/*
* tclWinTime.c --
*
* Contains Windows specific versions of Tcl functions that obtain time
* values from the operating system.
*
* Copyright 1995-1998 by Sun Microsystems, Inc.
*
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
* RCS: @(#) $Id: tclWinTime.c,v 1.33 2005/11/04 00:06:51 dkf Exp $
*/
#include "tclInt.h"
#define SECSPERDAY (60L * 60L * 24L)
#define SECSPERYEAR (SECSPERDAY * 365L)
#define SECSPER4YEAR (SECSPERYEAR * 4L + SECSPERDAY)
/*
* Number of samples over which to estimate the performance counter.
*/
#define SAMPLES 64
/*
* The following arrays contain the day of year for the last day of each
* month, where index 1 is January.
*/
static int normalDays[] = {
-1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364
};
static int leapDays[] = {
-1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
};
typedef struct ThreadSpecificData {
char tzName[64]; /* Time zone name */
struct tm tm; /* time information */
} ThreadSpecificData;
static Tcl_ThreadDataKey dataKey;
/*
* Data for managing high-resolution timers.
*/
typedef struct TimeInfo {
CRITICAL_SECTION cs; /* Mutex guarding this structure. */
int initialized; /* Flag == 1 if this structure is
* initialized. */
int perfCounterAvailable; /* Flag == 1 if the hardware has a performance
* counter. */
HANDLE calibrationThread; /* Handle to the thread that keeps the virtual
* clock calibrated. */
HANDLE readyEvent; /* System event used to trigger the requesting
* thread when the clock calibration procedure
* is initialized for the first time. */
HANDLE exitEvent; /* Event to signal out of an exit handler to
* tell the calibration loop to terminate. */
LARGE_INTEGER nominalFreq; /* Nominal frequency of the system performance
* counter, that is, the value returned from
* QueryPerformanceFrequency. */
/*
* The following values are used for calculating virtual time. Virtual
* time is always equal to:
* lastFileTime + (current perf counter - lastCounter)
* * 10000000 / curCounterFreq
* and lastFileTime and lastCounter are updated any time that virtual time
* is returned to a caller.
*/
ULARGE_INTEGER fileTimeLastCall;
LARGE_INTEGER perfCounterLastCall;
LARGE_INTEGER curCounterFreq;
/*
* Data used in developing the estimate of performance counter frequency
*/
Tcl_WideUInt fileTimeSample[SAMPLES];
/* Last 64 samples of system time. */
Tcl_WideInt perfCounterSample[SAMPLES];
/* Last 64 samples of performance counter. */
int sampleNo; /* Current sample number. */
} TimeInfo;
static TimeInfo timeInfo = {
{ NULL },
0,
0,
(HANDLE) NULL,
(HANDLE) NULL,
(HANDLE) NULL,
#ifdef HAVE_CAST_TO_UNION
(LARGE_INTEGER) (Tcl_WideInt) 0,
(ULARGE_INTEGER) (DWORDLONG) 0,
(LARGE_INTEGER) (Tcl_WideInt) 0,
(LARGE_INTEGER) (Tcl_WideInt) 0,
#else
0,
0,
0,
0,
#endif
{ 0 },
{ 0 },
0
};
/*
* Declarations for functions defined later in this file.
*/
static struct tm * ComputeGMT(const time_t *tp);
static void StopCalibration(ClientData clientData);
static DWORD WINAPI CalibrationThread(LPVOID arg);
static void UpdateTimeEachSecond(void);
static void ResetCounterSamples(Tcl_WideUInt fileTime,
Tcl_WideInt perfCounter, Tcl_WideInt perfFreq);
static Tcl_WideInt AccumulateSample(Tcl_WideInt perfCounter,
Tcl_WideUInt fileTime);
static void NativeScaleTime(Tcl_Time* timebuf,
ClientData clientData);
static void NativeGetTime(Tcl_Time* timebuf,
ClientData clientData);
/*
* TIP #233 (Virtualized Time): Data for the time hooks, if any.
*/
Tcl_GetTimeProc *tclGetTimeProcPtr = NativeGetTime;
Tcl_ScaleTimeProc *tclScaleTimeProcPtr = NativeScaleTime;
ClientData tclTimeClientData = NULL;
/*
*----------------------------------------------------------------------
*
* TclpGetSeconds --
*
* This procedure returns the number of seconds from the epoch. On most
* Unix systems the epoch is Midnight Jan 1, 1970 GMT.
