org.jooq.impl.Lazy Maven / Gradle / Ivy
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* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
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*
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package org.jooq.impl;
import java.util.function.Supplier;
/**
* A utility for lazy initialisation of constant values.
*
* Eager static initialisation of constant values has produced numerous race
* conditions and deadlocks in the past in user code that initialised jOOQ
* classes in parallel. For example:
*
* - https://github.com/jOOQ/jOOQ/issues/11200
* - https://github.com/jOOQ/jOOQ/issues/13814
* - https://github.com/jOOQ/jOOQ/issues/14769
*
*
* This generic Lazy utility should delay the initialisation of the constant in
* the absence of formal JDK support: https://openjdk.org/jeps/8209964
*
* @author Lukas Eder
*/
final class Lazy {
static Lazy of(Supplier supplier) {
return new Lazy<>(supplier);
}
private final Supplier supplier;
private volatile T value;
private Lazy(Supplier supplier) {
this.supplier = supplier;
}
T get() {
if (value == null) {
synchronized (this) {
if (value == null) {
value = supplier.get();
}
}
}
return value;
}
}