From 3edee0ace8f3f12653381e8038461689363c9541 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Lo=C3=AFc=20Hoguin?= Date: Mon, 19 Nov 2018 13:29:35 +0100 Subject: Cowboy 2.6.0 --- docs/en/cowboy/2.6/manual/cowboy_loop/index.html | 200 +++++++++++++++++++++++ 1 file changed, 200 insertions(+) create mode 100644 docs/en/cowboy/2.6/manual/cowboy_loop/index.html (limited to 'docs/en/cowboy/2.6/manual/cowboy_loop/index.html') diff --git a/docs/en/cowboy/2.6/manual/cowboy_loop/index.html b/docs/en/cowboy/2.6/manual/cowboy_loop/index.html new file mode 100644 index 00000000..efb257f5 --- /dev/null +++ b/docs/en/cowboy/2.6/manual/cowboy_loop/index.html @@ -0,0 +1,200 @@ + + + + + + + + + + Nine Nines: cowboy_loop(3) + + + + + + + + + + + + + + +
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cowboy_loop(3)

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Name

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cowboy_loop - Loop handlers

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Description

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The module cowboy_loop defines a callback interface for long running HTTP connections.

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You should switch to this behavior for long polling, server-sent events and similar long-running requests.

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There are generally two usage patterns:

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  • Loop until receiving a specific message, then send a response and stop execution (for example long polling); +
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  • Or initiate a response in init/2 and stream the body in info/3 as necessary (for example server-sent events). +
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Callbacks

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Loop handlers implement the following interface:

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init(Req, State)
+    -> {cowboy_loop, Req, State}
+     | {cowboy_loop, Req, State, hibernate}
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+info(Info, Req, State)
+    -> {ok, Req, State}
+     | {ok, Req, State, hibernate}
+     | {stop, Req, State}
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+terminate(Reason, Req, State) -> ok  %% optional
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+Req    :: cowboy_req:req()
+State  :: any()
+Info   :: any()
+Reason :: stop
+        | {crash, error | exit | throw, any()}
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The init/2 callback is common to all handlers. To switch to the loop behavior, it must return cowboy_loop as the first element of the tuple.

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The info/3 callback will be called for every Erlang message received. It may choose to continue the receive loop or stop it.

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The optional terminate/3 callback will ultimately be called with the reason for the termination of the handler. Cowboy will terminate the process right after this. There is no need to perform any cleanup in this callback.

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The following terminate reasons are defined for loop handlers:

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stop
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The handler requested to close the connection by returning a stop tuple.

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{crash, Class, Reason}
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A crash occurred in the handler. Class and Reason can be used to obtain more information about the crash. The function erlang:get_stacktrace/0 can also be called to obtain the stacktrace of the process when the crash occurred.

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Changelog

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  • 2.0: Loop handlers no longer need to handle overflow/timeouts. +
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  • 1.0: Behavior introduced. +
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See also

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cowboy(7), cowboy_handler(3)

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+ Cowboy + 2.6 + Function Reference + +

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Navigation

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