Re: [Boost-users] What is the effective way to use boost::asio::deadline_timer for udp socket receive_from?

Subject: Re: [Boost-users] What is the effective way to use boost::asio::deadline_timer for udp socket receive_from?
From: jupiter (jupiter.hce_at_[hidden])
Date: 2017-04-13 01:01:33

You are right, I did notice an example code given by
http://www.boost.org/doc/libs/1_52_0/doc/html/boost_asio/example/timeouts/blocking_udp_client.cpp
where the async_receive and timer are used. I left this out in my original
post because I have lots of issues from that example, let me know if you'd
like me to have a separate post, here are the problems:

(1) That example can only work with an IP address in local machine, if I
change to a remote machine IP address, it got an error of "Exception: bind:
Cannot assign requested address'.

(2) If my server is running at the same local machine with the same port
number, it got an error of "Exception: bind: Address already in use".

How can test that example? I need to add an async_send and I need to run it
with a local server.

Thank you.

On Thu, Apr 13, 2017 at 1:46 AM, TONGARI J via Boost-users <
boost-users_at_[hidden]> wrote:

> 2017-04-12 19:17 GMT+08:00 jupiter via Boost-users <
> boost-users_at_[hidden]>:
>
>> Hi,
>>
>> My program needs a sync udp socket send / receiver so I use the
>> deadline_timer as timeout for udp socket receive_from on Debian Jessie:
>>
>> boost::asio::deadline_timer deadline(io_service,
>> boost::posix_time::seconds(2));
>>
>> In checkDeadline function, when the timer expires, it calls
>> socket.cancel, otherwise calls the deadline.async_wait(checkDeadline);
>> again.
>>
>> Apparently when the program runs to socket.receive_from(), it is blocked
>> and the timer is never called because both socket.receive_from and the
>> timer in the same thread.
>>
>> I've been thinking to run the timer in another thread, but I checked
>> Internet, there are comments said deadline_timer is not thread safe, please
>> correct me if I am wrong here. It will be a simple solution for me if I can
>> run timer on another thread. Anyone has other ideas to run the timer
>> effectively?
>>
>
> Unfortunately, asio timers are useless with those blocking calls, you have
> to use the async version (e.g. async_receive_from) and code in async
> fashion instead.
>
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