3 * Win32 gettimeofday() replacement
5 * src/port/gettimeofday.c
7 * Copyright (c) 2003 SRA, Inc.
8 * Copyright (c) 2003 SKC, Inc.
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12 * written agreement is hereby granted, provided that the above
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16 * IN NO EVENT SHALL THE AUTHOR BE LIABLE TO ANY PARTY FOR DIRECT,
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19 * DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED
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22 * THE AUTHOR SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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33 /* FILETIME of Jan 1 1970 00:00:00, the PostgreSQL epoch */
34 static const unsigned __int64 epoch = UINT64CONST(116444736000000000);
37 * FILETIME represents the number of 100-nanosecond intervals since
38 * January 1, 1601 (UTC).
40 #define FILETIME_UNITS_PER_SEC 10000000L
41 #define FILETIME_UNITS_PER_USEC 10
44 * Both GetSystemTimeAsFileTime and GetSystemTimePreciseAsFileTime share a
45 * signature, so we can just store a pointer to whichever we find. This
46 * is the pointer's type.
48 typedef VOID(WINAPI * PgGetSystemTimeFn) (LPFILETIME);
50 /* One-time initializer function, must match that signature. */
51 static void WINAPI init_gettimeofday(LPFILETIME lpSystemTimeAsFileTime);
53 /* Storage for the function we pick at runtime */
54 static PgGetSystemTimeFn pg_get_system_time = &init_gettimeofday;
57 * One time initializer. Determine whether GetSystemTimePreciseAsFileTime
58 * is available and if so, plan to use it; if not, fall back to
59 * GetSystemTimeAsFileTime.
62 init_gettimeofday(LPFILETIME lpSystemTimeAsFileTime)
65 * Because it's guaranteed that kernel32.dll will be linked into our
66 * address space already, we don't need to LoadLibrary it and worry about
67 * closing it afterwards, so we're not using Pg's dlopen/dlsym() wrapper.
69 * We'll just look up the address of GetSystemTimePreciseAsFileTime if
72 * While we could look up the Windows version and skip this on Windows
73 * versions below Windows 8 / Windows Server 2012 there isn't much point,
74 * and determining the windows version is its self somewhat Windows
75 * version and development SDK specific...
77 pg_get_system_time = (PgGetSystemTimeFn) GetProcAddress(
78 GetModuleHandle(TEXT("kernel32.dll")),
79 "GetSystemTimePreciseAsFileTime");
80 if (pg_get_system_time == NULL)
83 * The expected error from GetLastError() is ERROR_PROC_NOT_FOUND, if
84 * the function isn't present. No other error should occur.
86 * We can't report an error here because this might be running in
87 * frontend code; and even if we're in the backend, it's too early to
88 * elog(...) if we get some unexpected error. Also, it's not a
89 * serious problem, so just silently fall back to
90 * GetSystemTimeAsFileTime irrespective of why the failure occurred.
92 pg_get_system_time = &GetSystemTimeAsFileTime;
95 (*pg_get_system_time) (lpSystemTimeAsFileTime);
99 * timezone information is stored outside the kernel so tzp isn't used anymore.
101 * Note: this function is not for Win32 high precision timing purposes. See
105 gettimeofday(struct timeval * tp, struct timezone * tzp)
108 ULARGE_INTEGER ularge;
110 (*pg_get_system_time) (&file_time);
111 ularge.LowPart = file_time.dwLowDateTime;
112 ularge.HighPart = file_time.dwHighDateTime;
114 tp->tv_sec = (long) ((ularge.QuadPart - epoch) / FILETIME_UNITS_PER_SEC);
115 tp->tv_usec = (long) (((ularge.QuadPart - epoch) % FILETIME_UNITS_PER_SEC)
116 / FILETIME_UNITS_PER_USEC);