-
Notifications
You must be signed in to change notification settings - Fork 228
/
LazyDeserializer.java
54 lines (48 loc) · 2.06 KB
/
LazyDeserializer.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
/*
* Licensed to Elasticsearch B.V. under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch B.V. licenses this file to you under
* the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package co.elastic.clients.json;
import java.util.function.Supplier;
/**
* A deserializer that delegates to another deserializer that is lazily created. This is needed to initialize deserializers as
* static fields. As some classes have cyclic dependencies, creating dependent deserializers lazily avoids cyclic dependencies
* between static class initialization code, which can lead to unwanted things like NPEs or stack overflows.
*
* @see JsonpDeserializable
* @see <a href="https://docs.oracle.com/javase/specs/jls/se8/html/jls-12.html#jls-12.4">Initialization of Classes and Interfaces</a>
*/
class LazyDeserializer<T> extends DelegatingDeserializer.SameType<T> {
private final Supplier<JsonpDeserializer<T>> ctor;
private volatile JsonpDeserializer<T> deserializer = null;
LazyDeserializer(Supplier<JsonpDeserializer<T>> ctor) {
this.ctor = ctor;
}
protected JsonpDeserializer<T> unwrap() {
// See SEI CERT LCK10-J https://wiki.sei.cmu.edu/confluence/x/6zdGBQ
JsonpDeserializer<T> d = deserializer;
if (d == null) {
synchronized (this) {
if (deserializer == null) {
d = ctor.get();
deserializer = d;
}
}
}
return d;
}
}