Re: [boost] [interprocess][process] Synchronizing libraries and efforts (+ bugs)

From: Boris (boriss_at_[hidden])
Date: 2008-09-01 14:33:41

On Mon, 01 Sep 2008 17:52:52 +0200, Ion Gaztañaga <igaztanaga_at_[hidden]>  
wrote:

> Boris wrote:
>> On Sun, 31 Aug 2008 23:20:10 +0200, Ion Gaztañaga  
>> <igaztanaga_at_[hidden]> wrote:
>>
>>> [...]I understand async I/O should be tied with ASIO. I think  
>>> Boost.Iostreams
>>  To give you an idea how asynchronous I/O with Boost.Process and  
>> Boost.Asio currently looks like:
>>  boost::process::child child; // somehow launched
>> #if defined(_WIN32)
>>   boost::asio::windows::stream_handle out(io_service,  
>> child.get_stdin().handle().release());
>>   boost::asio::windows::stream_handle in(io_service,  
>> child.get_stdout().handle().release());
>> #else
>>   boost::asio::posix::stream_descriptor out(io_service,  
>> child.get_stdin().handle().release());
>>   boost::asio::posix::stream_descriptor in(io_service,  
>> child.get_stdout().handle().release());
>> #endif
>> in.async_read_some(...);
>
> I don't know ASIO but it's a shame that it does not offer a portable  
> interface for async I/O.

It's not really Boost.Asio's fault here. The library is very portable but  
provides two platform-specific I/O objects which I use here. For better  
portability it would be Boost.Process' job to provide one I/O object  
instead of forcing developers to pass the underlying file descriptor or  
HANDLE to Boost.Asio's platform-specific I/O objects. :)

> [...]I don't have much idea about async I/O but we can try to write  
> something once we know what we need. I might be completly wrong but  
> boost::interprocess::shared_memory_object is based on a file descriptor  
> (shm_open in unix and a plan file on windows) so we can just obtain the  
> handle and see if select() and WaitForMultipleObject() work on them.  
> After all, write() should work on UNIX with a shared memory object  
> descritor.

Hm, sounds like a good idea. Is there any method I could call to access  
the file descriptor and handle? Then I could try and use the same  
Boost.Asio I/O objects as above to check if the idea basically works.

Boris