On 4 June 2016 at 21:52, Klemens Morgenstern
Hi all,
the boost.process 0.6 library is now in alpha, that is: it has some (compiling) examples, a documentation and tests that pass on windows as well as on linux.
It basically allows you to manage a process like this:
pstream pipe;
child c("some_prog", "--some-arg", env["PATH"]+="C:/stuff", std_in < "data.csv", std_out > pipe, std_err > null, start_dir="./bin");
std::string data; pipe >> data;
c.wait(); cout << c.exit_code() << endl;
You can find the documentation here: http://klemens-morgenstern.github.io/process/ Get the source code from here: https://github.com/klemens-morgenstern/boost-process
If you want to use it on windows, you currently would need to clone my boost.winapi fork also: https://github.com/klemens-morgenstern/winapi
As for the scope of the library, it is meant to implement a small, portable layer to allow platform-independent process management. Thereby it's functionality is (unless I missed something) basically what is possible on posix as well as on windows. There are some platform extension, but I would not recommend to use them. It is also possible (though not yet documented) to write extensions, and if they work on both platforms I will gladly add them.
It is however not the goal of the library, to be the be-all and end-all of process management; in past disscussions, different ideas where brought up, like implementing a DSEL for that or only allowing asynchronous communication. This library will never be that, since it would be much more fitting to build this on-top of it. E.g. a DSEL could be written (e.g. boost.shell) using boost.process underneath, so the library could concentrate only on the DSEL.
It doesn't depend on boost.iostreams anymore, though it still uses boost.asio, boost.fusion and boost.filesystem.
As for the open issues: some error handling is still lacking (but that'd be something like being unable to duplicate a handle), which would be required for proper extension, which is also why it's not documented. Also there's still an open discussion about the naming of the class and functions (child, system, spawn), so that may change also. But I consider this simple enough for a easy refactoring. If anyone has naming ideas, please tell me. One Idea was 'subprocess' but 'process::subprocess' just looks too strange to me.
I hope you try it out, and give me some feedbacks. Or write angry error reports, both helps.
Thanks!
Klemens
So far I had time only to go quickly through the documentation and a bit in the code so here are quick remarks: 1. It is not clear at all what happen when child object is destroyed. 2. The way child process termination is implemented for each platform should be documented. 3. On most platforms there is a way to send a "quit" command to the process and a way to kill it by force ("kill -9"). Clarifying what is happening in the default cases and having a way to terminate one way or the other (or a combination of both, that is requesting termination but force-kill after a time if it didn't die) On windows there is an issue with this because the "termination request" message can only be received if you didn't build a console application but a windows application (with a WinMain) but that only means that the message could be ignored by the process if it's console application (there are ways to have both WinMain and a console window, it's just a bit more clumsy to setup). In our (Softbank Robotics EU) use of child process tracking we need both termination request and forced. One could argue that the termination request do not need to be implemented by this library but it would be very useful to have a cross platform function doing this for simple cases. Joël Lamotte