*
* Results:
* Number of seconds from the epoch.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
unsigned long
TclpGetSeconds(void)
{
Tcl_Time t;
(*tclGetTimeProcPtr) (&t, tclTimeClientData); /* Tcl_GetTime inlined. */
return t.sec;
}
/*
*----------------------------------------------------------------------
*
* TclpGetClicks --
*
* This procedure returns a value that represents the highest resolution
* clock available on the system. There are no guarantees on what the
* resolution will be. In Tcl we will call this value a "click". The
* start time is also system dependant.
*
* Results:
* Number of clicks from some start time.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
unsigned long
TclpGetClicks(void)
{
/*
* Use the Tcl_GetTime abstraction to get the time in microseconds, as
* nearly as we can, and return it.
*/
Tcl_Time now; /* Current Tcl time */
unsigned long retval; /* Value to return */
(*tclGetTimeProcPtr) (&now, tclTimeClientData); /* Tcl_GetTime inlined */
retval = (now.sec * 1000000) + now.usec;
return retval;
}
/*
*----------------------------------------------------------------------
*
* TclpGetTimeZone --
*
* Determines the current timezone. The method varies wildly between
* different Platform implementations, so its hidden in this function.
*
* Results:
* Minutes west of GMT.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
int
TclpGetTimeZone(
unsigned long currentTime)
{
int timeZone;
tzset();
timeZone = timezone / 60;
return timeZone;
}
/*
*----------------------------------------------------------------------
*
* Tcl_GetTime --
*
* Gets the current system time in seconds and microseconds since the
* beginning of the epoch: 00:00 UCT, January 1, 1970.
*
* Results:
* Returns the current time in timePtr.
*
* Side effects:
* On the first call, initializes a set of static variables to keep track
* of the base value of the performance counter, the corresponding wall
* clock (obtained through ftime) and the frequency of the performance
* counter. Also spins a thread whose function is to wake up periodically
* and monitor these values, adjusting them as necessary to correct for
* drift in the performance counter's oscillator.
*
*----------------------------------------------------------------------
*/
void
Tcl_GetTime(
Tcl_Time *timePtr) /* Location to store time information. */
{
(*tclGetTimeProcPtr) (timePtr, tclTimeClientData);
}
/*
*----------------------------------------------------------------------
*
* NativeScaleTime --
*
* TIP #233: Scale from virtual time to the real-time. For native scaling
* the relationship is 1:1 and nothing has to be done.
*
* Results:
* Scales the time in timePtr.
*
* Side effects:
* See above.
*
*----------------------------------------------------------------------
*/
static void
NativeScaleTime(
Tcl_Time *timePtr,
ClientData clientData)
{
/*
* Native scale is 1:1. Nothing is done.
*/
}
/*
*----------------------------------------------------------------------
*
* NativeGetTime --
*
* TIP #233: Gets the current system time in seconds and microseconds
* since the beginning of the epoch: 00:00 UCT, January 1, 1970.
*
* Results:
* Returns the current time in timePtr.
*
* Side effects:
* On the first call, initializes a set of static variables to keep track
* of the base value of the performance counter, the corresponding wall
* clock (obtained through ftime) and the frequency of the performance
* counter. Also spins a thread whose function is to wake up periodically
* and monitor these values, adjusting them as necessary to correct for
* drift in the performance counter's oscillator.
*
*----------------------------------------------------------------------
*/
static void
NativeGetTime(
Tcl_Time *timePtr,
ClientData clientData)
{
struct timeb t;
int useFtime = 1; /* Flag == TRUE if we need to fall back on
* ftime rather than using the perf counter. */
/*
* Initialize static storage on the first trip through.
*
* Note: Outer check for 'initialized' is a performance win since it
* avoids an extra mutex lock in the common case.
*/
if (!timeInfo.initialized) {
TclpInitLock();
if (!timeInfo.initialized) {
timeInfo.perfCounterAvailable =
QueryPerformanceFrequency(&timeInfo.nominalFreq);
/*
* Some hardware abstraction layers use the CPU clock in place of
* the real-time clock as a performance counter reference. This
* results in:
* - inconsistent results among the processors on
* multi-processor systems.
* - unpredictable changes in performance counter frequency on
* "gearshift" processors such as Transmeta and SpeedStep.
*
* There seems to be no way to test whether the performance
* counter is reliable, but a useful heuristic is that if its
* frequency is 1.193182 MHz or 3.579545 MHz, it's derived from a
* colorburst crystal and is therefore the RTC rather than the
* TSC.
