Class: JSON::Util::UUID

Inherits:
Struct
  • Object
show all
Includes:
Comparable
Defined in:
lib/json-schema/util/uuid.rb,
lib/json-schema/util/uuid.rb

Overview

Pure ruby UUID generator, which is compatible with RFC4122

Constant Summary collapse

STATE_FILE =
'ruby-uuid'
NameSpace_DNS =

Pre-defined UUID Namespaces described in RFC4122 Appendix C.

parse "6ba7b810-9dad-11d1-80b4-00c04fd430c8"
NameSpace_URL =
parse "6ba7b811-9dad-11d1-80b4-00c04fd430c8"
NameSpace_OID =
parse "6ba7b812-9dad-11d1-80b4-00c04fd430c8"
NameSpace_X500 =
parse "6ba7b814-9dad-11d1-80b4-00c04fd430c8"
Nil =

The Nil UUID in RFC4122 Section 4.1.7

parse "00000000-0000-0000-0000-000000000000"

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#raw_bytesObject

Returns the value of attribute raw_bytes

Returns:

  • (Object)

    the current value of raw_bytes


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# File 'lib/json-schema/util/uuid.rb', line 35

def raw_bytes
  @raw_bytes
end

Class Method Details

.create(clock = nil, time = nil, mac_addr = nil) ⇒ Object Also known as: create_v1

create the “version 1” UUID with current system clock, current UTC timestamp, and the IEEE 802 address (so-called MAC address).

Speed notice: it's slow. It writes some data into hard drive on every invokation. If you want to speed this up, try remounting tmpdir with a memory based filesystem (such as tmpfs). STILL slow? then no way but rewrite it with c :)


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# File 'lib/json-schema/util/uuid.rb', line 140

def create clock=nil, time=nil, mac_addr=nil
	c = t = m = nil
	Dir.chdir Dir.tmpdir do
		unless FileTest.exist? STATE_FILE then
			# Generate a pseudo MAC address because we have no pure-ruby way
			# to know  the MAC  address of the  NIC this system  uses.  Note
			# that cheating  with pseudo arresses here  is completely legal:
			# see Section 4.5 of RFC4122 for details.
			sha1 = Digest::SHA1.new
			256.times do
				r = [rand(0x100000000)].pack "N"
				sha1.update r
			end
			str = sha1.digest
			r = rand 14 # 20-6
			node = str[r, 6] || str
			if RUBY_VERSION >= "1.9.0"
				nnode = node.bytes.to_a
				nnode[0] |= 0x01
				node = ''
				nnode.each { |s| node << s.chr }
			else
				node[0] |= 0x01 # multicast bit
			end
			k = rand 0x40000
			open STATE_FILE, 'w' do |fp|
				fp.flock IO::LOCK_EX
				write_state fp, k, node
				fp.chmod 0o777 # must be world writable
			end
		end
		open STATE_FILE, 'r+' do |fp|
			fp.flock IO::LOCK_EX
			c, m = read_state fp
			c = clock % 0x4000 if clock
			m = mac_addr if mac_addr
			t = time
			if t.nil? then
				# UUID epoch is 1582/Oct/15
				tt = Time.now
				t = tt.to_i*10000000 + tt.tv_usec*10 + 0x01B21DD213814000
			end
			c = c.succ # important; increment here
			write_state fp, c, m
		end
	end

	tl = t & 0xFFFF_FFFF
	tm = t >> 32
	tm = tm & 0xFFFF
	th = t >> 48
	th = th & 0x0FFF
	th = th | 0x1000
	cl = c & 0xFF
	ch = c & 0x3F00
	ch = ch >> 8
	ch = ch | 0x80
	pack tl, tm, th, cl, ch, m
end

.create_md5(str, namespace) ⇒ Object Also known as: create_v3

UUID generation using MD5 (for backward compat.)


