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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(fabric_db_create).
-export([go/2]).
-include_lib("fabric/include/fabric.hrl").
-include_lib("mem3/include/mem3.hrl").
-include_lib("couch/include/couch_db.hrl").
%% @doc Create a new database, and all its partition files across the cluster
%% Options is proplist with user_ctx, n, q, validate_name
go(DbName, Options) ->
case validate_dbname(DbName, Options) of
ok ->
couch_partition:validate_dbname(DbName, Options),
case db_exists(DbName) of
true ->
{error, file_exists};
false ->
{Shards, Doc} = generate_shard_map(DbName, Options),
CreateShardResult = create_shard_files(Shards, Options),
case CreateShardResult of
enametoolong ->
{error, {database_name_too_long, DbName}};
_ ->
case {CreateShardResult, create_shard_db_doc(Doc)} of
{ok, {ok, Status}} ->
Status;
{ok, {error, conflict} = ShardDocError} ->
% Check if it is just a race to create the shard doc
case db_exists(DbName) of
true -> {error, file_exists};
false -> ShardDocError
end;
{file_exists, {ok, _}} ->
{error, file_exists};
{_, Error} ->
Error
end
end
end;
Error ->
Error
end.
validate_dbname(DbName, Options) ->
case couch_util:get_value(validate_name, Options, true) of
false ->
ok;
true ->
couch_db:validate_dbname(DbName)
end.
generate_shard_map(DbName, Options) ->
Suffix = mem3:generate_shard_suffix(),
Shards = mem3:choose_shards(DbName, [{shard_suffix, Suffix} | Options]),
case mem3_util:open_db_doc(DbName) of
{ok, Doc} ->
% the DB already exists, and may have a different Suffix
ok;
{not_found, _} ->
Doc = make_document(Shards, Suffix, Options)
end,
{Shards, Doc}.
create_shard_files(Shards, Options) ->
Workers = fabric_util:submit_jobs(Shards, create_db, [Options]),
RexiMon = fabric_util:create_monitors(Shards),
try fabric_util:recv(Workers, #shard.ref, fun handle_message/3, Workers) of
{error, file_exists} ->
file_exists;
{error, enametoolong} ->
enametoolong;
{timeout, DefunctWorkers} ->
fabric_util:log_timeout(DefunctWorkers, "create_db"),
{error, timeout};
_ ->
ok
after
rexi_monitor:stop(RexiMon)
end.
handle_message({error, enametoolong}, _, _) ->
{error, enametoolong};
handle_message(file_exists, _, _) ->
{error, file_exists};
handle_message({rexi_DOWN, _, {_, Node}, _}, _, Workers) ->
case lists:filter(fun(S) -> S#shard.node =/= Node end, Workers) of
[] ->
{stop, ok};
RemainingWorkers ->
{ok, RemainingWorkers}
end;
handle_message(_, Worker, Workers) ->
case lists:delete(Worker, Workers) of
[] ->
{stop, ok};
RemainingWorkers ->
{ok, RemainingWorkers}
end.
create_shard_db_doc(Doc) ->
Shards = [#shard{node = N} || N <- mem3:nodes()],
RexiMon = fabric_util:create_monitors(Shards),
Workers = fabric_util:submit_jobs(Shards, create_shard_db_doc, [Doc]),
Acc0 = {length(Shards), fabric_dict:init(Workers, nil)},
try fabric_util:recv(Workers, #shard.ref, fun handle_db_update/3, Acc0) of
{timeout, {_, WorkersDict}} ->
DefunctWorkers = fabric_util:remove_done_workers(WorkersDict, nil),
fabric_util:log_timeout(
DefunctWorkers,
"create_shard_db_doc"
),
{error, timeout};
Else ->
Else
after
rexi_monitor:stop(RexiMon)
end.
handle_db_update({rexi_DOWN, _, {_, Node}, _}, _Worker, {W, Counters}) ->
New = fabric_dict:filter(fun(S, _) -> S#shard.node =/= Node end, Counters),
maybe_stop(W, New);
handle_db_update({rexi_EXIT, _Reason}, Worker, {W, Counters}) ->
maybe_stop(W, fabric_dict:erase(Worker, Counters));
handle_db_update(conflict, _, _) ->
% just fail when we get any conflicts
{error, conflict};
handle_db_update(Msg, Worker, {W, Counters}) ->
maybe_stop(W, fabric_dict:store(Worker, Msg, Counters)).
maybe_stop(W, Counters) ->
case fabric_dict:any(nil, Counters) of
true ->
{ok, {W, Counters}};
false ->
case lists:sum([1 || {_, ok} <- Counters]) of
NumOk when NumOk >= (W div 2 + 1) ->
{stop, ok};
NumOk when NumOk > 0 ->
{stop, accepted};
_ ->
{error, internal_server_error}
end
end.
make_document([#shard{dbname = DbName} | _] = Shards, Suffix, Options) ->
{RawOut, ByNodeOut, ByRangeOut} =
lists:foldl(
fun(#shard{node = N, range = [B, E]}, {Raw, ByNode, ByRange}) ->
Range = ?l2b([
couch_util:to_hex(<<B:32/integer>>),
"-",
couch_util:to_hex(<<E:32/integer>>)
]),
Node = couch_util:to_binary(N),
{
[[<<"add">>, Range, Node] | Raw],
orddict:append(Node, Range, ByNode),
orddict:append(Range, Node, ByRange)
}
end,
{[], [], []},
Shards
),
EngineProp =
case couch_util:get_value(engine, Options) of
E when is_binary(E) -> [{<<"engine">>, E}];
_ -> []
end,
DbProps =
case couch_util:get_value(props, Options) of
Props when is_list(Props) -> [{<<"props">>, {Props}}];
_ -> []
end,
#doc{
id = DbName,
body = {
[
{<<"shard_suffix">>, Suffix},
{<<"changelog">>, lists:sort(RawOut)},
{<<"by_node">>, {[{K, lists:sort(V)} || {K, V} <- ByNodeOut]}},
{<<"by_range">>, {[{K, lists:sort(V)} || {K, V} <- ByRangeOut]}}
] ++ EngineProp ++ DbProps
}
}.
db_exists(DbName) -> is_list(catch mem3:shards(DbName)).
-ifdef(TEST).
-include_lib("eunit/include/eunit.hrl").
db_exists_test_() ->
{
setup,
fun setup_all/0,
fun teardown_all/1,
[
fun db_exists_for_existing_db/0,
fun db_exists_for_missing_db/0
]
}.
setup_all() ->
meck:new(mem3).
teardown_all(_) ->
meck:unload().
db_exists_for_existing_db() ->
Mock = fun(DbName) when is_binary(DbName) ->
[#shard{dbname = DbName, range = [0, 100]}]
end,
ok = meck:expect(mem3, shards, Mock),
?assertEqual(true, db_exists(<<"foobar">>)),
?assertEqual(true, meck:validate(mem3)).
db_exists_for_missing_db() ->
Mock = fun(DbName) ->
erlang:error(database_does_not_exist, DbName)
end,
ok = meck:expect(mem3, shards, Mock),
?assertEqual(false, db_exists(<<"foobar">>)),
?assertEqual(false, meck:validate(mem3)).
-endif.
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