Spring/spring-integration
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

INT-3809: Improve SimpleIncrIdGenerator JavaDoc

Browse Source 
JIRA: https://jira.spring.io/browse/INT-3809
This commit is contained in:
Artem Bilan
2015-10-09 17:39:46 -04:00
committed by Gary Russell
parent 4d57acb45e
commit f049541b00
1 changed files with 20 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
spring-integration-core/src/main/java/org/springframework/integration/support/IdGenerators.java
View File

@@ -1,5 +1,5 @@
/*
* Copyright 2013 the original author or authors.
* Copyright 2013-2015 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
@@ -23,7 +23,7 @@ import org.springframework.util.IdGenerator;
/**
* Alterative {@link IdGenerator} implementations.
* Alternative {@link IdGenerator} implementations.
*
* @author Andy Wilkinson
* @since 4.0
@@ -45,8 +45,19 @@ public class IdGenerators {
}
/**
* Begins with 1; incremented on each use.
*
* Based on the two {@link AtomicLong}s, for {@code topBits} and {@code bottomBits},
* respectively.
* Begins with {0, 1}; incremented on each use.
* <p>
* Note: after each {@code 2^63} generations, a duplicate {@link UUID}
* can be returned in a multi-threaded environment, if a second thread sees the old topBits
* before it is incremented by the thread detecting the bottomBits roll over.
* The duplicate would be from around the previous rollover and
* the chance of such a value still being in the system is exceedingly small.
* If your system might be impacted by this situation, you should choose another {@link IdGenerator}.
* Also note that there is no persistence, so this generator starts at {0, 1} each time the system
* is initialized. Therefore, it is not suitable when persisting messages based on their ID; it should
* only be used when the absolute best performance is required and messages are not persisted.
*/
public static class SimpleIncrementingIdGenerator implements IdGenerator {
@@ -58,10 +69,13 @@ public class IdGenerators {
public UUID generateId() {
long bottomBits = this.bottomBits.incrementAndGet();
if (bottomBits == 0) {
this.topBits.incrementAndGet();
return new UUID(this.topBits.incrementAndGet(), bottomBits);
}
else {
return new UUID(this.topBits.get(), bottomBits);
}
return new UUID(this.topBits.get(), bottomBits);
}
}
}