Boost: is it safe to use multiple recursion in async calls?

Question

I'm pretty new in asio framework, so please be kind. I've investigated several boost asio example and found that people use async call like this:

void read()
{
    async_read(socket_, boost::asio::buffer(&user_[0], user_.size()),
       boost::bind(&Connection::handle_user_read, this,
       placeholders::error, placeholders::bytes_transferred));
}
void handle_user_read(...)
{
    ...
    read();
    ...
}

I think this code is not safe because it uses multiple recursion. So it cant be used when a lot of read operations are performed because of call stack overflow. I'm not 100% sure in this and unable to find any similar thoughts from other people.

Could anyone please explain this in details?

Minor Threat · Accepted Answer · 2015-11-18T09:50:35.850

5

I suppose the read() function just adds new async read request to the I/O queue and exits immediately, so there's no recursion in this code.

I mean, the read() doesn't call Connection::handle_user_read directly. It just store the function pointer inside the IO queue. This function is going to be invoked asynchronously by external code when some new chunk of data will be available.

edited Nov 18 '15 at 09:50

answered Nov 18 '15 at 09:34

Minor Threat

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So : yes it's safe. that's the way they do it in the boost documentation. – Unda Nov 18 '15 at 09:47
Thanks, I did not thought about that. Now it's perfectly clear. – Vladimir Tsyshnatiy Nov 18 '15 at 11:05

score 1 · Answer 2 · edited May 23 '17 at 12:10

1

It's not recursion, it's chained async operations; be aware of threading issues:

Why do I need strand per connection when using boost::asio?

edited May 23 '17 at 12:10

Community

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answered Nov 18 '15 at 13:46

sehe

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Boost: is it safe to use multiple recursion in async calls?

2 Answers2