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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.
%% @doc Reads CouchDB's ini file and gets queried for configuration parameters.
%% This module is initialized with a list of ini files that it
%% consecutively reads Key/Value pairs from and saves them in an ets
%% table. If more an one ini file is specified, the last one is used to
%% write changes that are made with store/2 back to that ini file.
-module(couch_config).
-include("couch_db.hrl").
-behaviour(gen_server).
-export([start_link/1, init/1, handle_call/3, handle_cast/2, handle_info/2,terminate/2, code_change/3]).
-export([all/0, get/1, get/2, get/3, delete/2, set/3, register/1, register/2,load_ini_file/1]).
-record(config,
{notify_funs=[],
writeback_filename=""
}).
%% Public API %%
%% @type etstable() = integer().
start_link(IniFiles) ->
gen_server:start_link({local, ?MODULE}, ?MODULE, IniFiles, []).
all() ->
gen_server:call(?MODULE, all).
get(Section) when is_binary(Section) ->
gen_server:call(?MODULE, {fetch, binary_to_list(Section)});
get(Section) ->
gen_server:call(?MODULE, {fetch, Section}).
get(Section, Key) when is_binary(Section) and is_binary(Key) ->
get(binary_to_list(Section), binary_to_list(Key), undefined);
get(Section, Key) ->
get(Section, Key, undefined).
get(Section, Key, Default) when is_binary(Section) and is_binary(Key) ->
gen_server:call(?MODULE, {fetch, binary_to_list(Section), binary_to_list(Key), Default});
get(Section, Key, Default) ->
gen_server:call(?MODULE, {fetch, Section, Key, Default}).
set(Section, Key, Value) when is_binary(Section) and is_binary(Key) ->
gen_server:call(?MODULE, {set, [{{binary_to_list(Section), binary_to_list(Key)}, Value}]});
set(Section, Key, Value) ->
gen_server:call(?MODULE, {set, [{{Section, Key}, Value}]}).
delete(Section, Key) when is_binary(Section) and is_binary(Key) ->
gen_server:call(?MODULE, {delete, {binary_to_list(Section), binary_to_list(Key)}});
delete(Section, Key) ->
gen_server:call(?MODULE, {delete, {Section, Key}}).
register(Fun) ->
?MODULE:register(Fun, self()).
register(Fun, Pid) ->
gen_server:call(?MODULE, {register, Fun, Pid}).
%% Private API %%
%% @spec init(List::list([])) -> {ok, Tab::etsatable()}
%% @doc Creates a new ets table of the type "set".
init(IniFiles) ->
ets:new(?MODULE, [named_table, set, protected]),
[ok = load_ini_file(IniFile) || IniFile <- IniFiles],
{ok, #config{writeback_filename=lists:last(IniFiles)}}.
handle_call(all, _From, Config) ->
{reply, lists:sort(ets:tab2list(?MODULE)), Config};
handle_call({fetch, Section}, _From, Config) ->
Matches = ets:match(?MODULE, {{Section, '$1'}, '$2'}),
{reply, [{Key, Value} || [Key, Value] <- Matches], Config};
handle_call({fetch, Section, Key, Default}, _From, Config) ->
Ret = case ets:lookup(?MODULE, {Section, Key}) of
[] -> Default;
[{_,Result}] -> Result
end,
{reply, Ret, Config};
handle_call({set, KVs}, _From, Config) ->
[ok = insert_and_commit(Config, KV) || KV <- KVs],
{reply, ok, Config};
handle_call({delete, Key}, _From, Config) ->
ets:delete(?MODULE, Key),
{reply, ok, Config};
handle_call({register, Fun, Pid}, _From, #config{notify_funs=PidFuns}=Config) ->
erlang:monitor(process, Pid),
{reply, ok, Config#config{notify_funs=[{Pid, Fun}|PidFuns]}}.
%% @spec insert_and_commit(Tab::etstable(), Config::any()) -> ok
%% @doc Inserts a Key/Value pair into the ets table, writes it to the storage
%% ini file and calls all registered callback functions for Key.
insert_and_commit(Config, KV) ->
true = ets:insert(?MODULE, KV),
% notify funs
[catch Fun(KV) || {_Pid, Fun} <- Config#config.notify_funs],
couch_config_writer:save_to_file(KV, Config#config.writeback_filename).
%% @spec load_ini_file(IniFile::filename()) -> ok
%% @doc Parses an ini file and stores Key/Value Pairs into the ets table.
load_ini_file(IniFile) ->
IniFilename = couch_util:abs_pathname(IniFile),
IniBin =
case file:read_file(IniFilename) of
{ok, IniBin0} ->
IniBin0;
{error, enoent} ->
Msg = io_lib:format("Couldn't find server configuration file ~s.", [IniFilename]),
io:format("~s~n", [Msg]),
throw({startup_error, Msg})
end,
{ok, Lines} = regexp:split(binary_to_list(IniBin), "\r\n|\n|\r|\032"),
{_, ParsedIniValues} =
lists:foldl(fun(Line, {AccSectionName, AccValues}) ->
case string:strip(Line) of
"[" ++ Rest ->
case regexp:split(Rest, "\\]") of
{ok, [NewSectionName, ""]} ->
{NewSectionName, AccValues};
_Else -> % end bracket not at end, ignore this line
{AccSectionName, AccValues}
end;
";" ++ _Comment ->
{AccSectionName, AccValues};
Line2 ->
case regexp:split(Line2, "\s?=\s?") of
{ok, [_SingleElement]} -> % no "=" found, ignore this line
{AccSectionName, AccValues};
{ok, [""|_LineValues]} -> % line begins with "=", ignore
{AccSectionName, AccValues};
{ok, [ValueName|LineValues]} -> % yeehaw, got a line!
RemainingLine = couch_util:implode(LineValues, "="),
{ok, [LineValue | _Rest]} = regexp:split(RemainingLine, " ;|\t;"), % removes comments
{AccSectionName, [{{AccSectionName, ValueName}, LineValue} | AccValues]}
end
end
end, {"", []}, Lines),
[ets:insert(?MODULE, {Key, Value}) || {Key, Value} <- ParsedIniValues],
ok.
% Unused gen_server behaviour API functions that we need to declare.
%% @doc Unused
handle_cast(foo, State) -> {noreply, State}.
handle_info({'DOWN', _, _, DownPid, _}, #config{notify_funs=PidFuns}=Config) ->
% remove any funs registered by the downed process
FilteredPidFuns = [{Pid,Fun} || {Pid,Fun} <- PidFuns, Pid /= DownPid],
{noreply, Config#config{notify_funs=FilteredPidFuns}}.
%% @doc Unused
terminate(_Reason, _State) -> ok.
%% @doc Unused
code_change(_OldVersion, State, _Extra) -> {ok, State}.
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