*
* A sloppier but serviceable heuristic is that the RTC crystal is
* normally less than 15 MHz while the TSC crystal is virtually
* assured to be greater than 100 MHz. Since Win98SE appears to
* fiddle with the definition of the perf counter frequency
* (perhaps in an attempt to calibrate the clock?), we use the
* latter rule rather than an exact match.
*
* We also assume (perhaps questionably) that the vendors have
* gotten their act together on Win64, so bypass all this rubbish
* on that platform.
*/
#if !defined(_WIN64)
if (timeInfo.perfCounterAvailable
/*
* The following lines would do an exact match on crystal
* frequency:
* && timeInfo.nominalFreq.QuadPart != (Tcl_WideInt)1193182
* && timeInfo.nominalFreq.QuadPart != (Tcl_WideInt)3579545
*/
&& timeInfo.nominalFreq.QuadPart > (Tcl_WideInt) 15000000){
/*
* As an exception, if every logical processor on the system
* is on the same chip, we use the performance counter anyway,
* presuming that everyone's TSC is locked to the same
* oscillator.
*/
SYSTEM_INFO systemInfo;
unsigned int regs[4];
GetSystemInfo(&systemInfo);
if (TclWinCPUID(0, regs) == TCL_OK
&& regs[1] == 0x756e6547 /* "Genu" */
&& regs[3] == 0x49656e69 /* "ineI" */
&& regs[2] == 0x6c65746e /* "ntel" */
&& TclWinCPUID(1, regs) == TCL_OK
&& ((regs[0]&0x00000F00) == 0x00000F00 /* Pentium 4 */
|| ((regs[0] & 0x00F00000) /* Extended family */
&& (regs[3] & 0x10000000))) /* Hyperthread */
&& (((regs[1]&0x00FF0000) >> 16)/* CPU count */
== systemInfo.dwNumberOfProcessors)) {
timeInfo.perfCounterAvailable = TRUE;
} else {
timeInfo.perfCounterAvailable = FALSE;
}
}
#endif /* above code is Win32 only */
/*
* If the performance counter is available, start a thread to
* calibrate it.
*/
if (timeInfo.perfCounterAvailable) {
DWORD id;
InitializeCriticalSection(&timeInfo.cs);
timeInfo.readyEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
timeInfo.exitEvent = CreateEvent(NULL, FALSE, FALSE, NULL);
timeInfo.calibrationThread = CreateThread(NULL, 256,
CalibrationThread, (LPVOID) NULL, 0, &id);
SetThreadPriority(timeInfo.calibrationThread,
THREAD_PRIORITY_HIGHEST);
/*
* Wait for the thread just launched to start running, and
* create an exit handler that kills it so that it doesn't
* outlive unloading tclXX.dll
*/
WaitForSingleObject(timeInfo.readyEvent, INFINITE);
CloseHandle(timeInfo.readyEvent);
Tcl_CreateExitHandler(StopCalibration, (ClientData) NULL);
}
timeInfo.initialized = TRUE;
}
TclpInitUnlock();
}
if (timeInfo.perfCounterAvailable && timeInfo.curCounterFreq.QuadPart!=0) {
/*
* Query the performance counter and use it to calculate the current
* time.
*/
LARGE_INTEGER curCounter;
/* Current performance counter. */
Tcl_WideInt curFileTime;/* Current estimated time, expressed as 100-ns
* ticks since the Windows epoch. */
static LARGE_INTEGER posixEpoch;
/* Posix epoch expressed as 100-ns ticks since
* the windows epoch. */
Tcl_WideInt usecSincePosixEpoch;
/* Current microseconds since Posix epoch. */
posixEpoch.LowPart = 0xD53E8000;
posixEpoch.HighPart = 0x019DB1DE;
EnterCriticalSection(&timeInfo.cs);
QueryPerformanceCounter(&curCounter);
/*
* If it appears to be more than 1.1 seconds since the last trip
* through the calibration loop, the performance counter may have
* jumped forward. (See MSDN Knowledge Base article Q274323 for a
* description of the hardware problem that makes this test
* necessary.) If the counter jumps, we don't want to use it directly.
* Instead, we must return system time. Eventually, the calibration
* loop should recover.
