64289760a2
On devices with an up-to-date kernel, the back-in-time bug affecting clock_gettime() has been fixed and it can safely be used as an alternative to the ANDROID_ALARM_GET_TIME ioctl. To ensure consistent behavior on existing devices, make clock_gettime() a fallback for when the alarm driver isn't available. Change-Id: I384af5e7ec9e73e0bad4b6b0f987a8ea4583cba6 Signed-off-by: Greg Hackmann <ghackmann@google.com>
161 lines
4.3 KiB
C++
161 lines
4.3 KiB
C++
/*
|
|
* Copyright (C) 2008 The Android Open Source Project
|
|
*
|
|
* Licensed under the Apache License, Version 2.0 (the "License");
|
|
* you may not use this file except in compliance with the License.
|
|
* You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS,
|
|
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
* See the License for the specific language governing permissions and
|
|
* limitations under the License.
|
|
*/
|
|
|
|
|
|
/*
|
|
* System clock functions.
|
|
*/
|
|
|
|
#ifdef HAVE_ANDROID_OS
|
|
#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 <errno.h>
|
|
#include <string.h>
|
|
|
|
#include <utils/SystemClock.h>
|
|
#include <utils/Timers.h>
|
|
|
|
#define LOG_TAG "SystemClock"
|
|
#include <utils/Log.h>
|
|
|
|
namespace android {
|
|
|
|
/*
|
|
* native public static long uptimeMillis();
|
|
*/
|
|
int64_t uptimeMillis()
|
|
{
|
|
int64_t when = systemTime(SYSTEM_TIME_MONOTONIC);
|
|
return (int64_t) nanoseconds_to_milliseconds(when);
|
|
}
|
|
|
|
/*
|
|
* native public static long elapsedRealtime();
|
|
*/
|
|
int64_t elapsedRealtime()
|
|
{
|
|
return nanoseconds_to_milliseconds(elapsedRealtimeNano());
|
|
}
|
|
|
|
#define METHOD_CLOCK_GETTIME 0
|
|
#define METHOD_IOCTL 1
|
|
#define METHOD_SYSTEMTIME 2
|
|
|
|
/*
|
|
* To debug/verify the timestamps returned by the kernel, change
|
|
* DEBUG_TIMESTAMP to 1 and call the timestamp routine from a single thread
|
|
* in the test program. b/10899829
|
|
*/
|
|
#define DEBUG_TIMESTAMP 0
|
|
|
|
static const char *gettime_method_names[] = {
|
|
"clock_gettime",
|
|
"ioctl",
|
|
"systemTime",
|
|
};
|
|
|
|
#if DEBUG_TIMESTAMP
|
|
static inline void checkTimeStamps(int64_t timestamp,
|
|
int64_t volatile *prevTimestampPtr,
|
|
int volatile *prevMethodPtr,
|
|
int curMethod)
|
|
{
|
|
/*
|
|
* Disable the check for SDK since the prebuilt toolchain doesn't contain
|
|
* gettid, and int64_t is different on the ARM platform
|
|
* (ie long vs long long).
|
|
*/
|
|
#ifdef ARCH_ARM
|
|
int64_t prevTimestamp = *prevTimestampPtr;
|
|
int prevMethod = *prevMethodPtr;
|
|
|
|
if (timestamp < prevTimestamp) {
|
|
ALOGW("time going backwards: prev %lld(%s) vs now %lld(%s), tid=%d",
|
|
prevTimestamp, gettime_method_names[prevMethod],
|
|
timestamp, gettime_method_names[curMethod],
|
|
gettid());
|
|
}
|
|
// NOTE - not atomic and may generate spurious warnings if the 64-bit
|
|
// write is interrupted or not observed as a whole.
|
|
*prevTimestampPtr = timestamp;
|
|
*prevMethodPtr = curMethod;
|
|
#endif
|
|
}
|
|
#else
|
|
#define checkTimeStamps(timestamp, prevTimestampPtr, prevMethodPtr, curMethod)
|
|
#endif
|
|
|
|
/*
|
|
* native public static long elapsedRealtimeNano();
|
|
*/
|
|
int64_t elapsedRealtimeNano()
|
|
{
|
|
#ifdef HAVE_ANDROID_OS
|
|
struct timespec ts;
|
|
int result;
|
|
int64_t timestamp;
|
|
#if DEBUG_TIMESTAMP
|
|
static volatile int64_t prevTimestamp;
|
|
static volatile int prevMethod;
|
|
#endif
|
|
|
|
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);
|
|
}
|
|
}
|
|
|
|
result = ioctl(s_fd,
|
|
ANDROID_ALARM_GET_TIME(ANDROID_ALARM_ELAPSED_REALTIME), &ts);
|
|
|
|
if (result == 0) {
|
|
timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
|
|
checkTimeStamps(timestamp, &prevTimestamp, &prevMethod, METHOD_IOCTL);
|
|
return timestamp;
|
|
}
|
|
|
|
// /dev/alarm doesn't exist, fallback to CLOCK_BOOTTIME
|
|
result = clock_gettime(CLOCK_BOOTTIME, &ts);
|
|
if (result == 0) {
|
|
timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
|
|
checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
|
|
METHOD_CLOCK_GETTIME);
|
|
return timestamp;
|
|
}
|
|
|
|
// XXX: there was an error, probably because the driver didn't
|
|
// exist ... this should return
|
|
// a real error, like an exception!
|
|
timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
|
|
checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
|
|
METHOD_SYSTEMTIME);
|
|
return timestamp;
|
|
#else
|
|
return systemTime(SYSTEM_TIME_MONOTONIC);
|
|
#endif
|
|
}
|
|
|
|
}; // namespace android
|