}],
{seq,
[{callout,dht_time,convert_time_unit,
[900000,milli_seconds,native],
900000},
{return,900000}]}},
{return,{ok,0,'ROUTING_TABLE'}}]}]}]}]}}]}},
{seq,[{seq,[]},{return,true}]}]}}}]}},
{set,
{var,2},
{call,dht_store_eqc,start_link,[],
[{id,2},
{self,{var,{pid,root}}},
{res,ok},
{callouts,
{seq,
[{internal,dht_time_eqc,send_after,
[300000,dht_store,evict],
[{id,2},{self,{var,{pid,root}}}],
{seq,
[{callout,dht_time,send_after,[300000,'_',evict],{tref,1}},
{return,{tref,1}}]}},
{return,ok}]}}]}},
{set,
{var,3},
{call,dht_net_eqc,init,
[0,[<<0,0,0,0,0,0,0,0>>,<<0,0,0,0,0,0,0,0>>]],
[{id,4},
{self,{var,{pid,root}}},
{res,true},
{callouts,
{seq,
[empty,
{seq,
[{callout,dht_socket,open,[0,'_'],{ok,'SOCKET_REF'}},
{seq,
[{internal,dht_time_eqc,send_after,
[300000,dht_net,renew_token],
[{id,4},{self,{var,{pid,root}}}],
{seq,
[{callout,dht_time,send_after,[300000,'_',renew_token],{tref,2}},
{return,{tref,2}}]}},
{return,true}]}]}]}}]}},
{set,
{var,4},
{call,dht_net_eqc,find_value,
[{{0,0,0,0},0},0],
[{id,14},
{self,{var,{pid,14}}},
{res,{'$eqc_block',{var,{pid,14}}}},
{callouts,
{seq,
{res,
{seq,
[{val,0,
{internal,dht_state_eqc,node_id,[],
[{id,14},{self,{var,{pid,14}}}],
{return,0}}},
{seq,
{res,{val,1,{callout,dht_rand,uniform,[65535],1}},1},
{seq,
{res,
{val,ok,
{callout,dht_socket,send,['SOCKET_REF',{0,0,0,0},0,'_'],ok}},
ok},
{seq,
{res,
{internal,dht_time_eqc,send_after,
[2000,dht_net,{request_timeout,{{{0,0,0,0},0},<<0,1>>}}],
[{id,14},{self,{var,{pid,14}}}],
{seq,
[{callout,dht_time,send_after,
[2000,'_',{request_timeout,{{{0,0,0,0},0},<<0,1>>}}],
{tref,3}},
{return,{tref,3}}]}},
{tref,3}},
{seq,
[{internal,dht_net_eqc,add_blocked,
[{var,{pid,14}},
{request,{tref,3},{{0,0,0,0},0},1,{find,value,0}}],
[{id,14},{self,{var,{pid,14}}}],
empty},
{seq,{res,{'$eqc_block',{var,{pid,14}}},no_res},empty}]}}}}]},
no_res},
empty}}]}},
{set,
{var,5},
{call,dht_net_eqc,store,
[{{0,0,0,0},0},<<0,0,0,0,0,0,0,0>>,0,0],
[{id,31},
{self,{var,{pid,31}}},
{res,{'$eqc_block',{var,{pid,31}}}},
{callouts,
{seq,
{res,
{seq,
[{val,0,
{internal,dht_state_eqc,node_id,[],
[{id,31},{self,{var,{pid,31}}}],
{return,0}}},
{seq,
{res,{val,1,{callout,dht_rand,uniform,[65535],1}},1},
{seq,
{res,
{val,ok,
{callout,dht_socket,send,['SOCKET_REF',{0,0,0,0},0,'_'],ok}},
ok},
{seq,
{res,
{internal,dht_time_eqc,send_after,
[2000,dht_net,{request_timeout,{{{0,0,0,0},0},<<0,1>>}}],
[{id,31},{self,{var,{pid,31}}}],
{seq,
[{callout,dht_time,send_after,
[2000,'_',{request_timeout,{{{0,0,0,0},0},<<0,1>>}}],
{tref,4}},
{return,{tref,4}}]}},
{tref,4}},
{seq,
[{internal,dht_net_eqc,add_blocked,
[{var,{pid,31}},
{request,
{tref,4},
{{0,0,0,0},0},
1,
{store,<<0,0,0,0,0,0,0,0>>,0,0}}],
[{id,31},{self,{var,{pid,31}}}],
empty},
{seq,{res,{'$eqc_block',{var,{pid,31}}},no_res},empty}]}}}}]},
no_res},
empty}}]}}]
dht_state_eqc:start_link(0, []) ->
0 = dht_time:monotonic_time(),
0 = dht_time:monotonic_time(),
0 = dht_time:convert_time_unit(0, native, milli_seconds),
{tref, 0} = dht_time:send_after(900000, <0.4713.1>, {inactive_range, {0, 128}}),
900000 = dht_time:convert_time_unit(900000, milli_seconds, native),
true.
dht_store_eqc:start_link() ->
{tref, 1} = dht_time:send_after(300000, dht_store, evict),
ok.
dht_net_eqc:init(0,
[<<0, 0, 0, 0, 0, 0, 0, 0>>, <<0, 0, 0, 0, 0, 0, 0, 0>>]) ->
{ok, 'SOCKET_REF'} = dht_socket:open(0, [binary, inet, {active, 16}]),
{tref, 2} = dht_time:send_after(300000, dht_net, renew_token),
true.
