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-rw-r--r--src/daemon/cpulimit.c236
1 files changed, 236 insertions, 0 deletions
diff --git a/src/daemon/cpulimit.c b/src/daemon/cpulimit.c
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--- /dev/null
+++ b/src/daemon/cpulimit.c
@@ -0,0 +1,236 @@
+/* $Id$ */
+
+/***
+ 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.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "cpulimit.h"
+#include <polypcore/util.h>
+#include <polypcore/log.h>
+
+#ifdef HAVE_SIGXCPU
+
+#include <errno.h>
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+#include <sys/time.h>
+#include <unistd.h>
+#include <signal.h>
+
+#ifdef HAVE_SYS_RESOURCE_H
+#include <sys/resource.h>
+#endif
+
+/* 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 pa_mainloop_api *api = NULL;
+static 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(pa_mainloop_api*m, pa_io_event*e, int fd, 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(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;
+ }
+}
+
+#else /* HAVE_SIGXCPU */
+
+int pa_cpu_limit_init(PA_GCC_UNUSED pa_mainloop_api *m) {
+ return 0;
+}
+
+void pa_cpu_limit_done(void) {
+}
+
+#endif