nxt_time.h (0:a63ceefd6ab0) nxt_time.h (2084:7d479274f334)
1
2/*
3 * Copyright (C) Igor Sysoev
4 * Copyright (C) NGINX, Inc.
5 */
6
7#ifndef _NXT_UNIX_TIME_H_INCLUDED_
8#define _NXT_UNIX_TIME_H_INCLUDED_
9
10
11typedef uint64_t nxt_nsec_t;
12typedef int64_t nxt_nsec_int_t;
13#define NXT_INFINITE_NSEC ((nxt_nsec_t) -1)
14
15
16typedef struct {
17 nxt_time_t sec;
18 nxt_uint_t nsec;
19} nxt_realtime_t;
20
21
22/*
23 * nxt_monotonic_time_t includes nxt_realtime_t to eliminate
24 * surplus gettimeofday() call on platform without monotonic time.
25 */
26
27typedef struct {
28 nxt_realtime_t realtime;
29 nxt_nsec_t monotonic;
30 nxt_nsec_t update;
31
32#if !(NXT_HAVE_CLOCK_MONOTONIC || NXT_SOLARIS || NXT_HPUX || NXT_MACOSX)
33 nxt_nsec_t previous;
34#endif
35} nxt_monotonic_time_t;
36
37
38NXT_EXPORT void nxt_realtime(nxt_realtime_t *now);
39NXT_EXPORT void nxt_monotonic_time(nxt_monotonic_time_t *now);
40NXT_EXPORT void nxt_localtime(nxt_time_t s, struct tm *tm);
41NXT_EXPORT void nxt_timezone_update(void);
42
43/*
44 * Both localtime() and localtime_r() are not Async-Signal-Safe, therefore,
45 * they can not be used in signal handlers. Since Daylight Saving Time (DST)
46 * state changes no more than twice a year, a simple workaround is to use
47 * a previously cached GMT offset value and nxt_gmtime():
48 *
49 * nxt_gmtime(GMT seconds + GMT offset, tm);
50 *
51 * GMT offset with account of current DST state can be obtained only
52 * using localtime()'s struct tm because:
53 *
54 * 1) gettimeofday() does not return GMT offset at almost all platforms.
55 * MacOSX returns a value cached after the first localtime() call.
56 * AIX returns GMT offset without account of DST state and indicates
57 * only that timezone has DST, but does not indicate current DST state.
58 *
59 * 2) There are the "timezone" and "daylight" variables on Linux, Solaris,
60 * HP-UX, IRIX, and other systems. The "daylight" variable indicates
61 * only that timezone has DST, but does not indicate current DST state.
62 *
63 * 3) Solaris and IRIX have the "altzone" variable which contains GMT offset
64 * for timezone with DST applied, but without account of DST state.
65 *
66 * 4) There is the "struct tm.tm_gmtoff" field on BSD systems and modern Linux.
67 * This field contains GMT offset with account of DST state.
68 *
69 * 5) The "struct tm.tm_isdst" field returned by localtime() indicates
70 * current DST state on all platforms. This field may have three values:
71 * positive means DST in effect, zero means DST is not in effect, and
72 * negative means DST state is unknown.
73 */
74
75#if (NXT_HAVE_TM_GMTOFF)
76
1
2/*
3 * Copyright (C) Igor Sysoev
4 * Copyright (C) NGINX, Inc.
5 */
6
7#ifndef _NXT_UNIX_TIME_H_INCLUDED_
8#define _NXT_UNIX_TIME_H_INCLUDED_
9
10
11typedef uint64_t nxt_nsec_t;
12typedef int64_t nxt_nsec_int_t;
13#define NXT_INFINITE_NSEC ((nxt_nsec_t) -1)
14
15
16typedef struct {
17 nxt_time_t sec;
18 nxt_uint_t nsec;
19} nxt_realtime_t;
20
21
22/*
23 * nxt_monotonic_time_t includes nxt_realtime_t to eliminate
24 * surplus gettimeofday() call on platform without monotonic time.
