1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache license, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the license for the specific language governing permissions and 15 * limitations under the license. 16 */ 17 package org.apache.logging.log4j.util; 18 19 /** 20 * Utility for preventing primitive parameter values from being auto-boxed. Auto-boxing creates temporary objects 21 * which contribute to pressure on the garbage collector. With this utility users can convert primitive values directly 22 * into text without allocating temporary objects. 23 * <p> 24 * Example usage: 25 * </p><pre> 26 * import static org.apache.logging.log4j.util.Unbox.box; 27 * ... 28 * long longValue = 123456L; 29 * double doubleValue = 3.14; 30 * // prevent primitive values from being auto-boxed 31 * logger.debug("Long value={}, double value={}", box(longValue), box(doubleValue)); 32 * </pre> 33 */ 34 @PerformanceSensitive("allocation") 35 public class Unbox { 36 private static final int MASK = 16 - 1; 37 38 private static class State { 39 private final StringBuilder[] ringBuffer = new StringBuilder[16]; 40 private int current; 41 State() { 42 for (int i = 0; i < ringBuffer.length; i++) { 43 ringBuffer[i] = new StringBuilder(21); 44 } 45 } 46 47 public StringBuilder getStringBuilder() { 48 final StringBuilder result = ringBuffer[MASK & current++]; 49 result.setLength(0); 50 return result; 51 } 52 53 public boolean isBoxedPrimitive(final StringBuilder text) { 54 for (int i = 0; i < ringBuffer.length; i++) { 55 if (text == ringBuffer[i]) { 56 return true; 57 } 58 } 59 return false; 60 } 61 } 62 private static ThreadLocal<State> threadLocalState = new ThreadLocal<>(); 63 64 /** 65 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 66 * This method will not allocate temporary objects. 67 * 68 * @param value the value whose text representation to return 69 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 70 */ 71 @PerformanceSensitive("allocation") 72 public static StringBuilder box(final float value) { 73 return getSB().append(value); 74 } 75 76 /** 77 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 78 * This method will not allocate temporary objects. 79 * 80 * @param value the value whose text representation to return 81 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 82 */ 83 @PerformanceSensitive("allocation") 84 public static StringBuilder box(final double value) { 85 return getSB().append(value); 86 } 87 88 /** 89 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 90 * This method will not allocate temporary objects. 91 * 92 * @param value the value whose text representation to return 93 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 94 */ 95 @PerformanceSensitive("allocation") 96 public static StringBuilder box(final short value) { 97 return getSB().append(value); 98 } 99 100 /** 101 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 102 * This method will not allocate temporary objects. 103 * 104 * @param value the value whose text representation to return 105 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 106 */ 107 @PerformanceSensitive("allocation") 108 public static StringBuilder box(final int value) { 109 return getSB().append(value); 110 } 111 112 /** 113 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 114 * This method will not allocate temporary objects. 115 * 116 * @param value the value whose text representation to return 117 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 118 */ 119 @PerformanceSensitive("allocation") 120 public static StringBuilder box(final char value) { 121 return getSB().append(value); 122 } 123 124 /** 125 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 126 * This method will not allocate temporary objects. 127 * 128 * @param value the value whose text representation to return 129 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 130 */ 131 @PerformanceSensitive("allocation") 132 public static StringBuilder box(final long value) { 133 return getSB().append(value); 134 } 135 136 /** 137 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 138 * This method will not allocate temporary objects. 139 * 140 * @param value the value whose text representation to return 141 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 142 */ 143 @PerformanceSensitive("allocation") 144 public static StringBuilder box(final byte value) { 145 return getSB().append(value); 146 } 147 148 /** 149 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 150 * This method will not allocate temporary objects. 151 * 152 * @param value the value whose text representation to return 153 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 154 */ 155 @PerformanceSensitive("allocation") 156 public static StringBuilder box(final boolean value) { 157 return getSB().append(value); 158 } 159 160 private static State getState() { 161 State state = threadLocalState.get(); 162 if (state == null) { 163 state = new State(); 164 threadLocalState.set(state); 165 } 166 return state; 167 } 168 169 private static StringBuilder getSB() { 170 return getState().getStringBuilder(); 171 } 172 }