112 lines
3.7 KiB
C
112 lines
3.7 KiB
C
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/*
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* Copyright (C) Igor Sysoev
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* Copyright (C) NGINX, Inc.
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*/
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#ifndef _NXT_UNIX_TIME_H_INCLUDED_
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#define _NXT_UNIX_TIME_H_INCLUDED_
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typedef uint64_t nxt_nsec_t;
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typedef int64_t nxt_nsec_int_t;
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#define NXT_INFINITE_NSEC ((nxt_nsec_t) -1)
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typedef struct {
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nxt_time_t sec;
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nxt_uint_t nsec;
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} nxt_realtime_t;
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/*
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* nxt_monotonic_time_t includes nxt_realtime_t to eliminate
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* surplus gettimeofday() call on platform without monotonic time.
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*/
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typedef struct {
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nxt_realtime_t realtime;
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nxt_nsec_t monotonic;
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nxt_nsec_t update;
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#if !(NXT_HAVE_CLOCK_MONOTONIC || NXT_SOLARIS || NXT_HPUX || NXT_MACOSX)
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nxt_nsec_t previous;
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#endif
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} nxt_monotonic_time_t;
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NXT_EXPORT void nxt_realtime(nxt_realtime_t *now);
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NXT_EXPORT void nxt_monotonic_time(nxt_monotonic_time_t *now);
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NXT_EXPORT void nxt_localtime(nxt_time_t s, struct tm *tm);
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NXT_EXPORT void nxt_timezone_update(void);
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/*
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* Both localtime() and localtime_r() are not Async-Signal-Safe, therefore,
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* they can not be used in signal handlers. Since Daylight Saving Time (DST)
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* state changes no more than twice a year, a simple workaround is to use
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* a previously cached GMT offset value and nxt_gmtime():
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*
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* nxt_gmtime(GMT seconds + GMT offset, tm);
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*
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* GMT offset with account of current DST state can be obtained only
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* using localtime()'s struct tm because:
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*
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* 1) gettimeofday() does not return GMT offset at almost all platforms.
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* MacOSX returns a value cached after the first localtime() call.
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* AIX returns GMT offset without account of DST state and indicates
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* only that timezone has DST, but does not indicate current DST state.
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*
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* 2) There are the "timezone" and "daylight" variables on Linux, Solaris,
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* HP-UX, IRIX, and other systems. The "daylight" variable indicates
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* only that timezone has DST, but does not indicate current DST state.
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*
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* 3) Solaris and IRIX have the "altzone" variable which contains GMT offset
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* for timezone with DST applied, but without account of DST state.
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*
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* 4) There is the "struct tm.tm_gmtoff" field on BSD systems and modern Linux.
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* This field contains GMT offset with account of DST state.
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*
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* 5) The "struct tm.tm_isdst" field returned by localtime() indicates
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* current DST state on all platforms. This field may have three values:
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* positive means DST in effect, zero means DST is not in effect, and
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* negative means DST state is unknown.
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*/
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#if (NXT_HAVE_TM_GMTOFF)
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#define \
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nxt_timezone(tm) \
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((tm)->tm_gmtoff)
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#elif (NXT_HAVE_ALTZONE)
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#define \
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nxt_timezone(tm) \
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(-(((tm)->tm_isdst > 0) ? altzone : timezone))
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#else
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#define \
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nxt_timezone(tm) \
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(-(((tm)->tm_isdst > 0) ? timezone + 3600 : timezone))
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#endif
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typedef uint32_t nxt_msec_t;
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typedef int32_t nxt_msec_int_t;
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#define NXT_INFINITE_MSEC ((nxt_msec_t) -1)
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/*
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* Since nxt_msec_t values are stored just in 32 bits, they overflow
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* every 49 days. This signed subtraction takes into account that overflow.
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* "nxt_msec_diff(m1, m2) < 0" means that m1 is lesser than m2.
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*/
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#define \
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nxt_msec_diff(m1, m2) \
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((int32_t) ((m1) - (m2)))
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#endif /* _NXT_UNIX_TIME_H_INCLUDED_ */
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