----- Original Message ----
From: Oliver Kowalke <k-oli@gmx.de>
Am 10.02.2011 15:03, schrieb Artyom:
Probably it would be ok to provide some parameter on how to wait asynchronously:
typedef enum { wait_default, // using thread+waitpid per-process on POSIX OS wait_using_sigaction, // install signal handler wait_using_sigwaitinfo, // install signal handler wait_polling, // poll all waiting pids for end, when // requested - for example by user's signal // handler } wait_method_type;
void async_wait(pid ,method_type m = wait_default) #ifdef BOOST_POSIX void poll_handlers(); // check if child completed // called by user when receives sigchld endif
what about this solution (without error handling) on POSIX in one special worker-thread:
sigset_t set; sigemptyset( & set), sigaddset( & set, SIGCHLD); // SIGTERM, SIGINT, SIGQUIT pthread_sigmask(SIG_BLOCK, & set, ...); int signo( 0); sigwait( set, & signo); switch ( signo) { case SIGCHLD: while (true) { int status( 0); pid_t child = waitpid( -1, % status, WUNTRACED|WCONTINUED); if ( -1 == child && ECHILD != child) throw runtime_error("waitpid() failed"); // select data/callabck associated with child // from internal storage } case: ... };
Oliver
Something like this is fine but and this what I mean when I had written: wait_using_sigwaitinfo Small notes: 1. waitpid should be done for specific pid I waiting for to allow other threads to use wait 2. You need to use WNOHANG so it would not be blocking, and allow to check specific ids. So basically such thread need forever ( sigwait(sigchld) foreach pid in waiting set if(waitpid(pid, WNOHANG) = done) notify io_service remove pid from waiting set } It may be a single global thread that handles or some kind of singletone thread that exits if # io_service > 0 Of course user should still be aware of fact that it can't just do what he wants with SIGCHLD Artyom