Initial version.

src/nxt_time.h

@@ -0,0 +1,111 @@
+
+/*
+ * Copyright (C) Igor Sysoev
+ * Copyright (C) NGINX, Inc.
+ */
+
+#ifndef _NXT_UNIX_TIME_H_INCLUDED_
+#define _NXT_UNIX_TIME_H_INCLUDED_
+
+
+typedef uint64_t           nxt_nsec_t;
+typedef int64_t            nxt_nsec_int_t;
+#define NXT_INFINITE_NSEC  ((nxt_nsec_t) -1)
+
+
+typedef struct {
+    nxt_time_t             sec;
+    nxt_uint_t             nsec;
+} nxt_realtime_t;
+
+
+/*
+ * nxt_monotonic_time_t includes nxt_realtime_t to eliminate
+ * surplus gettimeofday() call on platform without monotonic time.
+ */
+
+typedef struct {
+    nxt_realtime_t         realtime;
+    nxt_nsec_t             monotonic;
+    nxt_nsec_t             update;
+
+#if !(NXT_HAVE_CLOCK_MONOTONIC || NXT_SOLARIS || NXT_HPUX || NXT_MACOSX)
+    nxt_nsec_t             previous;
+#endif
+} nxt_monotonic_time_t;
+
+
+NXT_EXPORT void nxt_realtime(nxt_realtime_t *now);
+NXT_EXPORT void nxt_monotonic_time(nxt_monotonic_time_t *now);
+NXT_EXPORT void nxt_localtime(nxt_time_t s, struct tm *tm);
+NXT_EXPORT void nxt_timezone_update(void);
+
+/*
+ * Both localtime() and localtime_r() are not Async-Signal-Safe, therefore,
+ * they can not be used in signal handlers.  Since Daylight Saving Time (DST)
+ * state changes no more than twice a year, a simple workaround is to use
+ * a previously cached GMT offset value and nxt_gmtime():
+ *
+ *     nxt_gmtime(GMT seconds + GMT offset, tm);
+ *
+ * GMT offset with account of current DST state can be obtained only
+ * using localtime()'s struct tm because:
+ *
+ * 1) gettimeofday() does not return GMT offset at almost all platforms.
+ *    MacOSX returns a value cached after the first localtime() call.
+ *    AIX returns GMT offset without account of DST state and indicates
+ *    only that timezone has DST, but does not indicate current DST state.
+ *
+ * 2) There are the "timezone" and "daylight" variables on Linux, Solaris,
+ *    HP-UX, IRIX, and other systems.  The "daylight" variable indicates
+ *    only that timezone has DST, but does not indicate current DST state.
+ *
+ * 3) Solaris and IRIX have the "altzone" variable which contains GMT offset
+ *    for timezone with DST applied, but without account of DST state.
+ *
+ * 4) There is the "struct tm.tm_gmtoff" field on BSD systems and modern Linux.
+ *    This field contains GMT offset with account of DST state.
+ *
+ * 5) The "struct tm.tm_isdst" field returned by localtime() indicates
+ *    current DST state on all platforms.  This field may have three values:
+ *    positive means DST in effect, zero means DST is not in effect, and
+ *    negative means DST state is unknown.
+ */
+
+#if (NXT_HAVE_TM_GMTOFF)
+
+#define                                                                       \
+nxt_timezone(tm)                                                              \
+    ((tm)->tm_gmtoff)
+
+#elif (NXT_HAVE_ALTZONE)
+
+#define                                                                       \
+nxt_timezone(tm)                                                              \
+    (-(((tm)->tm_isdst > 0) ? altzone : timezone))
+
+#else
+
+#define                                                                       \
+nxt_timezone(tm)                                                              \
+    (-(((tm)->tm_isdst > 0) ? timezone + 3600 : timezone))
+
+#endif
+
+
+typedef uint32_t           nxt_msec_t;
+typedef int32_t            nxt_msec_int_t;
+#define NXT_INFINITE_MSEC  ((nxt_msec_t) -1)
+
+
+/*
+ * Since nxt_msec_t values are stored just in 32 bits, they overflow
+ * every 49 days.  This signed subtraction takes into account that overflow.
+ * "nxt_msec_diff(m1, m2) < 0" means that m1 is lesser than m2.
+ */
+#define                                                                       \
+nxt_msec_diff(m1, m2)                                                         \
+    ((int32_t) ((m1) - (m2)))
+
+
+#endif /* _NXT_UNIX_TIME_H_INCLUDED_ */