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rand: add uuid_v7(), session function, simplify uuid_v4() (#24313)
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4 changed files with 150 additions and 59 deletions
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@ -1,60 +1,99 @@
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module rand
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const clock_seq_hi_and_reserved_valid_values = [`8`, `9`, `a`, `b`]!
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import time
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// uuid_v4 generates a random (v4) UUID
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// See https://en.wikipedia.org/wiki/Universally_unique_identifier#Version_4_(random)
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// See https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-4
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pub fn uuid_v4() string {
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return internal_uuid_v4(mut default_rng)
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rand_1 := default_rng.u64()
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rand_2 := default_rng.u64()
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return internal_uuid(4, rand_1, rand_2)
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}
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@[direct_array_access]
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fn internal_uuid_v4(mut rng PRNG) string {
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buflen := 36
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@[direct_array_access; inline]
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fn internal_uuid(version u8, rand_1 u64, rand_2 u64) string {
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// 0 1 2 3
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// 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | rand_1 |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | rand_1 | ver | rand_1 |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// |var| rand_2 |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | rand_2 |
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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mut parts := [8]u16{}
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parts[0] = u16(rand_1 >> 48)
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parts[1] = u16(rand_1 >> 32)
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parts[2] = u16(rand_1 >> 16)
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parts[3] = u16(rand_1)
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parts[4] = u16(rand_2 >> 48)
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parts[5] = u16(rand_2 >> 32)
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parts[6] = u16(rand_2 >> 16)
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parts[7] = u16(rand_2)
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parts[3] = (parts[3] & 0x0FFF) | (u16(version) << 12) // set version
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parts[4] = (parts[4] & 0x3FFF) | 0x8000 // set variant = 0b10
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mut buf := unsafe { malloc_noscan(37) }
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mut i_buf := 0
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mut x := u64(0)
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mut d := u8(0)
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for i_buf < buflen {
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mut c := 0
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x = rng.u64()
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// do most of the bit manipulation at once:
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x &= 0x0F0F0F0F0F0F0F0F
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x += 0x3030303030303030
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// write the ASCII codes to the buffer:
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for c < 8 && i_buf < buflen {
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d = u8(x)
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unsafe {
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buf[i_buf] = if d > 0x39 { d + 0x27 } else { d }
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}
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i_buf++
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c++
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x = x >> 8
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}
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}
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// there are still some random bits in x:
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x = x >> 8
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d = u8(x)
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mut start := 0
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unsafe {
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// From https://www.ietf.org/rfc/rfc4122.txt :
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// >> Set the two most significant bits (bits 6 and 7) of the clock_seq_hi_and_reserved
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// >> to zero and one, respectively.
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// all nibbles starting with 10 are: 1000, 1001, 1010, 1011 -> hex digits `8`, `9`, `a`, `b`
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// these are stored in clock_seq_hi_and_reserved_valid_values, choose one of them at random:
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buf[19] = clock_seq_hi_and_reserved_valid_values[d & 0x03]
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// >> Set the four most significant bits (bits 12 through 15) of the
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// >> time_hi_and_version field to the 4-bit version number from Section 4.1.3.
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buf[14] = `4`
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buf[8] = `-`
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buf[13] = `-`
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buf[18] = `-`
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buf[23] = `-`
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buf[buflen] = 0 // ensure the string will be 0 terminated, just in case
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// for i in 0..37 { println('i: ${i:2} | ${buf[i].ascii_str()} | ${buf[i].hex()} | ${buf[i]:08b}') }
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return buf.vstring_with_len(buflen)
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for i in 0 .. 8 {
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val := parts[i]
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buf[start] = hex_chars[(val >> 12) & 0xF]
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buf[start + 1] = hex_chars[(val >> 8) & 0xF]
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buf[start + 2] = hex_chars[(val >> 4) & 0xF]
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buf[start + 3] = hex_chars[val & 0xF]
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start += 4
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// insert `_` at specified locations
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if start in [8, 13, 18, 23]! {
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buf[start] = `_`
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start++
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}
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}
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buf[36] = 0
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return buf.vstring_with_len(36)
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}
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}
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// uuid_v7 generates a time-ordered (v7) UUID
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// See https://datatracker.ietf.org/doc/html/rfc9562#name-uuid-version-7
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pub fn uuid_v7() string {
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timestamp_48 := u64(time.now().unix_milli()) << 16
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rand_1 := timestamp_48 | default_rng.u16()
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rand_2 := default_rng.u64()
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return internal_uuid(7, rand_1, rand_2)
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}
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pub struct UUIDSession {
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mut:
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counter u8 // 6 bits session counter
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}
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// new_uuid_v7_session create a new session for generating uuid_v7.
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// The 12 bits `rand_a` in the RFC 9652, is replaced by 6 bits
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// sub-millisecond timestamp + 6 bits session counter.
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// See https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=78c5e141e9c139fc2ff36a220334e4aa25e1b0eb
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pub fn new_uuid_v7_session() UUIDSession {
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return UUIDSession{}
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}
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// next get a new uuid_v7 from current session.
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pub fn (mut u UUIDSession) next() string {
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timestamp := u64(time.now().unix_nano())
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// make place for holding 4 bits `version`
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timestamp_shift_4bits := (timestamp & 0xFFFF_FFFF_FFFF_0000) | ((timestamp & 0x0000_0000_0000_FFFF) >> 4)
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rand_1 := (timestamp_shift_4bits & 0xFFFF_FFFF_FFFF_FFC0) | u64(u.counter & 0x3F) // 6 bits session counter
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rand_2 := default_rng.u64()
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u.counter++
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return internal_uuid(7, rand_1, rand_2)
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}
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const ulid_encoding = '0123456789ABCDEFGHJKMNPQRSTVWXYZ'
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@[direct_array_access]
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