[Help] Confused by a code snippet of global module

[Karl Velicka]

Seems like connecting to a node that is not in the cluster is a blocking
operation, and this code is trying to avoid blocking the caller on this
connect operation.

On Fri, 20 Mar 2020 at 08:48, Siyang Zhang <zhangsiyang0629725@REDACTED>
wrote:

> Hi
> I'm confused by the code snippet of global module. When the 'case clause'
> matches false, why use spawn_monitor ? Use erlang:monitor could be wrong ?
> Why ?
>
> Besides, what's the annotation
> <http://www.baidu.com/link?url=xAnXIoWhmKWFBSQUUyQVGU5R3vYAsHfGPJ2rSVSXGaR1kfiKNXdJxod0EhbZg3jq91oZaxYTc8khhaTLWjSW53tqqPMFmMBEtBfjIqW5q9m> mean
> ?
>
> Could anybody help me ? Thanks
>
> %% When/if erlang:monitor() returns before trying to connect to the
> %% other node this function can be removed.
> do_monitor(Pid) ->
>     case (node(Pid) =:= node()) orelse lists:member(node(Pid), nodes()) of
>         true ->
>             %% Assume the node is still up
>             {Pid, erlang:monitor(process, Pid)};
>         false ->
>             F = fun() ->
>                 Ref = erlang:monitor(process, Pid),
>                 receive
>                     {'DOWN', Ref, process, Pid, _Info} ->
>                         exit(normal)
>                 end
>                 end,
>             erlang:spawn_monitor(F)
>     end.
>
>
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