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author | Loïc Hoguin <[email protected]> | 2011-10-10 17:27:52 +0200 |
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committer | Loïc Hoguin <[email protected]> | 2011-10-10 17:27:52 +0200 |
commit | 5e006be01fb9af2cbb6b62bec695a2c160733cf4 (patch) | |
tree | 3e8cac6cd23f0db2024aad3d4d6758d2ac6860e7 /test/http_handler_long_polling.erl | |
parent | 25ae2028d6a9ce516b01f0ec126abeab00eb329d (diff) | |
download | cowboy-5e006be01fb9af2cbb6b62bec695a2c160733cf4.tar.gz cowboy-5e006be01fb9af2cbb6b62bec695a2c160733cf4.tar.bz2 cowboy-5e006be01fb9af2cbb6b62bec695a2c160733cf4.zip |
Add support for loops in standard HTTP handlers
Now init/3 can return one of the following values to enable loops:
- {loop, Req, State}
- {loop, Req, State, hibernate}
- {loop, Req, State, Timeout}
- {loop, Req, State, Timeout, hibernate}
Returning one of these tuples will activate looping in the HTTP handler.
When looping, handle/2 is never called. Instead, Cowboy will listen
for Erlang messages and forward them to the info/3 function of the
handler. If a timeout is defined, Cowboy will also close the connection
when no message has been received for Timeout milliseconds.
The info/3 function is defined as info(Msg, Req, State). It can return
either of the following tuples:
- {ok, Req, State}
- {loop, Req, State}
- {loop, Req, State, hibernate}
The first one ends the connection, calling terminate/2 before closing.
The others continue the loop.
Loops are useful when writing long-polling handlers that need to wait
and don't expect to receive anything. Therefore it is recommended to
set a timeout to close the connection if nothing arrives after a while
and to enable hibernate everywhere.
Normal HTTP handlers shouldn't need to use this and as such info/3
was made optional.
Diffstat (limited to 'test/http_handler_long_polling.erl')
-rw-r--r-- | test/http_handler_long_polling.erl | 22 |
1 files changed, 22 insertions, 0 deletions
diff --git a/test/http_handler_long_polling.erl b/test/http_handler_long_polling.erl new file mode 100644 index 0000000..374e244 --- /dev/null +++ b/test/http_handler_long_polling.erl @@ -0,0 +1,22 @@ +%% Feel free to use, reuse and abuse the code in this file. + +-module(http_handler_long_polling). +-behaviour(cowboy_http_handler). +-export([init/3, handle/2, info/3, terminate/2]). + +init({_Transport, http}, Req, _Opts) -> + erlang:send_after(500, self(), timeout), + {loop, Req, 9, 5000, hibernate}. + +handle(_Req, _State) -> + exit(badarg). + +info(timeout, Req, 0) -> + {ok, Req2} = cowboy_http_req:reply(102, [], [], Req), + {ok, Req2, 0}; +info(timeout, Req, State) -> + erlang:send_after(500, self(), timeout), + {loop, Req, State - 1, hibernate}. + +terminate(_Req, _State) -> + ok. |