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UUIDv7 and UUIDv4 in dlang
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import std.stdio : writeln; | |
void main() { | |
writeln(UUIDv4!string()); | |
writeln(UUIDv7!string()); | |
} | |
/// Generate a UUID v4 (random bytes) as string | |
string UUIDv4(T = string)() if(is(T==string)) { return formatUUID(UUIDv4!ubyte); } | |
/// Generate a UUID v4 (random bytes) as ubyte[16] | |
ubyte[16] UUIDv4(T)() if (is(T == ubyte)) | |
{ | |
ubyte[16] value; | |
randomBytes(value); | |
value[6] = (value[6] & 0x0f) | 0x40; | |
value[8] = (value[8] & 0x3f) | 0x80; | |
return value; | |
} | |
/// Generate a UUIDv7 (timestamp based + counter + random bytes) as string | |
string UUIDv7(T = string)() if(is(T==string)) { return formatUUID(UUIDv7!ubyte); } | |
/// Generate a UUIDv7 (timestamp based + counter + random bytes) as ubyte[16] | |
ubyte[16] UUIDv7(T)() if (is(T == ubyte)) | |
{ | |
import core.atomic : atomicFetchAdd; | |
import std.datetime : DateTime, SysTime, Clock, UTC; | |
shared static uint counter = 0; | |
shared static immutable unixEpoch = SysTime(DateTime(1970, 1, 1, 0, 0, 0), UTC()); | |
ubyte[16] value; | |
randomBytes(value); | |
// Current timestamp in ms | |
auto now = Clock.currTime(UTC()); | |
auto timestamp = (now - unixEpoch).total!"msecs"; | |
// Timestamp | |
value[0] = cast(ubyte)((timestamp >> 40) & 0xff); | |
value[1] = cast(ubyte)((timestamp >> 32) & 0xff); | |
value[2] = cast(ubyte)((timestamp >> 24) & 0xff); | |
value[3] = cast(ubyte)((timestamp >> 16) & 0xff); | |
value[4] = cast(ubyte)((timestamp >> 8) & 0xff); | |
value[5] = cast(ubyte)(timestamp & 0xff); | |
// Counter | |
auto localCounter = atomicFetchAdd(counter, 1); | |
value[6] = (value[6] & 0xF0) | cast(ubyte)((localCounter >> 8) & 0x0F); // first 4 bits [52-55] | |
value[7] = cast(ubyte)(localCounter & 0xFF); // last 8 bits [56-63] | |
// Version & Variant | |
value[6] = (value[6] & 0x0f) | 0x70; | |
value[8] = (value[8] & 0x3f) | 0x80; | |
return value; | |
} | |
private: | |
string formatUUID(ubyte[16] uuid) | |
{ | |
import std.string : toLower; | |
import std.format : format; | |
import std.digest : toHexString; | |
char[32] tmp = uuid.toHexString.toLower; | |
return format("%s-%s-%s-%s-%s", tmp[0..8], tmp[8..12], tmp[12..16], tmp[16..20], tmp[20..$]); | |
} | |
void randomBytes(ubyte[] buffer) | |
{ | |
// Random bytes | |
version(Windows) | |
{ | |
import core.sys.windows.windows; | |
import core.sys.windows.wincrypt; | |
HCRYPTPROV hProvider; | |
CryptAcquireContext(&hProvider, null, null, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT); | |
CryptGenRandom(hProvider, cast(uint)buffer.length, buffer.ptr); | |
CryptReleaseContext(hProvider, 0); | |
} | |
else | |
{ | |
import std.file : read; | |
buffer[0..$] = cast(ubyte[])read("/dev/urandom", buffer.length); | |
} | |
} |
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