Coverage Summary for Class: LongAddables (com.google.common.cache)

1 /*
2  * Copyright (C) 2012 The Guava Authors
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except
5  * in compliance with the License. You may obtain a copy of the License at
6  *
7  * http://www.apache.org/licenses/LICENSE-2.0
8  *
9  * Unless required by applicable law or agreed to in writing, software distributed under the License
10  * is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express
11  * or implied. See the License for the specific language governing permissions and limitations under
12  * the License.
13  */
14 
15 package com.google.common.cache;
16 
17 import com.google.common.annotations.GwtCompatible;
18 import com.google.common.base.Supplier;
19 import java.util.concurrent.atomic.AtomicLong;
20 
21 /**
22  * Source of {@link LongAddable} objects that deals with GWT, Unsafe, and all that.
23  *
24  * @author Louis Wasserman
25  */
26 @GwtCompatible(emulated = true)
27 final class LongAddables {
28   private static final Supplier<LongAddable> SUPPLIER;
29 
30   static {
31     Supplier<LongAddable> supplier;
32     try {
33       new LongAdder(); // trigger static initialization of the LongAdder class, which may fail
34       supplier =
35           new Supplier<LongAddable>() {
36             @Override
37             public LongAddable get() {
38               return new LongAdder();
39             }
40           };
41     } catch (Throwable t) { // we really want to catch *everything*
42       supplier =
43           new Supplier<LongAddable>() {
44             @Override
45             public LongAddable get() {
46               return new PureJavaLongAddable();
47             }
48           };
49     }
50     SUPPLIER = supplier;
51   }
52 
53   public static LongAddable create() {
54     return SUPPLIER.get();
55   }
56 
57   private static final class PureJavaLongAddable extends AtomicLong implements LongAddable {
58     @Override
59     public void increment() {
60       getAndIncrement();
61     }
62 
63     @Override
64     public void add(long x) {
65       getAndAdd(x);
66     }
67 
68     @Override
69     public long sum() {
70       return get();
71     }
72   }
73 }