SQUUID - a sequential UUID

gistfile1.txt

A very handy tool for sequential UUIDS fro https://github.com/clojure-cookbook/clojure-cookbook/blob/master/01_primitive-data/1-24_uuids.asciidoc

Here is the definition:


(defn squuid []
  (let [uuid (java.util.UUID/randomUUID)
        time (System/currentTimeMillis)
        secs (quot time 1000)
        lsb (.getLeastSignificantBits uuid)
        msb (.getMostSignificantBits uuid)
        timed-msb (bit-or (bit-shift-left secs 32)
                          (bit-and 0x00000000ffffffff msb))]
    (java.util.UUID. timed-msb lsb)))
  
  
Here is how to test it:  
    
    (def u1 (squuid))
u1
;; -> #uuid "527bf210-dfae-4c73-8b7a-302d3b511f41"

(def u2 (squuid))
u2
;; -> #uuid "527bf219-65f0-4241-a165-c5c541cb98ea"

(def u3 (squuid))
u3
;; -> #uuid "527bf232-42b2-44bc-8dd7-ddae2abfcb87"

(sort [u1 u2 u3])
;; -> (#uuid "527bf210-dfae-4c73-8b7a-302d3b511f41"
;;     #uuid "527bf219-65f0-4241-a165-c5c541cb98ea"
;;     #uuid "527bf232-42b2-44bc-8dd7-ddae2abfcb87")