Time

• HyperSpec: Time
• CLtL2: Time Functions

get-universal-time ⇒ universal-time

Returns the current universal time, which is the number of seconds that have elapsed since 00:00 of January 1, 1900 in the GMT time zone.

(get-universal-time) ;⇒ 3574524644

decode-universal-time universal-time [zone] ⇒ sec, min, hr, day, m, yr, day-of-week, daylight-p, zone

Returns the decoded time represented by the given universal time.

(defconstant +months+ '(1 "Jan" 2 "Feb" 3 "Mar" 4 "Apr" 5 "May" 6 "Jun"
                        7 "Jul" 8 "Aug" 9 "Sep" 10 "Oct" 11 "Nov" 12 "Dec"))
(defconstant +days+ '(0 "Mon" 1 "Tue" 3 "Wed" 4 "Thu" 5 "Fri" 6 "Sat" 7 "Sun"))

(defun universal-time-to-rfc822 (ut)
  (multiple-value-bind (s m h d month y weekday dst-p tz) (decode-universal-time ut)
    (declare (ignore dst-p))
    (let ((day (getf +days+ weekday))
          (mon (getf +months+ month))
          (tzsign (if (minusp tz) "-" "+")))
          (format nil "~a, ~2,'0d ~a ~d ~2,'0d:~2,'0d:~2,'0d ~a~2,'0d00" day d mon y h m s tzsign tz))))

(universal-time-to-rfc822 (get-universal-time)) ;⇒ "Tue, 09 Apr 2013 14:04:52 +0800"

get-decoded-time ⇒ sec, min, hour, day, month, year, day-of-week, daylight-p, zone

Equivalent to (decode-universal-time (get-universal-time)).

(multiple-value-bind (sec min hr day m yr day-of-week dst-p tz) (get-decoded-time)
  (list sec min hr date m yr day-of-week dst-p tz)) ;⇒ (51 31 12 9 4 2013 1 T 8)

encode-universal-time sec min hr day m yr [zone] ⇒ universal-time

Converts from decoded time format to a universal time.

get-internal-run-time ⇒ internal-time

Returns as an integer the current run time in internal time units. Its precise meaning is implementation-dependant, but the intent is that the difference between two calls to this function return the amount of time expended on behalf of the executing program.

get-internal-real-time ⇒ internal-time

Returns as an integer the current time in internal time units, relative to an arbitrary time base. The difference between the values of two calls to this function is the amount of elapsed real time (i.e., clock time) between the two calls.

sleep seconds ⇒ nil

Causes execution to cease and become dormant for approximately the seconds of real time indicated by seconds, whereupon execution is resumed.

(let ((then (get-universal-time)))
  (sleep 10)
  (- (get-universal-time) then))   ;⇒ 5 [secs elapsed]

internal-time-units-per-second

Constant, a positive integer. The number of internal time units in one second.