1 files changed, 236 insertions, 0 deletions
diff --git a/src/daemon/cpulimit.c b/src/daemon/cpulimit.c
new file mode 100644
index 00000000..6887796f
--- /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