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/* $Id$ */
/***
This file is part of polypaudio.
polypaudio 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 2 of the License,
or (at your option) any later version.
polypaudio 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 Lesser General Public License
along with polypaudio; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
USA.
***/
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <unistd.h>
#include <signal.h>
#include "cpulimit.h"
#include "util.h"
#include "log.h"
/* This module implements a watchdog that makes sure that the current
* process doesn't consume more than 70% CPU time for 10 seconds. This
* is very useful when using SCHED_FIFO scheduling which effectively
* disables multitasking. */
/* Method of operation: Using SIGXCPU a signal handler is called every
* 10s process CPU time. That function checks if less than 14s system
* time have passed. In that case, it tries to contact the main event
* loop through a pipe. After two additional seconds it is checked
* whether the main event loop contact was successful. If not, the
* program is terminated forcibly. */
/* Utilize this much CPU time at maximum */
#define CPUTIME_PERCENT 70
/* Check every 10s */
#define CPUTIME_INTERVAL_SOFT (10)
/* Recheck after 2s */
#define CPUTIME_INTERVAL_HARD (2)
/* Time of the last CPU load check */
static time_t last_time = 0;
/* Pipe for communicating with the main loop */
static int the_pipe[2] = {-1, -1};
/* Main event loop and IO event for the FIFO */
static struct pa_mainloop_api *api = NULL;
static struct pa_io_event *io_event = NULL;
/* Saved sigaction struct for SIGXCPU */
static struct sigaction sigaction_prev;
/* Nonzero after pa_cpu_limit_init() */
static int installed = 0;
/* The current state of operation */
static enum {
PHASE_IDLE, /* Normal state */
PHASE_SOFT /* After CPU overload has been detected */
} phase = PHASE_IDLE;
/* Reset the SIGXCPU timer to the next t seconds */
static void reset_cpu_time(int t) {
int r;
long n;
struct rlimit rl;
struct rusage ru;
/* Get the current CPU time of the current process */
r = getrusage(RUSAGE_SELF, &ru);
assert(r >= 0);
n = ru.ru_utime.tv_sec + ru.ru_stime.tv_sec + t;
r = getrlimit(RLIMIT_CPU, &rl);
assert(r >= 0);
rl.rlim_cur = n;
r = setrlimit(RLIMIT_CPU, &rl);
assert(r >= 0);
}
/* A simple, thread-safe puts() work-alike */
static void write_err(const char *p) {
pa_loop_write(2, p, strlen(p));
}
/* The signal handler, called on every SIGXCPU */
static void signal_handler(int sig) {
assert(sig == SIGXCPU);
if (phase == PHASE_IDLE) {
time_t now;
#ifdef PRINT_CPU_LOAD
char t[256];
#endif
time(&now);
#ifdef PRINT_CPU_LOAD
snprintf(t, sizeof(t), "Using %0.1f%% CPU\n", (double)CPUTIME_INTERVAL_SOFT/(now-last_time)*100);
write_err(t);
#endif
if (CPUTIME_INTERVAL_SOFT >= ((now-last_time)*(double)CPUTIME_PERCENT/100)) {
static const char c = 'X';
write_err("Soft CPU time limit exhausted, terminating.\n");
/* Try a soft cleanup */
write(the_pipe[1], &c, sizeof(c));
phase = PHASE_SOFT;
reset_cpu_time(CPUTIME_INTERVAL_HARD);
} else {
/* Everything's fine */
reset_cpu_time(CPUTIME_INTERVAL_SOFT);
last_time = now;
}
} else if (phase == PHASE_SOFT) {
write_err("Hard CPU time limit exhausted, terminating forcibly.\n");
_exit(1); /* Forced exit */
}
}
/* Callback for IO events on the FIFO */
static void callback(struct pa_mainloop_api*m, struct pa_io_event*e, int fd, enum pa_io_event_flags f, void *userdata) {
char c;
assert(m && e && f == PA_IO_EVENT_INPUT && e == io_event && fd == the_pipe[0]);
read(the_pipe[0], &c, sizeof(c));
m->quit(m, 1); /* Quit the main loop */
}
/* Initializes CPU load limiter */
int pa_cpu_limit_init(struct pa_mainloop_api *m) {
struct sigaction sa;
assert(m && !api && !io_event && the_pipe[0] == -1 && the_pipe[1] == -1 && !installed);
time(&last_time);
/* Prepare the main loop pipe */
if (pipe(the_pipe) < 0) {
pa_log(__FILE__": pipe() failed: %s\n", strerror(errno));
return -1;
}
pa_make_nonblock_fd(the_pipe[0]);
pa_make_nonblock_fd(the_pipe[1]);
pa_fd_set_cloexec(the_pipe[0], 1);
pa_fd_set_cloexec(the_pipe[1], 1);
api = m;
io_event = api->io_new(m, the_pipe[0], PA_IO_EVENT_INPUT, callback, NULL);
phase = PHASE_IDLE;
/* Install signal handler for SIGXCPU */
memset(&sa, 0, sizeof(sa));
sa.sa_handler = signal_handler;
sigemptyset(&sa.sa_mask);
sa.sa_flags = SA_RESTART;
if (sigaction(SIGXCPU, &sa, &sigaction_prev) < 0) {
pa_cpu_limit_done();
return -1;
}
installed = 1;
reset_cpu_time(CPUTIME_INTERVAL_SOFT);
return 0;
}
/* Shutdown CPU load limiter */
void pa_cpu_limit_done(void) {
int r;
if (io_event) {
assert(api);
api->io_free(io_event);
io_event = NULL;
api = NULL;
}
if (the_pipe[0] >= 0)
close(the_pipe[0]);
if (the_pipe[1] >= 0)
close(the_pipe[1]);
the_pipe[0] = the_pipe[1] = -1;
if (installed) {
r = sigaction(SIGXCPU, &sigaction_prev, NULL);
assert(r >= 0);
installed = 0;
}
}
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