+\f
+/* CPU usage tracking. */
+
+struct cpu_usage {
+ long long int when; /* Time that this sample was taken. */
+ unsigned long long int cpu; /* Total user+system CPU usage when sampled. */
+};
+
+static struct rusage recent_rusage;
+static struct cpu_usage older = { LLONG_MIN, 0 };
+static struct cpu_usage newer = { LLONG_MIN, 0 };
+static int cpu_usage = -1;
+
+static struct rusage *
+get_recent_rusage(void)
+{
+ return &recent_rusage;
+}
+
+static void
+refresh_rusage(void)
+{
+ long long int now;
+
+ now = time_msec();
+ getrusage(RUSAGE_SELF, &recent_rusage);
+
+ if (now >= newer.when + 3 * 1000) {
+ older = newer;
+ newer.when = now;
+ newer.cpu = (timeval_to_msec(&recent_rusage.ru_utime) +
+ timeval_to_msec(&recent_rusage.ru_stime));
+
+ if (older.when != LLONG_MIN && newer.cpu > older.cpu) {
+ unsigned int dividend = newer.cpu - older.cpu;
+ unsigned int divisor = (newer.when - older.when) / 100;
+ cpu_usage = divisor > 0 ? dividend / divisor : -1;
+ } else {
+ cpu_usage = -1;
+ }
+ }
+}
+
+/* Returns an estimate of this process's CPU usage, as a percentage, over the
+ * past few seconds of wall-clock time. Returns -1 if no estimate is available
+ * (which will happen if the process has not been running long enough to have
+ * an estimate, and can happen for other reasons as well). */
+int
+get_cpu_usage(void)
+{
+ return cpu_usage;
+}