1 /*
2 * #%L
3 * SeenString.java - mongodb-async-driver - Allanbank Consulting, Inc.
4 * %%
5 * Copyright (C) 2011 - 2014 Allanbank Consulting, Inc.
6 * %%
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
18 * #L%
19 */
20 package com.allanbank.mongodb.bson.io;
21
22 import java.util.Arrays;
23 import java.util.concurrent.atomic.AtomicInteger;
24 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
25
26 /**
27 * SeenString is a record of the byte[], value and count for each string/byte[]
28 * the cache sees.
29 *
30 * @api.no This class is <b>NOT</b> part of the drivers API. This class may be
31 * mutated in incompatible ways between any two releases of the driver.
32 * @copyright 2014, Allanbank Consulting, Inc., All Rights Reserved
33 */
34 class SeenString {
35 /**
36 * Atomic updated for all of the SeenString instances to cut down on the
37 * number of {@link AtomicInteger} entries required.
38 */
39 private final static AtomicIntegerFieldUpdater<SeenString> ourCountUpdater = AtomicIntegerFieldUpdater
40 .newUpdater(SeenString.class, "myCount");
41
42 /** The encoded bytes for the seen string. */
43 private final byte[] myBytes;
44
45 /** The number of times the string is seen. */
46 private volatile int myCount;
47
48 /** The value for the seen string. */
49 private final String myValue;
50
51 /**
52 * Creates a new SeenString.
53 *
54 * @param source
55 * The source of the bytes in the string.
56 * @param offset
57 * The offset of the first byte to decode.
58 * @param length
59 * The length of the bytes to decode with a terminal zero byte.
60 * @param decoded
61 * The value for the seen string.
62 */
63 public SeenString(final byte[] source, final int offset, final int length,
64 final String decoded) {
65 myBytes = Arrays.copyOfRange(source, offset, offset + length);
66 myValue = decoded;
67 myCount = 0;
68 }
69
70 /**
71 * Returns the encoded bytes for the seen string.
72 *
73 * @return The encoded bytes for the seen string.
74 */
75 public byte[] getBytes() {
76 return myBytes;
77 }
78
79 /**
80 * Returns the number of times the string is seen.
81 *
82 * @return The number of times the string is seen.
83 */
84 public int getCount() {
85 return myCount;
86 }
87
88 /**
89 * Returns the decoded string for the seen string.
90 *
91 * @return The decoded string for the seen string.
92 */
93 public String getValue() {
94 return myValue;
95 }
96
97 /**
98 * Increments the number of times that the string has been seen.
99 */
100 public void incrementCount() {
101 ourCountUpdater.incrementAndGet(this);
102 }
103
104 /**
105 * Sets the count to zero.
106 *
107 * @return the previous value for the count.
108 */
109 public int reset() {
110 return ourCountUpdater.getAndSet(this, 0);
111 }
112 }