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Unified Diff: src/platform-win32.cc

Issue 23690003: Revert "Add Chromium-style TimeDelta, Time and TimeTicks classes, and a new ElapsedTimer class." (Closed) Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge
Patch Set: Created 7 years, 4 months ago
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Index: src/platform-win32.cc
diff --git a/src/platform-win32.cc b/src/platform-win32.cc
index f822049883b4e85674161e0f0605e94df344b297..f52bb43d9c0ca8696c49cf4b8efe886fdba618b5 100644
--- a/src/platform-win32.cc
+++ b/src/platform-win32.cc
@@ -246,15 +246,19 @@ void MathSetup() {
// timestamps are represented as a doubles in milliseconds since 00:00:00 UTC,
// January 1, 1970.
-class Win32Time {
+class Time {
public:
// Constructors.
- explicit Win32Time(double jstime);
- Win32Time(int year, int mon, int day, int hour, int min, int sec);
+ Time();
+ explicit Time(double jstime);
+ Time(int year, int mon, int day, int hour, int min, int sec);
// Convert timestamp to JavaScript representation.
double ToJSTime();
+ // Set timestamp to current time.
+ void SetToCurrentTime();
+
// Returns the local timezone offset in milliseconds east of UTC. This is
// the number of milliseconds you must add to UTC to get local time, i.e.
// LocalOffset(CET) = 3600000 and LocalOffset(PST) = -28800000. This
@@ -296,6 +300,10 @@ class Win32Time {
// Return whether or not daylight savings time is in effect at this time.
bool InDST();
+ // Return the difference (in milliseconds) between this timestamp and
+ // another timestamp.
+ int64_t Diff(Time* other);
+
// Accessor for FILETIME representation.
FILETIME& ft() { return time_.ft_; }
@@ -317,20 +325,26 @@ class Win32Time {
// Static variables.
-bool Win32Time::tz_initialized_ = false;
-TIME_ZONE_INFORMATION Win32Time::tzinfo_;
-char Win32Time::std_tz_name_[kTzNameSize];
-char Win32Time::dst_tz_name_[kTzNameSize];
+bool Time::tz_initialized_ = false;
+TIME_ZONE_INFORMATION Time::tzinfo_;
+char Time::std_tz_name_[kTzNameSize];
+char Time::dst_tz_name_[kTzNameSize];
+
+
+// Initialize timestamp to start of epoc.
+Time::Time() {
+ t() = 0;
+}
// Initialize timestamp from a JavaScript timestamp.
-Win32Time::Win32Time(double jstime) {
+Time::Time(double jstime) {
t() = static_cast<int64_t>(jstime) * kTimeScaler + kTimeEpoc;
}
// Initialize timestamp from date/time components.
-Win32Time::Win32Time(int year, int mon, int day, int hour, int min, int sec) {
+Time::Time(int year, int mon, int day, int hour, int min, int sec) {
SYSTEMTIME st;
st.wYear = year;
st.wMonth = mon;
@@ -344,14 +358,14 @@ Win32Time::Win32Time(int year, int mon, int day, int hour, int min, int sec) {
// Convert timestamp to JavaScript timestamp.
-double Win32Time::ToJSTime() {
+double Time::ToJSTime() {
return static_cast<double>((t() - kTimeEpoc) / kTimeScaler);
}
// Guess the name of the timezone from the bias.
// The guess is very biased towards the northern hemisphere.
-const char* Win32Time::GuessTimezoneNameFromBias(int bias) {
+const char* Time::GuessTimezoneNameFromBias(int bias) {
static const int kHour = 60;
switch (-bias) {
case -9*kHour: return "Alaska";
@@ -376,7 +390,7 @@ const char* Win32Time::GuessTimezoneNameFromBias(int bias) {
// Initialize timezone information. The timezone information is obtained from
// windows. If we cannot get the timezone information we fall back to CET.
// Please notice that this code is not thread-safe.
-void Win32Time::TzSet() {
+void Time::TzSet() {
// Just return if timezone information has already been initialized.
if (tz_initialized_) return;
@@ -425,16 +439,78 @@ void Win32Time::TzSet() {
}
+// Return the difference in milliseconds between this and another timestamp.
+int64_t Time::Diff(Time* other) {
+ return (t() - other->t()) / kTimeScaler;
+}
+
+
+// Set timestamp to current time.
+void Time::SetToCurrentTime() {
+ // The default GetSystemTimeAsFileTime has a ~15.5ms resolution.
+ // Because we're fast, we like fast timers which have at least a
+ // 1ms resolution.
+ //
+ // timeGetTime() provides 1ms granularity when combined with
+ // timeBeginPeriod(). If the host application for v8 wants fast
+ // timers, it can use timeBeginPeriod to increase the resolution.
+ //
+ // Using timeGetTime() has a drawback because it is a 32bit value
+ // and hence rolls-over every ~49days.