%% self = <0.4716.1>
dht_net_eqc:find_value({{0, 0, 0, 0}, 0}, 0) ->
1 = dht_rand:uniform(65535),
ok = dht_socket:send('SOCKET_REF', {0, 0, 0, 0}, 0,
[<<175, 64, 13, 52, 167, 136, 55, 45, 0, 1, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0>>,
113,
<<102, 118, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0>>]),
{tref, 3} = dht_time:send_after(2000, dht_net,
{request_timeout, {{{0, 0, 0, 0}, 0}, <<0, 1>>}}),
?BLOCK(<0.4716.1>).
%% self = <0.4717.1>
dht_net_eqc:store({{0, 0, 0, 0}, 0}, <<0, 0, 0, 0, 0, 0, 0, 0>>, 0, 0) ->
1 = dht_rand:uniform(65535),
exit({mocking_error, unexpected}) = dht_rand:uniform(65535),
?BLOCK(<0.4717.1>).
Reason:
Post-condition failed:
Callout mismatch:
unexpected: dht_rand:uniform(65535)
expected: dht_socket:send('SOCKET_REF', {0, 0, 0, 0}, 0, _)
Unexpected unblock:
dht_net_eqc:find_value({{0, 0, 0, 0}, 0}, 0) ->
exit({{{{mocking_error, {unexpected, dht_rand:uniform(65535)}},
[{eqc_mocking, f6141523_0, [dht_rand, uniform, [65535]],
[{file, "../src/eqc_mocking.erl"}, {line, 401}]},
{eqc_mocking, do_action, 3,
[{file, "../src/eqc_mocking.erl"}, {line, 397}]},
{dht_net, unique_message_id, 3,
[{file,
"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line, 362}]},
{dht_net, send_query, 4,
[{file,
"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line, 380}]},
{dht_net, handle_call, 3,
[{file,
"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line, 225}]},
{gen_server, try_handle_call, 4,
[{file, "gen_server.erl"}, {line, 629}]},
{gen_server, handle_msg, 5,
[{file, "gen_server.erl"}, {line, 661}]},
{proc_lib, init_p_do_apply, 3,
[{file, "proc_lib.erl"}, {line, 240}]}]},
{gen_server, call,
[dht_net, {request, {{0, 0, 0, 0}, 0}, {find, value, 0}}]}},
[{gen_server, call, 2, [{file, "gen_server.erl"}, {line, 204}]},
{dht_net, find_value, 2,
[{file,
"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line, 148}]}]})
[prop_cluster_correct]
missing from erlang.mk
I think is a bug because notice how it was included in the past.
lookup for an ID assigned in 2 nodes is only returned once
Following our discussion on slack: The doc says:
Multiple peers can store the same identity. In that case, each peer is reflected in the table.
But when I run the following example on 3 nodes (started locally) I only get one result:
1) Launch 3 nodes:
node 1:
1> application:load(dht),
1> application:set_env(dht, port, 1729).
ok
2> application:ensure_all_started(dht).
{ok,[crypto,dht]}
node 2:
1> application:load(dht),
1> application:set_env(dht, port, 1730).
ok
2> application:ensure_all_started(dht).
{ok,[crypto,dht]}
node 3:
1> application:load(dht),
1> application:set_env(dht, port, 1731).
ok
2> application:ensure_all_started(dht).
{ok,[crypto,dht]}
2) Then node 2 and node 3 join node 1:
node2 & node3:
3> dht:ping({{127, 0, 0, 1}, 1729}).
{ok,164275074679377439255457697552131619293959778100}
3) register the ID 456 on node 1 and node 2
node1:
4> dht:enter(456, 5000).
node2:
4> dht:enter(456, 3000).
4) running lookup on different nodes return:
node1:
5> dht:lookup(456).
[{{127,0,0,1},3000}]
node2 & node3:
5> dht:lookup(456).
[{{127,0,0,1},5000}]
Where I would have expected on each nodes [{{127,0,0,1},3000},{{127,0,0,1},5000}] .
Find and write the contributor list
There are some old-timers who has written much of this code as well. We better start building the right contributor list.
