nginx ngx_times
/*
* Copyright (C) Igor Sysoev
*/
#ifndef _NGX_TIMES_H_INCLUDED_
#define _NGX_TIMES_H_INCLUDED_
#include <ngx_config.h>
#include <ngx_core.h>
typedef struct {
time_t sec;
ngx_uint_t msec;
ngx_int_t gmtoff;
} ngx_time_t;
void ngx_time_init(void);
void ngx_time_update(time_t sec, ngx_uint_t msec);
u_char *ngx_http_time(u_char *buf, time_t t);
u_char *ngx_http_cookie_time(u_char *buf, time_t t);
void ngx_gmtime(time_t t, ngx_tm_t *tp);
time_t ngx_next_time(time_t when);
#define ngx_next_time_n "mktime()"
extern volatile ngx_time_t *ngx_cached_time;
#define ngx_time() ngx_cached_time->sec
#define ngx_timeofday() (ngx_time_t *) ngx_cached_time
extern volatile ngx_str_t ngx_cached_err_log_time;
extern volatile ngx_str_t ngx_cached_http_time;
extern volatile ngx_str_t ngx_cached_http_log_time;
/*
* milliseconds elapsed since epoch and truncated to ngx_msec_t,
* used in event timers
*/
extern volatile ngx_msec_t ngx_current_msec;
#endif /* _NGX_TIMES_H_INCLUDED_ */
/*
* Copyright (C) Igor Sysoev
*/
#include <ngx_config.h>
#include <ngx_core.h>
/*
* The time may be updated by signal handler or by several threads.
* The time update operations are rare and require to hold the ngx_time_lock.
* The time read operations are frequent, so they are lock-free and get time
* values and strings from the current slot. Thus thread may get the corrupted
* values only if it is preempted while copying and then it is not scheduled
* to run more than NGX_TIME_SLOTS seconds.
*/
#define NGX_TIME_SLOTS 64
static ngx_uint_t slot;
static ngx_atomic_t ngx_time_lock;
volatile ngx_msec_t ngx_current_msec;
volatile ngx_time_t *ngx_cached_time;
volatile ngx_str_t ngx_cached_err_log_time;
volatile ngx_str_t ngx_cached_http_time;
volatile ngx_str_t ngx_cached_http_log_time;
static ngx_time_t cached_time[NGX_TIME_SLOTS];
static u_char cached_err_log_time[NGX_TIME_SLOTS]
[sizeof("1970/09/28 12:00:00")];
static u_char cached_http_time[NGX_TIME_SLOTS]
[sizeof("Mon, 28 Sep 1970 06:00:00 GMT")];
static u_char cached_http_log_time[NGX_TIME_SLOTS]
[sizeof("28/Sep/1970:12:00:00 +0600")];
static char *week[] = { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat" };
static char *months[] = { "Jan", "Feb", "Mar", "Apr", "May", "Jun",
"Jul", "Aug", "Sep", "Oct", "Nov", "Dec" };
void
ngx_time_init(void)
{
ngx_cached_err_log_time.len = sizeof("1970/09/28 12:00:00") - 1;
ngx_cached_http_time.len = sizeof("Mon, 28 Sep 1970 06:00:00 GMT") - 1;
ngx_cached_http_log_time.len = sizeof("28/Sep/1970:12:00:00 +0600") - 1;
ngx_cached_time = &cached_time[0];
ngx_time_update(0, 0);
}
void
ngx_time_update(time_t sec, ngx_uint_t msec)
{
u_char *p0, *p1, *p2;
ngx_tm_t tm, gmt;
ngx_time_t *tp;
struct timeval tv;
if ( !ngx_trylock( &ngx_time_lock ) )
{
return;
}
if ( sec == 0 )
{
ngx_gettimeofday( &tv );
sec = tv.tv_sec;
msec = tv.tv_usec / 1000;
}
ngx_current_msec = (ngx_msec_t) sec * 1000 + msec;
tp = &cached_time[slot];
if ( tp->sec == sec )
{
tp->msec = msec;
ngx_unlock(&ngx_time_lock);