+ //
+ // To use the clock, we use GetSystemTimeAsFileTime as our base;
+ // and then use timeGetTime to extrapolate current time from the
+ // start time. To deal with rollovers, we resync the clock
+ // any time when more than kMaxClockElapsedTime has passed or
+ // whenever timeGetTime creates a rollover.
+
+ static bool initialized = false;
+ static TimeStamp init_time;
+ static DWORD init_ticks;
+ static const int64_t kHundredNanosecondsPerSecond = 10000000;
+ static const int64_t kMaxClockElapsedTime =
+ 60*kHundredNanosecondsPerSecond; // 1 minute
+
+ // If we are uninitialized, we need to resync the clock.
+ bool needs_resync = !initialized;
+
+ // Get the current time.
+ TimeStamp time_now;
+ GetSystemTimeAsFileTime(&time_now.ft_);
+ DWORD ticks_now = timeGetTime();
+
+ // Check if we need to resync due to clock rollover.
+ needs_resync |= ticks_now < init_ticks;
+
+ // Check if we need to resync due to elapsed time.
+ needs_resync |= (time_now.t_ - init_time.t_) > kMaxClockElapsedTime;
+
+ // Check if we need to resync due to backwards time change.
+ needs_resync |= time_now.t_ < init_time.t_;
+
+ // Resync the clock if necessary.
+ if (needs_resync) {
+ GetSystemTimeAsFileTime(&init_time.ft_);
+ init_ticks = ticks_now = timeGetTime();
+ initialized = true;
+ }
+
+ // Finally, compute the actual time. Why is this so hard.
+ DWORD elapsed = ticks_now - init_ticks;
+ this->time_.t_ = init_time.t_ + (static_cast<int64_t>(elapsed) * 10000);
+}
+
+
// Return the local timezone offset in milliseconds east of UTC. This
// takes into account whether daylight saving is in effect at the time.
// Only times in the 32-bit Unix range may be passed to this function.
// Also, adding the time-zone offset to the input must not overflow.
// The function EquivalentTime() in date.js guarantees this.
-int64_t Win32Time::LocalOffset() {
+int64_t Time::LocalOffset() {
// Initialize timezone information, if needed.
TzSet();
- Win32Time rounded_to_second(*this);
+ Time rounded_to_second(*this);
rounded_to_second.t() = rounded_to_second.t() / 1000 / kTimeScaler *
1000 * kTimeScaler;
// Convert to local time using POSIX localtime function.
@@ -465,7 +541,7 @@ int64_t Win32Time::LocalOffset() {
// Return whether or not daylight savings time is in effect at this time.
-bool Win32Time::InDST() {
+bool Time::InDST() {
// Initialize timezone information, if needed.
TzSet();
@@ -489,14 +565,14 @@ bool Win32Time::InDST() {
// Return the daylight savings time offset for this time.
-int64_t Win32Time::DaylightSavingsOffset() {
+int64_t Time::DaylightSavingsOffset() {
return InDST() ? 60 * kMsPerMinute : 0;
}
// Returns a string identifying the current timezone for the
// timestamp taking into account daylight saving.
-char* Win32Time::LocalTimezone() {
+char* Time::LocalTimezone() {
// Return the standard or DST time zone name based on whether daylight
// saving is in effect at the given time.
return InDST() ? dst_tz_name_ : std_tz_name_;
@@ -538,14 +614,22 @@ int OS::GetUserTime(uint32_t* secs, uint32_t* usecs) {
// Returns current time as the number of milliseconds since
// 00:00:00 UTC, January 1, 1970.
double OS::TimeCurrentMillis() {
- return Time::Now().ToJsTime();
+ Time t;
+ t.SetToCurrentTime();
+ return t.ToJSTime();
+}
+
+
+// Returns the tickcounter based on timeGetTime.
+int64_t OS::Ticks() {
+ return timeGetTime() * 1000; // Convert to microseconds.
}
// Returns a string identifying the current timezone taking into
// account daylight saving.
const char* OS::LocalTimezone(double time) {
- return Win32Time(time).LocalTimezone();
+ return Time(time).LocalTimezone();
}
@@ -553,7 +637,7 @@ const char* OS::LocalTimezone(double time) {
// taking daylight savings time into account.
double OS::LocalTimeOffset() {
// Use current time, rounded to the millisecond.
- Win32Time t(TimeCurrentMillis());
+ Time t(TimeCurrentMillis());
// Time::LocalOffset inlcudes any daylight savings offset, so subtract it.
return static_cast<double>(t.LocalOffset() - t.DaylightSavingsOffset());
}
@@ -562,7 +646,7 @@ double OS::LocalTimeOffset() {
// Returns the daylight savings offset in milliseconds for the given
// time.
double OS::DaylightSavingsOffset(double time) {
- int64_t offset = Win32Time(time).DaylightSavingsOffset();
+ int64_t offset = Time(time).DaylightSavingsOffset();
return static_cast<double>(offset);
}
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