*/
if (curCounter.QuadPart - timeInfo.perfCounterLastCall.QuadPart <
11 * timeInfo.curCounterFreq.QuadPart / 10) {
curFileTime = timeInfo.fileTimeLastCall.QuadPart +
((curCounter.QuadPart - timeInfo.perfCounterLastCall.QuadPart)
* 10000000 / timeInfo.curCounterFreq.QuadPart);
timeInfo.fileTimeLastCall.QuadPart = curFileTime;
timeInfo.perfCounterLastCall.QuadPart = curCounter.QuadPart;
usecSincePosixEpoch = (curFileTime - posixEpoch.QuadPart) / 10;
timePtr->sec = (long) (usecSincePosixEpoch / 1000000);
timePtr->usec = (unsigned long) (usecSincePosixEpoch % 1000000);
useFtime = 0;
}
LeaveCriticalSection(&timeInfo.cs);
}
if (useFtime) {
/*
* High resolution timer is not available. Just use ftime.
*/
ftime(&t);
timePtr->sec = (long)t.time;
timePtr->usec = t.millitm * 1000;
}
}
/*
*----------------------------------------------------------------------
*
* StopCalibration --
*
* Turns off the calibration thread in preparation for exiting the
* process.
*
* Results:
* None.
*
* Side effects:
* Sets the 'exitEvent' event in the 'timeInfo' structure to ask the
* thread in question to exit, and waits for it to do so.
*
*----------------------------------------------------------------------
*/
static void
StopCalibration(
ClientData unused) /* Client data is unused */
{
SetEvent(timeInfo.exitEvent);
/*
* If Tcl_Finalize was called from DllMain, the calibration thread is in a
* paused state so we need to timeout and continue.
*/
WaitForSingleObject(timeInfo.calibrationThread, 100);
CloseHandle(timeInfo.exitEvent);
CloseHandle(timeInfo.calibrationThread);
}
/*
*----------------------------------------------------------------------
*
* TclpGetTZName --
*
* Gets the current timezone string.
*
* Results:
* Returns a pointer to a static string, or NULL on failure.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
char *
TclpGetTZName(
int dst)
{
int len;
char *zone, *p;
TIME_ZONE_INFORMATION tz;
Tcl_Encoding encoding;
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
char *name = tsdPtr->tzName;
/*
* tzset() under Borland doesn't seem to set up tzname[] at all.
* tzset() under MSVC has the following weird observed behavior:
* First time we call "clock format [clock seconds] -format %Z -gmt 1"
* we get "GMT", but on all subsequent calls we get the current time
* ezone string, even though env(TZ) is GMT and the variable _timezone
* is 0.
*/
name[0] = '\0';
zone = getenv("TZ");
if (zone != NULL) {
/*
* TZ is of form "NST-4:30NDT", where "NST" would be the name of the
* standard time zone for this area, "-4:30" is the offset from GMT in
* hours, and "NDT is the name of the daylight savings time zone in
* this area. The offset and DST strings are optional.
*/
len = strlen(zone);
if (len > 3) {
len = 3;
}
if (dst != 0) {
/*
* Skip the offset string and get the DST string.
*/
p = zone + len;
p += strspn(p, "+-:0123456789");
if (*p != '\0') {
zone = p;
len = strlen(zone);
if (len > 3) {
len = 3;
}
}
}
Tcl_ExternalToUtf(NULL, NULL, zone, len, 0, NULL, name,
sizeof(tsdPtr->tzName), NULL, NULL, NULL);
}
if (name[0] == '\0') {
if (GetTimeZoneInformation(&tz) == TIME_ZONE_ID_UNKNOWN) {
/*
* MSDN: On NT this is returned if DST is not used in the current
* TZ
*/
dst = 0;
}
encoding = Tcl_GetEncoding(NULL, "unicode");
Tcl_ExternalToUtf(NULL, encoding,
(char *) ((dst) ? tz.DaylightName : tz.StandardName), -1,
0, NULL, name, sizeof(tsdPtr->tzName), NULL, NULL, NULL);
Tcl_FreeEncoding(encoding);
}
return name;
}
/*
*----------------------------------------------------------------------
*
* TclpGetDate --
*
* This function converts between seconds and struct tm. If useGMT is
* true, then the returned date will be in Greenwich Mean Time (GMT).
* Otherwise, it will be in the local time zone.
*
* Results:
* Returns a static tm structure.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
struct tm *
TclpGetDate(
CONST time_t *t,
int useGMT)
{
struct tm *tmPtr;
time_t time;
if (!useGMT) {
tzset();
/*
* If we are in the valid range, let the C run-time library handle it.
* Otherwise we need to fake it. Note that this algorithm ignores
* daylight savings time before the epoch.
*/
/*
* Hm, Borland's localtime manages to return NULL under certain
* circumstances (e.g. wintime.test, test 1.2). Nobody tests for this,
* since 'localtime' isn't supposed to do this, possibly leading to
* crashes.
