Re: Can boost.asio read/write io of files asynchronously?

From: Gavin Lambert (boost_at_[hidden])
Date: 2020-08-31 04:08:45

On 31/08/2020 14:59, lampahome wrote:
> As title, I read boost.asio documents and generally said io about 
> http/network.
> 
> I don't see any info. of io of files. Does boost.asio support read/write 
> io of files asynchronously?

I haven't tried any of these methods, but it does provide the 
posix::stream_descriptor and windows::{stream,random_access}_handle 
classes which should be able to operate on native files.  (You'll have 
to use a native OS-level function to open the handle/descriptor for the 
file and pass ownership to the ASIO object; they lack means to do the 
opening itself.)

https://www.boost.org/doc/libs/1_74_0/doc/html/boost_asio/overview/posix/stream_descriptor.html

https://www.boost.org/doc/libs/1_74_0/doc/html/boost_asio/overview/windows/stream_handle.html
https://www.boost.org/doc/libs/1_74_0/doc/html/boost_asio/overview/windows/random_access_handle.html

Alternatively, there's another library (that I also haven't used) 
dedicated to async file I/O.  It originally started life based on ASIO 
but I think it's since diverged into something else.  And called 
something different from the last time I saw it as well.

Its current home appears to be: https://ned14.github.io/llfio/

(The impression I have, which may be mistaken, is that it is possibly 
overkill for general application use, unless you're trying to implement 
some kind of custom database engine rather than just using an 
off-the-shelf DB library.)