1 files changed, 169 insertions, 0 deletions
diff --git a/libnetdata/clocks/clocks.h b/libnetdata/clocks/clocks.h
new file mode 100644
index 0000000..cfe99f5
--- /dev/null
+++ b/libnetdata/clocks/clocks.h
@@ -0,0 +1,169 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_CLOCKS_H
+#define NETDATA_CLOCKS_H 1
+
+#include "../libnetdata.h"
+
+#ifndef HAVE_STRUCT_TIMESPEC
+struct timespec {
+    time_t tv_sec;  /* seconds */
+    long   tv_nsec; /* nanoseconds */
+};
+#endif
+
+#ifndef HAVE_CLOCKID_T
+typedef int clockid_t;
+#endif
+
+typedef unsigned long long nsec_t;
+typedef unsigned long long msec_t;
+typedef unsigned long long usec_t;
+typedef long long susec_t;
+
+typedef struct heartbeat {
+    usec_t monotonic;
+    usec_t realtime;
+} heartbeat_t;
+
+/* Linux value is as good as any other */
+#ifndef CLOCK_REALTIME
+#define CLOCK_REALTIME  0
+#endif
+
+#ifndef CLOCK_MONOTONIC
+/* fallback to CLOCK_REALTIME if not available */
+#define CLOCK_MONOTONIC CLOCK_REALTIME
+#endif
+
+/* Prefer CLOCK_MONOTONIC_COARSE where available to reduce overhead. It has the same semantics as CLOCK_MONOTONIC */
+#ifndef CLOCK_MONOTONIC_COARSE
+/* fallback to CLOCK_MONOTONIC if not available */
+#define CLOCK_MONOTONIC_COARSE CLOCK_MONOTONIC
+#endif
+
+#ifndef CLOCK_BOOTTIME
+
+#ifdef CLOCK_UPTIME
+/* CLOCK_BOOTTIME falls back to CLOCK_UPTIME on FreeBSD */
+#define CLOCK_BOOTTIME CLOCK_UPTIME
+#else // CLOCK_UPTIME
+/* CLOCK_BOOTTIME falls back to CLOCK_MONOTONIC */
+#define CLOCK_BOOTTIME  CLOCK_MONOTONIC_COARSE
+#endif // CLOCK_UPTIME
+
+#else // CLOCK_BOOTTIME
+
+#ifdef HAVE_CLOCK_GETTIME
+#define CLOCK_BOOTTIME_IS_AVAILABLE 1 // required for /proc/uptime
+#endif // HAVE_CLOCK_GETTIME
+
+#endif // CLOCK_BOOTTIME
+
+#ifndef NSEC_PER_MSEC
+#define NSEC_PER_MSEC   1000000ULL
+#endif
+
+#ifndef NSEC_PER_SEC
+#define NSEC_PER_SEC    1000000000ULL
+#endif
+#ifndef NSEC_PER_USEC
+#define NSEC_PER_USEC   1000ULL
+#endif
+
+#ifndef USEC_PER_SEC
+#define USEC_PER_SEC    1000000ULL
+#endif
+#ifndef MSEC_PER_SEC
+#define MSEC_PER_SEC    1000ULL
+#endif
+
+#define USEC_PER_MS     1000ULL
+
+#ifndef HAVE_CLOCK_GETTIME
+/* Fallback function for POSIX.1-2001 clock_gettime() function.
+ *
+ * We use a realtime clock from gettimeofday(), this will
+ * make systems without clock_gettime() support sensitive
+ * to time jumps or hibernation/suspend side effects.
+ */
+extern int clock_gettime(clockid_t clk_id, struct timespec *ts);
+#endif
+
+/*
+ * Three clocks are available (cf. man 3 clock_gettime):
+ *
+ * REALTIME clock (i.e. wall-clock):
+ *  This clock is affected by discontinuous jumps in the system time
+ *  (e.g., if the system administrator manually changes the clock), and by the incremental adjustments performed by adjtime(3) and NTP.
+ *
+ * MONOTONIC clock
+ *  Clock that cannot be set and represents monotonic time since some unspecified starting point.
+ *  This clock is not affected by discontinuous jumps in the system time
+ *  (e.g., if the system administrator manually changes the clock), but is affected by the incremental adjustments performed by adjtime(3) and NTP.
+ *  If not available on the system, this clock falls back to REALTIME clock.
+ *
+ * BOOTTIME clock
+ *  Identical to  CLOCK_MONOTONIC, except it also includes any time that the system is suspended.
+ *  This allows applications to get a suspend-aware monotonic clock without having to deal with the complications of CLOCK_REALTIME,
+ *  which may have discontinuities if the time is changed using settimeofday(2).
+ *  If not available on the system, this clock falls back to MONOTONIC clock.
+ *
+ * All now_*_timeval() functions fill the `struct timeval` with the time from the appropriate clock.
+ * Those functions return 0 on success, -1 else with errno set appropriately.
+ *
+ * All now_*_sec() functions return the time in seconds from the approriate clock, or 0 on error.
+ * All now_*_usec() functions return the time in microseconds from the approriate clock, or 0 on error.
+ *
+ * Most functions will attempt to use CLOCK_MONOTONIC_COARSE if available to reduce contention overhead and improve
+ * performance scaling. If high precision is required please use one of the available now_*_high_precision_* functions.
+ */
+extern int now_realtime_timeval(struct timeval *tv);
+extern time_t now_realtime_sec(void);
+extern usec_t now_realtime_usec(void);
+
+extern int now_monotonic_timeval(struct timeval *tv);
+extern time_t now_monotonic_sec(void);
+extern usec_t now_monotonic_usec(void);
+extern int now_monotonic_high_precision_timeval(struct timeval *tv);
+extern time_t now_monotonic_high_precision_sec(void);
+extern usec_t now_monotonic_high_precision_usec(void);
+
+extern int now_boottime_timeval(struct timeval *tv);
+extern time_t now_boottime_sec(void);
+extern usec_t now_boottime_usec(void);
+
+
+extern usec_t timeval_usec(struct timeval *tv);
+extern msec_t timeval_msec(struct timeval *tv);
+
+extern usec_t dt_usec(struct timeval *now, struct timeval *old);
+extern susec_t dt_usec_signed(struct timeval *now, struct timeval *old);
+
+extern void heartbeat_init(heartbeat_t *hb);
+
+/* Sleeps until next multiple of tick using monotonic clock.
+ * Returns elapsed time in microseconds since previous heartbeat
+ */
+extern usec_t heartbeat_next(heartbeat_t *hb, usec_t tick);
+
+/* Returns elapsed time in microseconds since last heartbeat */
+extern usec_t heartbeat_monotonic_dt_to_now_usec(heartbeat_t *hb);
+
+extern int sleep_usec(usec_t usec);
+
+/*
+ * When running a binary with CLOCK_BOOTTIME defined on a system with a linux kernel older than Linux 2.6.39 the
+ * clock_gettime(2) system call fails with EINVAL. In that case it must fall-back to CLOCK_MONOTONIC.
+ */
+void test_clock_boottime(void);
+
+/*
+ * When running a binary with CLOCK_MONOTONIC_COARSE defined on a system with a linux kernel older than Linux 2.6.32 the
+ * clock_gettime(2) system call fails with EINVAL. In that case it must fall-back to CLOCK_MONOTONIC.
+ */
+void test_clock_monotonic_coarse(void);
+
+extern collected_number uptime_msec(char *filename);
+
+#endif /* NETDATA_CLOCKS_H */