001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache license, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the license for the specific language governing permissions and 015 * limitations under the license. 016 */ 017package org.apache.logging.log4j.util; 018 019/** 020 * Utility for preventing primitive parameter values from being auto-boxed. Auto-boxing creates temporary objects 021 * which contribute to pressure on the garbage collector. With this utility users can convert primitive values directly 022 * into text without allocating temporary objects. 023 * <p> 024 * Example usage: 025 * </p><pre> 026 * import static org.apache.logging.log4j.util.Unbox.box; 027 * ... 028 * long longValue = 123456L; 029 * double doubleValue = 3.14; 030 * // prevent primitive values from being auto-boxed 031 * logger.debug("Long value={}, double value={}", box(longValue), box(doubleValue)); 032 * </pre> 033 */ 034@PerformanceSensitive("allocation") 035public class Unbox { 036 private static final int MASK = 16 - 1; 037 038 private static class State { 039 private final StringBuilder[] ringBuffer = new StringBuilder[16]; 040 private int current; 041 State() { 042 for (int i = 0; i < ringBuffer.length; i++) { 043 ringBuffer[i] = new StringBuilder(21); 044 } 045 } 046 047 public StringBuilder getStringBuilder() { 048 final StringBuilder result = ringBuffer[MASK & current++]; 049 result.setLength(0); 050 return result; 051 } 052 053 public boolean isBoxedPrimitive(final StringBuilder text) { 054 for (int i = 0; i < ringBuffer.length; i++) { 055 if (text == ringBuffer[i]) { 056 return true; 057 } 058 } 059 return false; 060 } 061 } 062 private static ThreadLocal<State> threadLocalState = new ThreadLocal<>(); 063 064 /** 065 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 066 * This method will not allocate temporary objects. 067 * 068 * @param value the value whose text representation to return 069 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 070 */ 071 @PerformanceSensitive("allocation") 072 public static StringBuilder box(final float value) { 073 return getSB().append(value); 074 } 075 076 /** 077 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 078 * This method will not allocate temporary objects. 079 * 080 * @param value the value whose text representation to return 081 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 082 */ 083 @PerformanceSensitive("allocation") 084 public static StringBuilder box(final double value) { 085 return getSB().append(value); 086 } 087 088 /** 089 * Returns a {@code StringBuilder} containing the text representation of the specified primitive value. 090 * This method will not allocate temporary objects. 091 * 092 * @param value the value whose text representation to return 093 * @return a {@code StringBuilder} containing the text representation of the specified primitive value 094 */ 095 @PerformanceSensitive("allocation") 096 public static StringBuilder box(final short value) { 097 return getSB().append(value); 098 } 099 100 /** 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}