-
-
Notifications
You must be signed in to change notification settings - Fork 105
Commit
This commit does not belong to any branch on this repository, and may belong to a fork outside of the repository.
Add alternate version to UUIDv7 generator. TimeBaseEpochGenerator cre…
…ates very similar values when calls to generate are made within same millisecond. This may be unsafe in some enviroments. To solve this added TimeBaseEpochRandomGenerator to create random value on every call to generate but still in v7 manner.
- Loading branch information
Showing
6 changed files
with
276 additions
and
8 deletions.
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
161 changes: 161 additions & 0 deletions
161
src/main/java/com/fasterxml/uuid/impl/TimeBasedEpochRandomGenerator.java
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,161 @@ | ||
| package com.fasterxml.uuid.impl; | ||
|
|
||
| import com.fasterxml.uuid.NoArgGenerator; | ||
| import com.fasterxml.uuid.UUIDClock; | ||
| import com.fasterxml.uuid.UUIDType; | ||
|
|
||
| import java.security.SecureRandom; | ||
| import java.util.Random; | ||
| import java.util.UUID; | ||
| import java.util.concurrent.locks.Lock; | ||
| import java.util.concurrent.locks.ReentrantLock; | ||
|
|
||
| /** | ||
| * Implementation of UUID generator that uses time/location based generation | ||
| * method field from the Unix Epoch timestamp source - the number of | ||
| * milliseconds seconds since midnight 1 Jan 1970 UTC, leap seconds excluded. | ||
| * This is usually referred to as "Version 7". | ||
| * In addition to that random part is regenerated for every new UUID. | ||
| * This removes possibilities to have almost similar UUID, when calls | ||
| * to generate are made within same millisecond. | ||
| * <p> | ||
| * As all JUG provided implementations, this generator is fully thread-safe. | ||
| * Additionally it can also be made externally synchronized with other instances | ||
| * (even ones running on other JVMs); to do this, use | ||
| * {@link com.fasterxml.uuid.ext.FileBasedTimestampSynchronizer} (or | ||
| * equivalent). | ||
| * | ||
| * @since 4.1 | ||
| */ | ||
| public class TimeBasedEpochRandomGenerator extends NoArgGenerator | ||
| { | ||
| private static final int ENTROPY_BYTE_LENGTH = 10; | ||
|
|
||
| /* | ||
| /********************************************************************** | ||
| /* Configuration | ||
| /********************************************************************** | ||
| */ | ||
|
|
||
| /** | ||
| * Random number generator that this generator uses. | ||
| */ | ||
| protected final Random _random; | ||
|
|
||
| /** | ||
| * Underlying {@link UUIDClock} used for accessing current time, to use for | ||
| * generation. | ||
| * | ||
| * @since 4.3 | ||
| */ | ||
| protected final UUIDClock _clock; | ||
|
|
||
| private final byte[] _lastEntropy = new byte[ENTROPY_BYTE_LENGTH]; | ||
| private final Lock lock = new ReentrantLock(); | ||
|
|
||
| /* | ||
| /********************************************************************** | ||
| /* Construction | ||
| /********************************************************************** | ||
| */ | ||
|
|
||
| /** | ||
| * @param rnd Random number generator to use for generating UUIDs; if null, | ||
| * shared default generator is used. Note that it is strongly recommend to | ||
| * use a <b>good</b> (pseudo) random number generator; for example, JDK's | ||
| * {@link SecureRandom}. | ||
| */ | ||
| public TimeBasedEpochRandomGenerator(Random rnd) { | ||
| this(rnd, UUIDClock.systemTimeClock()); | ||
| } | ||
|
|
||
| /** | ||
| * @param rnd Random number generator to use for generating UUIDs; if null, | ||
| * shared default generator is used. Note that it is strongly recommend to | ||
| * use a <b>good</b> (pseudo) random number generator; for example, JDK's | ||
| * {@link SecureRandom}. | ||
| * @param clock clock Object used for accessing current time to use for generation | ||
| */ | ||
| public TimeBasedEpochRandomGenerator(Random rnd, UUIDClock clock) | ||
| { | ||
| if (rnd == null) { | ||
| rnd = LazyRandom.sharedSecureRandom(); | ||
| } | ||
| _random = rnd; | ||
| _clock = clock; | ||
| } | ||
|
|
||
| /* | ||
| /********************************************************************** | ||
| /* Access to config | ||
| /********************************************************************** | ||
| */ | ||
|
|
||
| @Override | ||
| public UUIDType getType() { return UUIDType.TIME_BASED_EPOCH; } | ||
|
|
||
| /* | ||
| /********************************************************************** | ||
| /* UUID generation | ||
| /********************************************************************** | ||
| */ | ||
|
|
||
| @Override | ||
| public UUID generate() | ||
| { | ||
| return construct(_clock.currentTimeMillis()); | ||
| } | ||
|
|
||
| /** | ||
| * Method that will construct actual {@link UUID} instance for given | ||
| * unix epoch timestamp: called by {@link #generate()} but may alternatively be | ||
| * called directly to construct an instance with known timestamp. | ||
| * NOTE: calling this method directly produces somewhat distinct UUIDs as | ||
| * "entropy" value is still generated as necessary to avoid producing same | ||
| * {@link UUID} even if same timestamp is being passed. | ||
| * | ||
| * @param rawTimestamp unix epoch millis | ||
| * | ||
| * @return unix epoch time based UUID | ||
| * | ||
| * @since 4.3 | ||
| */ | ||
| public UUID construct(long rawTimestamp) | ||
| { | ||
| lock.lock(); | ||
| try { | ||
| _random.nextBytes(_lastEntropy); | ||
| return UUIDUtil.constructUUID(UUIDType.TIME_BASED_EPOCH, (rawTimestamp << 16) | _toShort(_lastEntropy, 0), _toLong(_lastEntropy, 2)); | ||
| } finally { | ||
| lock.unlock(); | ||
| } | ||
| } | ||
|
|
||
| /* | ||
| /********************************************************************** | ||
| /* Internal methods | ||
| /********************************************************************** | ||
| */ | ||
|
|
||
| protected final static long _toLong(byte[] buffer, int offset) | ||
| { | ||
| long l1 = _toInt(buffer, offset); | ||
| long l2 = _toInt(buffer, offset+4); | ||
| long l = (l1 << 32) + ((l2 << 32) >>> 32); | ||
| return l; | ||
| } | ||
|
|
||
| private final static long _toInt(byte[] buffer, int offset) | ||
| { | ||
| return (buffer[offset] << 24) | ||
| + ((buffer[++offset] & 0xFF) << 16) | ||
| + ((buffer[++offset] & 0xFF) << 8) | ||
| + (buffer[++offset] & 0xFF); | ||
| } | ||
|
|
||
| private final static long _toShort(byte[] buffer, int offset) | ||
| { | ||
| return ((buffer[offset] & 0xFF) << 8) | ||
| + (buffer[++offset] & 0xFF); | ||
| } | ||
| } |
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.