From a45813c60f0f983a24ea29d491b37f0590fdd087 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Sat, 18 Feb 2017 18:26:20 +0100 Subject: Allow passing options to sub protocols Before this commit we had an issue where configuring a Websocket connection was simply not possible without doing magic, adding callbacks or extra return values. The init/2 function only allowed setting hibernate and timeout options. After this commit, when switching to a different type of handler you can either return {module, Req, State} or {module, Req, State, Opts} where Opts is any value (as far as the sub protocol interface is concerned) and is ultimately checked by the custom handlers. A large protocol like Websocket would accept only a map there, with many different options, while a small interface like loop handlers would allow passing hibernate and nothing else. For Websocket, hibernate must be set from the websocket_init/1 callback, because init/2 executes in a separate process. Sub protocols now have two callbacks: one with the Opts value, one without. The loop handler code was largely reworked and simplified. It does not need to manage a timeout or read from the socket anymore, it's the job of the protocol code. A lot of unnecessary stuff was therefore removed. Websocket compression must now be enabled from the handler options instead of per listener. This means that a project can have two separate Websocket handlers with different options. Compression is still disabled by default, and the idle_timeout value was changed from inifnity to 60000 (60 seconds), as that's safer and is also a good value for mobile devices. --- doc/src/guide/loop_handlers.asciidoc | 27 +++------------------------ 1 file changed, 3 insertions(+), 24 deletions(-) (limited to 'doc/src/guide/loop_handlers.asciidoc') diff --git a/doc/src/guide/loop_handlers.asciidoc b/doc/src/guide/loop_handlers.asciidoc index 2c82c53..dbee927 100644 --- a/doc/src/guide/loop_handlers.asciidoc +++ b/doc/src/guide/loop_handlers.asciidoc @@ -34,7 +34,7 @@ loop handler behavior. This tuple may optionally contain a timeout value and/or the atom `hibernate` to make the process enter hibernation until a message is received. -This snippet enables the loop handler. +This snippet enables the loop handler: [source,erlang] ---- @@ -42,14 +42,12 @@ init(Req, State) -> {cowboy_loop, Req, State}. ---- -However it is largely recommended that you set a timeout -value. The next example sets a timeout value of 30s and -also makes the process hibernate. +This also makes the process hibernate: [source,erlang] ---- init(Req, State) -> - {cowboy_loop, Req, State, 30000, hibernate}. + {cowboy_loop, Req, State, hibernate}. ---- === Receive loop @@ -123,25 +121,6 @@ a subsequent request. Please refer to the xref:handlers[Handlers chapter] for general instructions about cleaning up. -=== Timeout - -Note that this feature currently does not work. It will be -brought back in a future 2.0 pre-release. - -By default Cowboy will not attempt to close the connection -if there is no activity from the client. This is not always -desirable, which is why you can set a timeout. Cowboy will -close the connection if no data was received from the client -after the configured time. The timeout only needs to be set -once and can't be modified afterwards. - -Because the request may have had a body, or may be followed -by another request, Cowboy is forced to buffer all data it -receives. This data may grow to become too large though, -so there is a configurable limit for it. The default buffer -size is of 5000 bytes, but it may be changed by setting the -`loop_max_buffer` middleware environment value. - === Hibernate To save memory, you may hibernate the process in between -- cgit v1.2.3