lib/etorrent-1.0/src/etorrent_fs_process.erl

   1 %%%-------------------------------------------------------------------
   2 %%% File    : file_process.erl
   3 %%% Author  : User Jlouis <jesper.louis.andersen@gmail.com>
   4 %%% License : See COPYING
   5 %%% Description : The file process implements an interface to a given
   6 %%%  file. It is possible to carry out the wished operations on the file
   7 %%%  in question for operating in a Torrent Client. The implementation has
   8 %%%  an automatic handler for file descriptors: If no request has been
   9 %%%  received in a given timeout, then the file is closed.
  10 %%%
  11 %%% Created : 18 Jun 2007 by User Jlouis <jesper.louis.andersen@gmail.com>
  12 %%%-------------------------------------------------------------------
  13 -module(etorrent_fs_process).
  14
  15 -include("etorrent_mnesia_table.hrl").
  16 -include("log.hrl").
  17
  18 -behaviour(gen_server).
  19
  20 %% API
  21 -export([start_link/2, get_data/3, put_data/4, stop/1]).
  22
  23 %% gen_server callbacks
  24 -export([init/1, handle_call/3, handle_cast/2, handle_info/2,
  25          terminate/2, code_change/3]).
  26
  27 -record(state, {path = none,
  28                 iodev = none}).
  29
  30 % If no request has been received in this interval, close the server.
  31 -define(REQUEST_TIMEOUT, 60000).
  32
  33 %%====================================================================
  34 %% API
  35 %%====================================================================
  36 %%--------------------------------------------------------------------
  37 %% Function: start_link() -> {ok,Pid} | ignore | {error,Error}
  38 %% Description: Starts the server
  39 %%--------------------------------------------------------------------
  40 start_link(Path, Id) ->
  41     gen_server:start_link(?MODULE, [Path, Id], []).
  42
  43 get_data(Pid, OffSet, Size) ->
  44     gen_server:call(Pid, {read_request, OffSet, Size}).
  45
  46 put_data(Pid, Chunk, Offset, _Size) ->
  47     gen_server:call(Pid, {write_request, Offset, Chunk}).
  48
  49 stop(Pid) ->
  50     gen_server:cast(Pid, stop).
  51
  52 %%====================================================================
  53 %% gen_server callbacks
  54 %%====================================================================
  55 init([Id, TorrentId]) ->
  56     %% We'll clean up file descriptors gracefully on termination.
  57     process_flag(trap_exit, true),
  58     #path_map { path = Path} = etorrent_path_map:select(Id, TorrentId),
  59     {ok, Workdir} = application:get_env(etorrent, dir),
  60     FullPath = filename:join([Workdir, Path]),
  61     {ok, IODev} = file:open(FullPath, [read, write, binary, raw, read_ahead]),
  62     {ok, #state{iodev = IODev,
  63                 path = FullPath}, ?REQUEST_TIMEOUT}.
  64
  65 %%--------------------------------------------------------------------
  66 %% Function: %% handle_call(Request, From, State) -> {reply, Reply, State} |
  67 %%                                      {reply, Reply, State, Timeout} |
  68 %%                                      {noreply, State} |
  69 %%                                      {noreply, State, Timeout} |
  70 %%                                      {stop, Reason, Reply, State} |
  71 %%                                      {stop, Reason, State}
  72 %% Description: Handling call messages
  73 %%--------------------------------------------------------------------
  74 handle_call({read_request, Offset, Size}, _From, State) ->
  75     Data = read_request(Offset, Size, State),
  76     {reply, Data, State, ?REQUEST_TIMEOUT};
  77 handle_call({write_request, Offset, Data}, _From, S) ->
  78     ok = write_request(Offset, Data, S),
  79     {reply, ok, S, ?REQUEST_TIMEOUT}.
  80
  81 %%--------------------------------------------------------------------
  82 %% Function: handle_cast(Msg, State) -> {noreply, State} |
  83 %%                                      {noreply, State, Timeout} |
  84 %%                                      {stop, Reason, State}
  85 %% Description: Handling cast messages
  86 %%--------------------------------------------------------------------
  87 handle_cast(stop, S) ->
  88     {stop, normal, S};
  89 handle_cast(_Msg, State) ->
  90     {noreply, State, ?REQUEST_TIMEOUT}.
  91
  92 handle_info(timeout, State) ->
  93     {stop, normal, State};
  94 handle_info(Info, State) ->
  95     error_logger:warning_report([unknown_fs_process, Info]),
  96     {noreply, State}.
  97
  98 terminate(_Reason, State) ->
  99     case file:close(State#state.iodev) of
 100         ok -> ok;
 101         E -> ?log([cant_close_file, E]), ok
 102     end.
 103
 104 %%--------------------------------------------------------------------
 105 %% Func: code_change(OldVsn, State, Extra) -> {ok, NewState}
 106 %% Description: Convert process state when code is changed
 107 %%--------------------------------------------------------------------
 108 code_change(_OldVsn, State, _Extra) ->
 109     {ok, State}.
 110
 111 %%--------------------------------------------------------------------
 112 %%% Internal functions
 113 %%--------------------------------------------------------------------
 114
 115 %%--------------------------------------------------------------------
 116 %% Func: read_request(Offset, Size, State) -> {ok, Data}
 117 %%                                          | {read_error, posix()}
 118 %%                                          | {pos_error, posix()}
 119 %% Description: Attempt to read at Offset; Size bytes. Either returns
 120 %%  ok or an error from the positioning or reading with a posix()
 121 %%  error message.
 122 %%--------------------------------------------------------------------
 123 read_request(Offset, Size, State) ->
 124     {ok, NP} = file:position(State#state.iodev, Offset),
 125     Offset = NP,
 126     {ok, Data} = file:read(State#state.iodev, Size),
 127     Data.
 128
 129 %%--------------------------------------------------------------------
 130 %% Func: write_request(Offset, Bytes, State) -> ok
 131 %%                                            | {pos_error, posix()}
 132 %%                                            | {write_error, posix()}
 133 %% Description: Attempt to write Bytes at offset Offset. Either returns
 134 %%   ok, or an error from positioning or writing which is posix().
 135 %%--------------------------------------------------------------------
 136 write_request(Offset, Bytes, State) ->
 137     {ok, NP} = file:position(State#state.iodev, Offset),
 138     Offset = NP,
 139     ok = file:write(State#state.iodev, Bytes).
 140
 141 %%--------------------------------------------------------------------
 142 %% Func:
 143 %% Description:
 144 %%--------------------------------------------------------------------