[be] bibledit-git polling

[Dan Dennison]

I ran bibledit-git through callgrind.

It seems the bulk of its CPU load is in the following while loop,  
located in ipc.cpp:350:

    while ((method_called_type != method) && (time(0) <= (oldtime +  
timeout))) {
      g_usleep(100);
    }

I need to double-check this on Windows, but it seems to me off-hand  
that this loop is going to be CPU-expensive regardless of platform.  
bibledit-git is so expensive CPU-wise on Windows right now that it's  
hard to recommend for laptop users.

Should InterprocessCommunication::receive() just register a callback  
with InterprocessCommunication::send() ? It seems like that would  
really lower the CPU demand while an event-driven solution in bibledit- 
git.cpp gets worked out.

Callgrind reports that of 7 calls to  
InterprocessCommunication::receive from bibledit-git's main(), there  
were 186804 calls to g_usleep from line 350 of ipc.cpp. FWIW, g_usleep  
is about 10x as expensive as calling time() in the while-loop  
conditional. (34.30% of CPU in g_usleep() vs. 3.92% CPU in time())

If you want to inspect the results, see https://thedennisons.org/~dand/ 
callgrind.out.14640.gz Gunzip it, and open in kcachegrind. If you  
don't have kcachegrind, apt-get install kcachegrind.

dan :)