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/*
* gettimeofday.c
* Win32 gettimeofday() replacement
*
* src/port/gettimeofday.c
*
* Copyright (c) 2003 SRA, Inc.
* Copyright (c) 2003 SKC, Inc.
*
* Permission to use, copy, modify, and distribute this software and
* its documentation for any purpose, without fee, and without a
* written agreement is hereby granted, provided that the above
* copyright notice and this paragraph and the following two
* paragraphs appear in all copies.
*
* IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
* INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING
* LOST PROFITS, ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS
* DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*
* THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS
* IS" BASIS, AND THE AUTHOR HAS NO OBLIGATIONS TO PROVIDE MAINTENANCE,
* SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
*/
#include "c.h"
#include <sys/time.h>
/* FILETIME of Jan 1 1970 00:00:00, the PostgreSQL epoch */
static const unsigned __int64 epoch = UINT64CONST(116444736000000000);
/*
* FILETIME represents the number of 100-nanosecond intervals since
* January 1, 1601 (UTC).
*/
#define FILETIME_UNITS_PER_SEC 10000000L
#define FILETIME_UNITS_PER_USEC 10
/*
* Both GetSystemTimeAsFileTime and GetSystemTimePreciseAsFileTime share a
* signature, so we can just store a pointer to whichever we find. This
* is the pointer's type.
*/
typedef VOID (WINAPI *PgGetSystemTimeFn)(LPFILETIME);
/* Storage for the function we pick at runtime */
static PgGetSystemTimeFn pg_get_system_time = NULL;
/*
* During backend startup, determine if GetSystemTimePreciseAsFileTime is
* available and use it; if not, fall back to GetSystemTimeAsFileTime.
*/
void
init_win32_gettimeofday(void)
{
/*
* Because it's guaranteed that kernel32.dll will be linked into our
* address space already, we don't need to LoadLibrary it and worry about
* closing it afterwards, so we're not using Pg's dlopen/dlsym() wrapper.
*
* We'll just look up the address of GetSystemTimePreciseAsFileTime if
* present.
*
* While we could look up the Windows version and skip this on Windows
* versions below Windows 8 / Windows Server 2012 there isn't much point,
* and determining the windows version is its self somewhat Windows version
* and development SDK specific...
*/
pg_get_system_time = (PgGetSystemTimeFn) GetProcAddress(
GetModuleHandle(TEXT("kernel32.dll")),
"GetSystemTimePreciseAsFileTime");
if (pg_get_system_time == NULL)
{
/*
* The expected error from GetLastError() is ERROR_PROC_NOT_FOUND, if
* the function isn't present. No other error should occur.
*
* It's too early in startup to elog(...) if we get some unexpected
* error, and not serious enough to warrant a fprintf to stderr about
* it or save the error and report it later. So silently fall back to
* GetSystemTimeAsFileTime irrespective of why the failure occurred.
*/
pg_get_system_time = &GetSystemTimeAsFileTime;
}
}
/*
* timezone information is stored outside the kernel so tzp isn't used anymore.
*
* Note: this function is not for Win32 high precision timing purposes. See
* elapsed_time().
*/
int
gettimeofday(struct timeval * tp, struct timezone * tzp)
{
FILETIME file_time;
ULARGE_INTEGER ularge;
(*pg_get_system_time)(&file_time);
ularge.LowPart = file_time.dwLowDateTime;
ularge.HighPart = file_time.dwHighDateTime;
tp->tv_sec = (long) ((ularge.QuadPart - epoch) / FILETIME_UNITS_PER_SEC);
tp->tv_usec = (long) (((ularge.QuadPart - epoch) % FILETIME_UNITS_PER_SEC)
/ FILETIME_UNITS_PER_USEC);
return 0;
}
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