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

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We've removed the Android alarm driver from our supported kernels.
clock_gettime(CLOCK_BOOTTIME) has been a viable option since 2.6.39, so
there's no need for the legacy code path anymore.

We can use this on Linux hosts too, since no one should be building
Android on hosts with kernels that old.

Bug: 28357356

Change-Id: I0aa164383c95e77c53d2c85883d83f85d4abc7b1
Signed-off-by: Greg Hackmann <ghackmann@google.com>
This commit is contained in:
Greg Hackmann 2016-04-25 10:39:55 -07:00
parent 340079df26
commit e94c92cd48
1 changed files with 9 additions and 28 deletions
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37
libutils/SystemClock.cpp
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@ -19,18 +19,13 @@
* 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>
@ -61,30 +56,16 @@ int64_t elapsedRealtime()
*/
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);
return seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
#else
return systemTime(SYSTEM_TIME_MONOTONIC);
#endif