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honhimWhonhimW
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update
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14 files changed

+206
-37
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14 files changed

+206
-37
lines changed

‎src/main/java/io/github/honhimw/uuid/ClockSequence.java‎

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Original file line numberDiff line numberDiff line change
@@ -29,4 +29,11 @@ default Instant now() {
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return Instant.now();
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}
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32+
static Instant fastNow() {
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long millis = System.currentTimeMillis();
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long seconds = Maths.div1000(millis);
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int nanos = (int) (millis - (seconds * Maths.ONE_THOUSAND)) * 1_000_000;
36+
return Instant.ofEpochSecond(seconds, nanos);
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}
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}

‎src/main/java/io/github/honhimw/uuid/Maths.java‎

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@@ -0,0 +1,88 @@
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package io.github.honhimw.uuid;
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import java.math.BigDecimal;
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import java.math.BigInteger;
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import java.math.RoundingMode;
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/// Prevent from using division. Make it as fast as possible.
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///
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/// @author honhimW
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/// @since 2025-12-30
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public class Maths {
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13+
public static final long ONE_THOUSAND = 1_000L;
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public static final long ONE_MILLION = 1_000_000L;
15+
/// 1 << 10 == 1024 greater than 1000, so we just take highest 10-bits in i64, 64 - 10 = 54
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public static final int NANOS_TO_MILLIS_SHIFT = 54;
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public static final long NANOS_TO_MILLIS_MULTIPLIER = ((1L) << NANOS_TO_MILLIS_SHIFT) / ONE_MILLION;
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public static final long DIV_1000_MULTIPLIER = new BigDecimal(BigInteger.ONE.shiftLeft(64)).divide(BigDecimal.valueOf(125), RoundingMode.CEILING).longValueExact();
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/// Optimize division by one million
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///
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/// @param nanos range 1_000_000 - 1_000_000_000
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/// @return millis seconds
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public static int ns2ms(int nanos) {
26+
return (int) (((nanos + 1) * NANOS_TO_MILLIS_MULTIPLIER) >>> NANOS_TO_MILLIS_SHIFT);
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}
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/// Optimize remainder of one million
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///
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/// @param nanos range 1_000_000 - 1_000_000_000
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/// @return lower nano seconds
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public static int nsMod(int nanos) {
34+
int ms = ns2ms(nanos);
35+
return nanos - (int) (ms * ONE_MILLION);
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}
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/// Optimize division by one thousand.
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///
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/// 1000 == 8 * 125
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/// 1. right shift 3(>>> 3) for division by 8
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/// 2. divide by 125 using the "magic number" method. For odd divisors, we can compute [#DIV_1000_MULTIPLIER]
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/// as the multiplier constant.
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/// 3. use [#multiplyHigh(long, long)] to compute the high 64 bits of the 128-bit product.
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/// This effectively performs floor(x / 125) for all 64‑bit inputs.
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///
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/// @param l long value
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/// @return result of division by 1000
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public static long div1000(long l) {
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l = l >>> 3; // division by 8
51+
return multiplyHigh(l, DIV_1000_MULTIPLIER);
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}
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/// Convert the lowest 3 decimal digits of milliseconds into nanoseconds.
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///
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/// @param millis milli seconds
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/// @return nano seconds
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public static int ms2ns(long millis) {
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long l = div1000(millis);
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l = millis - (l * ONE_THOUSAND);
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return (int) (l * ONE_MILLION);
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}
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/// Returns as a `long` the most significant 64 bits of the 128-bit product of two 64-bit factors.
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///
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/// Copied from JDK9+
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///
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/// @param x the first value
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/// @param y the second value
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/// @return the result
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public static long multiplyHigh(long x, long y) {
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// Use technique from section 8-2 of Henry S. Warren, Jr.,
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// Hacker's Delight (2nd ed.) (Addison Wesley, 2013), 173-174.
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long x1 = x >> 32;
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long x2 = x & 0xFFFFFFFFL;
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long y1 = y >> 32;
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long y2 = y & 0xFFFFFFFFL;
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long z2 = x2 * y2;
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long t = x1 * y2 + (z2 >>> 32);
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long z1 = t & 0xFFFFFFFFL;
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long z0 = t >> 32;
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z1 += x2 * y1;
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return x1 * y1 + z0 + (z1 >> 32);
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}
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}

‎src/main/java/io/github/honhimw/uuid/Timestamp.java‎

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Original file line numberDiff line numberDiff line change
@@ -33,7 +33,7 @@ public Timestamp(long seconds, int nanos, long counter, int usableCounterBits) {
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3434
public long asEpochMillis() {
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long millis = seconds * 1_000L;
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return millis + (nanos / 1_000_000);
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return millis + Maths.ns2ms(nanos);
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}
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public Instant asInstant() {