*
* Patch: We only call this function if we are at least one day into
* the epoch, else we handle it ourselves (like we do for times < 0).
* H. Giese, June 2003
*/
#ifdef __BORLANDC__
#define LOCALTIME_VALIDITY_BOUNDARY SECSPERDAY
#else
#define LOCALTIME_VALIDITY_BOUNDARY 0
#endif
if (*t >= LOCALTIME_VALIDITY_BOUNDARY) {
return TclpLocaltime(t);
}
time = *t - timezone;
/*
* If we aren't near to overflowing the long, just add the bias and
* use the normal calculation. Otherwise we will need to adjust the
* result at the end.
*/
if (*t < (LONG_MAX - 2*SECSPERDAY) && *t > (LONG_MIN + 2*SECSPERDAY)) {
tmPtr = ComputeGMT(&time);
} else {
tmPtr = ComputeGMT(t);
tzset();
/*
* Add the bias directly to the tm structure to avoid overflow.
* Propagate seconds overflow into minutes, hours and days.
*/
time = tmPtr->tm_sec - timezone;
tmPtr->tm_sec = (int)(time % 60);
if (tmPtr->tm_sec < 0) {
tmPtr->tm_sec += 60;
time -= 60;
}
time = tmPtr->tm_min + time/60;
tmPtr->tm_min = (int)(time % 60);
if (tmPtr->tm_min < 0) {
tmPtr->tm_min += 60;
time -= 60;
}
time = tmPtr->tm_hour + time/60;
tmPtr->tm_hour = (int)(time % 24);
if (tmPtr->tm_hour < 0) {
tmPtr->tm_hour += 24;
time -= 24;
}
time /= 24;
tmPtr->tm_mday += (int)time;
tmPtr->tm_yday += (int)time;
tmPtr->tm_wday = (tmPtr->tm_wday + (int)time) % 7;
}
} else {
tmPtr = ComputeGMT(t);
}
return tmPtr;
}
/*
*----------------------------------------------------------------------
*
* ComputeGMT --
*
* This function computes GMT given the number of seconds since the epoch
* (midnight Jan 1 1970).
*
* Results:
* Returns a (per thread) statically allocated struct tm.
*
* Side effects:
* Updates the values of the static struct tm.
*
*----------------------------------------------------------------------
*/
static struct tm *
ComputeGMT(
const time_t *tp)
{
struct tm *tmPtr;
long tmp, rem;
int isLeap;
int *days;
ThreadSpecificData *tsdPtr = TCL_TSD_INIT(&dataKey);
tmPtr = &tsdPtr->tm;
/*
* Compute the 4 year span containing the specified time.
*/
tmp = (long)(*tp / SECSPER4YEAR);
rem = (long)(*tp % SECSPER4YEAR);
/*
* Correct for weird mod semantics so the remainder is always positive.
*/
if (rem < 0) {
tmp--;
rem += SECSPER4YEAR;
}
/*
* Compute the year after 1900 by taking the 4 year span and adjusting for
* the remainder. This works because 2000 is a leap year, and 1900/2100
* are out of the range.
*/
tmp = (tmp * 4) + 70;
isLeap = 0;
if (rem >= SECSPERYEAR) { /* 1971, etc. */
tmp++;
rem -= SECSPERYEAR;
if (rem >= SECSPERYEAR) { /* 1972, etc. */
tmp++;
rem -= SECSPERYEAR;
if (rem >= SECSPERYEAR + SECSPERDAY) { /* 1973, etc. */
tmp++;
rem -= SECSPERYEAR + SECSPERDAY;
} else {
isLeap = 1;
}
}
}
tmPtr->tm_year = tmp;
/*
* Compute the day of year and leave the seconds in the current day in the
* remainder.
*/
tmPtr->tm_yday = rem / SECSPERDAY;
rem %= SECSPERDAY;
/*
* Compute the time of day.
*/
tmPtr->tm_hour = rem / 3600;
rem %= 3600;
tmPtr->tm_min = rem / 60;
tmPtr->tm_sec = rem % 60;
/*
* Compute the month and day of month.
*/
days = (isLeap) ? leapDays : normalDays;
for (tmp = 1; days[tmp] < tmPtr->tm_yday; tmp++) {
/* empty body */
}
tmPtr->tm_mon = --tmp;
tmPtr->tm_mday = tmPtr->tm_yday - days[tmp];
/*
* Compute day of week. Epoch started on a Thursday.
