diff options
Diffstat (limited to 'examples/redis-unstable/src/localtime.c')
| -rw-r--r-- | examples/redis-unstable/src/localtime.c | 103 |
1 files changed, 0 insertions, 103 deletions
diff --git a/examples/redis-unstable/src/localtime.c b/examples/redis-unstable/src/localtime.c deleted file mode 100644 index e95eb69..0000000 --- a/examples/redis-unstable/src/localtime.c +++ /dev/null @@ -1,103 +0,0 @@ -/* - * Copyright (c) 2018-Present, Redis Ltd. - * All rights reserved. - * - * Licensed under your choice of (a) the Redis Source Available License 2.0 - * (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the - * GNU Affero General Public License v3 (AGPLv3). - */ - -#include <time.h> - -/* This is a safe version of localtime() which contains no locks and is - * fork() friendly. Even the _r version of localtime() cannot be used safely - * in Redis. Another thread may be calling localtime() while the main thread - * forks(). Later when the child process calls localtime() again, for instance - * in order to log something to the Redis log, it may deadlock: in the copy - * of the address space of the forked process the lock will never be released. - * - * This function takes the timezone 'tz' as argument, and the 'dst' flag is - * used to check if daylight saving time is currently in effect. The caller - * of this function should obtain such information calling tzset() ASAP in the - * main() function to obtain the timezone offset from the 'timezone' global - * variable. To obtain the daylight information, if it is currently active or not, - * one trick is to call localtime() in main() ASAP as well, and get the - * information from the tm_isdst field of the tm structure. However the daylight - * time may switch in the future for long running processes, so this information - * should be refreshed at safe times. - * - * Note that this function does not work for dates < 1/1/1970, it is solely - * designed to work with what time(NULL) may return, and to support Redis - * logging of the dates, it's not really a complete implementation. */ -static int is_leap_year(time_t year) { - if (year % 4) return 0; /* A year not divisible by 4 is not leap. */ - else if (year % 100) return 1; /* If div by 4 and not 100 is surely leap. */ - else if (year % 400) return 0; /* If div by 100 *and* not by 400 is not leap. */ - else return 1; /* If div by 100 and 400 is leap. */ -} - -void nolocks_localtime(struct tm *tmp, time_t t, time_t tz, int dst) { - const time_t secs_min = 60; - const time_t secs_hour = 3600; - const time_t secs_day = 3600*24; - - t -= tz; /* Adjust for timezone. */ - t += 3600*dst; /* Adjust for daylight time. */ - time_t days = t / secs_day; /* Days passed since epoch. */ - time_t seconds = t % secs_day; /* Remaining seconds. */ - - tmp->tm_isdst = dst; - tmp->tm_hour = seconds / secs_hour; - tmp->tm_min = (seconds % secs_hour) / secs_min; - tmp->tm_sec = (seconds % secs_hour) % secs_min; - - /* 1/1/1970 was a Thursday, that is, day 4 from the POV of the tm structure - * where sunday = 0, so to calculate the day of the week we have to add 4 - * and take the modulo by 7. */ - tmp->tm_wday = (days+4)%7; - - /* Calculate the current year. */ - tmp->tm_year = 1970; - while(1) { - /* Leap years have one day more. */ - time_t days_this_year = 365 + is_leap_year(tmp->tm_year); - if (days_this_year > days) break; - days -= days_this_year; - tmp->tm_year++; - } - tmp->tm_yday = days; /* Number of day of the current year. */ - - /* We need to calculate in which month and day of the month we are. To do - * so we need to skip days according to how many days there are in each - * month, and adjust for the leap year that has one more day in February. */ - int mdays[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31}; - mdays[1] += is_leap_year(tmp->tm_year); - - tmp->tm_mon = 0; - while(days >= mdays[tmp->tm_mon]) { - days -= mdays[tmp->tm_mon]; - tmp->tm_mon++; - } - - tmp->tm_mday = days+1; /* Add 1 since our 'days' is zero-based. */ - tmp->tm_year -= 1900; /* Surprisingly tm_year is year-1900. */ -} - -#ifdef LOCALTIME_TEST_MAIN -#include <stdio.h> - -int main(void) { - /* Obtain timezone and daylight info. */ - tzset(); /* Now 'timezone' global is populated. */ - time_t t = time(NULL); - struct tm *aux = localtime(&t); - int daylight_active = aux->tm_isdst; - - struct tm tm; - char buf[1024]; - - nolocks_localtime(&tm,t,timezone,daylight_active); - strftime(buf,sizeof(buf),"%d %b %H:%M:%S",&tm); - printf("[timezone: %d, dl: %d] %s\n", (int)timezone, (int)daylight_active, buf); -} -#endif |