‎src/main/java/io/github/honhimw/uuid/UUIDs.java‎

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Original file line numberDiff line numberDiff line change
@@ -58,10 +58,7 @@ public class UUIDs {
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V7 v7 = new V7(Context.builder().clock(new RandomSequence(random) {
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@Override
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public Instant now() {
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long millis = System.currentTimeMillis();
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long seconds = millis / 1000;
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int nanos = (int) (millis % 1000) * 1_000_000;
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return Instant.ofEpochSecond(seconds, nanos);
61+
return ClockSequence.fastNow();
6562
}
6663
}).random(random).build());
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FAST = new Generators(v1, v3, v4, v5, v6, v7);

‎src/main/java/io/github/honhimw/uuid/Uuid.java‎

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@@ -119,8 +119,8 @@ public Optional<Timestamp> timestamp() {
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millis |= (Byte.toUnsignedLong(bb.get(4))) << 8;
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millis |= Byte.toUnsignedLong(bb.get(5));
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122-
long seconds = millis / 1000;
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int nanos = (int) (millis % 1000) * 1_000_000;
122+
long seconds = Maths.div1000(millis);
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int nanos = (int) (millis - (seconds * Maths.ONE_THOUSAND)) * 1_000_000;
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125125
long counter = (Byte.toUnsignedLong(bb.get(6)) & 0xF) << 38;
126126
counter |= (Byte.toUnsignedLong(bb.get(7))) << 30;

‎src/main/java/io/github/honhimw/uuid/UuidBuilder.java‎

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@@ -14,10 +14,18 @@ private UuidBuilder() {
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this.bytes = new Bytes(new byte[16]);
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}
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/// set variant field
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///
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/// @param variant uuid variant
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/// @return self
1721
public UuidBuilder variant(int variant) {
1822
return variant(Variant.of(variant));
1923
}
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/// set variant field
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///
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/// @param variant uuid variant
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/// @return self
2129
public UuidBuilder variant(Variant variant) {
2230
byte b = this.bytes.get(8);
2331
switch (variant) {
@@ -40,10 +48,18 @@ public UuidBuilder variant(Variant variant) {
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return this;
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}
4250

51+
/// set version field
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///
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/// @param version uuid version
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/// @return self
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public UuidBuilder version(Version version) {
4456
return version(version.value());
4557
}
4658

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/// set version field
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///
61+
/// @param version uuid version
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/// @return self
4763
public UuidBuilder version(int version) {
4864
byte b = this.bytes.get(6);
4965
b &= 0x0F;
@@ -56,6 +72,9 @@ public UUID build() {
5672
return new UUID(this.bytes.getLong(0), this.bytes.getLong(Long.BYTES));
5773
}
5874

75+
/// create an empty uuid builder with [UUIDs#NIL] as default.
76+
///
77+
/// @return new empty builder
5978
public static UuidBuilder empty() {
6079
return new UuidBuilder();
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}

‎src/main/java/io/github/honhimw/uuid/gen/V1.java‎

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@@ -4,7 +4,8 @@
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import java.util.UUID;
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/// [Version 1](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-1)
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/// UUID [Version 1](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-1) Generator, aka Time-Based UUID.
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///
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/// ```text
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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
@@ -17,7 +18,7 @@
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/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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/// | node |
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/// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
20-
/// ```
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///```
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///
2223
/// - time_low: The least significant 32 bits of the 60-bit starting timestamp. Occupies bits 0 through 31 (octets 0-3).
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/// - time_mid: The middle 16 bits of the 60-bit starting timestamp. Occupies bits 32 through 47 (octets 4-5).

‎src/main/java/io/github/honhimw/uuid/gen/V3.java‎

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@@ -8,7 +8,8 @@
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import java.security.MessageDigest;
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import java.util.UUID;
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11-
/// [Version 3](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-3)
11+
/// UUID [Version 3](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-3) Generator, aka Named-Based(MD5) UUID.
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///
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/// ```text
1314
/// 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

‎src/main/java/io/github/honhimw/uuid/gen/V4.java‎

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@@ -5,7 +5,8 @@
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import java.util.Random;
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import java.util.UUID;
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/// [Version 4](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-4)
8+
/// UUID [Version 4](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-4) generator, aka Random-Based UUID.
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///
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/// ```text
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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

‎src/main/java/io/github/honhimw/uuid/gen/V5.java‎

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@@ -9,7 +9,8 @@
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import java.security.MessageDigest;
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import java.util.UUID;
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/// [Version 5](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-5)
12+
/// UUID [Version 5](https://www.rfc-editor.org/rfc/rfc9562.html#name-uuid-version-5) generator, aka Name-Based(SHA1) UUID.
13+
///
1314
/// ```text
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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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