*/
tmPtr->tm_wday = (long)(*tp / SECSPERDAY) + 4;
if ((*tp % SECSPERDAY) < 0) {
tmPtr->tm_wday--;
}
tmPtr->tm_wday %= 7;
if (tmPtr->tm_wday < 0) {
tmPtr->tm_wday += 7;
}
return tmPtr;
}
/*
*----------------------------------------------------------------------
*
* CalibrationThread --
*
* Thread that manages calibration of the hi-resolution time derived from
* the performance counter, to keep it synchronized with the system
* clock.
*
* Parameters:
* arg - Client data from the CreateThread call. This parameter points to
* the static TimeInfo structure.
*
* Return value:
* None. This thread embeds an infinite loop.
*
* Side effects:
* At an interval of 1s, this thread performs virtual time discipline.
*
* Note: When this thread is entered, TclpInitLock has been called to
* safeguard the static storage. There is therefore no synchronization in the
* body of this procedure.
*
*----------------------------------------------------------------------
*/
static DWORD WINAPI
CalibrationThread(
LPVOID arg)
{
FILETIME curFileTime;
DWORD waitResult;
/*
* Get initial system time and performance counter.
*/
GetSystemTimeAsFileTime(&curFileTime);
QueryPerformanceCounter(&timeInfo.perfCounterLastCall);
QueryPerformanceFrequency(&timeInfo.curCounterFreq);
timeInfo.fileTimeLastCall.LowPart = curFileTime.dwLowDateTime;
timeInfo.fileTimeLastCall.HighPart = curFileTime.dwHighDateTime;
ResetCounterSamples(timeInfo.fileTimeLastCall.QuadPart,
timeInfo.perfCounterLastCall.QuadPart,
timeInfo.curCounterFreq.QuadPart);
/*
* Wake up the calling thread. When it wakes up, it will release the
* initialization lock.
*/
SetEvent(timeInfo.readyEvent);
/*
* Run the calibration once a second.
*/
while (timeInfo.perfCounterAvailable) {
/*
* If the exitEvent is set, break out of the loop.
*/
waitResult = WaitForSingleObjectEx(timeInfo.exitEvent, 1000, FALSE);
if (waitResult == WAIT_OBJECT_0) {
break;
}
UpdateTimeEachSecond();
}
/* lint */
return (DWORD) 0;
}
/*
*----------------------------------------------------------------------
*
* UpdateTimeEachSecond --
*
* Callback from the waitable timer in the clock calibration thread that
* updates system time.
*
* Parameters:
* info - Pointer to the static TimeInfo structure
*
* Results:
* None.
*
* Side effects:
* Performs virtual time calibration discipline.
*
*----------------------------------------------------------------------
*/
static void
UpdateTimeEachSecond(void)
{
LARGE_INTEGER curPerfCounter;
/* Current value returned from
* QueryPerformanceCounter. */
FILETIME curSysTime; /* Current system time. */
LARGE_INTEGER curFileTime; /* File time at the time this callback was
* scheduled. */
Tcl_WideInt estFreq; /* Estimated perf counter frequency. */
Tcl_WideInt vt0; /* Tcl time right now. */
Tcl_WideInt vt1; /* Tcl time one second from now. */
Tcl_WideInt tdiff; /* Difference between system clock and Tcl
* time. */
Tcl_WideInt driftFreq; /* Frequency needed to drift virtual time into
* step over 1 second. */
/*
* Sample performance counter and system time.
*/
QueryPerformanceCounter(&curPerfCounter);
GetSystemTimeAsFileTime(&curSysTime);
curFileTime.LowPart = curSysTime.dwLowDateTime;
curFileTime.HighPart = curSysTime.dwHighDateTime;
EnterCriticalSection(&timeInfo.cs);
/*
* We devide by timeInfo.curCounterFreq.QuadPart in several places. That
* value should always be positive on a correctly functioning system. But
* it is good to be defensive about such matters. So if something goes
* wrong and the value does goes to zero, we clear the
* timeInfo.perfCounterAvailable in order to cause the calibration thread
* to shut itself down, then return without additional processing.
*/
if (timeInfo.curCounterFreq.QuadPart == 0){
LeaveCriticalSection(&timeInfo.cs);
timeInfo.perfCounterAvailable = 0;
return;
}
/*
* Several things may have gone wrong here that have to be checked for.
* (1) The performance counter may have jumped.
* (2) The system clock may have been reset.
*
* In either case, we'll need to reinitialize the circular buffer with
* samples relative to the current system time and the NOMINAL performance
* frequency (not the actual, because the actual has probably run slow in
* the first case). Our estimated frequency will be the nominal frequency.
