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Add persistent_term support to the router

This commit is contained in:
Loïc Hoguin 2019-09-28 15:40:41 +02:00
parent 7bccad4d21
commit cf84f59d9b
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5 changed files with 80 additions and 3 deletions

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@ -210,13 +210,34 @@ Dispatch = cowboy_router:compile([
%% {HostMatch, list({PathMatch, Handler, InitialState})}
{'_', [{'_', my_handler, #{}}]}
]),
%% Name, NbAcceptors, TransOpts, ProtoOpts
%% Name, TransOpts, ProtoOpts
cowboy:start_clear(my_http_listener,
[{port, 8080}],
#{env => #{dispatch => Dispatch}}
).
----
=== Using persistent_term
The routes can be stored in `persistent_term` starting from
Erlang/OTP 21.2. This may give a performance improvement when
there are a large number of routes.
To use this functionality you need to compile the routes,
store them in `persistent_term` and then inform Cowboy:
[source,erlang]
----
Dispatch = cowboy_router:compile([
{'_', [{'_', my_handler, #{}}]}
]),
persistent_term:put(my_app_dispatch, Dispatch),
cowboy:start_clear(my_http_listener,
[{port, 8080}],
#{env => #{dispatch => {persistent_term, my_app_dispatch}}}
).
----
=== Live update
You can use the `cowboy:set_env/3` function for updating the dispatch
@ -228,3 +249,6 @@ Dispatch = cowboy_router:compile(Routes),
cowboy:set_env(my_http_listener, dispatch, Dispatch).
Note that you need to compile the routes again before updating.
When using `persistent_term` there is no need to call this function,
you can simply put the new routes in the storage.

View file

@ -13,7 +13,10 @@ The router takes the `dispatch` rules as input from the
middleware environment. Dispatch rules are generated by
calling the
link:man:cowboy_router:compile(3)[cowboy_router:compile(3)]
function.
function. The environment can contain the rules directly
or a tuple `{persistent_term, Key}`, in which case Cowboy
will call `persistent_term:get(Key)` to retrieve the
dispatch rules.
When a route matches, the router sets the `handler` and
`handler_opts` middleware environment values containing