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% Licensed under the Apache License, Version 2.0 (the "License"); you may not
% use this file except in compliance with the License. You may obtain a copy of
% the License at
%
% http://www.apache.org/licenses/LICENSE-2.0
%
% Unless required by applicable law or agreed to in writing, software
% distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
% WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
% License for the specific language governing permissions and limitations under
% the License.
-module(custodian_util).
-include_lib("mem3/include/mem3.hrl").
-include_lib("couch/include/couch_db.hrl").
-export([summary/0, report/0]).
-export([ensure_dbs_exists/0]).
% Old design doc which should be cleaned up
-define(CUSTODIAN_ID, <<"_design/custodian">>).
-record(state, {live, safe, callback, db, acc}).
%% public functions.
summary() ->
Dict0 = dict:from_list([{conflicted, 0}] ++
[{{live, N}, 0} || N <- lists:seq(0, cluster_n() - 1)] ++
[{{safe, N}, 0} || N <- lists:seq(0, cluster_n() - 1)]),
Fun = fun(_Id, _Range, {conflicted, _N}, Dict) ->
dict:update_counter(conflicted, 1, Dict);
(_Id, _Range, Item, Dict) ->
dict:update_counter(Item, 1, Dict)
end,
dict:to_list(fold_dbs(Dict0, Fun)).
report() ->
Fun = fun(Id, _Range, {conflicted, N}, Acc) ->
[{Id, {conflicted, N}} | Acc];
(Id, Range, Item, Acc) ->
[{Id, Range, Item} | Acc]
end,
fold_dbs([], Fun).
ensure_dbs_exists() ->
DbName = mem3_sync:shards_db(),
{ok, Db} = mem3_util:ensure_exists(DbName),
ensure_custodian_ddoc_is_deleted(Db),
{ok, Db}.
%% private functions.
fold_dbs(Acc, Fun) ->
Safe = maybe_redirect([node() | nodes()]),
Live = Safe -- maintenance_nodes(Safe),
{ok, Db} = ensure_dbs_exists(),
try
State0 = #state{live=Live, safe=Safe, callback=Fun, db=Db, acc=Acc},
{ok, State1} = couch_db:fold_docs(Db, fun fold_dbs1/2, State0, []),
State1#state.acc
after
couch_db:close(Db)
end.
fold_dbs1(#full_doc_info{id = <<"_design/", _/binary>>}, Acc) ->
{ok, Acc};
fold_dbs1(#full_doc_info{deleted=true}, Acc) ->
{ok, Acc};
fold_dbs1(#full_doc_info{id = Id} = FDI, State) ->
InternalAcc = case count_conflicts(FDI) of
0 ->
State#state.acc;
ConflictCount ->
(State#state.callback)(Id, null, {conflicted, ConflictCount}, State#state.acc)
end,
fold_dbs(Id, load_shards(State#state.db, FDI), State#state{acc=InternalAcc}).
fold_dbs(Id, Shards, State) ->
IsSafe = fun(#shard{node = N}) -> lists:member(N, State#state.safe) end,
IsLive = fun(#shard{node = N}) -> lists:member(N, State#state.live) end,
LiveShards = lists:filter(IsLive, Shards),
SafeShards = lists:filter(IsSafe, Shards),
TargetN = mem3_util:calculate_max_n(Shards),
Acc0 = State#state.acc,
Acc1 = case mem3_util:calculate_max_n(LiveShards) of
LiveN when LiveN < TargetN ->
LiveRanges = get_range_counts(LiveN, LiveShards, Shards),
lists:foldl(fun({Range, N}, FAcc) ->
(State#state.callback)(Id, Range, {live, N}, FAcc)
end, Acc0, LiveRanges);
_ ->
Acc0
end,
Acc2 = case mem3_util:calculate_max_n(SafeShards) of
SafeN when SafeN < TargetN ->
SafeRanges = get_range_counts(SafeN, SafeShards, Shards),
lists:foldl(fun({Range, N}, FAcc) ->
(State#state.callback)(Id, Range, {safe, N}, FAcc)
end, Acc1, SafeRanges);
_ ->
Acc1
end,
{ok, State#state{acc = Acc2}}.
get_range_counts(MaxN, Shards, AllShards) ->
Ranges = ranges(Shards),
AllRanges = ranges(AllShards),
% Get a list of ranges that were used to fill the MaxN rings. Also return
% whatever was left (not part of the rings).
{UnusedRanges, UsedRanges} = get_n_rings(MaxN, Ranges, []),
% All the ranges that participated in filling the N rings will get
% their number of copies set to MaxN.
UsedCounts = update_counts(UsedRanges, #{}, 1, fun(_) -> MaxN end),
% Add ranges that were present but didn't get picked in the rings
PresentCounts = update_counts(UnusedRanges, UsedCounts, 1, fun(N) ->
max(N + 1, MaxN)
end),
% Handle shards that are not present at all. Mark these ranges as missing.
