pixelflut-rgb-matrix-server/lib/thread.cc

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2020-12-26 12:23:47 +00:00
// -*- mode: c++; c-basic-offset: 2; indent-tabs-mode: nil; -*-
// Copyright (C) 2013 Henner Zeller <h.zeller@acm.org>
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation version 2.
//
// 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, see <http://gnu.org/licenses/gpl-2.0.txt>
#include "thread.h"
#include <assert.h>
#include <limits.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
namespace rgb_matrix {
void *Thread::PthreadCallRun(void *tobject) {
reinterpret_cast<Thread*>(tobject)->Run();
return NULL;
}
Thread::Thread() : started_(false) {}
Thread::~Thread() {
WaitStopped();
}
void Thread::WaitStopped() {
if (!started_) return;
int result = pthread_join(thread_, NULL);
if (result != 0) {
perror("Issue joining thread");
}
started_ = false;
}
void Thread::Start(int priority, uint32_t affinity_mask) {
assert(!started_); // Did you call WaitStopped() ?
pthread_create(&thread_, NULL, &PthreadCallRun, this);
int err;
if (priority > 0) {
struct sched_param p;
p.sched_priority = priority;
if ((err = pthread_setschedparam(thread_, SCHED_FIFO, &p))) {
char buffer[PATH_MAX];
const char *bin = realpath("/proc/self/exe", buffer); // Linux specific.
fprintf(stderr, "Can't set realtime thread priority=%d: %s.\n"
"\tYou are probably not running as root ?\n"
"\tThis will seriously mess with color stability and flicker\n"
"\tof the matrix. Please run as `root` (e.g. by invoking this\n"
"\tprogram with `sudo`), or setting the capability on this\n"
"\tbinary by calling\n"
"\tsudo setcap 'cap_sys_nice=eip' %s\n",
p.sched_priority, strerror(err), bin ? bin : "<this binary>");
}
}
if (affinity_mask != 0) {
cpu_set_t cpu_mask;
CPU_ZERO(&cpu_mask);
for (int i = 0; i < 32; ++i) {
if ((affinity_mask & (1<<i)) != 0) {
CPU_SET(i, &cpu_mask);
}
}
if ((err=pthread_setaffinity_np(thread_, sizeof(cpu_mask), &cpu_mask))) {
// On a Pi1, this won't work as there is only one core. Don't worry in
// that case.
}
}
started_ = true;
}
bool Mutex::WaitOn(pthread_cond_t *cond, long timeout_ms) {
if (timeout_ms < 0) {
pthread_cond_wait(cond, &mutex_);
return true;
}
else {
struct timespec t;
clock_gettime(CLOCK_REALTIME, &t);
t.tv_sec += timeout_ms / 1000;
t.tv_nsec += (timeout_ms % 1000) * 1000000;
t.tv_sec += t.tv_nsec / 1000000000;
t.tv_nsec %= 1000000000;
// TODO(hzeller): It doesn't seem we return with EINTR on signal. We should.
return pthread_cond_timedwait(cond, &mutex_, &t) == 0;
}
}
} // namespace rgb_matrix