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Fix TimeUTCMicros resolution on Windows

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making it return actual microseconds instead of being limited to
millisecond resolution.

This uses GetSystemTimeAsFileTime
  https://learn.microsoft.com/en-us/windows/win32/api/sysinfoapi/nf-sysinfoapi-getsystemtimeasfiletime
which returns a timestamp in multiples of 100ns since January 1st 1601.

BUG=webrtc:15212

Change-Id: I293868d8f683289a9dbcf6eccb910bd9c6694e57
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/306440
Reviewed-by: Henrik Boström <hbos@webrtc.org>
Commit-Queue: Philipp Hancke <phancke@microsoft.com>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#40360}
This commit is contained in:
Philipp Hancke 2023-06-27 13:08:44 +02:00 committed by WebRTC LUCI CQ
parent 58ee9dff08
commit 3adaeefbc6
3 changed files with 24 additions and 14 deletions
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3
rtc_base/BUILD.gn
View file

@ -551,6 +551,7 @@ rtc_library("timeutils") {
":stringutils",
"system:rtc_export",
]
if (rtc_exclude_system_time) {
defines = [ "WEBRTC_EXCLUDE_SYSTEM_TIME" ]
}
@ -558,6 +559,7 @@ rtc_library("timeutils") {
libs = []
if (is_win) {
libs += [ "winmm.lib" ]
deps += [ ":win32" ]
}
}
@ -1070,7 +1072,6 @@ if (is_win) {
deps = [
":byte_order",
":checks",
":logging",
":macromagic",
":stringutils",
]

34
rtc_base/time_utils.cc
View file

@ -14,17 +14,27 @@
#include <sys/time.h>
#endif
#if defined(WEBRTC_WIN)
#include <sys/timeb.h>
#endif
#include "rtc_base/checks.h"
#include "rtc_base/numerics/safe_conversions.h"
#include "rtc_base/system_time.h"
#include "rtc_base/time_utils.h"
#if defined(WEBRTC_WIN)
#include "rtc_base/win32.h"
#endif
#if defined(WEBRTC_WIN)
#include <minwinbase.h>
#endif
namespace rtc {
#if defined(WEBRTC_WIN) || defined(WINUWP)
// FileTime (January 1st 1601) to Unix time (January 1st 1970)
// offset in units of 100ns.
static constexpr uint64_t kFileTimeToUnixTimeEpochOffset =
116444736000000000ULL;
static constexpr uint64_t kFileTimeToMicroSeconds = 10LL;
#endif
ClockInterface* g_clock = nullptr;
ClockInterface* SetClockForTesting(ClockInterface* clock) {
@ -115,8 +125,6 @@ class TimeHelper final {
}
private:
static constexpr uint64_t kFileTimeToUnixTimeEpochOffset =
116444736000000000ULL;
static constexpr uint64_t kNTPTimeToUnixTimeEpochOffset = 2208988800000L;
// The number of nanoseconds since unix system epoch
@ -231,13 +239,15 @@ int64_t TimeUTCMicros() {
// Convert from second (1.0) and microsecond (1e-6).
return (static_cast<int64_t>(time.tv_sec) * rtc::kNumMicrosecsPerSec +
time.tv_usec);
#elif defined(WEBRTC_WIN)
struct _timeb time;
_ftime(&time);
// Convert from second (1.0) and milliseconds (1e-3).
return (static_cast<int64_t>(time.time) * rtc::kNumMicrosecsPerSec +
static_cast<int64_t>(time.millitm) * rtc::kNumMicrosecsPerMillisec);
FILETIME ft;
// This will give us system file in UTC format in multiples of 100ns.
GetSystemTimeAsFileTime(&ft);
LARGE_INTEGER li;
li.HighPart = ft.dwHighDateTime;
li.LowPart = ft.dwLowDateTime;
return (li.QuadPart - kFileTimeToUnixTimeEpochOffset) /
kFileTimeToMicroSeconds;
#endif
}

1
rtc_base/win32.cc
View file

@ -18,7 +18,6 @@
#include "rtc_base/arraysize.h"
#include "rtc_base/byte_order.h"
#include "rtc_base/checks.h"
#include "rtc_base/logging.h"
#include "rtc_base/string_utils.h"
namespace rtc {