return;
}
if ( slot == NGX_TIME_SLOTS - 1 )
{
slot = 0;
}
else
{
slot++;
}
tp = &cached_time[slot];
tp->sec = sec;
tp->msec = msec;
ngx_gmtime(sec, &gmt);
p0 = &cached_http_time[slot][0];
(void) ngx_sprintf(p0, "%s, %02d %s %4d %02d:%02d:%02d GMT",
week[gmt.ngx_tm_wday], gmt.ngx_tm_mday,
months[gmt.ngx_tm_mon - 1], gmt.ngx_tm_year,
gmt.ngx_tm_hour, gmt.ngx_tm_min, gmt.ngx_tm_sec);
#if (NGX_HAVE_GETTIMEZONE)
tp->gmtoff = ngx_gettimezone();
ngx_gmtime(sec + tp->gmtoff * 60, &tm);
#elif (NGX_HAVE_GMTOFF)
ngx_localtime(sec, &tm);
tp->gmtoff = (ngx_int_t) (tm.ngx_tm_gmtoff / 60);
#else
ngx_localtime(sec, &tm);
tp->gmtoff = ngx_timezone(tm.ngx_tm_isdst);
#endif
p1 = &cached_err_log_time[slot][0];
(void) ngx_sprintf(p1, "%4d/%02d/%02d %02d:%02d:%02d",
tm.ngx_tm_year, tm.ngx_tm_mon,
tm.ngx_tm_mday, tm.ngx_tm_hour,
tm.ngx_tm_min, tm.ngx_tm_sec);
p2 = &cached_http_log_time[slot][0];
(void) ngx_sprintf(p2, "%02d/%s/%d:%02d:%02d:%02d %c%02d%02d",
tm.ngx_tm_mday, months[tm.ngx_tm_mon - 1],
tm.ngx_tm_year, tm.ngx_tm_hour,
tm.ngx_tm_min, tm.ngx_tm_sec,
tp->gmtoff < 0 ? '-' : '+',
ngx_abs(tp->gmtoff / 60), ngx_abs(tp->gmtoff % 60));
ngx_memory_barrier(); // NB, 告诉编译器不要优化排序，因为如果乱序的话，前面还没有填充好内容，
//下面就把这个没有初始化好内容的指针赋值给了多线程访问的ngx_cached_time
ngx_cached_time = tp;
ngx_cached_http_time.data = p0;
ngx_cached_err_log_time.data = p1;
ngx_cached_http_log_time.data = p2;
ngx_unlock( &ngx_time_lock );
}
//另一种格式的字符串
u_char *
ngx_http_time( u_char *buf, time_t t )
{
ngx_tm_t tm;
ngx_gmtime( t, &tm );
return ngx_sprintf( buf, "%s, %02d %s %4d %02d:%02d:%02d GMT",
week[tm.ngx_tm_wday],
tm.ngx_tm_mday,
months[tm.ngx_tm_mon - 1],
tm.ngx_tm_year,
tm.ngx_tm_hour,
tm.ngx_tm_min,
tm.ngx_tm_sec );
}
//将时间t格式化为 nginx的tm结构体类型，然后组装成一个字符串
u_char *
ngx_http_cookie_time( u_char *buf, time_t t )
{
ngx_tm_t tm;
ngx_gmtime( t, &tm );
/*
* Netscape 3.x does not understand 4-digit years at all and
* 2-digit years more than "37"
*/
return ngx_sprintf( buf,
(tm.ngx_tm_year > 2037) ?
"%s, %02d-%s-%d %02d:%02d:%02d GMT":
"%s, %02d-%s-%02d %02d:%02d:%02d GMT",
week[tm.ngx_tm_wday],
tm.ngx_tm_mday,
months[tm.ngx_tm_mon - 1],
(tm.ngx_tm_year > 2037) ? tm.ngx_tm_year:
tm.ngx_tm_year % 100,
tm.ngx_tm_hour,
tm.ngx_tm_min,
tm.ngx_tm_sec );
}
//将time_t变为 ngx的tm结构体类型
void
ngx_gmtime(time_t t, ngx_tm_t *tp)
{
ngx_int_t yday;
ngx_uint_t n, sec, min, hour, mday, mon, year, wday, days, leap;
/* the calculation is valid for positive time_t only */
n = (ngx_uint_t) t;
days = n / 86400;
/* Jaunary 1, 1970 was Thursday */
wday = (4 + days) % 7;
n %= 86400;
hour = n / 3600;
n %= 3600;
min = n / 60;
sec = n % 60;
/*
* the algorithm based on Gauss' formula,
* see src/http/ngx_http_parse_time.c
*/
/* days since March 1, 1 BC */
days = days - (31 + 28) + 719527;
/*
* The "days" should be adjusted to 1 only, however, some March 1st's go
* to previous year, so we adjust them to 2. This causes also shift of the
* last Feburary days to next year, but we catch the case when "yday"
* becomes negative.