Check why state isn't dumped regularly
This is an odd mistake by the system we need to figure out. Manual state dumping seems to work as expected.
Consider eliminating wildcards from the model
There are a couple of wildcard calls in the model. These are quite bad when you have internal calls, so consider some wildcard elimination runs.
Search can fail with a function_clause error
Code outside the EQC kernel might fail. This looks like a traditional bug
=ERROR REPORT==== 26-Sep-2015::22:55:20 ===
** Generic server dht_track terminating
** Last message in was {refresh,456,3000}
** When Server state == {state,#{456 => 3000}}
** Reason for termination ==
** {function_clause,
[{dht_search,accum_results,
[[{{36204707630545954172038695459673098801770676921,
{192,168,1,105},
3723},
{error,timeout}}]],
[{file,
"/export/home/jlouis/P/dht/_build/default/lib/dht/src/dht_search.erl"},
{line,120}]},
{dht_search,accum_peers,3,
[{file,
"/export/home/jlouis/P/dht/_build/default/lib/dht/src/dht_search.erl"},
{line,117}]},
{dht_search,track_state,3,
[{file,
"/export/home/jlouis/P/dht/_build/default/lib/dht/src/dht_search.erl"},
{line,91}]},
{dht_search,dht_iter_search,6,
[{file,
"/export/home/jlouis/P/dht/_build/default/lib/dht/src/dht_search.erl"},
{line,58}]},
{dht_track,refresh,2,
[{file,
"/export/home/jlouis/P/dht/_build/default/lib/dht/src/dht_track.erl"},
{line,105}]},
{dht_track,handle_info,2,
[{file,
"/export/home/jlouis/P/dht/_build/default/lib/dht/src/dht_track.erl"},
{line,88}]},
{gen_server,try_dispatch,4,[{file,"gen_server.erl"},{line,615}]},
{gen_server,handle_msg,5,[{file,"gen_server.erl"},{line,681}]}]}
Invert the call path in request_success verification
Ok, dht_net is sitting and calling dht_state. Then the dht_state code delivers a message back to dht_net. It is much easier to just return a value and then do stuff based on this.
It will solve many troublesome parts of races.
When refreshing a node, the DHT network stack deadlocks
First, the error report, then the explanation:
=ERROR REPORT==== 15-Aug-2015::23:18:22 ===
** Generic server dht_net terminating
** Last message in was {udp,'SOCKET_REF',
{165,9981,16961,47768,50511,56659,47148,46353},
50662,
<<175,64,13,52,167,136,55,45,196,185,0,0,0,0,0,0,
0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
0,7,114,112>>}
** When Server state == {state,'SOCKET_REF',
#{{{{0,0,0,0},0},<<0,1>>} => {{<0.5497.0>,#Ref<0.0.2.58709>},{tref,3}},
{{{215,166,165,189},62174},<<139,148>>} => {{<0.5499.0>,#Ref<0.0.2.58747>},{tref,6}},
{{{165,9981,16961,47768,50511,56659,47148,
46353},
50662},
<<"Ĺ">>} => {{<0.5504.0>,#Ref<0.0.2.58915>},{tref,14}}},
{[<<0,0,0,0,0,0,0,0>>],[<<0,0,0,0,0,0,0,0>>]}}
** Reason for termination ==
** {{timeout,{gen_server,call,
[dht_net,
{request,{{60522,46801,463,33476,34447,62268,2848,
41219},
58448},
ping}]}},
[{gen_server,call,2,[{file,"gen_server.erl"},{line,204}]},
{dht_net,ping,1,
[{file,"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line,101}]},
{dht_state,refresh_node,1,
[{file,"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_state.erl"},
{line,164}]},
{dht_state,request_success,2,
[{file,"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_state.erl"},
{line,141}]},
{dht_net,handle_packet,3,
[{file,"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line,311}]},
{dht_net,handle_info,2,
[{file,"/home/jlouis/Store/P/dht/_build/default/lib/dht/src/dht_net.erl"},
{line,250}]},
{gen_server,try_dispatch,4,[{file,"gen_server.erl"},{line,615}]},
{gen_server,handle_msg,5,[{file,"gen_server.erl"},{line,681}]}]}
Whenever a peer is found, a call is made to the state system in order to figure out the node state of the possibly new peer. If this happens on a full bucket, we need to verify peers. This invokes a call to the network system.
But if the caller is the network system, currently executing, then it is not possible to call yourself, which will happen and then the system deadlocks.
The solution is to make verification asynchronous. Send a message to the network stack and let it handle that message instead. Add special provision for these messages as being "ping verifications". Once such a message completes, the underlying insert is part of it and will be retried.
The state system becomes much simpler since the code base doesn't have to worry about retries anymore. And the network stack doesn't become much more complex since it already has 99% of all the pieces in place.
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