Re: [asio-users] thread-safe async_write with streambuf

[Scott G. <sgi...@su...>]

Derek Taylor <dt...@da...> writes:

[...]

> I haven't found any asio feature which will guarantee ordering on these
> accesses for multiple sender threads.  Short of that, I was about to set out to
> write the code to maintain outgoing streambufs in a pending list when previous
> writes haven't completed.  The completion handler can check this list and call
> async_write on the next item in the list if it's not empty.  Of course, this
> all has to be written in a thread safe way, and for that I'll use
> locks.

I implemented something very similar, and found that it worked
reliably and performance was fine.  Asio can actually write a whole
vector of buffers at once, so I simply kept a vector of buffers
waiting to be written, and when I flushed the write buffer I would ask
asio to send the entire vector, then start working in a new vector.

I tried doing the same thing by appending to buffers directly instead
of vectors of buffers, but found performance wasn't much better, and
it was a little harder to manage.

I have some test programs I used to implement this lying around, I can
dig them out if you'd like to take a look.

----Scott.