*/
year = (days + 2) * 400 / (365 * 400 + 100 - 4 + 1);
yday = days - (365 * year + year / 4 - year / 100 + year / 400);
if (yday < 0) {
leap = (year % 4 == 0) && (year % 100 || (year % 400 == 0));
yday = 365 + leap + yday;
year--;
}
/*
* The empirical formula that maps "yday" to month.
* There are at least 10 variants, some of them are:
* mon = (yday + 31) * 15 / 459
* mon = (yday + 31) * 17 / 520
* mon = (yday + 31) * 20 / 612
*/
mon = (yday + 31) * 10 / 306;
/* the Gauss' formula that evaluates days before the month */
mday = yday - (367 * mon / 12 - 30) + 1;
if (yday >= 306) {
year++;
mon -= 10;
/*
* there is no "yday" in Win32 SYSTEMTIME
*
* yday -= 306;
*/
} else {
mon += 2;
/*
* there is no "yday" in Win32 SYSTEMTIME
*
* yday += 31 + 28 + leap;
*/
}
tp->ngx_tm_sec = (ngx_tm_sec_t) sec;
tp->ngx_tm_min = (ngx_tm_min_t) min;
tp->ngx_tm_hour = (ngx_tm_hour_t) hour;
tp->ngx_tm_mday = (ngx_tm_mday_t) mday;
tp->ngx_tm_mon = (ngx_tm_mon_t) mon;
tp->ngx_tm_year = (ngx_tm_year_t) year;
tp->ngx_tm_wday = (ngx_tm_wday_t) wday;
}
//今天0:00:00开始，过when秒后是多少时间, 获取本地时间，递增指定的秒数，再转化为time_t
time_t
ngx_next_time( time_t when )
{
time_t now, next;
struct tm tm;
now = ngx_time();
ngx_libc_localtime( now, &tm );
tm.tm_hour = (int) ( when / 3600 );
when %= 3600;
tm.tm_min = (int) (when / 60);
tm.tm_sec = (int) (when % 60);
next = mktime( &tm );
if ( next == -1 )
{
return -1;
}
if ( next - now > 0 )
{
return next;
}
tm.tm_mday++;
/* mktime() should normalize a date (Jan 32, etc) */
next = mktime( &tm );
if ( next != -1 )
{
return next;
}
return -1;
}
参考文章： http://blog.csdn.net/fengmo_q/article/details/6302354
nginx为了减少系统调用的次数，将时间缓存起来， 缓存了几种格式的字符串， 老的内容读到也没有问题，1秒的误差也是可以接受的
每次 epoll_wait返回的时候更新一下时间 （可设定）调用下 ngx_time_update 函数 ，还有一个是在信号处理函数中调用
if ( ngx_timer_resolution && !(ngx_event_flags & NGX_USE_TIMER_EVENT ) )
{
struct sigaction sa;
struct itimerval itv;
ngx_memzero(&sa, sizeof(struct sigaction));
sa.sa_handler = ngx_timer_signal_handler;
sigemptyset(&sa.sa_mask);
if ( sigaction(SIGALRM, &sa, NULL) == -1 )
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"sigaction(SIGALRM) failed");
return NGX_ERROR;
}
itv.it_interval.tv_sec = ngx_timer_resolution / 1000;
itv.it_interval.tv_usec = (ngx_timer_resolution % 1000) * 1000;
itv.it_value.tv_sec = ngx_timer_resolution / 1000;
itv.it_value.tv_usec = (ngx_timer_resolution % 1000 ) * 1000;
if ( setitimer(ITIMER_REAL, &itv, NULL) == -1 )
{
ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
"setitimer() failed");
}
}
void
ngx_timer_signal_handler(int signo)
{
ngx_event_timer_alarm = 1;
ngx_time_update(0, 0);
#if 1
ngx_log_debug0(NGX_LOG_DEBUG_EVENT, ngx_cycle->log, 0, "timer signal");
#endif
}