flm01/server/api/webmachine/src/webmachine_resource.erl

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2010-02-25 17:45:11 +00:00
%% @author Justin Sheehy <justin@basho.com>
%% @author Andy Gross <andy@basho.com>
%% @copyright 2007-2009 Basho Technologies
%%
%% 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.
-module(webmachine_resource, [R_Mod, R_ModState, R_ModExports, R_Trace]).
-author('Justin Sheehy <justin@basho.com>').
-author('Andy Gross <andy@basho.com>').
-export([wrap/2]).
-export([do/2,log_d/1,stop/0]).
default(ping) ->
no_default;
default(service_available) ->
true;
default(resource_exists) ->
true;
default(auth_required) ->
true;
default(is_authorized) ->
true;
default(forbidden) ->
false;
default(allow_missing_post) ->
false;
default(malformed_request) ->
false;
default(uri_too_long) ->
false;
default(known_content_type) ->
true;
default(valid_content_headers) ->
true;
default(valid_entity_length) ->
true;
default(options) ->
[];
default(allowed_methods) ->
['GET', 'HEAD'];
default(known_methods) ->
['GET', 'HEAD', 'POST', 'PUT', 'DELETE', 'TRACE', 'CONNECT', 'OPTIONS'];
default(content_types_provided) ->
[{"text/html", to_html}];
default(content_types_accepted) ->
[];
default(delete_resource) ->
false;
default(delete_completed) ->
true;
default(post_is_create) ->
false;
default(create_path) ->
undefined;
default(process_post) ->
false;
default(language_available) ->
true;
default(charsets_provided) ->
no_charset; % this atom causes charset-negotation to short-circuit
% the default setting is needed for non-charset responses such as image/png
% an example of how one might do actual negotiation
% [{"iso-8859-1", fun(X) -> X end}, {"utf-8", make_utf8}];
default(encodings_provided) ->
[{"identity", fun(X) -> X end}];
% this is handy for auto-gzip of GET-only resources:
% [{"identity", fun(X) -> X end}, {"gzip", fun(X) -> zlib:gzip(X) end}];
default(variances) ->
[];
default(is_conflict) ->
false;
default(multiple_choices) ->
false;
default(previously_existed) ->
false;
default(moved_permanently) ->
false;
default(moved_temporarily) ->
false;
default(last_modified) ->
undefined;
default(expires) ->
undefined;
default(generate_etag) ->
undefined;
default(finish_request) ->
true;
default(_) ->
no_default.
wrap(Mod, Args) ->
case Mod:init(Args) of
{ok, ModState} ->
{ok, webmachine_resource:new(Mod, ModState,
dict:from_list(Mod:module_info(exports)), false)};
{{trace, Dir}, ModState} ->
{ok, File} = open_log_file(Dir, Mod),
log_decision(File, v3b14),
log_call(File, attempt, Mod, init, Args),
log_call(File, result, Mod, init, {{trace, Dir}, ModState}),
{ok, webmachine_resource:new(Mod, ModState,
dict:from_list(Mod:module_info(exports)), File)};
_ ->
{stop, bad_init_arg}
end.
do(Fun, ReqProps) when is_atom(Fun) andalso is_list(ReqProps) ->
Self = proplists:get_value(resource, ReqProps),
Req = proplists:get_value(req, ReqProps),
RD0 = Req:get_reqdata(),
{Reply, RD1, NewModState} = handle_wm_call(Fun, RD0),
case Reply of
{error, Err} -> {Err, Self};
_ ->
Req:set_reqdata(RD1),
{Reply,
webmachine_resource:new(R_Mod, NewModState, R_ModExports, R_Trace)}
end.
handle_wm_call(Fun, ReqData) ->
case default(Fun) of
no_default ->
resource_call(Fun, ReqData);
Default ->
case dict:is_key(Fun, R_ModExports) of % XXX SLOW PROBABLY
true ->
resource_call(Fun, ReqData);
false ->
if is_pid(R_Trace) ->
log_call(R_Trace,
not_exported,
R_Mod, Fun, [ReqData, R_ModState]);
true -> ok
end,
{Default, ReqData, R_ModState}
end
end.
resource_call(F, ReqData) ->
case R_Trace of
false -> nop;
_ -> log_call(R_Trace, attempt, R_Mod, F, [ReqData, R_ModState])
end,
Result = try
apply(R_Mod, F, [ReqData, R_ModState])
catch C:R ->
Reason = {C, R, erlang:get_stacktrace()},
{{error, Reason}, ReqData, R_ModState}
end,
case R_Trace of
false -> nop;
_ -> log_call(R_Trace, result, R_Mod, F, Result)
end,
Result.
log_d(DecisionID) ->
case R_Trace of
false -> nop;
_ -> log_decision(R_Trace, DecisionID)
end.
stop() -> close_log_file(R_Trace).
log_call(File, Type, M, F, Data) ->
io:format(File,
"{~p, ~p, ~p,~n ~p}.~n",
[Type, M, F, escape_trace_data(Data)]).
escape_trace_data(Fun) when is_function(Fun) ->
{'WMTRACE_ESCAPED_FUN',
[erlang:fun_info(Fun, module),
erlang:fun_info(Fun, name),
erlang:fun_info(Fun, arity),
erlang:fun_info(Fun, type)]};
escape_trace_data(Pid) when is_pid(Pid) ->
{'WMTRACE_ESCAPED_PID', pid_to_list(Pid)};
escape_trace_data(List) when is_list(List) ->
escape_trace_list(List, []);
escape_trace_data(Tuple) when is_tuple(Tuple) ->
list_to_tuple(escape_trace_data(tuple_to_list(Tuple)));
escape_trace_data(Other) ->
Other.
escape_trace_list([Head|Tail], Acc) ->
escape_trace_list(Tail, [escape_trace_data(Head)|Acc]);
escape_trace_list([], Acc) ->
%% proper, nil-terminated list
lists:reverse(Acc);
escape_trace_list(Final, Acc) ->
%% non-nil-terminated list, like the dict module uses
lists:reverse(tl(Acc))++[hd(Acc)|escape_trace_data(Final)].
log_decision(File, DecisionID) ->
io:format(File, "{decision, ~p}.~n", [DecisionID]).
open_log_file(Dir, Mod) ->
Now = {_,_,US} = now(),
{{Y,M,D},{H,I,S}} = calendar:now_to_universal_time(Now),
Filename = io_lib:format(
"~s/~p-~4..0B-~2..0B-~2..0B"
"-~2..0B-~2..0B-~2..0B.~6..0B.wmtrace",
[Dir, Mod, Y, M, D, H, I, S, US]),
file:open(Filename, [write]).
close_log_file(File) when is_pid(File) ->
file:close(File);
close_log_file(_) ->
ok.