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Add the early_error cowboy_stream callback

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This callback is called when an error occurs before the request
(including headers, excluding body) was fully received. The
init/3 callback will not be called. The callback receives the
partial Req object (possibly empty), the reason for the error
and the response command that the server will send. It allows
you to be aware of the error and possibly modify the response
before it is sent.
This commit is contained in:
Loïc Hoguin 2017-03-27 10:26:13 +02:00
parent 14a01f71cb
commit 10dfd8c910
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GPG key ID: 71366FF21851DF03
4 changed files with 100 additions and 28 deletions
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24
src/cowboy_stream.erl
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@ -25,7 +25,11 @@
%% @todo Perhaps it makes more sense to have resp_body in this module?
-type commands() :: [{response, cowboy:http_status(), cowboy:http_headers(), cowboy_req:resp_body()}
-type resp_command()
:: {response, cowboy:http_status(), cowboy:http_headers(), cowboy_req:resp_body()}.
-export_type([resp_command/0]).
-type commands() :: [resp_command()
| {headers, cowboy:http_status(), cowboy:http_headers()}
| {data, fin(), iodata()}
| {push, binary(), binary(), binary(), inet:port_number(),
@ -51,10 +55,15 @@
| {stop, cow_http2:frame(), human_reason()}.
-export_type([reason/0]).
-type partial_req() :: map(). %% @todo Take what's in cowboy_req with everything? optional.
-export_type([partial_req/0]).
-callback init(streamid(), cowboy_req:req(), cowboy:opts()) -> {commands(), state()}.
-callback data(streamid(), fin(), binary(), State) -> {commands(), State} when State::state().
-callback info(streamid(), any(), State) -> {commands(), State} when State::state().
-callback terminate(streamid(), reason(), state()) -> any().
-callback early_error(streamid(), reason(), partial_req(), Resp, cowboy:opts())
-> Resp when Resp::resp_command().
%% @todo To optimize the number of active timers we could have a command
%% that enables a timeout that is called in the absence of any other call,
@ -71,6 +80,7 @@
-export([data/4]).
-export([info/3]).
-export([terminate/3]).
-export([early_error/5]).
%% Note that this and other functions in this module do NOT catch
%% exceptions. We want the exception to go all the way down to the
@ -127,3 +137,15 @@ terminate(_, _, undefined) ->
terminate(StreamID, Reason, {Handler, State}) ->
_ = Handler:terminate(StreamID, Reason, State),
ok.
-spec early_error(streamid(), reason(), partial_req(), Resp, cowboy:opts())
-> Resp when Resp::resp_command().
early_error(StreamID, Reason, PartialReq, Resp, Opts) ->
case maps:get(stream_handlers, Opts, [cowboy_stream_h]) of
[] ->
Resp;
[Handler|Tail] ->
%% This is the same behavior as in init/3.
Handler:early_error(StreamID, Reason,
PartialReq, Resp, Opts#{stream_handlers => Tail})
end.