src/mkrl_task.erl

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