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# File 'lib/json-schema/util/uuid.rb', line 90

def create_md5 str, namespace
	md5 = Digest::MD5.new
	md5.update namespace.raw_bytes
	md5.update str
	sum = md5.digest
	raw = mask 3, sum[0..16]
	ret = new raw
	ret.freeze
	ret
end

.create_randomObject Also known as: create_v4

UUID generation using random-number generator. From it's random nature, there's no warranty that the created ID is really universaly unique.


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# File 'lib/json-schema/util/uuid.rb', line 105

def create_random
	rnd = [
		rand(0x100000000),
		rand(0x100000000),
		rand(0x100000000),
		rand(0x100000000),
	].pack "N4"
	raw = mask 4, rnd
	ret = new raw
	ret.freeze
	ret
end

.create_sha1(str, namespace) ⇒ Object Also known as: create_v5

UUID generation using SHA1. Recommended over create_md5. Namespace object is another UUID, some of them are pre-defined below.


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# File 'lib/json-schema/util/uuid.rb', line 77

def create_sha1 str, namespace
	sha1 = Digest::SHA1.new
	sha1.update namespace.raw_bytes
	sha1.update str
	sum = sha1.digest
	raw = mask 5, sum[0..15]
	ret = new raw
	ret.freeze
	ret
end

.pack(tl, tm, th, ch, cl, n) ⇒ Object

The 'primitive constructor' of this class Note UUID.pack(uuid.unpack) == uuid


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# File 'lib/json-schema/util/uuid.rb', line 214

def pack tl, tm, th, ch, cl, n
	raw = [tl, tm, th, ch, cl, n].pack "NnnCCa6"
	ret = new raw
	ret.freeze
	ret
end

.parse(obj) ⇒ Object

A simple GUID parser: just ignores unknown characters and convert hexadecimal dump into 16-octet object.


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# File 'lib/json-schema/util/uuid.rb', line 203

def parse obj
	str = obj.to_s.sub %r/\Aurn:uuid:/, ''
	str.gsub! %r/[^0-9A-Fa-f]/, ''
	raw = str[0..31].lines.to_a.pack 'H*'
	ret = new raw
	ret.freeze
	ret
end

Instance Method Details

#<=>(other) ⇒ Object

UUIDs are comparable (don't know what benefits are there, though).


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# File 'lib/json-schema/util/uuid.rb', line 271

def <=> other
	to_s <=> other.to_s
end

#==(other) ⇒ Object

Two UUIDs are said to be equal if and only if their (byte-order canonicalized) integer representations are equivallent. Refer RFC4122 for details.


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# File 'lib/json-schema/util/uuid.rb', line 265

def == other
	to_i == other.to_i
end

#to_intObject Also known as: to_i

Convert into 128-bit unsigned integer Typically a Bignum instance, but can be a Fixnum.


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# File 'lib/json-schema/util/uuid.rb', line 245

def to_int
	tmp = self.raw_bytes.unpack "C*"
	tmp.inject do |r, i|
		r * 256 | i
	end
end

#to_sObject Also known as: guid

Generate the string representation (a.k.a GUID) of this UUID


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# File 'lib/json-schema/util/uuid.rb', line 229

def to_s
	a = unpack
	tmp = a[-1].unpack 'C*'
	a[-1] = sprintf '%02x%02x%02x%02x%02x%02x', *tmp
	"%08x-%04x-%04x-%02x%02x-%s" % a
end

#to_uriObject Also known as: urn

Convert into a RFC4122-comforming URN representation


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# File 'lib/json-schema/util/uuid.rb', line 238

def to_uri
	"urn:uuid:" + self.to_s
end

#unpackObject

The 'primitive deconstructor', or the dual to pack. Note UUID.pack(uuid.unpack) == uuid


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# File 'lib/json-schema/util/uuid.rb', line 224

def unpack
	raw_bytes.unpack "NnnCCa6"
end

#versionObject

Gets the version of this UUID returns nil if bad version


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# File 'lib/json-schema/util/uuid.rb', line 255

def version
	a = unpack
	v = (a[2] & 0xF000).to_s(16)[0].chr.to_i
	return v if (1..5).include? v
	return nil
end