src/task.erl

   1 %%%-------------------------------------------------------------------
   2 %%% File    : task.erl
   3 %%% Author  :  <>
   4 %%% Description :
   5 %%%
   6 %%% Created : 25 Mar 2011 by  <>
   7 %%%-------------------------------------------------------------------
   8 -module(makerl.task).
   9 -include("makerl.hrl").
  10
  11 -import(gen_server).
  12
  13 -behaviour(gen_server).
  14
  15
  16
  17 %% API
  18 -export([new/1,
  19          build_target/1]).
  20
  21 %% gen_server callbacks
  22 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  23          terminate/2, code_change/3]).
  24
  25 -define(TIMEOUT, infinity).
  26
  27 %% Status: fulfilled,
  28
  29 % The status field could be calculated each time through Hook:build, but a
  30 % poorly implemented hook could hang the system, so we considered a hook fulfilled
  31 % if it has run once... and thus we need a field.
  32 -record(state, { status :: status_type(),
  33                  target :: string(),
  34                  result :: build_result() }).
  35
  36 %%====================================================================
  37 %% API
  38 %%====================================================================
  39
  40 %% @doc Create a new task and register it.
  41 -spec new(string()) -> {ok, pid()}.
  42 new(Target) ->
  43     gen_server:start_link(?MODULE, [Target], []).
  44
  45 build_target(Target) ->
  46     {ok, Pid} = makerl.task_registry:find_pid_by_target(Target),
  47     gen_server:call(Pid, build_target, ?TIMEOUT).
  48
  49 %%====================================================================
  50 %% gen_server callbacks
  51 %%====================================================================
  52
  53 %%--------------------------------------------------------------------
  54 %% Function: init(Args) -> {ok, State} |
  55 %%                         {ok, State, Timeout} |
  56 %%                         ignore               |
  57 %%                         {stop, Reason}
  58 %% Description: Initiates the server
  59 %%--------------------------------------------------------------------
  60 init([Target]) ->
  61     {ok, Task} = makerl.task_registry:find_by_target(Target),
  62     Hook = Task#task.module,
  63     InitialStatus = Hook:get_status(Target,
  64                                     Task#task.prerequisites,
  65                                     Task#task.options),
  66     makerl.task_registry:set_pid(Target, self()),
  67     {ok, #state{status=InitialStatus,
  68                 target = Target,
  69                 result= makerl.dispatcher:unit() }}.
  70
  71 %%--------------------------------------------------------------------
  72 %% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
  73 %%                                      {reply, Reply, State, Timeout} |
  74 %%                                      {noreply, State} |
  75 %%                                      {noreply, State, Timeout} |
  76 %%                                      {stop, Reason, Reply, State} |
  77 %%                                      {stop, Reason, State}
  78 %% Description: Handling call messages
  79 %%--------------------------------------------------------------------
  80 handle_call(build_target, _From, State) ->
  81     case State#state.status of
  82         fulfilled -> {reply, State#state.result, State};
  83         %% Shouldn't we issue a warning and execute nevertheless?. This should't happen if
  84         %% get_status worked properly *and* nothing strange happened...
  85         unfulfilled ->
  86             Task = get_task_from_state(State),
  87             ?DEBUG("BUILDING: ~p~n", [Task]),
  88             DepResultList = makerl.dispatcher:build_dependencies(Task#task.prerequisites),
  89             AggregatedResult = makerl.dispatcher:aggregate_results(DepResultList),
  90             Hook = Task#task.module,
  91             Result = Hook:build(Task#task.target, Task#task.prerequisites, Task#task.options),
  92             CombinedResult = makerl.dispatcher:combine_result(AggregatedResult, Result),
  93             {reply, CombinedResult, State#state{ status = fulfilled, result = State#state.result } }
  94     end.
  95
  96 handle_cast(_Msg, State) -> {noreply, State}.
  97 handle_info(_Info, State) -> {noreply, State}.
  98 terminate(_Reason, _State) -> ok.
  99 code_change(_OldVsn, State, _Extra) -> {ok, State}.
 100
 101 %%--------------------------------------------------------------------
 102 %% Internal functions
 103 %%--------------------------------------------------------------------
 104 get_task_from_state(State) ->
 105     {ok, Task} = makerl.task_registry:find_by_target(State#state.target),
 106     Task.