| 1 | // Copyright (c) 2002 SPY internetworking <dustin@spy.net> |
| 2 | |
| 3 | package net.spy.memcached.compat.log; |
| 4 | |
| 5 | import java.lang.reflect.Constructor; |
| 6 | import java.lang.reflect.InvocationTargetException; |
| 7 | import java.util.concurrent.ConcurrentHashMap; |
| 8 | import java.util.concurrent.ConcurrentMap; |
| 9 | |
| 10 | /** |
| 11 | * Factory to get logger instances. |
| 12 | * |
| 13 | * The system property <code>net.spy.compat.log.LoggerImpl</code> |
| 14 | * should point to an implementation of net.spy.compat.log.Logger to |
| 15 | * use. |
| 16 | * |
| 17 | * <p> |
| 18 | * Depending on how and where this was compiled, a sun logger (jdk 1.4) |
| 19 | * and/or <a href="http://jakarta.apache.org/log4j/docs/">log4j</a> logger |
| 20 | * implementation may be included. Both are included with the official |
| 21 | * distribution. |
| 22 | * </p> |
| 23 | * |
| 24 | * @see AbstractLogger |
| 25 | */ |
| 26 | public final class LoggerFactory extends Object { |
| 27 | |
| 28 | private static LoggerFactory instance=null; |
| 29 | |
| 30 | private final ConcurrentMap<String, Logger> instances; |
| 31 | private Constructor<? extends Logger> instanceConstructor; |
| 32 | |
| 33 | /** |
| 34 | * Get an instance of LoggerFactory. |
| 35 | */ |
| 36 | private LoggerFactory() { |
| 37 | super(); |
| 38 | |
| 39 | instances=new ConcurrentHashMap<String, Logger>(); |
| 40 | } |
| 41 | |
| 42 | private static void init() { |
| 43 | if(instance == null) { |
| 44 | instance=new LoggerFactory(); |
| 45 | } |
| 46 | } |
| 47 | |
| 48 | /** |
| 49 | * Get a logger by class. |
| 50 | * |
| 51 | * @param clazz the class for which we want the logger. |
| 52 | * @return a Logger instance |
| 53 | */ |
| 54 | public static Logger getLogger(Class<?> clazz) { |
| 55 | return(getLogger(clazz.getName())); |
| 56 | } |
| 57 | |
| 58 | /** |
| 59 | * Get a logger by name. |
| 60 | * |
| 61 | * @param name the name for which we want the logger |
| 62 | * @return a Logger instance |
| 63 | */ |
| 64 | public static Logger getLogger(String name) { |
| 65 | if(name == null) { |
| 66 | throw new NullPointerException("Logger name may not be null."); |
| 67 | } |
| 68 | init(); |
| 69 | return(instance.internalGetLogger(name)); |
| 70 | } |
| 71 | |
| 72 | // Get an instance of Logger from internal mechanisms. |
| 73 | private Logger internalGetLogger(String name) { |
| 74 | assert name != null : "Name was null"; |
| 75 | Logger rv=instances.get(name); |
| 76 | |
| 77 | if (rv==null) { |
| 78 | Logger newLogger=null; |
| 79 | try { |
| 80 | newLogger=getNewInstance(name); |
| 81 | } catch(Exception e) { |
| 82 | throw new RuntimeException("Problem getting logger", e); |
| 83 | } |
| 84 | Logger tmp=instances.putIfAbsent(name, newLogger); |
| 85 | // Return either the new logger we've just made, or one that was |
| 86 | // created while we were waiting |
| 87 | rv = tmp == null ? newLogger : tmp; |
| 88 | } |
| 89 | |
| 90 | return(rv); |
| 91 | |
| 92 | } |
| 93 | |
| 94 | private Logger getNewInstance(String name) |
| 95 | throws InstantiationException, IllegalAccessException, |
| 96 | IllegalArgumentException, InvocationTargetException { |
| 97 | |
| 98 | if(instanceConstructor==null) { |
| 99 | getConstructor(); |
| 100 | } |
| 101 | Object[] args={name}; |
| 102 | Logger rv=instanceConstructor.newInstance(args); |
| 103 | |
| 104 | return (rv); |
| 105 | } |
| 106 | |
| 107 | // Find the appropriate constructor |
| 108 | @SuppressWarnings("unchecked") |
| 109 | private void getConstructor() { |
| 110 | Class<? extends Logger> c=DefaultLogger.class; |
| 111 | String className=System.getProperty("net.spy.log.LoggerImpl"); |
| 112 | |
| 113 | if(className!=null) { |
| 114 | try { |
| 115 | c=(Class<? extends Logger>) Class.forName(className); |
| 116 | } catch(NoClassDefFoundError e) { |
| 117 | System.err.println("Warning: " + className |
| 118 | + " not found while initializing" |
| 119 | + " net.spy.compat.log.LoggerFactory"); |
| 120 | e.printStackTrace(); |
| 121 | c=DefaultLogger.class; |
| 122 | } catch(ClassNotFoundException e) { |
| 123 | System.err.println("Warning: " + className |
| 124 | + " not found while initializing" |
| 125 | + " net.spy.compat.log.LoggerFactory"); |
| 126 | e.printStackTrace(); |
| 127 | c=DefaultLogger.class; |
| 128 | } |
| 129 | } |
| 130 | |
| 131 | // Find the best constructor |
| 132 | try { |
| 133 | // Try to find a constructor that takes a single string |
| 134 | Class[] args={String.class}; |
| 135 | instanceConstructor=c.getConstructor(args); |
| 136 | } catch(NoSuchMethodException e) { |
| 137 | try { |
| 138 | // Try to find an empty constructor |
| 139 | Class[] args={}; |
| 140 | instanceConstructor=c.getConstructor(args); |
| 141 | } catch(NoSuchMethodException e2) { |
| 142 | System.err.println("Warning: " + className |
| 143 | + " has no appropriate constructor, using defaults."); |
| 144 | |
| 145 | // Try to find a constructor that takes a single string |
| 146 | try { |
| 147 | Class[] args={String.class}; |
| 148 | instanceConstructor= |
| 149 | DefaultLogger.class.getConstructor(args); |
| 150 | } catch(NoSuchMethodException e3) { |
| 151 | // This shouldn't happen. |
| 152 | throw new NoSuchMethodError( |
| 153 | "There used to be a constructor that takes a single " |
| 154 | + "String on " |
| 155 | + DefaultLogger.class + ", but I can't " |
| 156 | + "find one now."); |
| 157 | } // SOL |
| 158 | } // No empty constructor |
| 159 | } // No constructor that takes a string |
| 160 | } // getConstructor |
| 161 | |
| 162 | } |