Missing = [R || R <- AllRanges, not lists:member(R, Ranges)],
RangeCounts = update_counts(Missing, PresentCounts, 0, fun(_) -> 0 end),
% Report only shards with counts =< MaxN
RangeCounts1 = maps:filter(fun(_, N) -> N =< MaxN end, RangeCounts),
lists:sort(maps:to_list(RangeCounts1)).
update_counts(Ranges, Acc0, Init, UpdateFun) ->
lists:foldl(fun({B, E}, Acc) ->
maps:update_with({B, E}, UpdateFun, Init, Acc)
end, Acc0, Ranges).
ranges(Shards) ->
lists:map(fun(S) -> [B, E] = mem3:range(S), {B, E} end, Shards).
get_n_rings(N, Ranges, Rings) when N =< 0 ->
{Ranges, Rings};
get_n_rings(N, Ranges, Rings) ->
Ring = mem3_util:get_ring(Ranges),
get_n_rings(N - 1, Ranges -- Ring, Rings ++ Ring).
cluster_n() ->
config:get_integer("cluster", "n", 3).
maintenance_nodes(Nodes) ->
{Modes, _} = rpc:multicall(Nodes, config, get, ["couchdb", "maintenance_mode"]),
[N || {N, Mode} <- lists:zip(Nodes, Modes), Mode =:= "true"].
load_shards(Db, #full_doc_info{id = Id} = FDI) ->
case couch_db:open_doc(Db, FDI, [ejson_body]) of
{ok, #doc{body = {Props}}} ->
mem3_util:build_shards(Id, Props);
{not_found, _} ->
erlang:error(database_does_not_exist, ?b2l(Id))
end.
maybe_redirect(Nodes) ->
maybe_redirect(Nodes, []).
maybe_redirect([], Acc) ->
Acc;
maybe_redirect([Node|Rest], Acc) ->
case config:get("mem3.redirects", atom_to_list(Node)) of
undefined ->
maybe_redirect(Rest, [Node|Acc]);
Redirect ->
maybe_redirect(Rest, [list_to_atom(Redirect)|Acc])
end.
count_conflicts(#full_doc_info{rev_tree = T}) ->
Leafs = [1 || {#leaf{deleted=false}, _} <- couch_key_tree:get_all_leafs(T)],
length(Leafs) - 1.
% Ensure the design doc which was added 3.2.0 is deleted as we switched to using a BDU
% function instead. After a few releases this function could be removed as well
%
ensure_custodian_ddoc_is_deleted(Db) ->
case couch_db:open_doc(Db, ?CUSTODIAN_ID, [ejson_body]) of
{not_found, _Reason} ->
ok;
{ok, Doc} ->
DeletedDoc = Doc#doc{deleted = true, body = {[]}},
try couch_db:update_doc(Db, DeletedDoc, [?ADMIN_CTX]) of
{ok, _} ->
LogMsg = "~p : deleted custodian ddoc ~s",
couch_log:notice(LogMsg, [?MODULE, ?CUSTODIAN_ID]),
ok
catch
conflict ->
{ok, NewDb} = couch_db:reopen(Db),
ensure_custodian_ddoc_is_deleted(NewDb)
end
end.
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
get_range_counts_test_() ->
[?_assertEqual(Res, get_range_counts(N, Shards, AllShards)) || {N, Shards,
AllShards, Res} <- [
% No shards are present. There is a full range shard that would
% fit. Report that range as missing.
{0, [], [full()], [{{0, ?RING_END}, 0}]},
% Can't complete the ring. But would complete it if had the
% {2, ?RING_END} interval available.
{0, [sh(0, 1)], [sh(0, 1), sh(2, ?RING_END)], [{{2, ?RING_END}, 0}]},
% Can complete the ring only 1 time. Report that range as the
% one available with a count of 1
{1, [full()], [full(), full()], [{{0, ?RING_END}, 1}]},
% Can complete the ring only 1 time with a full range shard, but
% there is also {2, ?RING_END} that would complete another the
% the ring as well if {0, 1} was present.
{1, [sh(2, ?RING_END), full()], [sh(0, 1), sh(2, ?RING_END), full()],
[
{{0, 1}, 0},
{{0, ?RING_END}, 1},
{{2, ?RING_END}, 1}
]
},
% Can complete the ring 2 times [{0, 2},{3, ?RING_END)] and full(),
% and there is remnant of a 5, 9 range that would comlete the ring
% as well if {0, 4} and {10, ?RING_END} were present. So report
{2, [sh(0, 2), sh(3, ?RING_END), sh(5, 9), full()], [sh(0, 2), sh(3,
?RING_END), full(), sh(0, 4), sh(5, 9), sh(10, ?RING_END)],
[
{{0, 2}, 1},
{{0, 4}, 0},
{{0, ?RING_END}, 1},
{{3, ?RING_END}, 1},
{{5, 9}, 1},
{{10, ?RING_END}, 0}
]
}
]].
full() ->
#shard{range = [0, ?RING_END]}.
sh(B, E) ->
#shard{range = [B, E]}.
-endif.
|
