c++ linux Eventloop vs. sleep() vs select() -


i have so/dll program needs sleep -> check stuff -> sleep.

which better way perform operation:

// sleep loop while ( true ) {     sleep( 1 );   // whatever time    if ( flag_quit ) leave;    if ( flag_something_else ) do_whatever(); }

or 

// select loop     while ( true ) {     timeout.sec = 1.0;       // whatever time    timeout.msec = 0;    zeroiftimedout = select( fdmax, fdlist, null, null, timeout  );       if ( flag_quit )              break;     // leave while loop    if ( flag_something_else )    do_whatever();    if ( 0 == zeroiftimedout )    continue;    //  }

or

// well, write event loop in c++

the real questions are,

  • which option less processor intensive?

  • is there yield() both windows , linux replace sleep?

  • if decide use in application, is, not in dll/so, there better way handle stdin select() method?

  • would interruptable sleep better in method?

  • an infinite (well, until there's input) sleep accompanies std::cin or getchar(). sleep yield process?


Comments

Post a Comment

Popular posts from this blog

linux - xterm copying to CLIPBOARD using copy-selection causes automatic updating of CLIPBOARD upon mouse selection -

i've tried various ways coerce xterm (versions 285 , 292) copy selection clipboard clipboard whenever press ctrl-shift-c. promising way far has been, in ~/.xresources, put this: xterm*vt100.translations: #override \ ctrl shift <keypress> c: copy-selection(clipboard) \n\ ctrl shift <keypress> v: insert-selection(clipboard) ctrl-shift-v works perfectly, copying has nuance... if restart xterm, highlighting text puts things in primary clipboard; expected, proper, default behavior. if hit ctrl-shift-c, copies current selection clipboard clipboard. the bug, however, if highlight text after first time pressed ctrl-shift-c, you'll see highlighting copies both primary and clipboard. cannot figure out how stop xterm updating clipboard upon selection... , doesn't make sense me in first place. i said, @ specific point in time, copy selection clipboard... yet starts updating automatically upon selection after doing once... anyone have workaround...
Read more

c++ - qgraphicsview horizontal scrolling always has a vertical delta -

Image
i've subclassed qgraphicsview custom canvas used in cad application. i've reimplemented qgraphicsview::wheelevent check keyboard modifiers control key and, if control key pressed, zoom. i'm trying implement horizontal scroll when user holds shift , uses wheel. the problem i'm having horizontal scrolling always scrolls 0.279. not huge problem, hugely annoying , points else being wrong. so, here questions: is right way implement horizontal scrolling? if not, is? how eliminate delta of 0.279? thanks in advance. code , sample output below void myview::zoom(int delta) { double factor = pow(1.2, delta/abs(delta)); this->scale(factor, factor); } void myview::scrollhorizontal(int level) { qpointf center = maptoscene(viewport()->rect().center()); qdebug() << "center: " << center.x() << ", " << center.y(); centeron(qpointf(center.x() - level, center.y())); } void myview::wheelevent(qwheeleve...
Read more