001/** 002 * Copyright (c) 2004-2011 QOS.ch 003 * All rights reserved. 004 * 005 * Permission is hereby granted, free of charge, to any person obtaining 006 * a copy of this software and associated documentation files (the 007 * "Software"), to deal in the Software without restriction, including 008 * without limitation the rights to use, copy, modify, merge, publish, 009 * distribute, sublicense, and/or sell copies of the Software, and to 010 * permit persons to whom the Software is furnished to do so, subject to 011 * the following conditions: 012 * 013 * The above copyright notice and this permission notice shall be 014 * included in all copies or substantial portions of the Software. 015 * 016 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 017 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 018 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 019 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 020 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 021 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 022 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 023 * 024 */ 025package org.slf4j; 026 027import java.io.IOException; 028import java.net.URL; 029import java.util.ArrayList; 030import java.util.Arrays; 031import java.util.Enumeration; 032import java.util.LinkedHashSet; 033import java.util.List; 034import java.util.ServiceLoader; 035import java.util.Set; 036import java.util.concurrent.LinkedBlockingQueue; 037 038import org.slf4j.event.SubstituteLoggingEvent; 039import org.slf4j.helpers.NOPServiceProvider; 040import org.slf4j.helpers.SubstituteServiceProvider; 041import org.slf4j.helpers.SubstituteLogger; 042 043import org.slf4j.helpers.Util; 044import org.slf4j.spi.SLF4JServiceProvider; 045 046/** 047 * The <code>LoggerFactory</code> is a utility class producing Loggers for 048 * various logging APIs, most notably for log4j, logback and JDK 1.4 logging. 049 * Other implementations such as {@link org.slf4j.nop.NOPLogger NOPLogger} and 050 * {@link org.slf4j.simple.SimpleLogger SimpleLogger} are also supported. 051 * 052 * <p><code>LoggerFactory</code> is essentially a wrapper around an 053 * {@link ILoggerFactory} instance bound with <code>LoggerFactory</code> at 054 * compile time. 055 * 056 * <p> 057 * Please note that all methods in <code>LoggerFactory</code> are static. 058 * 059 * @author Alexander Dorokhine 060 * @author Robert Elliot 061 * @author Ceki Gülcü 062 * 063 */ 064public final class LoggerFactory { 065 066 static final String CODES_PREFIX = "http://www.slf4j.org/codes.html"; 067 068 static final String NO_PROVIDERS_URL = CODES_PREFIX + "#noProviders"; 069 static final String IGNORED_BINDINGS_URL = CODES_PREFIX + "#ignoredBindings"; 070 071 static final String NO_STATICLOGGERBINDER_URL = CODES_PREFIX + "#StaticLoggerBinder"; 072 static final String MULTIPLE_BINDINGS_URL = CODES_PREFIX + "#multiple_bindings"; 073 static final String NULL_LF_URL = CODES_PREFIX + "#null_LF"; 074 static final String VERSION_MISMATCH = CODES_PREFIX + "#version_mismatch"; 075 static final String SUBSTITUTE_LOGGER_URL = CODES_PREFIX + "#substituteLogger"; 076 static final String LOGGER_NAME_MISMATCH_URL = CODES_PREFIX + "#loggerNameMismatch"; 077 static final String REPLAY_URL = CODES_PREFIX + "#replay"; 078 079 static final String UNSUCCESSFUL_INIT_URL = CODES_PREFIX + "#unsuccessfulInit"; 080 static final String UNSUCCESSFUL_INIT_MSG = "org.slf4j.LoggerFactory in failed state. Original exception was thrown EARLIER. See also " 081 + UNSUCCESSFUL_INIT_URL; 082 083 static final int UNINITIALIZED = 0; 084 static final int ONGOING_INITIALIZATION = 1; 085 static final int FAILED_INITIALIZATION = 2; 086 static final int SUCCESSFUL_INITIALIZATION = 3; 087 static final int NOP_FALLBACK_INITIALIZATION = 4; 088 089 static volatile int INITIALIZATION_STATE = UNINITIALIZED; 090 static final SubstituteServiceProvider SUBST_PROVIDER = new SubstituteServiceProvider(); 091 static final NOPServiceProvider NOP_FALLBACK_FACTORY = new NOPServiceProvider(); 092 093 // Support for detecting mismatched logger names. 