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Diffstat (limited to 'guide/loop_handlers.md')
-rw-r--r-- | guide/loop_handlers.md | 31 |
1 files changed, 31 insertions, 0 deletions
diff --git a/guide/loop_handlers.md b/guide/loop_handlers.md index 67f8ec9..6d67c62 100644 --- a/guide/loop_handlers.md +++ b/guide/loop_handlers.md @@ -12,6 +12,10 @@ a response. They are most useful when performing long-polling operations or when using server-sent events. +While the same can be accomplished using plain HTTP handlers, +it is recommended to use loop handlers because they are well-tested +and allow using built-in features like hibernation and timeouts. + Callbacks --------- @@ -21,3 +25,30 @@ Usage ----- @todo Explain how to use them. + +The following handler waits for a message `{reply, Body}` before +sending a response. If this message doesn't arrive within 60 +seconds, it gives up and a `204 No Content` will be replied. +It also hibernates the process to save memory while waiting for +this message. + +``` erlang +-module(my_loop_handler). +-behaviour(cowboy_loop_handler). + +-export([init/3]). +-export([info/3]). +-export([terminate/2]). + +init({tcp, http}, Req, Opts) -> + {loop, Req, undefined_state, 60000, hibernate}. + +info({reply, Body}, Req, State) -> + {ok, Req2} = cowboy_req:reply(200, [], Body, Req), + {ok, Req2, State}; +info(Message, Req, State) -> + {loop, Req, State, hibernate}. + +terminate(Req, State) -> + ok. +``` |