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/*
* utils/threads.cc
*
* Copyright 2017 Medical Research Council
* Author: Paul Emsley
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published
* by the Free Software Foundation; either version 3 of the License, or (at
* your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*/
#include <stdexcept>
#include <iostream>
#include <algorithm>
#include "coot-utils.hh"
#ifdef _WIN32
#include <windows.h>
#else
#include <unistd.h>
#endif
// can return -1 if name is invalid
//
long coot::get_number_of_threads_by_system_call() {
#ifdef _WIN32
SYSTEM_INFO sysinfo;
GetSystemInfo(&sysinfo);
return sysinfo.dwNumberOfProcessors;
#else
return sysconf(_SC_NPROCESSORS_CONF);
#endif
}
// unsigned int coot::coot_n_threads = 0; // static
unsigned int coot::get_max_number_of_threads() {
unsigned int n_threads_default = 4;
// only do this once:
// (if coot_n_threads is unset, then set it)
//
// is this initially set to 0 by the compiler?
//
if (coot_n_threads == 0) {
// coot_n_threads_cs is null then
const char *e = getenv("COOT_N_THREADS");
if (e) {
try {
// can throw an runtime_error exception on unable to convert
unsigned int t = util::string_to_int(e);
if (t >= 1024) t = n_threads_default;
coot_n_threads = t;
}
catch (const std::runtime_error &rte) {
coot_n_threads = 1;
}
} else {
// no environment variable, use system call.
coot_n_threads = n_threads_default;
long n = get_number_of_threads_by_system_call();
if (n > 0)
coot_n_threads = n;
}
}
return coot_n_threads;
}
void
coot::set_max_number_of_threads(unsigned int n) {
coot_n_threads = n;
}
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