*
* Store the current sample into the circular buffer of samples, and
* estimate the performance counter frequency.
*/
estFreq = AccumulateSample(curPerfCounter.QuadPart,
(Tcl_WideUInt) curFileTime.QuadPart);
/*
* We want to adjust things so that time appears to be continuous.
* Virtual file time, right now, is
*
* vt0 = 10000000 * (curPerfCounter - perfCounterLastCall)
* / curCounterFreq
* + fileTimeLastCall
*
* Ideally, we would like to drift the clock into place over a period of 2
* sec, so that virtual time 2 sec from now will be
*
* vt1 = 20000000 + curFileTime
*
* The frequency that we need to use to drift the counter back into place
* is estFreq * 20000000 / (vt1 - vt0)
*/
vt0 = 10000000 * (curPerfCounter.QuadPart
- timeInfo.perfCounterLastCall.QuadPart)
/ timeInfo.curCounterFreq.QuadPart
+ timeInfo.fileTimeLastCall.QuadPart;
vt1 = 20000000 + curFileTime.QuadPart;
/*
* If we've gotten more than a second away from system time, then drifting
* the clock is going to be pretty hopeless. Just let it jump. Otherwise,
* compute the drift frequency and fill in everything.
*/
tdiff = vt0 - curFileTime.QuadPart;
if (tdiff > 10000000 || tdiff < -10000000) {
timeInfo.fileTimeLastCall.QuadPart = curFileTime.QuadPart;
timeInfo.curCounterFreq.QuadPart = estFreq;
} else {
driftFreq = estFreq * 20000000 / (vt1 - vt0);
if (driftFreq > 1003*estFreq/1000) {
driftFreq = 1003*estFreq/1000;
} else if (driftFreq < 997*estFreq/1000) {
driftFreq = 997*estFreq/1000;
}
timeInfo.fileTimeLastCall.QuadPart = vt0;
timeInfo.curCounterFreq.QuadPart = driftFreq;
}
timeInfo.perfCounterLastCall.QuadPart = curPerfCounter.QuadPart;
LeaveCriticalSection(&timeInfo.cs);
}
/*
*----------------------------------------------------------------------
*
* ResetCounterSamples --
*
* Fills the sample arrays in 'timeInfo' with dummy values that will
* yield the current performance counter and frequency.
*
* Results:
* None.
*
* Side effects:
* The array of samples is filled in so that it appears that there are
* SAMPLES samples at one-second intervals, separated by precisely the
* given frequency.
*
*----------------------------------------------------------------------
*/
static void
ResetCounterSamples(
Tcl_WideUInt fileTime, /* Current file time */
Tcl_WideInt perfCounter, /* Current performance counter */
Tcl_WideInt perfFreq) /* Target performance frequency */
{
int i;
for (i=SAMPLES-1 ; i>=0 ; --i) {
timeInfo.perfCounterSample[i] = perfCounter;
timeInfo.fileTimeSample[i] = fileTime;
perfCounter -= perfFreq;
fileTime -= 10000000;
}
timeInfo.sampleNo = 0;
}
/*
*----------------------------------------------------------------------
*
* AccumulateSample --
*
* Updates the circular buffer of performance counter and system time
* samples with a new data point.
*
* Results:
* None.
*
* Side effects:
* The new data point replaces the oldest point in the circular buffer,
* and the descriptive statistics are updated to accumulate the new
* point.
*
* Several things may have gone wrong here that have to be checked for.
* (1) The performance counter may have jumped.
* (2) The system clock may have been reset.
*
* In either case, we'll need to reinitialize the circular buffer with samples
* relative to the current system time and the NOMINAL performance frequency
* (not the actual, because the actual has probably run slow in the first
* case).
*/
static Tcl_WideInt
AccumulateSample(
Tcl_WideInt perfCounter,
Tcl_WideUInt fileTime)
{
Tcl_WideUInt workFTSample; /* File time sample being removed from or
* added to the circular buffer. */
Tcl_WideInt workPCSample; /* Performance counter sample being removed
* from or added to the circular buffer. */
Tcl_WideUInt lastFTSample; /* Last file time sample recorded */
Tcl_WideInt lastPCSample; /* Last performance counter sample recorded */
Tcl_WideInt FTdiff; /* Difference between last FT and current */
Tcl_WideInt PCdiff; /* Difference between last PC and current */
Tcl_WideInt estFreq; /* Estimated performance counter frequency */
/*
* Test for jumps and reset the samples if we have one.
