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-module(db).
-behaviour(gen_server).
%% API.
-export([start_link/0, stop/0, init_tables/0]).
-export([add/1, find/1]).
%% API for testing.
-export([dump/1, destroy_tables/0, info_tables/0, dump_to_file/1]).
%% gen_server callbacks.
-export([init/1, handle_call/3, terminate/2, handle_cast/2, handle_info/2,
code_change/3]).
-include_lib("stdlib/include/qlc.hrl").
-include("plop.hrl").
%% @doc Run once, or rather every time you start on a new database.
%% If run more than once, we'll get {aborted, {already_exists, TABLE}}.
init_tables() ->
%% We've once upon a time invoked mnesia:create_schema/1 with the
%% nodes that will be part of the database.
RamCopies = [],
DiscCopies = [],
DiscOnlyCopies = [node()],
mnesia:start(),
mnesia:create_table(plop, [{type, set},
{ram_copies, RamCopies},
{disc_copies, DiscCopies},
{disc_only_copies, DiscOnlyCopies},
{attributes, record_info(fields, plop)}]),
mnesia:add_table_index(plop, hash).
destroy_tables() ->
mnesia:delete_table(plop).
info_tables() ->
mnesia:table_info(plop, all).
dump_to_file(Filename) ->
mnesia:dump_to_textfile(Filename).
init(_Args) ->
{ok, []}. % TODO: return state
start_link() ->
gen_server:start_link({local, ?MODULE}, ?MODULE, [], []).
stop() ->
gen_server:call(?MODULE, stop).
add(Entry) ->
gen_server:call(?MODULE, {add, Entry}).
find(Hash) ->
gen_server:call(?MODULE, {find, Hash}).
dump(Table) ->
gen_server:call(?MODULE, {dump, Table}).
%%%%%%%%%%%%%%%%%%%%
handle_cast(_Request, State) ->
{noreply, State}.
handle_info(_Info, State) ->
{noreply, State}.
code_change(_OldVsn, State, _Extra) ->
{ok, State}.
terminate(_Reason, _State) ->
ok.
%%%%%%%%%%%%%%%%%%%%
handle_call(stop, _From, State) ->
{stop, normal, stopped, State};
handle_call({add, Entry}, _From, State) ->
F = fun() ->
mnesia:write(Entry)
end,
Res = mnesia:transaction(F),
{reply, Res, State};
handle_call({dump, Table}, _From, State) ->
F = fun() ->
Q = qlc:q([E || E <- mnesia:table(Table)]),
qlc:e(Q)
end,
Res = mnesia:transaction(F),
{reply, Res, State};
handle_call({find, Hash}, _From, State) ->
{reply, mnesia:dirty_read({plop, Hash}), State}.
|