25 */
26
27typedef struct {
28 nxt_realtime_t realtime;
29 nxt_nsec_t monotonic;
30 nxt_nsec_t update;
31
32#if !(NXT_HAVE_CLOCK_MONOTONIC || NXT_SOLARIS || NXT_HPUX || NXT_MACOSX)
33 nxt_nsec_t previous;
34#endif
35} nxt_monotonic_time_t;
36
37
38NXT_EXPORT void nxt_realtime(nxt_realtime_t *now);
39NXT_EXPORT void nxt_monotonic_time(nxt_monotonic_time_t *now);
40NXT_EXPORT void nxt_localtime(nxt_time_t s, struct tm *tm);
41NXT_EXPORT void nxt_timezone_update(void);
42
43/*
44 * Both localtime() and localtime_r() are not Async-Signal-Safe, therefore,
45 * they can not be used in signal handlers. Since Daylight Saving Time (DST)
46 * state changes no more than twice a year, a simple workaround is to use
47 * a previously cached GMT offset value and nxt_gmtime():
48 *
49 * nxt_gmtime(GMT seconds + GMT offset, tm);
50 *
51 * GMT offset with account of current DST state can be obtained only
52 * using localtime()'s struct tm because:
53 *
54 * 1) gettimeofday() does not return GMT offset at almost all platforms.
55 * MacOSX returns a value cached after the first localtime() call.
56 * AIX returns GMT offset without account of DST state and indicates
57 * only that timezone has DST, but does not indicate current DST state.
58 *
59 * 2) There are the "timezone" and "daylight" variables on Linux, Solaris,
60 * HP-UX, IRIX, and other systems. The "daylight" variable indicates
61 * only that timezone has DST, but does not indicate current DST state.
62 *
63 * 3) Solaris and IRIX have the "altzone" variable which contains GMT offset
64 * for timezone with DST applied, but without account of DST state.
65 *
66 * 4) There is the "struct tm.tm_gmtoff" field on BSD systems and modern Linux.
67 * This field contains GMT offset with account of DST state.
68 *
69 * 5) The "struct tm.tm_isdst" field returned by localtime() indicates
70 * current DST state on all platforms. This field may have three values:
71 * positive means DST in effect, zero means DST is not in effect, and
72 * negative means DST state is unknown.
73 */
74
75#if (NXT_HAVE_TM_GMTOFF)
76
77#define \
78nxt_timezone(tm) \
77#define nxt_timezone(tm) \
79 ((tm)->tm_gmtoff)
80
81#elif (NXT_HAVE_ALTZONE)
82
78 ((tm)->tm_gmtoff)
79
80#elif (NXT_HAVE_ALTZONE)
81
83#define \
84nxt_timezone(tm) \
82#define nxt_timezone(tm) \
85 (-(((tm)->tm_isdst > 0) ? altzone : timezone))
86
87#else
88
83 (-(((tm)->tm_isdst > 0) ? altzone : timezone))
84
85#else
86
89#define \
90nxt_timezone(tm) \
87#define nxt_timezone(tm) \
91 (-(((tm)->tm_isdst > 0) ? timezone + 3600 : timezone))
92
93#endif
94
95
96typedef uint32_t nxt_msec_t;
97typedef int32_t nxt_msec_int_t;
98#define NXT_INFINITE_MSEC ((nxt_msec_t) -1)
99
100
101/*
102 * Since nxt_msec_t values are stored just in 32 bits, they overflow
103 * every 49 days. This signed subtraction takes into account that overflow.
104 * "nxt_msec_diff(m1, m2) < 0" means that m1 is lesser than m2.
105 */
88 (-(((tm)->tm_isdst > 0) ? timezone + 3600 : timezone))
89
90#endif
91
92
93typedef uint32_t nxt_msec_t;
94typedef int32_t nxt_msec_int_t;
95#define NXT_INFINITE_MSEC ((nxt_msec_t) -1)
96
97
98/*
99 * Since nxt_msec_t values are stored just in 32 bits, they overflow
100 * every 49 days. This signed subtraction takes into account that overflow.
101 * "nxt_msec_diff(m1, m2) < 0" means that m1 is lesser than m2.
102 */
106#define \
107nxt_msec_diff(m1, m2) \
103#define nxt_msec_diff(m1, m2) \
108 ((int32_t) ((m1) - (m2)))
109
110
111#endif /* _NXT_UNIX_TIME_H_INCLUDED_ */
104 ((int32_t) ((m1) - (m2)))
105
106
107#endif /* _NXT_UNIX_TIME_H_INCLUDED_ */