*/
if (timeInfo.sampleNo == 0) {
lastPCSample =
timeInfo.perfCounterSample[timeInfo.sampleNo + SAMPLES - 1];
lastFTSample =
timeInfo.fileTimeSample[timeInfo.sampleNo + SAMPLES - 1];
} else {
lastPCSample = timeInfo.perfCounterSample[timeInfo.sampleNo - 1];
lastFTSample = timeInfo.fileTimeSample[timeInfo.sampleNo - 1];
}
PCdiff = perfCounter - lastPCSample;
FTdiff = fileTime - lastFTSample;
if (PCdiff < timeInfo.nominalFreq.QuadPart * 9 / 10
|| PCdiff > timeInfo.nominalFreq.QuadPart * 11 / 10
|| FTdiff < 9000000 || FTdiff > 11000000) {
ResetCounterSamples(fileTime, perfCounter,
timeInfo.nominalFreq.QuadPart);
return timeInfo.nominalFreq.QuadPart;
} else {
/*
* Estimate the frequency.
*/
workPCSample = timeInfo.perfCounterSample[timeInfo.sampleNo];
workFTSample = timeInfo.fileTimeSample[timeInfo.sampleNo];
estFreq = 10000000 * (perfCounter - workPCSample)
/ (fileTime - workFTSample);
timeInfo.perfCounterSample[timeInfo.sampleNo] = perfCounter;
timeInfo.fileTimeSample[timeInfo.sampleNo] = (Tcl_WideInt) fileTime;
/*
* Advance the sample number.
*/
if (++timeInfo.sampleNo >= SAMPLES) {
timeInfo.sampleNo = 0;
}
return estFreq;
}
}
/*
*----------------------------------------------------------------------
*
* TclpGmtime --
*
* Wrapper around the 'gmtime' library function to make it thread safe.
*
* Results:
* Returns a pointer to a 'struct tm' in thread-specific data.
*
* Side effects:
* Invokes gmtime or gmtime_r as appropriate.
*
*----------------------------------------------------------------------
*/
struct tm *
TclpGmtime(
CONST time_t *timePtr) /* Pointer to the number of seconds since the
* local system's epoch */
{
/*
* The MS implementation of gmtime is thread safe because it returns the
* time in a block of thread-local storage, and Windows does not provide a
* Posix gmtime_r function.
*/
return gmtime(timePtr);
}
/*
*----------------------------------------------------------------------
*
* TclpLocaltime --
*
* Wrapper around the 'localtime' library function to make it thread
* safe.
*
* Results:
* Returns a pointer to a 'struct tm' in thread-specific data.
*
* Side effects:
* Invokes localtime or localtime_r as appropriate.
*
*----------------------------------------------------------------------
*/
struct tm *
TclpLocaltime(
CONST time_t *timePtr) /* Pointer to the number of seconds since the
* local system's epoch */
{
/*
* The MS implementation of localtime is thread safe because it returns
* the time in a block of thread-local storage, and Windows does not
* provide a Posix localtime_r function.
*/
return localtime(timePtr);
}
/*
*----------------------------------------------------------------------
*
* Tcl_SetTimeProc --
*
* TIP #233 (Virtualized Time): Registers two handlers for the
* virtualization of Tcl's access to time information.
*
* Results:
* None.
*
* Side effects:
* Remembers the handlers, alters core behaviour.
*
*----------------------------------------------------------------------
*/
void
Tcl_SetTimeProc(
Tcl_GetTimeProc *getProc,
Tcl_ScaleTimeProc *scaleProc,
ClientData clientData)
{
tclGetTimeProcPtr = getProc;
tclScaleTimeProcPtr = scaleProc;
tclTimeClientData = clientData;
}
/*
*----------------------------------------------------------------------
*
* Tcl_QueryTimeProc --
*
* TIP #233 (Virtualized Time): Query which time handlers are registered.
*
* Results:
* None.
*
* Side effects:
* None.
*
*----------------------------------------------------------------------
*/
void
Tcl_QueryTimeProc(
Tcl_GetTimeProc **getProc,
Tcl_ScaleTimeProc **scaleProc,
ClientData *clientData)
{
if (getProc) {
*getProc = tclGetTimeProcPtr;
}
if (scaleProc) {
*scaleProc = tclScaleTimeProcPtr;
}
if (clientData) {
*clientData = tclTimeClientData;
}
}
/*
* Local Variables:
* mode: c
* c-basic-offset: 4
* fill-column: 78
* End:
*/
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