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Diffstat (limited to 'src/couchdb/couch_config.erl')
| -rw-r--r-- | src/couchdb/couch_config.erl | 195 |
1 files changed, 195 insertions, 0 deletions
diff --git a/src/couchdb/couch_config.erl b/src/couchdb/couch_config.erl new file mode 100644 index 00000000..07d47dff --- /dev/null +++ b/src/couchdb/couch_config.erl @@ -0,0 +1,195 @@ +% 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([store/2, register/1, register/2, + get/1, get/2, + lookup_match/1, lookup_match/2, + all/0, unset/1, 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, []). + +%% @spec store(Key::any(), Value::any()) -> {ok, Tab::etsatable()} +%% @doc Public API function that triggers storage of a Key/Value pair into the +%% local ets table and writes it to the storage ini file. +store(Key, Value) -> gen_server:call(?MODULE, {store, [{Key, Value}]}). + +%% @spec get(Key::any()) -> Value::any() | undefined +%% @doc Returns the value that is stored under key::any() or undefined::atom() if no +%% such Key exists. +get(Key) -> + ?MODULE:get(Key, undefined). + +%% @spec get(Key::any(), Default::any()) -> Value::any() | Default +%% @doc Returns the value that is stored under key::any() or Default::any() if +%% no such Key exists. +get(Key, Default) -> + fix_lookup_result(ets:lookup(?MODULE, Key), Default). + +%% @spec lookup_match(Key::any()) -> Value::any() | undefined:atom() +%% @doc Lets you look for a Key's Value specifying a pattern that gets passed +%% to ets::match(). Returns undefined::atom() if no Key is found. +lookup_match(Key) -> gen_server:call(?MODULE, {lookup_match, Key}). + +%% @spec lookup_match(Key::any(), Default::any()) -> Value::any() | Default +%% @doc Lets you look for a Key's Value specifying a pattern that gets passed +%% to ets::match(). Returns Default::any() if no Key is found +lookup_match(Key, Default) -> gen_server:call(?MODULE, {lookup_match, Key, Default}). + +all() -> gen_server:call(?MODULE, all). + +register(Fun) -> gen_server:call(?MODULE, {register, Fun, self()}). + + +register(Fun, Pid) -> gen_server:call(?MODULE, {register, Fun, Pid}). + +%% @spec unset(Key::any) -> ok +%% @doc Public API call to remove the configuration entry from the internal +%% ets table. This change is _not_ written to the storage ini file. +unset(Key) -> gen_server:call(?MODULE, {unset, Key}). + +%% 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)}}. + +%% @doc see store/2 +handle_call({store, KVs}, _From, Config) -> + [ok = insert_and_commit(Config, KV) || KV <- KVs], + {reply, ok, Config}; + + +%% @doc See init_value/2 +handle_call({init_value, Key, Value}, _From, Config) -> + Reply = ets:insert(?MODULE, {Key, Value}), + {reply, Reply, Config}; + +%% @doc See unset/1 +handle_call({unset, Key}, _From, Config) -> + ets:delete(?MODULE, Key), + {reply, ok, Config}; + + +%% @doc See lookup_match/2 +handle_call({lookup_match, Key, Default}, _From, Config) -> + {reply, fix_lookup_result(ets:match(?MODULE, Key), Default), Config}; + +handle_call(all, _From, Config) -> + {reply, lists:sort(ets:tab2list(?MODULE)), Config}; + +%% @doc See register/2 +handle_call({register, Fun, Pid}, _From, #config{notify_funs=PidFuns}=Config) -> + erlang:monitor(process, Pid), + {reply, ok, Config#config{notify_funs=[{Pid, Fun}|PidFuns]}}. + + +fix_lookup_result([{_Key, Value}], _Default) -> + Value; +fix_lookup_result([], Default) -> + Default; +fix_lookup_result(Values, _Default) -> + [list_to_tuple(Value) || Value <- Values]. + +%% @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, "=") 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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