Merge "SystemClock: elapsedRealtimeNano() should use clock_gettime() on Linux"

 * System clock functions.

 */

#if defined(__ANDROID__)

#include <linux/ioctl.h>

#include <linux/rtc.h>

#include <utils/Atomic.h>

#include <linux/android_alarm.h>

#endif

#include <sys/time.h>

#include <limits.h>

#include <fcntl.h>

#include <string.h>

#include <errno.h>

#include <cutils/compiler.h>

#include <utils/SystemClock.h>

#include <utils/Timers.h>

 */

int64_t elapsedRealtimeNano()

{

#if defined(__ANDROID__)

    static int s_fd = -1;

    if (s_fd == -1) {

        int fd = open("/dev/alarm", O_RDONLY);

        if (android_atomic_cmpxchg(-1, fd, &s_fd)) {

            close(fd);

        }

    }

#if defined(__linux__)

    struct timespec ts;

    if (ioctl(s_fd, ANDROID_ALARM_GET_TIME(ANDROID_ALARM_ELAPSED_REALTIME), &ts) == 0) {

        return seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;

    int err = clock_gettime(CLOCK_BOOTTIME, &ts);

    if (CC_UNLIKELY(err)) {

        // This should never happen, but just in case ...

        ALOGE("clock_gettime(CLOCK_BOOTTIME) failed: %s", strerror(errno));

        return 0;

    }

    // /dev/alarm doesn't exist, fallback to CLOCK_BOOTTIME

    if (clock_gettime(CLOCK_BOOTTIME, &ts) == 0) {

    return seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;

    }

    // XXX: there was an error, probably because the driver didn't

    // exist ... this should return

    // a real error, like an exception!

    return systemTime(SYSTEM_TIME_MONOTONIC);

#else

    return systemTime(SYSTEM_TIME_MONOTONIC);

#endif