nginx/src/core/ngx_times.c

/*
 * Copyright (C) Igor Sysoev
 * Copyright (C) Nginx, Inc.
 */


#include <ngx_config.h>
#include <ngx_core.h>


static ngx_msec_t ngx_monotonic_time(time_t sec, ngx_uint_t msec);


/*
 * 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 …

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;
volatile ngx_str_t       ngx_cached_http_log_iso8601;
volatile ngx_str_t       ngx_cached_syslog_time;

#if !(NGX_WIN32)

/*
 * localtime() and localtime_r() are not Async-Signal-Safe functions, therefore,
 * they must not be called by a signal handler, so we use the cached
 * GMT offset value. Fortunately the value is changed only two times a year.
 */

static ngx_int_t         cached_gmtoff;
#endif

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 u_char            cached_http_log_iso8601[NGX_TIME_SLOTS]
                                    [sizeof("1970-09-28T12:00:00+06:00")];
static u_char            cached_syslog_time[NGX_TIME_SLOTS]
                                    [sizeof("Sep 28 12:00:00")];


static char  *week[] = …;
static char  *months[] = …;

void
ngx_time_init(void)
{ … }


void
ngx_time_update(void)
{ … }


static ngx_msec_t
ngx_monotonic_time(time_t sec, ngx_uint_t msec)
{ … }


#if !(NGX_WIN32)

void
ngx_time_sigsafe_update(void)
{ … }

#endif


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)
{ … }