094 static final String DETECT_LOGGER_NAME_MISMATCH_PROPERTY = "slf4j.detectLoggerNameMismatch"; 095 static final String JAVA_VENDOR_PROPERTY = "java.vendor.url"; 096 097 static boolean DETECT_LOGGER_NAME_MISMATCH = Util.safeGetBooleanSystemProperty(DETECT_LOGGER_NAME_MISMATCH_PROPERTY); 098 099 static volatile SLF4JServiceProvider PROVIDER; 100 101 private static List<SLF4JServiceProvider> findServiceProviders() { 102 ServiceLoader<SLF4JServiceProvider> serviceLoader = ServiceLoader.load(SLF4JServiceProvider.class); 103 List<SLF4JServiceProvider> providerList = new ArrayList<SLF4JServiceProvider>(); 104 for (SLF4JServiceProvider provider : serviceLoader) { 105 providerList.add(provider); 106 } 107 return providerList; 108 } 109 110 /** 111 * It is LoggerFactory's responsibility to track version changes and manage 112 * the compatibility list. 113 * <p> 114 * <p> 115 * It is assumed that all versions in the 1.6 are mutually compatible. 116 */ 117 static private final String[] API_COMPATIBILITY_LIST = new String[] { "1.8", "1.7" }; 118 119 // private constructor prevents instantiation 120 private LoggerFactory() { 121 } 122 123 /** 124 * Force LoggerFactory to consider itself uninitialized. 125 * <p> 126 * <p> 127 * This method is intended to be called by classes (in the same package) for 128 * testing purposes. This method is internal. It can be modified, renamed or 129 * removed at any time without notice. 130 * <p> 131 * <p> 132 * You are strongly discouraged from calling this method in production code. 133 */ 134 static void reset() { 135 INITIALIZATION_STATE = UNINITIALIZED; 136 } 137 138 private final static void performInitialization() { 139 bind(); 140 if (INITIALIZATION_STATE == SUCCESSFUL_INITIALIZATION) { 141 versionSanityCheck(); 142 } 143 } 144 145 private final static void bind() { 146 try { 147 List<SLF4JServiceProvider> providersList = findServiceProviders(); 148 reportMultipleBindingAmbiguity(providersList); 149 if (providersList != null && !providersList.isEmpty()) { 150 PROVIDER = providersList.get(0); 151 PROVIDER.initialize(); 152 INITIALIZATION_STATE = SUCCESSFUL_INITIALIZATION; 153 reportActualBinding(providersList); 154 fixSubstituteLoggers(); 155 replayEvents(); 156 // release all resources in SUBST_FACTORY 157 SUBST_PROVIDER.getSubstituteLoggerFactory().clear(); 158 } else { 159 INITIALIZATION_STATE = NOP_FALLBACK_INITIALIZATION; 160 Util.report("No SLF4J providers were found."); 161 Util.report("Defaulting to no-operation (NOP) logger implementation"); 162 Util.report("See " + NO_PROVIDERS_URL + " for further details."); 163 164 Set<URL> staticLoggerBinderPathSet = findPossibleStaticLoggerBinderPathSet(); 165 reportIgnoredStaticLoggerBinders(staticLoggerBinderPathSet); 166 } 167 } catch (Exception e) { 168 failedBinding(e); 169 throw new IllegalStateException("Unexpected initialization failure", e); 170 } 171 } 172 173 private static void reportIgnoredStaticLoggerBinders(Set<URL> staticLoggerBinderPathSet) { 174 if (staticLoggerBinderPathSet.isEmpty()) { 175 return; 176 } 177 Util.report("Class path contains SLF4J bindings targeting slf4j-api versions prior to 1.8."); 178 for (URL path : staticLoggerBinderPathSet) { 179 Util.report("Ignoring binding found at [" + path + "]"); 180 } 181 Util.report("See " + IGNORED_BINDINGS_URL + " for an explanation."); 182 183 184 } 185 186 // We need to use the name of the StaticLoggerBinder class, but we can't 187 // reference the class itself. 188 private static String STATIC_LOGGER_BINDER_PATH = "org/slf4j/impl/StaticLoggerBinder.class"; 189 190 static Set<URL> findPossibleStaticLoggerBinderPathSet() { 191 // use Set instead of list in order to deal with bug #138 192 // LinkedHashSet appropriate here because it preserves insertion order 193 // during iteration 194 Set<URL> staticLoggerBinderPathSet = new LinkedHashSet<URL>(); 195 try { 196 ClassLoader loggerFactoryClassLoader = LoggerFactory.class.getClassLoader(); 197 Enumeration<URL> paths; 198 if (loggerFactoryClassLoader == null) { 199 paths = ClassLoader.getSystemResources(STATIC_LOGGER_BINDER_PATH); 200 } else { 201 paths = loggerFactoryClassLoader.getResources(STATIC_LOGGER_BINDER_PATH); 202 } 203 while (paths.hasMoreElements()) { 204 URL path = paths.nextElement(); 205 staticLoggerBinderPathSet.add(path); 206 } 207 } catch (IOException ioe) { 208 Util.report("Error getting resources from path", ioe); 209 } 210 return staticLoggerBinderPathSet; 211 } 212 213 private static void fixSubstituteLoggers() { 214 synchronized (SUBST_PROVIDER) { 215 SUBST_PROVIDER.getSubstituteLoggerFactory().postInitialization(); 216 for (SubstituteLogger substLogger : SUBST_PROVIDER.getSubstituteLoggerFactory().getLoggers()) { 217 Logger logger = getLogger(substLogger.getName()); 218 substLogger.setDelegate(logger); 219 } 220 } 221 222 } 223 224 static void failedBinding(Throwable t) { 225 INITIALIZATION_STATE = FAILED_INITIALIZATION; 226 Util.report("Failed to instantiate SLF4J LoggerFactory", t); 227 } 228 229 private static void replayEvents() { 230 final LinkedBlockingQueue<SubstituteLoggingEvent> queue = SUBST_PROVIDER.getSubstituteLoggerFactory().getEventQueue(); 231 final int queueSize = queue.size(); 232 int count = 0; 233 final int maxDrain = 128; 234 List<SubstituteLoggingEvent> eventList = new ArrayList<SubstituteLoggingEvent>(maxDrain); 235 while (true) { 236 int numDrained = queue.drainTo(eventList, maxDrain); 237 if (numDrained == 0) 238 break; 239 for (SubstituteLoggingEvent event : eventList) { 240 replaySingleEvent(event); 241 if (count++ == 0) 242 emitReplayOrSubstituionWarning(event, queueSize); 243 } 244 eventList.clear(); 245 } 246 } 247 248 private static void emitReplayOrSubstituionWarning(SubstituteLoggingEvent event, int queueSize) { 249 if (event.getLogger().isDelegateEventAware()) { 250 emitReplayWarning(queueSize); 251 } else if (event.getLogger().isDelegateNOP()) { 252 // nothing to do 253 } else { 254 emitSubstitutionWarning(); 255 } 256 } 257 258 private static void replaySingleEvent(SubstituteLoggingEvent event) { 259 if (event == null) 260 return; 261 262 SubstituteLogger substLogger = event.getLogger(); 263 String loggerName = substLogger.getName(); 264 if (substLogger.isDelegateNull()) { 265 throw new IllegalStateException("Delegate logger cannot be null at this state."); 266 } 267 268 if (substLogger.isDelegateNOP()) { 269 // nothing to do 270 } else if (substLogger.isDelegateEventAware()) { 271 substLogger.log(event); 272 } else { 273 Util.report(loggerName); 274 } 275 } 276 277 private static void emitSubstitutionWarning() { 278 Util.report("The following set of substitute loggers may have been accessed"); 279 Util.report("during the initialization phase. Logging calls during this"); 280 Util.report("phase were not honored. However, subsequent logging calls to these"); 281 Util.report("loggers will work as normally expected."); 282 Util.report("See also " + SUBSTITUTE_LOGGER_URL); 283 } 284 285 private static void emitReplayWarning(int eventCount) { 286 Util.report("A number (" + eventCount + ") of logging calls during the initialization phase have been intercepted and are"); 287 Util.report("now being replayed. These are subject to the filtering rules of the underlying logging system."); 288 Util.report("See also " + REPLAY_URL); 289 } 290 291 private final static void versionSanityCheck() { 292 try { 293 String requested = PROVIDER.getRequesteApiVersion(); 294 295 boolean match = false; 296 for (String aAPI_COMPATIBILITY_LIST : API_COMPATIBILITY_LIST) { 297 if (requested.startsWith(aAPI_COMPATIBILITY_LIST)) { 298 match = true; 299 } 300 } 301 if (!match) { 302 Util.report("The requested version " + requested + " by your slf4j binding is not compatible with " 303 + Arrays.asList(API_COMPATIBILITY_LIST).toString()); 304 Util.report("See " + VERSION_MISMATCH + " for further details."); 305 } 306 } catch (java.lang.NoSuchFieldError nsfe) { 307 // given our large user base and SLF4J's commitment to backward 308 // compatibility, we cannot cry here. Only for implementations 309 // which willingly declare a REQUESTED_API_VERSION field do we 310 // emit compatibility warnings. 