Class: WithUuid::CombUuid

Inherits:
Object
  • Object
show all
Defined in:
lib/with_uuid/comb_uuid.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(uuid_str) ⇒ CombUuid

Returns a new instance of CombUuid.



4
5
6
 
# File 'lib/with_uuid/comb_uuid.rb', line 4

def initialize( uuid_str )
  @uuid_str = uuid_str
end

Class Method Details

.uuid ⇒ Object 



28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
 
# File 'lib/with_uuid/comb_uuid.rb', line 28

def self.uuid
  # See:
  #   http://stackoverflow.com/questions/7747145/is-comb-guid-a-good-idea-with-rails-3-1-if-i-use-guids-for-primary-keys
  #   http://www.codeproject.com/Articles/32597/Performance-Comparison-Identity-x-NewId-x-NewSeque

  # MS SQL syntax: SELECT CAST(CAST(NEWID() AS BINARY(10)) + CAST(GETDATE() AS BINARY(6)) AS UNIQUEIDENTIFIER)

  # Get current Time object
  utc_timestamp = Time.now.utc

  # Convert to integer with milliseconds:  (Seconds since Epoch * 1000) + (6-digit microsecond fraction / 1000)
  utc_timestamp_with_ms_int = (utc_timestamp.tv_sec * 1000) + (utc_timestamp.tv_usec / 1000)

  # Format as hex, minimum of 12 digits, with leading zero.  Note that 12 hex digits handles to year 10889 (*).
  utc_timestamp_with_ms_hexstring = "%012x" % utc_timestamp_with_ms_int

  # If we supply UUIDTOOLS with a MAC address, it will use that rather than retrieving from system.
  # Use a regular expression to split into array, then insert ":" characters so it "looks" like a MAC address.
  UUIDTools::UUID.mac_address = (utc_timestamp_with_ms_hexstring.scan( /.{2}/ )).join(":")

  # Generate Version 1 UUID (see RFC 4122).
  uuid_str = UUIDTools::UUID.timestamp_create().to_s.upcase

  # (*) A note on maximum time handled by 6-byte timestamp that includes milliseconds:
  # If utc_timestamp_with_ms_hexstring = "FFFFFFFFFFFF" (12 F's), then
  # Time.at(Float(utc_timestamp_with_ms_hexstring.hex)/1000).utc.iso8601(10) = "10889-08-02T05:31:50.6550292968Z".

  self.new( uuid_str )
end

Instance Method Details

#[](idx) ⇒ Object 



16
17
18
 
# File 'lib/with_uuid/comb_uuid.rb', line 16

def []( idx )
  parts[idx]
end

#first ⇒ Object 



20
21
22
 
# File 'lib/with_uuid/comb_uuid.rb', line 20

def first
  parts[0]
end

#last ⇒ Object 



24
25
26
 
# File 'lib/with_uuid/comb_uuid.rb', line 24

def last
  parts[4]
end

#parts ⇒ Object 



12
13
14
 
# File 'lib/with_uuid/comb_uuid.rb', line 12

def parts
  @parts ||= @uuid_str.split( '-' )
end

#to_s ⇒ Object 



8
9
10
 
# File 'lib/with_uuid/comb_uuid.rb', line 8

def to_s
  uuid_str
end