311 } catch (Throwable e) { 312 // we should never reach here 313 Util.report("Unexpected problem occured during version sanity check", e); 314 } 315 } 316 317 private static boolean isAmbiguousProviderList(List<SLF4JServiceProvider> providerList) { 318 return providerList.size() > 1; 319 } 320 321 /** 322 * Prints a warning message on the console if multiple bindings were found 323 * on the class path. No reporting is done otherwise. 324 * 325 */ 326 private static void reportMultipleBindingAmbiguity(List<SLF4JServiceProvider> providerList) { 327 if (isAmbiguousProviderList(providerList)) { 328 Util.report("Class path contains multiple SLF4J providers."); 329 for (SLF4JServiceProvider provider : providerList) { 330 Util.report("Found provider [" + provider + "]"); 331 } 332 Util.report("See " + MULTIPLE_BINDINGS_URL + " for an explanation."); 333 } 334 } 335 336 private static void reportActualBinding(List<SLF4JServiceProvider> providerList) { 337 // binderPathSet can be null under Android 338 if (!providerList.isEmpty() && isAmbiguousProviderList(providerList)) { 339 Util.report("Actual provider is of type [" + providerList.get(0) + "]"); 340 } 341 } 342 343 /** 344 * Return a logger named according to the name parameter using the 345 * statically bound {@link ILoggerFactory} instance. 346 * 347 * @param name 348 * The name of the logger. 349 * @return logger 350 */ 351 public static Logger getLogger(String name) { 352 ILoggerFactory iLoggerFactory = getILoggerFactory(); 353 return iLoggerFactory.getLogger(name); 354 } 355 356 /** 357 * Return a logger named corresponding to the class passed as parameter, 358 * using the statically bound {@link ILoggerFactory} instance. 359 * 360 * <p> 361 * In case the the <code>clazz</code> parameter differs from the name of the 362 * caller as computed internally by SLF4J, a logger name mismatch warning 363 * will be printed but only if the 364 * <code>slf4j.detectLoggerNameMismatch</code> system property is set to 365 * true. By default, this property is not set and no warnings will be 366 * printed even in case of a logger name mismatch. 367 * 368 * @param clazz 369 * the returned logger will be named after clazz 370 * @return logger 371 * 372 * 373 * @see <a 374 * href="http://www.slf4j.org/codes.html#loggerNameMismatch">Detected 375 * logger name mismatch</a> 376 */ 377 public static Logger getLogger(Class<?> clazz) { 378 Logger logger = getLogger(clazz.getName()); 379 if (DETECT_LOGGER_NAME_MISMATCH) { 380 Class<?> autoComputedCallingClass = Util.getCallingClass(); 381 if (autoComputedCallingClass != null && nonMatchingClasses(clazz, autoComputedCallingClass)) { 382 Util.report(String.format("Detected logger name mismatch. Given name: \"%s\"; computed name: \"%s\".", logger.getName(), 383 autoComputedCallingClass.getName())); 384 Util.report("See " + LOGGER_NAME_MISMATCH_URL + " for an explanation"); 385 } 386 } 387 return logger; 388 } 389 390 private static boolean nonMatchingClasses(Class<?> clazz, Class<?> autoComputedCallingClass) { 391 return !autoComputedCallingClass.isAssignableFrom(clazz); 392 } 393 394 /** 395 * Return the {@link ILoggerFactory} instance in use. 396 * <p> 397 * <p> 398 * ILoggerFactory instance is bound with this class at compile time. 399 * 400 * @return the ILoggerFactory instance in use 401 */ 402 public static ILoggerFactory getILoggerFactory() { 403 return getProvider().getLoggerFactory(); 404 } 405 406 /** 407 * Return the {@link SLF4JServiceProvider} in use. 408 409 * @return provider in use 410 * @since 1.8.0 411 */ 412 static SLF4JServiceProvider getProvider() { 413 if (INITIALIZATION_STATE == UNINITIALIZED) { 414 synchronized (LoggerFactory.class) { 415 if (INITIALIZATION_STATE == UNINITIALIZED) { 416 INITIALIZATION_STATE = ONGOING_INITIALIZATION; 417 performInitialization(); 418 } 419 } 420 } 421 switch (INITIALIZATION_STATE) { 422 case SUCCESSFUL_INITIALIZATION: 423 return PROVIDER; 424 case NOP_FALLBACK_INITIALIZATION: 425 return NOP_FALLBACK_FACTORY; 426 case FAILED_INITIALIZATION: 427 throw new IllegalStateException(UNSUCCESSFUL_INIT_MSG); 428 case ONGOING_INITIALIZATION: 429 // support re-entrant behavior. 430 // See also http://jira.qos.ch/browse/SLF4J-97 431 return SUBST_PROVIDER; 432 } 433 throw new IllegalStateException("Unreachable code"); 434 } 435}